- Email: [email protected]
Eastern association of electroencephalographers
Electroencephalography and Clinical Neurophysiology, 1975, 38:105-111 c Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
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PROCEEDINGS
E A S T E R N A S S O C I A T I O N OF E L E C T R O E N C E P H A L O G R A P H E R S Jefferso,wille, Vermont, Feb. 28-March 2, 1974
Secretary-Treasurer: HUNTINGTON
MAVOR
Veterans Administration Hospital, 500 Foothill Blvd., Salt Lake City, Utah 84113 (U.S.A.)
1. Variability in form and distribution of the vertex sharp wave of sleep. - - S. Devi and E. Goldensohn (New York City, N.Y. ).
The normal variability in spatial distribution and voltage symmetry of vertex sharp waves and K-complexes during sleep have not been previously studied although their basic form and distribution have been described in detail. Variations of amplitude of single (not averaged) auditory evoked vertex potentials have been ascribed to the interaction of a random process with parameters such as intensity and interstimulus intervals. Recordings in early sleep were obtained from normal subjects. A common noncephalic electrode consisting of six equidistant interconnected electrodes on the neck was used as a reference for a full set of electrodes placed according to the International System. The initial surface positive phase and the ascending and descending limbs of the negative phase of the vertex sharp waves were measured by hand. Mild asymmetry is very common, and marked asymmetry not uncommon, particularly in the young. Vertex sharp waves often sharply limited to the vertex and centroparietal areas are at other times widely distributed. Variations in distribution did not appear to be related to the state of sleep. The negative phase of the vertex wave is usually predominant but on many occasions it is the positive phase. Acceptable limits of normal variability in clinical records are defined. 2. Hypersonmia with rapid eye movements: a new syndrome. - - R. Broughton and A. Guzman (Ottawa, Ont., Canada ).
An 18-year-old male had a 5 week history of excessive sleep, usually 16-20 h/day, and severe ocular discomfort. There were no irresistible sleep attacks, daytime sleep coming on progressively. There was no history of cataplexy, sleep paralysis or vivid hypnagogic hallucinations, nor of drug intake, head trauma or other evident etiologies. The condition was progressive, not episodic. Three weeks o.n methylphenidate had no effect. Apart from slight euphoria, poor concentration, darkening around the eyes and hypotonia, physical examination was normal, as were PBI, CSF, EEG, brain scan and angiograms. Polygraphic EEG studies showed that daytime sleep (up to I0 h) consisted of a 9 c/sec alpha rhythm associated wit REM bursts, occasional cardio-respiratory irregularity and some maintained submental EMG tone. It was therefore
called "alpha-REM sleep". Nocturnal sleep was preceded by 1-2 h of this ct-REM sleep, but otherwise was fairly normal, showing typical NREM stages 1--4 and cyclic REM sleep lacking an alpha rhythm and submental EMG tone. Occasional episodes of nocturnal ct-REM sleep were observed, including direct transitions without arousal into and out of REM sleep. Imipramine rapidly produced improvement. Abnormal (apparently dissociated) REM sleep can therefore present clinically as hypersomnia resistant to stimulants but responding to antidepressants. 3. Polygraphic investigation of a case of Pickwickinn syndrome. - - L. F. Quesney, P. Gloor, M. Kryger and P. Jimenez (Montreal, Queb., Canada). A massively obese male complaining of somnolence during the daytime, periodic breathing and disturbance of nocturnal sleep, was studied with polygraphic recordings which included: EEG, EOG, respirogram and ECG. It was shown that during drowsiness or sleep which rarely lead to a spindle stage, there was periodic apnea caused by occlusion of the upper airway, which lead to recurrent periodic arousal and bradyarrhythmia probably caused by vagal stimulation. The bradyarrhythmia was blocked by intravenous administration of atropine. PaCO 2 and ventilatory response to carbon dioxide were normal. Less frequently episodes of central apnea were also recorded during the night. It was concluded that daytime somnolence was a consequence of sleep deprivation. This was supported by the effect of tracheostomy, after which the disturbance of nocturnal sleep, daytime somnolence and bradyarrhythmia were no longer present. This observation indicates that besides interfering with respiratory function and sleep-wakefulness regulation, this variety of the Pickwickian syndrome may also seriously compromise cardiac function. 4. Twenty-four hour 4-channel cassette tape recorder for monitoring the EEG. - - J. R. Ives and J. F. Woods (Montreal, Queb., Canada ).
A major limitation of EEG recording is restriction placed on the patient's mobility. Recordings can be done for only short periods in a laboratory setting. For most purposes this is adequate. For some patients this method provides inadequate information and a continuous recording of the EEG in their normal environment would be desirable. We have recently
106 tested a small cassette tape recorder which can record 4 channels of EEG continuously for 24 h. The cassette and batteries can easily be changed daily by the patient so that recordings may continue uninterrupted for several days. The recording can be done on out-patients because the electrode and wires can easily be hidden from view in the hair. The cassette can be conveniently worn over the shoulder or on the belt. The cassette is played back on a separate unit at 60 times the speed of recording. Each 24 h cassette recording is thus written out in 24 min. Intermittent abnormalities such as bursts of epileptic activity can be easily recognized. Recordings have been done on patients with absence epileptic seizures, blackouts of unknown origin and narcolepsy. The results will be discussed. 5. Computer recognition of generalized spike-wave paroxysms. - - B. L. Ehrenberg and J. K. Peary (Betbesda, Md. ). Twelve 12 h daytime telemetered EEGs (4-channel) were obtained from 8 patients and were recorded on both magnetic tape and paper. The EEGs were read independently by 3 electroencephalographers, and the 12 h tapes were played back at high speed i1.5 h per record) through a PDP-12-minicomputer. The computer was programmed to identify only generalized spike-wave paroxysms, their location on the record and their duration. A consensus was derived from the readings by selecting only those bursts identified as generalized S-W by all 3 readers. The computer's count agreed with the consensus on 85 o~, of the paroxysms. False-positive computer recognitions (high-voltage transients not recognized by any of the readers) occurred in 15 (1~o) of 1.462 total discharges. The computer's accuracy improved to 9 2 ~ of the consensus for the waking EEG when portions containing sleep were discounted. Likewise. 10 of the 15 false-positives also occurred during sleep sections, contributing to the majority of over-recognitions by the computer. The computer results were then pooled with those from the 3 readers to permit an inter-reader comparison of variability (with the computer treated as one of the readers). The computer was comparable to any of the h u m a n readers and tended to be closer to the most conservative reader than to the most liberal. 6. Computer analysis of EEG elements of significance for elhakld interpretation. - - R. N. Harner and K. Ostergren (Philadelphia, Pa. ). The h u m a n interpretative process has been under-utilized as a model for the design of computer programs to aid in E E G interpretation. Both analysis and synthesis are used in the successive steps of detection, description, comparison and correlation used consciously or subconsciously by the electroencephalographer. Sequential analysis ~Amer. J. EEG Technol,, 1973, 13: 139) treats the E E G as a population of individual half waves in sequence, in real time, from a minim u m of 8 head regions. Visual presentation ofthesewaves as a scattergram for each channel, according to the amplitude and wave length of each half wave, provide a useful s u m m a r y
SOCIETY PROCEEDINGS of the variability and distribution of wave forms, including the detection of infrequent or paroxysmal elements. A method has now been developed to use these data for realtime computation of the number, frequency and amplitude of waves, per cent time occurrence, and estimates of variability for up to 8 separate elements in each of 8 channels of EEG over periods ranging from 10 sec to 10 rain. A printed s u m m a r y is immediately available for quantitative comparison wJ_th those EEG elements detected visually by the electroencephalographer. More important, these numerical data can serve as quantitative input to programs already available for evaluation of EEG elements according to agerelated criteria of normality and abnormality. 7. Effects of antipsychotic medication exposure on EEG spectral power in chronic schizophrenics. - - K. Lifshitz and J. Gradijan (Orangeburg, N.Y. ). The time course of antipsychotic medication effects on the EEG is important in ascribing E E G findings to pathology or medication in schizophrenia. Studied were 10 male chronic schizophrenic patients on medication longer than 2 m o n t h s (median 16 weeks); 10 withdrawn from medication longer than 6 weeks (median 12 weeks1:10 withdrawn more than I week but tess than I m o n t h Imedian 19 days), the latter group respresentative of patients commonly used in studies. In each subject 150 2.8 sec segments of EEG. randomly spaced at intervals greater than 12 sec, were collected. screened for artifact, and digitized on-line. The power density spectrum was calculated for each E E G segment. Patients on medication showed less delta-band (0.35-3.8 c/see) power than either of the groups withdrawn from medication ( P < 0 . 0 0 2 for C2 and less significantly for O1, 2-tailed M a n n - W h i t n e y U test). The patients in intermediary withdrawal showed the highest delta power. Overall spectra power 10.35-54 c/secl reflected the same findings but at lesser significance. Since delta power may be considered an indicator of arousal, and since intrasubject delta power variance was similar for all three groups of patients and smaller than that of normal control subjects, a narrower range of "arousal" in the patients may be indicated. 8. The convul~nt effects of bicucuilin compared with metrazol. - - E. Rodia, H. Kitano, S. Wasson and M. Rodin (Detroit, Mich. ). The convulsant properties of bicucullin have recently attracted attention because they are regarded to result from inhibition of G A B A . The c o m p o u n d was therefore compared with metrazol as to its clinical and E E G effects. Chronically implanted cats were studied with each animal receiving both drugs. Videotape recordings showed that the clinical effects were exceedingly similar and could not be distinguished o n a blind basis. The E E G s were likewise very similar. Pre-ictal myoclonic jerking was associated in either instance by diffuse spikewave discharges and the seizure itself appeared to arise in cortex and thalamus. Multiple unit recordings showed, however, that the earliest onset of seizure activity occurred mostly in the pons. This was likewise c o m m o n to both drugs. Limbic system structures--e.g., ventral and dorsal bippo-
EASTERN EEG SOCIETY campus, amygdala--participated in the seizure activity consistently later than the other sampled brain structures and showed excellent correlations between the EEG and multiple unit records. It is concluded that bicucullin exerts its primary convulsant effect, similar to metrazol, on brainstem structures with secondary involvement of the limbic system. The term "primary generalized seizures" may therefore result in misleading conceptualizations. 9. EEG and behavioral effects of naltrexone in man. - J. Volavka, P. Gaztanaga, R. B. Resnick and A. M. Freedman (New York, N.Y. ).
Naltrexone is a new narcotic antagonist; its effectiveness in blocking heroin effects on mood and pupil size have been demonstrated. The purpose of the present study was to determine whether naltrexone p e r se has any effects on the EEG, and whether it antagonizes the EEG effects o f heroin. Visual evaluation of the pre- and post-naltrexone recordings in 13 patients showed no EEG changes attributable to this drug. The dose ranged between 3 and 160 mg daily, given for 1-17 days. The opiate antagonism of naltrexone was tested in 8 patients. Each patient was given 25 mg of heroin i.v. on two occasions: first without premedication, second, after premedication with naltrexone. EEG was recorded before and after each injection. A continuous auditory detection task was administered concurrently with the EEG. The heroin effects on EEG and on task performance were antagonized by naltrexone. The conclusion is that naltrexone causes no EEG changes p e r se but suppresses the effects of heroin on the EEG. 10. Persistent EEG changes in primates and humans fol|owing organophosphate (Sarin) exposure. - - F. H. Duffy and J. L. Burchfiel (Boston, Mass. ).
EEGs were recorded from 79 industrial workers with a documented history of exposure to Sarin and compared with recordings from a matched group of 38 controls. Sarin is an organophosphate with anticholinesterase action and has been used as an insecticide and "nerve agent". It is very similar structurally but more potent than malathion and parathion. Spectral analysis was performed on the EEGs from several leads and in several states. Comparison was made by T-test, Mann-Whitney U test, and chi-square analysis. The exposure population exhibited significant changes in many frequency bands. Beta and delta were increased in the frontal region, fast theta was increased posteriorly, and alpha was reduced in the frontal and temporal regions. As all exposed workers were free of Sarin exposure for at least one year before study, the possibility of long term changes from organophosphate exposure is raised. A parallel study on rhesus monkeys demonstrated similar changes. 11. EEG, brain scan, and angiography in the evaluation of subdural hematoma: a comparative study. - - R. Jaffe and J. Lusins (New York, N.Y. ). This study presents evidence based on serial brain scans. EEGs, and angiogram studies performed on 9 unoperated subdural hematoma patients followed over a period of 3-5
107 years. The results of this study indicate that the EEG is a more reliable correlate of clinical dysfunction in the presence of a subdural collection than is the radiographic appearance of the lesion. The present study shows, in addition, that radionuclide scanning may be a reliable indicator of the physical presence of the subdural .collections as well as a practical method for long term follow-up of the resolution of the hematoma. However, the scan is no more reliable than the angiogram in indicating whether the lesion is likely to be causing clinical evidence of cerebral dysfunction. If criteria related to the degree of clinical dysfunction are to be used in determining whether the patient is to be operated, it is apparent that the EEG is the laboratory method which is, more significant in the management of those cases once the diagnosis has been confirmed. 12. Muscular stress tests during simultaneous E O G and EEG recordings used to differentiate some types of cerebral palsy, and to help determine hubilitative training procedures. - - C. Kris (Cambridge, Mass. ).
A review of the EEG findings in cerebral palsy shows little correlation of EEG abnormalities with severity of dysfunction or potential benefit obtainable through habilitative training. The use of combined EOG and EEG during resting and active states has led to the development of three simple tests that have been found helpful in differentiating between types and levels o f severity of CP impairment, and between chronic CP and developmental incoordination. Several subject populations, following standard E O G EEG, were subjected to tests involving muscular stress, i.e., clenching of fingers and toes alternately on each side, and maintaning eye position at peripheral extremes. Chronic spastic and ataxic cerebrally palsied persons showed continuous irritability and high frequency muscle-artifact changes in the EEG, while a distonic athetoid CP youth presented long trains of slow-wave activity. In contrast, several children diagnosed as mildly cerebrally palsied showed neither of the above effects, and hyperkinetic incoordinated children showed intermittent high frequency and slow-wave discharges. The above electrodiagnostic monitoring methods were used to measure the intensity and duration of the stress tests, and to evaluate habilitative benefit and fatigue factors resulting from successive training sessions. 13. The early components of the auditory evoked response: a reference study. - - L. J. Streletz and L. Kutz (Philadelphia, Pa. and Wilmington, Del. ).
The early components (less than 10 msec peak latency) of the human scalp recorded auditory evoked response have been studied in 3 normal adults. Clicks o f 0.5 msec duration and 70 dB SL were delivered binaurally at a rate o f 10/see. Recording electrodes were attached widely over the scalp. Nose, ear, balanced noncephalic reference and bipolar recordings were obtained. In all recordings the first 20 msec following stimulus onset were analyzed and 1024 responses were summated. The frequency response of the amplifiers was linear between 1 and 10,000 c/see. Level of consciousness
108 was electroencephalographically monitored. The sharply contoured 6 msec positive wave complex described by Jewett et aL {1971) was recorded and found to be present widely over the scalp with its potential maximum at the vertex. Later components are also described. Comparison of reference systems reveals that some of these arise from the reference recording electrodes. Others appear to arise in the cerebrum. These findings suggest that the choice of various reference recording sites (ear. nose or balanced noncephalic) can aid in the interpretauon of different wave forms of the early components of the scalp recorded auditory evoked response.
14. Five year follow-up of geriatric EEGs. H . F . Muller. B. Grad and F. Engelsmann (Montreal, Queb.. Canada ). This study relates EEG and clinical-psychological variables obtained in several groups of geropsychiatric patients and healthy volunteers matched for age and sex (3", Geront., 1974. 29: 28) to their survival and health 5 years after the original assessment. For 180 of the original 210 subjects Ior 86~o) the necessary follow-up information has been obtained. The results demonstrate an intense statistical relationship between the two sets of data. and thus imply a predictive power for the EEG and psychological data which were utilized {counts of slow and fast EEG frequencies and assessments of motor performance and memory were the most useful ones}. Although age was significantly correlated with the chances of survival, statistical elimination of the age factor did not noticeably alter the results. The results are noteworthy in view of the common difficulties in the differential diagnosis of these subjects, and of the implications for treatment, for instance with stimulant, antidepressive or antipsychotic medications. This implies, of course, that acute disturbance of brain function and localized lesions have been ruled out.
15. EEG t'mdings and evoked responses in congenital defects of the corpus eallosum. G. Erba. Y. M. Matsumiya, N. Alvarez and C. T. Lombroso (Boston. Mass. ). Agenesis of the corpus cattosum has been reported as an accidental autopsy finding in adult subjects with no apparent neurological deficit during life. This is in contrast w~th the now well recognized perceptual and functional impairments m patients who underwent surgical split of the corpus callosum. Infants born with multiple congenital midline defects often involving the major interhemispheric commissure usually show severe psychomotor retardation: this may be related to other associated CNS anomalies rather than to the commissural defect although detection of callosal agenes~s adds a new dimension to the overall clinical evaluation in terms of prognosis and possible treatment. So far. a definite diagnosis has been achieved by PEG. Recently we have reported criteria by which the same diagnosis can be established by two-dimensional echoencephalography {B-scan). This observation prompted a review of 12 cases of proven congenital dysgenesis of the corpus callosum to assess the diagnostic value of other non-invasive procedures such as EEG and evoked potentials. Whereas the EEG findings vary a great deal from grossly abnormal tracings to non-diagnostic ones. somatosensory, visual, and auditory evoked responds
SOCIETY PROCEEDINGS appeared to show consistently extreme distortion of the late long latency components, The significance of the neurophysiological correlates m relauon to the extem and complexity of the multiple structural defects and to the syndrome of hemispheral disconnection will be discussed.
16. A characteristic EEG finding in newborns with maple syrup urine disease (branched-chain ketoaciduria ). - A. G. Trottier. K. Metrakos. G. Geoffroy and F. Andermann (Montreal, Queb.. Canada). EEG tracings of 4 patients with classical map!e syrup urmc disease show a characteristic pattern in the sec(~nd and third weeks of life: it consists of bursts of rhythmic. 7 q c, sec spindle-like sharp waves, of moderate amplitude, over the central regaons, which could be termed a "'comb-like rh3 thin". Such discharges are otherwise most unusual in this age group. There are also other severe abnormalities: multiple, shifting spikes and sharp waves, modified suppressionbursts, and excessive delta activity. The infants are lethargtc and it is usually impossible to state whether they are asleep or awake, Diet therapy was mnmted m the second week of lit~:, and the "'comb-like rhythm" disappeared by 5 or 6 weeks of age. Normal tracings emerged in 2 patients, and residual epileptiform discharges persisted in a third: the latter had a normal EEG by age 9 months. Although probably not pathognomonic of maple syrup urine disease, this "comb-likepattern should lead one to suspect the diagnosis when observed m a neonate presenting with lethargy and seizures. ]n patients diagnosed after the neonatal period or tn untreated surwving patients the EEG shows diffuse, nonspecific abnormalit3 with or without epileptogenic discharge.
17. ]'he specificity of eye-movement patterns for reading. J. S. Barlow (Boston. Mass. ). Attempted smooth eye movements over a featureless whtte visual field yield an actual pattern of eye movements superficially resembling that during reading, t.e.. a sequence of saccadic [quick} movements alternating with brief fixations. The patterns of eye movement under the two condition,s were therefore compared quantitatively by computing intersaccadic time-interval histograms on recordings of eye movements monitored by the infrared technique in ~ small group of normal subjects. In contrast to the pattern for the histograms for reading, which showed a more-or-less well-defined peak at 200-300 msec superimposed on a broad base (Abstracts. Third Imernational Biophysics Congress. 1969: 114|. the histograms for attempted smooth movements were relatively flat over the entire time base analyzed t512 msec). On the other hand. the histograms for "'reading" upside-down printed material {with almost no attendant comprehension) were essentially indistinguishable from those for the same subject for normal reading. These findings suggest that the presence of a finely structured visual field ~s required for the pattern of eye movements characteristic of reading to become manifest. but that the latter may be relatively stereotyped for a gwen
EASTERN EEG SOCIETY subject, irrespective of the actual intelligibility (i.e., specific information processing) of the material. 18. Suheortical factors in experimental Jacksonian seizures. - W. F. Caveness and H. Ueno (Bethesda, Md. ). Cyclic paroxysmal activity occurs following injection of penicillin in the cerebral cortex, right face-hand area, of the adult Macaca mulatta. With each episode there is an increase in extent and severity of electrographic and clinical expression, followed by an abrupt cessation of abnormal activity. To provide a concurrent appraisal of cortical and subcortical neuronal activity at selected stages in the events described, the C14 antipyrine regional Cerebral Blood Flow method of Sokoloff was used. Results: During a generalized seizure that had progressed from focal paroxysmal activity to bilateral, high amplitude, 3-4 sec, EEG spikes accompanied by synchronous movements of the face and all four limbs, there was an overall increase in cerebral blood flow with laterality only in right putamen and substantia nigra. At the cessation of a similar generalized seizure there was unilateral increase in blood flow in right motor cortex, globus pallidus, substantia nigra, thalamic VPL, VPm, and left cerebellar cortex. Suggested is a deactivating influence of the cerebellum and thalamic nuclei, with remaining activating influence in the circumscribed right motor cortex. 19. Role of the intrncarotid amytal-metrazol EEG test in the surgical treatment of patients with complex seizure problems. - - T. Rasmussen, P. Glonr, A. Altuzarra and H. Garretson (Montreal, Queb., Canada). The intracarotid amytal-metrazol test was devised to help identify those seizure patients with bilateral epileptfform abnormality in the EEG whose seizures were actually arising in one hemisphere and were thus potential candidates for surgical therapy by unilateral cortical excision. Two groups of patients were involved, those with bilaterally synchronous 2-3.5/sec spike and slow wave abnormality and those with temporal lobe epilepsy and bilateral, independent temporal lobe spiking. The test was carried out in 94 patients in the 10 year period 1963-72, with cortical excision being subsequently carried out in 30. The role of the test in selecting patients for operation, and its predictive value as to a subsequent satisfactory reduction in seizure tendency is analyzed. The importance of accurate information as to the symmetry of the cerebral arterial supply in interpreting the test results is emphasized. 20. Chronic depth electrode recording in patients with bitemporal epilepsy. - - A. Olivier, P. Gloor, J. Ives, C. Thompson, F. Andermann, J. Woods and G. Bertrand (Montreal, Queb., Canada). In the past, patients with EEG signs of bilateral temporal lobe epilepsy were generally rejected as surgical candidates for temporal lobectomy. Chronic depth stereotaxic recording has changed this concept. Seven patients suffering from intractable cerebral sei-
109 zures, and in whom repeated EEGs had shown bitemporal epileptic activity, were submitted to this procedure. Multiple contact stainless-steel wire electrodes were implanted stereotaxically and bilaterally in temporal cortex, amygdala, hippocampus and parahippocampal gyrus for a period of time averaging 3 weeks. Prolonged recordings were carried out with standard 16-channel EEG machines, or with an 8-channel or 16-channel EEG telemetry system. A computer program was used to recognize and store ictal epileptiform activity recorded by telemetry. In all these patients, the study confirmed the existence of interictal epileptic activity bilaterally, with clear predominance of the ictal events on one side. All patients were later submitted to standard temporal lobectomy. Repeated onset of spontaneous seizures localized in one temporal lobe represents the principal criterion upon which the decision to operate is based. There were no complications. 21. Predicting the plasma diphenylhydantoin level: effects of age, sex, pregnancy and protein binding. - - A. L. Sherwin and J. S. Loynd (Montreal, Queb., Canada ). While plasma levels of diphenylhydantoin (DPH) exhibit a general relationship to dosage in individual patients, studies of larger groups show a high degree of variability. The ability to predict the approximate plasma levels of patients on stable therapy is essential to detect non-compliance, drug interaction or altered drug disposition. The dose-~plasma level relationship of DPH was determined in 700 patients divided into carefully defined groups. Equivalent dosages of DPH were compared in each group. Higher plasma DPH levels were observed in adult males when compared with children, while the levels in females were similar to children. Females over 65 years exhibited a marked increase in plasma levels which may be of clinical significance. Consistent alterations in plasma DPH levels were not observed during pregnancy. There was no difference in the response of overweight patients nor in the mean plasma DPH levels of patients receiving concurrent phenobarbital or primidone. Impaired plasma protein binding resulted in a marked decrease in the dose-plasma level response. A highly significant (P< 0.001) linear dose (per m2}-plasma level relationship was observed in a group of adult males receiving total DPH as a single morning dose. If the appropriate parameters are considered, the expected plasma DPH level can be predicted. 22. The relationship of seizure activity to anticonvulsant blood concentrations: 24 h sleep-waking studies. - - J. H. French, A. J. Rowan, C. E. Pippenger and P. A. McGregor (New Haven, Conn. ). The feasibility of effecting correlative studies of clinical seizures, continuous 24 h EEG recordings, and concomitant frequent serum anticonvulsant determinations in the instance of major motor attacks has been demonstrated (Rowan et al., Electroenceph. elin. Neurophysiol., 1973, 34: 745 and 1974, 37: 194). Longitudinal application of this study technique to 2 patients with poorly controlled major motor seizures suggests that objective documentation of the
110 efficacy of a specific anticonvulsant drug is practicable. Also. the results indicate an inverse relationship between the serum concentration of an effective anticonvulsant drug and paroxysmal activity at specific points in time. Application of the derived information to the therapeutic regimen o f these patients has resulted in marked improvement of seizure control. This improvement has persisted for 11 and 4 m o n t h periods of follow-up.
23. The interaction of genetic and environmental factors in patients operated for focal epilepsy. E. Andermonn, L. Dansky and J. D. Metrakos (Montreal, Queb., Canada ). Both genetic and environmental factors have been shown to play a significant role in the etiology of focal epilepsy, which appears to be compatible with multifactoriat inheritance. In a study of 60 patients treated surgically for focal epilepsy at the Montreal Neurological Hospital. the various exogenous etiological factors were analyzed, seizure histories obtained on 377 near relatives, and EEGs on 322 relatives. When the interactions of genetic and environmental factors in these probands were studied, significant correlations were found for 9 of 11 exogenous factors with respect to history of seizures, epilepsy, and/or specific EEG abnormalities in relatives. A history of seizures was least frequent in relatives of patients with definite exogenous etiological factors, postnatal trauma, and definite pathological diagnosis. These findings are m agreement with prior hypothesis. On the other hand, relatives of patients with a definite infectious etiology had the highest frequency of seizures. Spike-and-wave EEG abnormalities were significantly increased in relatives of patients who had only temporal lobe removals, and in relatives of patients with postnatal infection as an etiological factor. Although some of these findings are in contrast with prior hypothesis, they are in good agreement with newer concepts regarding the pathogenesis o f focal epilepsy proposed by Ounsted and Falconer.
24. Computed unit-EEG correlations and laminar profiles of barbiturate spindle EEGs. G . J . BaH and P. Gioor (Montreal, Queb., Canada ). In an effort to understand the basis of EEG of the barbiturate spindle type, methods of recording unit activity with concurrent EEG activity and methods of recording EEG at various depths intracortically of barbiturate anesthetized cats are presented together with techniques of analysis of the recorded data by the computer. A process of averaging the EEG during unit acttvity showed a high correlation of the unit with the positive phase of a biphasic surface-positive-negative average, the duration of which was within the range of the dominant frequency of the EEG. Histograms of unit activity associated with selected. averaged surface spindle waves showed peaks o f unit activity supporting the results obtained in unit-EEG analysis. A clear indication of the depth, in the cortex, at which the E E G inverted, was portrayed by averaging selected surface spindle waves and the accompanying EEG at various depths within the cortex. Levels of inversion of the E E G were at 1000 p m
SOCIETY PROCEEDINGS depth in the cortex. Conclusions were made that the spindle EEG was a statistical product of dipoles created by synaptic input, at the 1000.urn level, to the s o m a or proximal dendrites of pyramidal cells whose apical dendritesextended to the cortical surface.
25. What function do glial cells have in epileptogenesis? W. J. Adelman Jr. ondW. F. Caveaem (Bethesda, Md. ). Repetitively firing neurons release potassium tons which may accumulate in perineuronal spaces. Green (Physiol. Rev.. 44: 561) and Fertziger and Ranck (Exp. Neurol.. 26: 571 ) suggest that potassium ion accumulation contributes to epileptogenesis. Pollen and Trachtenberg (Science. 167: 1252) suggest that: ( 1) glial cells are potassium ion permeable and act as potassium buffers: and {2) that glia in scars lose buffering because of increased membrane resistance. Glotzner {Brain Res.. 1973, 55: 159) showed that: (1) gliat cell membrane resistance in epileptogenic foci decreases from 600 ~ c m 2 to 300 f~cm 2, and that (2) glial cell volume mcreases with no reduction in glial cell numbers. We can calculate the effect o f these changes on total tissue resistance using the Maxwell equation (Cole et aL. Exp. Neurol.. 24: 459). A decrease in intergliat space (resulting from increased glial celt volume) would increase tissue resistance despite observed cell m e m b r a n e resistance changes. This suggests that the major ion diffusional path across brain tissues is the clefts between brain cells. We propose an alternative to the PollenTrachtenberg hypothesis: (1) Perineuronal potassium ion concentration is buffered more by diffusion through spaces between glia than by uptake by glia, (2) Gliosis decreases space between glia, reduces potassium diffusion, and increases perineuronal p o t a s s i u m ion concentration leading to abnormal neuronal excitability.
26. Neocortical-amygdaloid relations in the cat. - - W. M. Burnham, S. Prelevic and P. Gloor (Montreal, Queb.. Canada ). Extracellular unil recording was done in the baso-lateral area of the amygdala in barbiturate anesthetized cats during electrical stimulation o f the ipsilateral neocortex. Data were stored on magnetic tape, poststimutus time histograms being later computed and compared to the averaged field potentials. Of 278 amygdaloid units recorded and analyzed, well over half responded to neocorticat stimulation. Both excitatory and inhibitory responses were seen, the most c o m m o n response pattern being excitation with a latency of about 10 msec followed by inhibition which lasted 100 msec or even longer depending on the intensity of neocortical stimulation. In agreement with previous neuroanatomical studies, the neocortical areas found to be most effective for driving amygdaloid units were the post-sylvian and post-ectosylvian gyri (homologues of the temporat-dnsular cortex in primates). When two or more cortical inputs were seen to influence the same amygdaloid unit. inhibitory interactions could generally be demonstrated. These findings add further support to recent conceptualizations of the amygdala as an important link between the
EASTERN EEG SOCIETY sensory analyzers of the neocortex and the fundamental motivational mechanisms of the hypothalamus. 27. Power spectral analysis of telemetered EEG during behavioral aberrations and prolonged reaction time in patients with schizophrenia and other severe psychiatric disorders. - - J. R. Stevens (Portland, Ore.). In previous studies of power spectral characteristics of the EEG of epileptic cat and man, a "'ramp" pattern consisting of monotonic decline in power from low to high frequencies was calculated from spike-free scalp or dural recordings coincident with subcortical spike activity (Stevens et al., Science, 1972, 176: 1346) and from spike-free epochs of scalp EEG from patients with focal and generalized epilepsy during a reaction-time task preceding prolonged latencies or
111 erroneous response. In contrast, normal control subjects display slower frequencies consistent with diminished arousal prior to long latency response. Utilizing this technique in the study of hospitalized psychotic patients in the search for EEG changes coincident with delayed response and psychomotor blocking, a different spectral pattern emerged in half the schizophrenic patients studied to date. These individuals display a "noise" spectrum, i.e., loss of central frequency tendency and dispersion of power relatively evenly over the entire EEG frequency band (1-30 c/sec) prior to delayed, erroneous or non-response trials. In a second study, employing prolonged recording of telemetered EEG with tagging of spontaneous behavioral aberrations, power spectra plotted in the compressed spectral array format of Bickford and Fleming display similar "noise" patterns during catatonic episodes.
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PROCEEDINGS
E A S T E R N A S S O C I A T I O N OF E L E C T R O E N C E P H A L O G R A P H E R S Jefferso,wille, Vermont, Feb. 28-March 2, 1974
Secretary-Treasurer: HUNTINGTON
MAVOR
Veterans Administration Hospital, 500 Foothill Blvd., Salt Lake City, Utah 84113 (U.S.A.)
1. Variability in form and distribution of the vertex sharp wave of sleep. - - S. Devi and E. Goldensohn (New York City, N.Y. ).
The normal variability in spatial distribution and voltage symmetry of vertex sharp waves and K-complexes during sleep have not been previously studied although their basic form and distribution have been described in detail. Variations of amplitude of single (not averaged) auditory evoked vertex potentials have been ascribed to the interaction of a random process with parameters such as intensity and interstimulus intervals. Recordings in early sleep were obtained from normal subjects. A common noncephalic electrode consisting of six equidistant interconnected electrodes on the neck was used as a reference for a full set of electrodes placed according to the International System. The initial surface positive phase and the ascending and descending limbs of the negative phase of the vertex sharp waves were measured by hand. Mild asymmetry is very common, and marked asymmetry not uncommon, particularly in the young. Vertex sharp waves often sharply limited to the vertex and centroparietal areas are at other times widely distributed. Variations in distribution did not appear to be related to the state of sleep. The negative phase of the vertex wave is usually predominant but on many occasions it is the positive phase. Acceptable limits of normal variability in clinical records are defined. 2. Hypersonmia with rapid eye movements: a new syndrome. - - R. Broughton and A. Guzman (Ottawa, Ont., Canada ).
An 18-year-old male had a 5 week history of excessive sleep, usually 16-20 h/day, and severe ocular discomfort. There were no irresistible sleep attacks, daytime sleep coming on progressively. There was no history of cataplexy, sleep paralysis or vivid hypnagogic hallucinations, nor of drug intake, head trauma or other evident etiologies. The condition was progressive, not episodic. Three weeks o.n methylphenidate had no effect. Apart from slight euphoria, poor concentration, darkening around the eyes and hypotonia, physical examination was normal, as were PBI, CSF, EEG, brain scan and angiograms. Polygraphic EEG studies showed that daytime sleep (up to I0 h) consisted of a 9 c/sec alpha rhythm associated wit REM bursts, occasional cardio-respiratory irregularity and some maintained submental EMG tone. It was therefore
called "alpha-REM sleep". Nocturnal sleep was preceded by 1-2 h of this ct-REM sleep, but otherwise was fairly normal, showing typical NREM stages 1--4 and cyclic REM sleep lacking an alpha rhythm and submental EMG tone. Occasional episodes of nocturnal ct-REM sleep were observed, including direct transitions without arousal into and out of REM sleep. Imipramine rapidly produced improvement. Abnormal (apparently dissociated) REM sleep can therefore present clinically as hypersomnia resistant to stimulants but responding to antidepressants. 3. Polygraphic investigation of a case of Pickwickinn syndrome. - - L. F. Quesney, P. Gloor, M. Kryger and P. Jimenez (Montreal, Queb., Canada). A massively obese male complaining of somnolence during the daytime, periodic breathing and disturbance of nocturnal sleep, was studied with polygraphic recordings which included: EEG, EOG, respirogram and ECG. It was shown that during drowsiness or sleep which rarely lead to a spindle stage, there was periodic apnea caused by occlusion of the upper airway, which lead to recurrent periodic arousal and bradyarrhythmia probably caused by vagal stimulation. The bradyarrhythmia was blocked by intravenous administration of atropine. PaCO 2 and ventilatory response to carbon dioxide were normal. Less frequently episodes of central apnea were also recorded during the night. It was concluded that daytime somnolence was a consequence of sleep deprivation. This was supported by the effect of tracheostomy, after which the disturbance of nocturnal sleep, daytime somnolence and bradyarrhythmia were no longer present. This observation indicates that besides interfering with respiratory function and sleep-wakefulness regulation, this variety of the Pickwickian syndrome may also seriously compromise cardiac function. 4. Twenty-four hour 4-channel cassette tape recorder for monitoring the EEG. - - J. R. Ives and J. F. Woods (Montreal, Queb., Canada ).
A major limitation of EEG recording is restriction placed on the patient's mobility. Recordings can be done for only short periods in a laboratory setting. For most purposes this is adequate. For some patients this method provides inadequate information and a continuous recording of the EEG in their normal environment would be desirable. We have recently
106 tested a small cassette tape recorder which can record 4 channels of EEG continuously for 24 h. The cassette and batteries can easily be changed daily by the patient so that recordings may continue uninterrupted for several days. The recording can be done on out-patients because the electrode and wires can easily be hidden from view in the hair. The cassette can be conveniently worn over the shoulder or on the belt. The cassette is played back on a separate unit at 60 times the speed of recording. Each 24 h cassette recording is thus written out in 24 min. Intermittent abnormalities such as bursts of epileptic activity can be easily recognized. Recordings have been done on patients with absence epileptic seizures, blackouts of unknown origin and narcolepsy. The results will be discussed. 5. Computer recognition of generalized spike-wave paroxysms. - - B. L. Ehrenberg and J. K. Peary (Betbesda, Md. ). Twelve 12 h daytime telemetered EEGs (4-channel) were obtained from 8 patients and were recorded on both magnetic tape and paper. The EEGs were read independently by 3 electroencephalographers, and the 12 h tapes were played back at high speed i1.5 h per record) through a PDP-12-minicomputer. The computer was programmed to identify only generalized spike-wave paroxysms, their location on the record and their duration. A consensus was derived from the readings by selecting only those bursts identified as generalized S-W by all 3 readers. The computer's count agreed with the consensus on 85 o~, of the paroxysms. False-positive computer recognitions (high-voltage transients not recognized by any of the readers) occurred in 15 (1~o) of 1.462 total discharges. The computer's accuracy improved to 9 2 ~ of the consensus for the waking EEG when portions containing sleep were discounted. Likewise. 10 of the 15 false-positives also occurred during sleep sections, contributing to the majority of over-recognitions by the computer. The computer results were then pooled with those from the 3 readers to permit an inter-reader comparison of variability (with the computer treated as one of the readers). The computer was comparable to any of the h u m a n readers and tended to be closer to the most conservative reader than to the most liberal. 6. Computer analysis of EEG elements of significance for elhakld interpretation. - - R. N. Harner and K. Ostergren (Philadelphia, Pa. ). The h u m a n interpretative process has been under-utilized as a model for the design of computer programs to aid in E E G interpretation. Both analysis and synthesis are used in the successive steps of detection, description, comparison and correlation used consciously or subconsciously by the electroencephalographer. Sequential analysis ~Amer. J. EEG Technol,, 1973, 13: 139) treats the E E G as a population of individual half waves in sequence, in real time, from a minim u m of 8 head regions. Visual presentation ofthesewaves as a scattergram for each channel, according to the amplitude and wave length of each half wave, provide a useful s u m m a r y
SOCIETY PROCEEDINGS of the variability and distribution of wave forms, including the detection of infrequent or paroxysmal elements. A method has now been developed to use these data for realtime computation of the number, frequency and amplitude of waves, per cent time occurrence, and estimates of variability for up to 8 separate elements in each of 8 channels of EEG over periods ranging from 10 sec to 10 rain. A printed s u m m a r y is immediately available for quantitative comparison wJ_th those EEG elements detected visually by the electroencephalographer. More important, these numerical data can serve as quantitative input to programs already available for evaluation of EEG elements according to agerelated criteria of normality and abnormality. 7. Effects of antipsychotic medication exposure on EEG spectral power in chronic schizophrenics. - - K. Lifshitz and J. Gradijan (Orangeburg, N.Y. ). The time course of antipsychotic medication effects on the EEG is important in ascribing E E G findings to pathology or medication in schizophrenia. Studied were 10 male chronic schizophrenic patients on medication longer than 2 m o n t h s (median 16 weeks); 10 withdrawn from medication longer than 6 weeks (median 12 weeks1:10 withdrawn more than I week but tess than I m o n t h Imedian 19 days), the latter group respresentative of patients commonly used in studies. In each subject 150 2.8 sec segments of EEG. randomly spaced at intervals greater than 12 sec, were collected. screened for artifact, and digitized on-line. The power density spectrum was calculated for each E E G segment. Patients on medication showed less delta-band (0.35-3.8 c/see) power than either of the groups withdrawn from medication ( P < 0 . 0 0 2 for C2 and less significantly for O1, 2-tailed M a n n - W h i t n e y U test). The patients in intermediary withdrawal showed the highest delta power. Overall spectra power 10.35-54 c/secl reflected the same findings but at lesser significance. Since delta power may be considered an indicator of arousal, and since intrasubject delta power variance was similar for all three groups of patients and smaller than that of normal control subjects, a narrower range of "arousal" in the patients may be indicated. 8. The convul~nt effects of bicucuilin compared with metrazol. - - E. Rodia, H. Kitano, S. Wasson and M. Rodin (Detroit, Mich. ). The convulsant properties of bicucullin have recently attracted attention because they are regarded to result from inhibition of G A B A . The c o m p o u n d was therefore compared with metrazol as to its clinical and E E G effects. Chronically implanted cats were studied with each animal receiving both drugs. Videotape recordings showed that the clinical effects were exceedingly similar and could not be distinguished o n a blind basis. The E E G s were likewise very similar. Pre-ictal myoclonic jerking was associated in either instance by diffuse spikewave discharges and the seizure itself appeared to arise in cortex and thalamus. Multiple unit recordings showed, however, that the earliest onset of seizure activity occurred mostly in the pons. This was likewise c o m m o n to both drugs. Limbic system structures--e.g., ventral and dorsal bippo-
EASTERN EEG SOCIETY campus, amygdala--participated in the seizure activity consistently later than the other sampled brain structures and showed excellent correlations between the EEG and multiple unit records. It is concluded that bicucullin exerts its primary convulsant effect, similar to metrazol, on brainstem structures with secondary involvement of the limbic system. The term "primary generalized seizures" may therefore result in misleading conceptualizations. 9. EEG and behavioral effects of naltrexone in man. - J. Volavka, P. Gaztanaga, R. B. Resnick and A. M. Freedman (New York, N.Y. ).
Naltrexone is a new narcotic antagonist; its effectiveness in blocking heroin effects on mood and pupil size have been demonstrated. The purpose of the present study was to determine whether naltrexone p e r se has any effects on the EEG, and whether it antagonizes the EEG effects o f heroin. Visual evaluation of the pre- and post-naltrexone recordings in 13 patients showed no EEG changes attributable to this drug. The dose ranged between 3 and 160 mg daily, given for 1-17 days. The opiate antagonism of naltrexone was tested in 8 patients. Each patient was given 25 mg of heroin i.v. on two occasions: first without premedication, second, after premedication with naltrexone. EEG was recorded before and after each injection. A continuous auditory detection task was administered concurrently with the EEG. The heroin effects on EEG and on task performance were antagonized by naltrexone. The conclusion is that naltrexone causes no EEG changes p e r se but suppresses the effects of heroin on the EEG. 10. Persistent EEG changes in primates and humans fol|owing organophosphate (Sarin) exposure. - - F. H. Duffy and J. L. Burchfiel (Boston, Mass. ).
EEGs were recorded from 79 industrial workers with a documented history of exposure to Sarin and compared with recordings from a matched group of 38 controls. Sarin is an organophosphate with anticholinesterase action and has been used as an insecticide and "nerve agent". It is very similar structurally but more potent than malathion and parathion. Spectral analysis was performed on the EEGs from several leads and in several states. Comparison was made by T-test, Mann-Whitney U test, and chi-square analysis. The exposure population exhibited significant changes in many frequency bands. Beta and delta were increased in the frontal region, fast theta was increased posteriorly, and alpha was reduced in the frontal and temporal regions. As all exposed workers were free of Sarin exposure for at least one year before study, the possibility of long term changes from organophosphate exposure is raised. A parallel study on rhesus monkeys demonstrated similar changes. 11. EEG, brain scan, and angiography in the evaluation of subdural hematoma: a comparative study. - - R. Jaffe and J. Lusins (New York, N.Y. ). This study presents evidence based on serial brain scans. EEGs, and angiogram studies performed on 9 unoperated subdural hematoma patients followed over a period of 3-5
107 years. The results of this study indicate that the EEG is a more reliable correlate of clinical dysfunction in the presence of a subdural collection than is the radiographic appearance of the lesion. The present study shows, in addition, that radionuclide scanning may be a reliable indicator of the physical presence of the subdural .collections as well as a practical method for long term follow-up of the resolution of the hematoma. However, the scan is no more reliable than the angiogram in indicating whether the lesion is likely to be causing clinical evidence of cerebral dysfunction. If criteria related to the degree of clinical dysfunction are to be used in determining whether the patient is to be operated, it is apparent that the EEG is the laboratory method which is, more significant in the management of those cases once the diagnosis has been confirmed. 12. Muscular stress tests during simultaneous E O G and EEG recordings used to differentiate some types of cerebral palsy, and to help determine hubilitative training procedures. - - C. Kris (Cambridge, Mass. ).
A review of the EEG findings in cerebral palsy shows little correlation of EEG abnormalities with severity of dysfunction or potential benefit obtainable through habilitative training. The use of combined EOG and EEG during resting and active states has led to the development of three simple tests that have been found helpful in differentiating between types and levels o f severity of CP impairment, and between chronic CP and developmental incoordination. Several subject populations, following standard E O G EEG, were subjected to tests involving muscular stress, i.e., clenching of fingers and toes alternately on each side, and maintaning eye position at peripheral extremes. Chronic spastic and ataxic cerebrally palsied persons showed continuous irritability and high frequency muscle-artifact changes in the EEG, while a distonic athetoid CP youth presented long trains of slow-wave activity. In contrast, several children diagnosed as mildly cerebrally palsied showed neither of the above effects, and hyperkinetic incoordinated children showed intermittent high frequency and slow-wave discharges. The above electrodiagnostic monitoring methods were used to measure the intensity and duration of the stress tests, and to evaluate habilitative benefit and fatigue factors resulting from successive training sessions. 13. The early components of the auditory evoked response: a reference study. - - L. J. Streletz and L. Kutz (Philadelphia, Pa. and Wilmington, Del. ).
The early components (less than 10 msec peak latency) of the human scalp recorded auditory evoked response have been studied in 3 normal adults. Clicks o f 0.5 msec duration and 70 dB SL were delivered binaurally at a rate o f 10/see. Recording electrodes were attached widely over the scalp. Nose, ear, balanced noncephalic reference and bipolar recordings were obtained. In all recordings the first 20 msec following stimulus onset were analyzed and 1024 responses were summated. The frequency response of the amplifiers was linear between 1 and 10,000 c/see. Level of consciousness
108 was electroencephalographically monitored. The sharply contoured 6 msec positive wave complex described by Jewett et aL {1971) was recorded and found to be present widely over the scalp with its potential maximum at the vertex. Later components are also described. Comparison of reference systems reveals that some of these arise from the reference recording electrodes. Others appear to arise in the cerebrum. These findings suggest that the choice of various reference recording sites (ear. nose or balanced noncephalic) can aid in the interpretauon of different wave forms of the early components of the scalp recorded auditory evoked response.
14. Five year follow-up of geriatric EEGs. H . F . Muller. B. Grad and F. Engelsmann (Montreal, Queb.. Canada ). This study relates EEG and clinical-psychological variables obtained in several groups of geropsychiatric patients and healthy volunteers matched for age and sex (3", Geront., 1974. 29: 28) to their survival and health 5 years after the original assessment. For 180 of the original 210 subjects Ior 86~o) the necessary follow-up information has been obtained. The results demonstrate an intense statistical relationship between the two sets of data. and thus imply a predictive power for the EEG and psychological data which were utilized {counts of slow and fast EEG frequencies and assessments of motor performance and memory were the most useful ones}. Although age was significantly correlated with the chances of survival, statistical elimination of the age factor did not noticeably alter the results. The results are noteworthy in view of the common difficulties in the differential diagnosis of these subjects, and of the implications for treatment, for instance with stimulant, antidepressive or antipsychotic medications. This implies, of course, that acute disturbance of brain function and localized lesions have been ruled out.
15. EEG t'mdings and evoked responses in congenital defects of the corpus eallosum. G. Erba. Y. M. Matsumiya, N. Alvarez and C. T. Lombroso (Boston. Mass. ). Agenesis of the corpus cattosum has been reported as an accidental autopsy finding in adult subjects with no apparent neurological deficit during life. This is in contrast w~th the now well recognized perceptual and functional impairments m patients who underwent surgical split of the corpus callosum. Infants born with multiple congenital midline defects often involving the major interhemispheric commissure usually show severe psychomotor retardation: this may be related to other associated CNS anomalies rather than to the commissural defect although detection of callosal agenes~s adds a new dimension to the overall clinical evaluation in terms of prognosis and possible treatment. So far. a definite diagnosis has been achieved by PEG. Recently we have reported criteria by which the same diagnosis can be established by two-dimensional echoencephalography {B-scan). This observation prompted a review of 12 cases of proven congenital dysgenesis of the corpus callosum to assess the diagnostic value of other non-invasive procedures such as EEG and evoked potentials. Whereas the EEG findings vary a great deal from grossly abnormal tracings to non-diagnostic ones. somatosensory, visual, and auditory evoked responds
SOCIETY PROCEEDINGS appeared to show consistently extreme distortion of the late long latency components, The significance of the neurophysiological correlates m relauon to the extem and complexity of the multiple structural defects and to the syndrome of hemispheral disconnection will be discussed.
16. A characteristic EEG finding in newborns with maple syrup urine disease (branched-chain ketoaciduria ). - A. G. Trottier. K. Metrakos. G. Geoffroy and F. Andermann (Montreal, Queb.. Canada). EEG tracings of 4 patients with classical map!e syrup urmc disease show a characteristic pattern in the sec(~nd and third weeks of life: it consists of bursts of rhythmic. 7 q c, sec spindle-like sharp waves, of moderate amplitude, over the central regaons, which could be termed a "'comb-like rh3 thin". Such discharges are otherwise most unusual in this age group. There are also other severe abnormalities: multiple, shifting spikes and sharp waves, modified suppressionbursts, and excessive delta activity. The infants are lethargtc and it is usually impossible to state whether they are asleep or awake, Diet therapy was mnmted m the second week of lit~:, and the "'comb-like rhythm" disappeared by 5 or 6 weeks of age. Normal tracings emerged in 2 patients, and residual epileptiform discharges persisted in a third: the latter had a normal EEG by age 9 months. Although probably not pathognomonic of maple syrup urine disease, this "comb-likepattern should lead one to suspect the diagnosis when observed m a neonate presenting with lethargy and seizures. ]n patients diagnosed after the neonatal period or tn untreated surwving patients the EEG shows diffuse, nonspecific abnormalit3 with or without epileptogenic discharge.
17. ]'he specificity of eye-movement patterns for reading. J. S. Barlow (Boston. Mass. ). Attempted smooth eye movements over a featureless whtte visual field yield an actual pattern of eye movements superficially resembling that during reading, t.e.. a sequence of saccadic [quick} movements alternating with brief fixations. The patterns of eye movement under the two condition,s were therefore compared quantitatively by computing intersaccadic time-interval histograms on recordings of eye movements monitored by the infrared technique in ~ small group of normal subjects. In contrast to the pattern for the histograms for reading, which showed a more-or-less well-defined peak at 200-300 msec superimposed on a broad base (Abstracts. Third Imernational Biophysics Congress. 1969: 114|. the histograms for attempted smooth movements were relatively flat over the entire time base analyzed t512 msec). On the other hand. the histograms for "'reading" upside-down printed material {with almost no attendant comprehension) were essentially indistinguishable from those for the same subject for normal reading. These findings suggest that the presence of a finely structured visual field ~s required for the pattern of eye movements characteristic of reading to become manifest. but that the latter may be relatively stereotyped for a gwen
EASTERN EEG SOCIETY subject, irrespective of the actual intelligibility (i.e., specific information processing) of the material. 18. Suheortical factors in experimental Jacksonian seizures. - W. F. Caveness and H. Ueno (Bethesda, Md. ). Cyclic paroxysmal activity occurs following injection of penicillin in the cerebral cortex, right face-hand area, of the adult Macaca mulatta. With each episode there is an increase in extent and severity of electrographic and clinical expression, followed by an abrupt cessation of abnormal activity. To provide a concurrent appraisal of cortical and subcortical neuronal activity at selected stages in the events described, the C14 antipyrine regional Cerebral Blood Flow method of Sokoloff was used. Results: During a generalized seizure that had progressed from focal paroxysmal activity to bilateral, high amplitude, 3-4 sec, EEG spikes accompanied by synchronous movements of the face and all four limbs, there was an overall increase in cerebral blood flow with laterality only in right putamen and substantia nigra. At the cessation of a similar generalized seizure there was unilateral increase in blood flow in right motor cortex, globus pallidus, substantia nigra, thalamic VPL, VPm, and left cerebellar cortex. Suggested is a deactivating influence of the cerebellum and thalamic nuclei, with remaining activating influence in the circumscribed right motor cortex. 19. Role of the intrncarotid amytal-metrazol EEG test in the surgical treatment of patients with complex seizure problems. - - T. Rasmussen, P. Glonr, A. Altuzarra and H. Garretson (Montreal, Queb., Canada). The intracarotid amytal-metrazol test was devised to help identify those seizure patients with bilateral epileptfform abnormality in the EEG whose seizures were actually arising in one hemisphere and were thus potential candidates for surgical therapy by unilateral cortical excision. Two groups of patients were involved, those with bilaterally synchronous 2-3.5/sec spike and slow wave abnormality and those with temporal lobe epilepsy and bilateral, independent temporal lobe spiking. The test was carried out in 94 patients in the 10 year period 1963-72, with cortical excision being subsequently carried out in 30. The role of the test in selecting patients for operation, and its predictive value as to a subsequent satisfactory reduction in seizure tendency is analyzed. The importance of accurate information as to the symmetry of the cerebral arterial supply in interpreting the test results is emphasized. 20. Chronic depth electrode recording in patients with bitemporal epilepsy. - - A. Olivier, P. Gloor, J. Ives, C. Thompson, F. Andermann, J. Woods and G. Bertrand (Montreal, Queb., Canada). In the past, patients with EEG signs of bilateral temporal lobe epilepsy were generally rejected as surgical candidates for temporal lobectomy. Chronic depth stereotaxic recording has changed this concept. Seven patients suffering from intractable cerebral sei-
109 zures, and in whom repeated EEGs had shown bitemporal epileptic activity, were submitted to this procedure. Multiple contact stainless-steel wire electrodes were implanted stereotaxically and bilaterally in temporal cortex, amygdala, hippocampus and parahippocampal gyrus for a period of time averaging 3 weeks. Prolonged recordings were carried out with standard 16-channel EEG machines, or with an 8-channel or 16-channel EEG telemetry system. A computer program was used to recognize and store ictal epileptiform activity recorded by telemetry. In all these patients, the study confirmed the existence of interictal epileptic activity bilaterally, with clear predominance of the ictal events on one side. All patients were later submitted to standard temporal lobectomy. Repeated onset of spontaneous seizures localized in one temporal lobe represents the principal criterion upon which the decision to operate is based. There were no complications. 21. Predicting the plasma diphenylhydantoin level: effects of age, sex, pregnancy and protein binding. - - A. L. Sherwin and J. S. Loynd (Montreal, Queb., Canada ). While plasma levels of diphenylhydantoin (DPH) exhibit a general relationship to dosage in individual patients, studies of larger groups show a high degree of variability. The ability to predict the approximate plasma levels of patients on stable therapy is essential to detect non-compliance, drug interaction or altered drug disposition. The dose-~plasma level relationship of DPH was determined in 700 patients divided into carefully defined groups. Equivalent dosages of DPH were compared in each group. Higher plasma DPH levels were observed in adult males when compared with children, while the levels in females were similar to children. Females over 65 years exhibited a marked increase in plasma levels which may be of clinical significance. Consistent alterations in plasma DPH levels were not observed during pregnancy. There was no difference in the response of overweight patients nor in the mean plasma DPH levels of patients receiving concurrent phenobarbital or primidone. Impaired plasma protein binding resulted in a marked decrease in the dose-plasma level response. A highly significant (P< 0.001) linear dose (per m2}-plasma level relationship was observed in a group of adult males receiving total DPH as a single morning dose. If the appropriate parameters are considered, the expected plasma DPH level can be predicted. 22. The relationship of seizure activity to anticonvulsant blood concentrations: 24 h sleep-waking studies. - - J. H. French, A. J. Rowan, C. E. Pippenger and P. A. McGregor (New Haven, Conn. ). The feasibility of effecting correlative studies of clinical seizures, continuous 24 h EEG recordings, and concomitant frequent serum anticonvulsant determinations in the instance of major motor attacks has been demonstrated (Rowan et al., Electroenceph. elin. Neurophysiol., 1973, 34: 745 and 1974, 37: 194). Longitudinal application of this study technique to 2 patients with poorly controlled major motor seizures suggests that objective documentation of the
110 efficacy of a specific anticonvulsant drug is practicable. Also. the results indicate an inverse relationship between the serum concentration of an effective anticonvulsant drug and paroxysmal activity at specific points in time. Application of the derived information to the therapeutic regimen o f these patients has resulted in marked improvement of seizure control. This improvement has persisted for 11 and 4 m o n t h periods of follow-up.
23. The interaction of genetic and environmental factors in patients operated for focal epilepsy. E. Andermonn, L. Dansky and J. D. Metrakos (Montreal, Queb., Canada ). Both genetic and environmental factors have been shown to play a significant role in the etiology of focal epilepsy, which appears to be compatible with multifactoriat inheritance. In a study of 60 patients treated surgically for focal epilepsy at the Montreal Neurological Hospital. the various exogenous etiological factors were analyzed, seizure histories obtained on 377 near relatives, and EEGs on 322 relatives. When the interactions of genetic and environmental factors in these probands were studied, significant correlations were found for 9 of 11 exogenous factors with respect to history of seizures, epilepsy, and/or specific EEG abnormalities in relatives. A history of seizures was least frequent in relatives of patients with definite exogenous etiological factors, postnatal trauma, and definite pathological diagnosis. These findings are m agreement with prior hypothesis. On the other hand, relatives of patients with a definite infectious etiology had the highest frequency of seizures. Spike-and-wave EEG abnormalities were significantly increased in relatives of patients who had only temporal lobe removals, and in relatives of patients with postnatal infection as an etiological factor. Although some of these findings are in contrast with prior hypothesis, they are in good agreement with newer concepts regarding the pathogenesis o f focal epilepsy proposed by Ounsted and Falconer.
24. Computed unit-EEG correlations and laminar profiles of barbiturate spindle EEGs. G . J . BaH and P. Gioor (Montreal, Queb., Canada ). In an effort to understand the basis of EEG of the barbiturate spindle type, methods of recording unit activity with concurrent EEG activity and methods of recording EEG at various depths intracortically of barbiturate anesthetized cats are presented together with techniques of analysis of the recorded data by the computer. A process of averaging the EEG during unit acttvity showed a high correlation of the unit with the positive phase of a biphasic surface-positive-negative average, the duration of which was within the range of the dominant frequency of the EEG. Histograms of unit activity associated with selected. averaged surface spindle waves showed peaks o f unit activity supporting the results obtained in unit-EEG analysis. A clear indication of the depth, in the cortex, at which the E E G inverted, was portrayed by averaging selected surface spindle waves and the accompanying EEG at various depths within the cortex. Levels of inversion of the E E G were at 1000 p m
SOCIETY PROCEEDINGS depth in the cortex. Conclusions were made that the spindle EEG was a statistical product of dipoles created by synaptic input, at the 1000.urn level, to the s o m a or proximal dendrites of pyramidal cells whose apical dendritesextended to the cortical surface.
25. What function do glial cells have in epileptogenesis? W. J. Adelman Jr. ondW. F. Caveaem (Bethesda, Md. ). Repetitively firing neurons release potassium tons which may accumulate in perineuronal spaces. Green (Physiol. Rev.. 44: 561) and Fertziger and Ranck (Exp. Neurol.. 26: 571 ) suggest that potassium ion accumulation contributes to epileptogenesis. Pollen and Trachtenberg (Science. 167: 1252) suggest that: ( 1) glial cells are potassium ion permeable and act as potassium buffers: and {2) that glia in scars lose buffering because of increased membrane resistance. Glotzner {Brain Res.. 1973, 55: 159) showed that: (1) gliat cell membrane resistance in epileptogenic foci decreases from 600 ~ c m 2 to 300 f~cm 2, and that (2) glial cell volume mcreases with no reduction in glial cell numbers. We can calculate the effect o f these changes on total tissue resistance using the Maxwell equation (Cole et aL. Exp. Neurol.. 24: 459). A decrease in intergliat space (resulting from increased glial celt volume) would increase tissue resistance despite observed cell m e m b r a n e resistance changes. This suggests that the major ion diffusional path across brain tissues is the clefts between brain cells. We propose an alternative to the PollenTrachtenberg hypothesis: (1) Perineuronal potassium ion concentration is buffered more by diffusion through spaces between glia than by uptake by glia, (2) Gliosis decreases space between glia, reduces potassium diffusion, and increases perineuronal p o t a s s i u m ion concentration leading to abnormal neuronal excitability.
26. Neocortical-amygdaloid relations in the cat. - - W. M. Burnham, S. Prelevic and P. Gloor (Montreal, Queb.. Canada ). Extracellular unil recording was done in the baso-lateral area of the amygdala in barbiturate anesthetized cats during electrical stimulation o f the ipsilateral neocortex. Data were stored on magnetic tape, poststimutus time histograms being later computed and compared to the averaged field potentials. Of 278 amygdaloid units recorded and analyzed, well over half responded to neocorticat stimulation. Both excitatory and inhibitory responses were seen, the most c o m m o n response pattern being excitation with a latency of about 10 msec followed by inhibition which lasted 100 msec or even longer depending on the intensity of neocortical stimulation. In agreement with previous neuroanatomical studies, the neocortical areas found to be most effective for driving amygdaloid units were the post-sylvian and post-ectosylvian gyri (homologues of the temporat-dnsular cortex in primates). When two or more cortical inputs were seen to influence the same amygdaloid unit. inhibitory interactions could generally be demonstrated. These findings add further support to recent conceptualizations of the amygdala as an important link between the
EASTERN EEG SOCIETY sensory analyzers of the neocortex and the fundamental motivational mechanisms of the hypothalamus. 27. Power spectral analysis of telemetered EEG during behavioral aberrations and prolonged reaction time in patients with schizophrenia and other severe psychiatric disorders. - - J. R. Stevens (Portland, Ore.). In previous studies of power spectral characteristics of the EEG of epileptic cat and man, a "'ramp" pattern consisting of monotonic decline in power from low to high frequencies was calculated from spike-free scalp or dural recordings coincident with subcortical spike activity (Stevens et al., Science, 1972, 176: 1346) and from spike-free epochs of scalp EEG from patients with focal and generalized epilepsy during a reaction-time task preceding prolonged latencies or
111 erroneous response. In contrast, normal control subjects display slower frequencies consistent with diminished arousal prior to long latency response. Utilizing this technique in the study of hospitalized psychotic patients in the search for EEG changes coincident with delayed response and psychomotor blocking, a different spectral pattern emerged in half the schizophrenic patients studied to date. These individuals display a "noise" spectrum, i.e., loss of central frequency tendency and dispersion of power relatively evenly over the entire EEG frequency band (1-30 c/sec) prior to delayed, erroneous or non-response trials. In a second study, employing prolonged recording of telemetered EEG with tagging of spontaneous behavioral aberrations, power spectra plotted in the compressed spectral array format of Bickford and Fleming display similar "noise" patterns during catatonic episodes.