- Email: [email protected]
Western electroencephalography society, 35th annual meeting
58P
Electroencephalography and Clinical Neurophysiology, 1980, 50: 58P--60P © Elsevier/North-Holland Scientific Publishers, Ltd.
Society proceedings WESTERN ELECTROENCEPHALOGRAPHY SOCIETY, 35TH ANNUAL MEETING Maui, Hawaii, February 16--17, 1979
Secretary: Dr. JOHN G. ROTH University of Oregon, Health Sciences Center, 3181 S.W. Sam Jackson Park Road, Portland, Ore. 97201 (U.S.A.)
1. Towards objective assessment o f routine clinical EEGs. -- C.L. Yeager and A.S. Givens (San Francisco, Calif. ) Because of the many uncontrolled and uncontrollable variables, electrophysiological changes in cerebral function often hear little direct relationship to clinically recognized pathological states. Furthermore, standard methods of interpreting EEGs are highly subjective since the report is molded by the training, personal knowledge and feelings of EEGers. Attempts to address the first problem will be discussed elsewhere. We have attempted to deal with the latter problem by: (1) compiling a data base of norreal and abnormal EEGs; (2) developing a concise, objective method for clinical interpretation of EEGs; and (3) implementing an interactive computer system (ADIEEG) which performs a complete analysis of the EEG, including background characteristics and sharp transients, artifact rejection and multivariate pattern classification. In a preliminary study, 307 routine clinical EEGs were interpreted by several EEGers using either the polygraph or compressed spectral array. Interpretation of the former was more consistent, suggesting that displays of spectral analysis may not be substituted for the polygraph. Use of a concise, objective method for interpreting EEGs is suggested as a means of improving current practice.
2. NP 'limbic spindles' are an artifact of nasopharyngeal vibration. - - J . Engel, Jr. and R.G. Bickford (Los Angeles and San Diego, Calif.) Rhythmic spindle bursts are known to occur in limbic structures of both animals and. man with respiration and sniffing of odorants. The origin of spindles recorded in man from nasopharyngeal (NP) electrodes, however, is controversial. EEG tracings from patients were recorded simultaneously from NP and sphenoidal electrodes as well as from depth electrodes placed in amygdala, hippocampus and hippocampal gyrus during snoring and sniffing of odorants. 'Limbic
spindles' recorded from NP electrodes occurred during snoring only. Using a specially constructed NP electrode with a piezo electrode tip, it was demonstrated that NP spindles could be correlated exactly with vibration of the nasopharynx while spindles did not appear in depth or sphenoidal electrodes. In a few patients, low voltage spindles were also seen in the limbic depth during snoring which were exactly in phase with the NP spindles. These depth spindles also could be correlated exactly with nasopharyngeal vibration recorded from the piezo electrode. This study proves the artifactual nature of spindles recorded from NP electrodes in man and suggests that even some depth recorded 'limbic spindles' may be of extracerebral origin.
3. The electroencephalographic aspects of phenylketonuria under early initiated treatment, a collaborative study. -- M. Blaskovics, R. Podosin, C. Gillen Azen, E. Gross Friedman and R. Engel (Los Angeles, Calif. and Portland, Ore. ) Nineteen of 161 infants with a confirmed diagnosis of phenylketonuria (PKU) had initially abnormal electroencephalograms (EEGs) obtained within days of diagnosis. The abnormalities consisted of single repetitive or multiple spikes and/or sharp waves, focal or scattered, which rarely occurred in paroxysmal bursts. Initial maximum diagnostic serum phenylalanine (phe) levels were significantly higher (P < 0.001) for the abnormal group. The mean diagnostic serum phe level was 56 mg/dl in the group with the abnormal EEGs, whereas the mean diagnostic phe level was 48 mg/dl in the group with normal tracings. The average age at initiation of restrictive dietary treatment was approximately 3 weeks. The initially abnormal EEGs became normal by 1 year of age in all but two patients who had a minimal and a mild abnormality, respectively. Hypsarrhythmic patterns were not seen.
WESTERN EEG SOCIETY 4. Clinical application of Mini-CEARS computer and the ACE test. -- R.G. Bickford, D. Brunet, K. Hanson and C. McCutchen (San Diego, Calif. ) The Mini-CEARS computer is an LSI-11 microprocessor (2 floppy discs) using CEARS programs (PDP1140). This system computes a new combined EEG and evoked potential test called ACE (automated cerebral electrogram). The ACE test takes 50 min, has a special fee schedule, and can be performed on an economically priced computer. It yields: (1) compressed spectral array (CSA); (2) n u m e r o g r a m - - microvoltage for delta, theta, alpha and beta bands for each electrode; (3) area display of numerogram and evoked potentials as contour plots; (4) s p i k e p a c k - - spikes recognized by the computer algorhythm arrayed on a head diagram for visual validation; (5) visual, a u d i t o r y , somat o s e n s o r y e v o k e d p o t e n t i a l s on 16 channels; (6) brain s t e m a u d i t o r y e v o k e d p o t e n t i a l s . The tests are interwoven with the clinical EEG. Mini-CEARS also produces the s o m n o g r a m (for the study of sleep disorders and clinical coma). Stored normative data aids clinician interpretation. ACE is a powerful diagnostic procedure which may replace conventional EEG in neurology.
5. Abnormal pattern visual evoked response and brain stem auditory evoked response in patients with definite multiple sclerosis. -- J.P. Spire and P. Prieto (Chicago, l]l.) Seventeen patients in whom the clinical findings and evolution, including the presence of oligbclonal bands in the CSF confirmed a diagnosis of definite multiple sclerosis (MS) were examined repeatedly by pattern visual evoked responses and brain stem auditory evoked responses. These data were compared to the result obtained from a larger pool of patients with other neurological conditions and age matched normal controls. In all the cases of definitive MS b o t h the pattern visual evoked response and the brain stem auditory evoked response were significantly and distinctly abnormal. The abnormality most consistently observed for pattern VER was a delay of the first largest positive peak latency (/>2 S.D.). The abnormality for the brain stem auditory evoked response was the increase of the I--V wave peak latency interval (/> 2 S.D.) or the unilateral or bilateral absence of all the peaks following wave II (especially in the acute cases). Comparing these results to those of patients with other neurological conditions, it seems reasonable to conclude that in the absence of a demonstrable anatomical lesion by other conventional techniques (either EMI scanning or myelography), the combination of VER and BAER abnormalities in a
59P given patient with symptoms suggestive of MS, but normal vision and hearing, would confirm this diagnosis.
6. Use of cerebral evoked potentials to evaluate spinal somatosensory function in patients with traumatic and surgical myelopatbies. -- L.J. Dorfman, I. Perkash and T.M. Bosley (Palo Alto, Calif.) Cerebral somatosensory evoked potentials (SEPs) were elicited by electrical stimulation of the median nerve in the arm (SEPA) and of the posterior tibial nerve in the leg (SEPL) in 22 patients with incomplete localized lesions of the lower cervical, thoracic or lumbar spinal cord. SEPL could not be recorded in 7 of 44 attempts (left and right sides). Of the remaining 37 sides, spinal somatosensory conduction velocity (SSCV, indirectly estimated) was abnormally slow (<35 m/sec) in 21, and the amplitude of SEPL relative to SEPA (L:A ratio) was abnormally low (<0.5) in 19 (P < 0.001 in each case, compared to normal controls). All 3 criteria of abnormality yielded a combined 82% incidence of abnormality, correlating best with impairment of joint position sense. Serial postoperative studies in 3 cases documented increase in SSCV and L:A ratio following spinal decompression. These results confirm that the latency and amplitude characteristics of cerebral SEPs from arm and leg permit quantitative evaluation of spinal somatosensory function.
7. Evoked response habituation effects in cerebrovascular and normal age-matched controls. -- G. Brent, R.E. Saul, H.J. Michalewski and L.W. Thompson (Downey, Calif.) The effects of stimulus change and habituation upon the averaged auditory evoked response (AER) were investigated in a group of left (n = 3) and right in = 5) cerebrovascular patients (3--8 weeks post CVA) and compared to a group of age-matched controls (n = 8). Scalp electrical activity was collected from Fz, C3, Cz, C4 and Pz sites in a modified Ritter et al. (1968) paradigm. The experimental conditions allowed the evaluation of AER changes to repetitive background tones and randomly interspersed rare or novel tones. Subject alertness was controlled by having the number of tones presented totaled and recalled over a series of 15 block (of 30 trials) presentations. Six components of the AER were identified and statistically evaluated (P1, N1, P2, N2, P3, and N3). AERs to stimulus change were demonstrated for both CVA patients and controls. Significant increases in P2 and P3 amplitudes were found for the rare tones in contrast to AERs before or after the presentation
60P of the rare tones. Significant differences in the latency of N 1 were found for the CVA patients that corresponded to the side of injury; for both background and rare tones, N1 latencies were longer over the affected hemisphere.
8. Subacute sclerosing panencephalitis (SSPE) and brain stem auditory evoked responses ( B A E R ) . J.P. Spire, P. Prieto and P. Huttenlocher (Chicago,
SOCIETY PROCEEDINGS This paper reviews the recently published work of Sewell, Norris and Guth on the detection of an auditory nerve-activating substance secreted into the perilymph of frogs and guinea-pigs during sound stimulation. Hopefully this may lead to the detection of the afferent neurotransmitter of the auditory system. The context of this specific finding as well as the possible significance of auditory evoked responses in the behavior of animals and humans is discussed.
Ill.) Eight patients with a diagnosis of SSPE confirmed by either brain biopsy or immunological features, EEG abnormalities and a clinical evolution typical for this disease were studied by serial brain stem auditory evoked responses. At the time of testing, 5 patients were considered clinically chronic or stable; 3 patients presented a rapid evolution and were markedly obtunded. All the chronic-stable cases had normal BAERs compared to age-matched controls. The 3 acute cases had significant latency delays (/>2 S.D.) for waves III and V with a normal latency for wave I. The abnormal BAER in these cases appeared distinctly different from the BAER of patients with demyelinating conditions. These data would suggest that SSPE although widespread in the CNS and in some ways similar to multiple sclerosis has different electrophysiologic features. 9. A window on neuroscience. IV. Now hear this. -E.R. Grass (Quincy, Mass.) The emergence of brain stem auditory evoked potentials as a diagnostic strategy in clinical neurology has in turn evoked a resurgence of interest in the neuroanatomy and neurophysiology of the auditory system.
10. Ectopic action potential generation in peripheral trigeminal axons. -- K.J. Burchiel and A.R. Wyler (Seattle, Wash.)
Spontaneous and evoked (orthodromic and antidromic) activity of 115 trigeminal ganglion neurons were studied. Three percent of cells stimulated at low frequency (less than 10 Hz) and 96% of cells stimulated at high frequencies (10--100 Hz) demonstrated ectopic action potentials (regardless of whether stimuli were anti- or orthodromic). However, this phen o m e n o n was maximal in response to moderate frequency stimuli (20--30 Hz) following periods of high frequency stimulation. Collision experiments demonstrated that these extra spikes arose from the neurons' peripheral axon, and persisted following section of the retrogasserian root. Both conditioning antidromic action potentials and subthreshold orthodromic stimuli were found to increase greatly the incidence of extra spikes produced by low frequency orthodromic and antidromic stimuli, respectively. Repetitive firing was abolished by cooling of the neurons' receptive field. This repetitive firing appears to be generated from the peripheral axon, possibly its terminal myelinated segment. The theoretical basis of this phenomenon and its implications for the mechanism of trigeminal neuralgia are discussed.
Electroencephalography and Clinical Neurophysiology, 1980, 50: 58P--60P © Elsevier/North-Holland Scientific Publishers, Ltd.
Society proceedings WESTERN ELECTROENCEPHALOGRAPHY SOCIETY, 35TH ANNUAL MEETING Maui, Hawaii, February 16--17, 1979
Secretary: Dr. JOHN G. ROTH University of Oregon, Health Sciences Center, 3181 S.W. Sam Jackson Park Road, Portland, Ore. 97201 (U.S.A.)
1. Towards objective assessment o f routine clinical EEGs. -- C.L. Yeager and A.S. Givens (San Francisco, Calif. ) Because of the many uncontrolled and uncontrollable variables, electrophysiological changes in cerebral function often hear little direct relationship to clinically recognized pathological states. Furthermore, standard methods of interpreting EEGs are highly subjective since the report is molded by the training, personal knowledge and feelings of EEGers. Attempts to address the first problem will be discussed elsewhere. We have attempted to deal with the latter problem by: (1) compiling a data base of norreal and abnormal EEGs; (2) developing a concise, objective method for clinical interpretation of EEGs; and (3) implementing an interactive computer system (ADIEEG) which performs a complete analysis of the EEG, including background characteristics and sharp transients, artifact rejection and multivariate pattern classification. In a preliminary study, 307 routine clinical EEGs were interpreted by several EEGers using either the polygraph or compressed spectral array. Interpretation of the former was more consistent, suggesting that displays of spectral analysis may not be substituted for the polygraph. Use of a concise, objective method for interpreting EEGs is suggested as a means of improving current practice.
2. NP 'limbic spindles' are an artifact of nasopharyngeal vibration. - - J . Engel, Jr. and R.G. Bickford (Los Angeles and San Diego, Calif.) Rhythmic spindle bursts are known to occur in limbic structures of both animals and. man with respiration and sniffing of odorants. The origin of spindles recorded in man from nasopharyngeal (NP) electrodes, however, is controversial. EEG tracings from patients were recorded simultaneously from NP and sphenoidal electrodes as well as from depth electrodes placed in amygdala, hippocampus and hippocampal gyrus during snoring and sniffing of odorants. 'Limbic
spindles' recorded from NP electrodes occurred during snoring only. Using a specially constructed NP electrode with a piezo electrode tip, it was demonstrated that NP spindles could be correlated exactly with vibration of the nasopharynx while spindles did not appear in depth or sphenoidal electrodes. In a few patients, low voltage spindles were also seen in the limbic depth during snoring which were exactly in phase with the NP spindles. These depth spindles also could be correlated exactly with nasopharyngeal vibration recorded from the piezo electrode. This study proves the artifactual nature of spindles recorded from NP electrodes in man and suggests that even some depth recorded 'limbic spindles' may be of extracerebral origin.
3. The electroencephalographic aspects of phenylketonuria under early initiated treatment, a collaborative study. -- M. Blaskovics, R. Podosin, C. Gillen Azen, E. Gross Friedman and R. Engel (Los Angeles, Calif. and Portland, Ore. ) Nineteen of 161 infants with a confirmed diagnosis of phenylketonuria (PKU) had initially abnormal electroencephalograms (EEGs) obtained within days of diagnosis. The abnormalities consisted of single repetitive or multiple spikes and/or sharp waves, focal or scattered, which rarely occurred in paroxysmal bursts. Initial maximum diagnostic serum phenylalanine (phe) levels were significantly higher (P < 0.001) for the abnormal group. The mean diagnostic serum phe level was 56 mg/dl in the group with the abnormal EEGs, whereas the mean diagnostic phe level was 48 mg/dl in the group with normal tracings. The average age at initiation of restrictive dietary treatment was approximately 3 weeks. The initially abnormal EEGs became normal by 1 year of age in all but two patients who had a minimal and a mild abnormality, respectively. Hypsarrhythmic patterns were not seen.
WESTERN EEG SOCIETY 4. Clinical application of Mini-CEARS computer and the ACE test. -- R.G. Bickford, D. Brunet, K. Hanson and C. McCutchen (San Diego, Calif. ) The Mini-CEARS computer is an LSI-11 microprocessor (2 floppy discs) using CEARS programs (PDP1140). This system computes a new combined EEG and evoked potential test called ACE (automated cerebral electrogram). The ACE test takes 50 min, has a special fee schedule, and can be performed on an economically priced computer. It yields: (1) compressed spectral array (CSA); (2) n u m e r o g r a m - - microvoltage for delta, theta, alpha and beta bands for each electrode; (3) area display of numerogram and evoked potentials as contour plots; (4) s p i k e p a c k - - spikes recognized by the computer algorhythm arrayed on a head diagram for visual validation; (5) visual, a u d i t o r y , somat o s e n s o r y e v o k e d p o t e n t i a l s on 16 channels; (6) brain s t e m a u d i t o r y e v o k e d p o t e n t i a l s . The tests are interwoven with the clinical EEG. Mini-CEARS also produces the s o m n o g r a m (for the study of sleep disorders and clinical coma). Stored normative data aids clinician interpretation. ACE is a powerful diagnostic procedure which may replace conventional EEG in neurology.
5. Abnormal pattern visual evoked response and brain stem auditory evoked response in patients with definite multiple sclerosis. -- J.P. Spire and P. Prieto (Chicago, l]l.) Seventeen patients in whom the clinical findings and evolution, including the presence of oligbclonal bands in the CSF confirmed a diagnosis of definite multiple sclerosis (MS) were examined repeatedly by pattern visual evoked responses and brain stem auditory evoked responses. These data were compared to the result obtained from a larger pool of patients with other neurological conditions and age matched normal controls. In all the cases of definitive MS b o t h the pattern visual evoked response and the brain stem auditory evoked response were significantly and distinctly abnormal. The abnormality most consistently observed for pattern VER was a delay of the first largest positive peak latency (/>2 S.D.). The abnormality for the brain stem auditory evoked response was the increase of the I--V wave peak latency interval (/> 2 S.D.) or the unilateral or bilateral absence of all the peaks following wave II (especially in the acute cases). Comparing these results to those of patients with other neurological conditions, it seems reasonable to conclude that in the absence of a demonstrable anatomical lesion by other conventional techniques (either EMI scanning or myelography), the combination of VER and BAER abnormalities in a
59P given patient with symptoms suggestive of MS, but normal vision and hearing, would confirm this diagnosis.
6. Use of cerebral evoked potentials to evaluate spinal somatosensory function in patients with traumatic and surgical myelopatbies. -- L.J. Dorfman, I. Perkash and T.M. Bosley (Palo Alto, Calif.) Cerebral somatosensory evoked potentials (SEPs) were elicited by electrical stimulation of the median nerve in the arm (SEPA) and of the posterior tibial nerve in the leg (SEPL) in 22 patients with incomplete localized lesions of the lower cervical, thoracic or lumbar spinal cord. SEPL could not be recorded in 7 of 44 attempts (left and right sides). Of the remaining 37 sides, spinal somatosensory conduction velocity (SSCV, indirectly estimated) was abnormally slow (<35 m/sec) in 21, and the amplitude of SEPL relative to SEPA (L:A ratio) was abnormally low (<0.5) in 19 (P < 0.001 in each case, compared to normal controls). All 3 criteria of abnormality yielded a combined 82% incidence of abnormality, correlating best with impairment of joint position sense. Serial postoperative studies in 3 cases documented increase in SSCV and L:A ratio following spinal decompression. These results confirm that the latency and amplitude characteristics of cerebral SEPs from arm and leg permit quantitative evaluation of spinal somatosensory function.
7. Evoked response habituation effects in cerebrovascular and normal age-matched controls. -- G. Brent, R.E. Saul, H.J. Michalewski and L.W. Thompson (Downey, Calif.) The effects of stimulus change and habituation upon the averaged auditory evoked response (AER) were investigated in a group of left (n = 3) and right in = 5) cerebrovascular patients (3--8 weeks post CVA) and compared to a group of age-matched controls (n = 8). Scalp electrical activity was collected from Fz, C3, Cz, C4 and Pz sites in a modified Ritter et al. (1968) paradigm. The experimental conditions allowed the evaluation of AER changes to repetitive background tones and randomly interspersed rare or novel tones. Subject alertness was controlled by having the number of tones presented totaled and recalled over a series of 15 block (of 30 trials) presentations. Six components of the AER were identified and statistically evaluated (P1, N1, P2, N2, P3, and N3). AERs to stimulus change were demonstrated for both CVA patients and controls. Significant increases in P2 and P3 amplitudes were found for the rare tones in contrast to AERs before or after the presentation
60P of the rare tones. Significant differences in the latency of N 1 were found for the CVA patients that corresponded to the side of injury; for both background and rare tones, N1 latencies were longer over the affected hemisphere.
8. Subacute sclerosing panencephalitis (SSPE) and brain stem auditory evoked responses ( B A E R ) . J.P. Spire, P. Prieto and P. Huttenlocher (Chicago,
SOCIETY PROCEEDINGS This paper reviews the recently published work of Sewell, Norris and Guth on the detection of an auditory nerve-activating substance secreted into the perilymph of frogs and guinea-pigs during sound stimulation. Hopefully this may lead to the detection of the afferent neurotransmitter of the auditory system. The context of this specific finding as well as the possible significance of auditory evoked responses in the behavior of animals and humans is discussed.
Ill.) Eight patients with a diagnosis of SSPE confirmed by either brain biopsy or immunological features, EEG abnormalities and a clinical evolution typical for this disease were studied by serial brain stem auditory evoked responses. At the time of testing, 5 patients were considered clinically chronic or stable; 3 patients presented a rapid evolution and were markedly obtunded. All the chronic-stable cases had normal BAERs compared to age-matched controls. The 3 acute cases had significant latency delays (/>2 S.D.) for waves III and V with a normal latency for wave I. The abnormal BAER in these cases appeared distinctly different from the BAER of patients with demyelinating conditions. These data would suggest that SSPE although widespread in the CNS and in some ways similar to multiple sclerosis has different electrophysiologic features. 9. A window on neuroscience. IV. Now hear this. -E.R. Grass (Quincy, Mass.) The emergence of brain stem auditory evoked potentials as a diagnostic strategy in clinical neurology has in turn evoked a resurgence of interest in the neuroanatomy and neurophysiology of the auditory system.
10. Ectopic action potential generation in peripheral trigeminal axons. -- K.J. Burchiel and A.R. Wyler (Seattle, Wash.)
Spontaneous and evoked (orthodromic and antidromic) activity of 115 trigeminal ganglion neurons were studied. Three percent of cells stimulated at low frequency (less than 10 Hz) and 96% of cells stimulated at high frequencies (10--100 Hz) demonstrated ectopic action potentials (regardless of whether stimuli were anti- or orthodromic). However, this phen o m e n o n was maximal in response to moderate frequency stimuli (20--30 Hz) following periods of high frequency stimulation. Collision experiments demonstrated that these extra spikes arose from the neurons' peripheral axon, and persisted following section of the retrogasserian root. Both conditioning antidromic action potentials and subthreshold orthodromic stimuli were found to increase greatly the incidence of extra spikes produced by low frequency orthodromic and antidromic stimuli, respectively. Repetitive firing was abolished by cooling of the neurons' receptive field. This repetitive firing appears to be generated from the peripheral axon, possibly its terminal myelinated segment. The theoretical basis of this phenomenon and its implications for the mechanism of trigeminal neuralgia are discussed.