Society Proceedings / Electroencephalography mately 0 in 40-60 set components begins 5-10 burst suppression pattern, min. The average rate of 40% of baseline/h. Thus, brain function in response
of asphyxia. The recovery of power in all min after successful resuscitation efforts with a and continuous activity is observed after 30-45 recovery in the total power varies from 2.5 to AR modeling may be useful in quantitating the to a hypoxic-asphyxic insult.
63. Quantitative electroencephalography in dementia (brain map).
- I. Ahmed (Trinity Lutheran Hospital) The usefulness of quantitative electroencephalography in clinical neurology is controversial. There are many reports that indicate it best be reserved in patients with dementia. Clinical utility in dementia is also not very well documented. We examined 150 consecutive cases of dementia. Apart from routine electroencephalography (EEG), a quantitative analysis of brain electrical activity was also performed. Both procedures were compared with other neurodiagnostic procedures including psychological testing and magnetic resonance imaging of the brain. In all the patients so examined, we did not find a single instance where any additional information obtained by brain mapping was superior to routine EEG. On 2 different occasions brain mapping was negative. In addition, in 4 cases patients had paroxysmal abnormalities on routine EEG, which was not seen on brain mapping. For focal abnormality, we find magnetic resonance imaging to be more informative than quantitative electroencephalography. Based on the present study and review of the literature, we find little evidence to support an expensive procedure like brain mapping in the evaluation of patients with dementia, especially when the yield is less than routine EEG. Delineation of focal abnormality is inferior to the neuroimaging procedure and lack of demonstrating paroxysmal activity as well. 64. PSO evoked potentials in epilepsy. -
M.E. Drake, Jr., J.L. Moore and S.J. Weate (Division of Epilepsy and Clinical Neurophysiology, Departments of Neurology and Psychiatry, Ohio State University Medical Center, Columbus, OH)
Event-related potentials have been occasionally investigated in epilepsy. We recorded P50 auditory evoked potentials in patients with complex partial seizures of frontal and temporal lobe origin. Fifty patients and 50 controls were compared. P50 was elicited by paired rarefaction clicks presented first every 10 set then S/set, binaurally at 76 dB SL, with 200 msec analysis time, 0.1200 Hz filter bandpass, and 100 averages recorded from Fz and Cz to linked-ear reference. P50 was significantly reduced in amplitude and prolonged in latency in temporal lobe seizure patients as compared to controls. Patients with complex partial seizures originating in the frontal lobes did not differ from controls in P50 amplitude. P50 attenuation with more rapid stimulation was greater among controls than in both groups of seizure patients, P50 abnormality in partial epilepsy of temporal lobe origin may support suggestions of a temporal cortical origin for this potential. P50 attenuation differences may be related to interictal behavioral or cognitive changes, but could also reflect medication effects. Event-related potentials may be helpful in differentiating frontal and temporal seizure foci. Supported in part by the Galbraith Ohio State University.
and Spafford
Research
Funds,
65. EEG frequency analysis in obsessive-compulsive disorder. -
M.E. Drake, Jr., A. Pakalnis and S.A. Newell (Division of Epilepsy and Clinical Neurophysiology, Departments of Neurology and Psychiatry, Ohio State University Medical Center, Columbus, OH) The cerebral basis of obsessions creasing
attention
in neuropsychology
and compulsions has attracted inand neuropsychiatry. Clinical and
and clinical Neurophysiology 95 (I 995) 15P-41P
27P
imaging studies have suggested frontal lobe dysfunction in some cases of obsessive-compulsive disorder and Tourette’s syndrome with obsessional symptoms. We compared EEG spectral measures in 20 such patients on no medication and 12 neurologically intact unmedicated controls. EEG was recorded from Ol-Al + A2, 02-Al + A2, Fz-Al + A2, F7-C3, F8C4, T5-01 and T6-02. One minute epochs of artifact-free EEG were used for compressed spectral array and calculation of time domain descriptors. We measured modal alpha frequency (MAF), maximal alpha frequency (MxAF), spectral edge frequency (SEF) and spectral mobility in left and right frontal regions (MOLF and MORF). MAF and MxAF were reduced in the frontal regions in patients as compared to controls, and MOLF and MORF were both lower. No significant differences between patients and controls were found in the temporal or occipital areas. These observations support the suggestions of an organic basis for obsessions and compulsions, and of frontal lobe disturbance in their pathophysiology. Supported in part by the Galbraith Ohio State University.
and Spafford
Research
Funds,
66. Quantitative changes in the EEG of adult rat offspring prena-
tally exposed to lorazepam. - G.T. Livezey and C.V. Smith (Department of Obstetrics and Gynecology, University of Nebraska Medical Center, Omaha, NE) Quantitative analysis of the EEGs of infants exposed prenatally to centrally acting drugs may be predictive of delays in subsequent motor and cognitive development. We have applied a quantitative approach to the analysis of EEGs from adult rat offspring exposed in utero to lorazepam (LZ), an anxiolytic agent commonly used in women of childbearing age. Female Sprague-Dawley rats were administered 1 mg LZ/kg/day (equivalent to 4 mg/day in a 60 kg woman) for 21 days prior to breeding, and continued throughout their 21 day gestation. The EEGs of l-year-old offspring of both sexes were telemetrically monitored for 24 h before and 24 h after a 1 mg/kg challenge dose of LZ. Total spectral power and the percentage of the total spectral power distributed to delta (l-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), middle beta (12-16 and 16-20 Hz) and fast beta (20-24, 24-28 and 28-32 Hz) frequency bands were examined by ANOVA. Offspring exhibited both dose- and sex-dependent alterations in baseline and drug challenged EEGs consistent with a general deficit in the capacity to synchronize neuronal activity as well as permanent functional tolerance to LZ. These results are compared to data from a previous study of phenobarbital. 67. Inter-intra-patient comparison and quantification of normalized
3D basal wire Dame maps of ictal and interictal temporal lobe epileptic discharges. - J.R Ives, L.J. Gruber and D.L. Schemer (Department of Neurology, Beth Israel Hospital and Harvard Medical School, Boston, MA) Unlike traditional top-down, coloured brain maps, the use of normalized, 3D, wire frame, topographical, basal-view maps permits quantification of temporal lobe epileptic discharge activity as well as inter-patient and intra-patient comparison of ictal and interictal discharges. In the same patients, the comparison between their averaged ictal map and their averaged interictal map can be obtained by simple subtraction. A flat topographical result indicates that the anatomical source of the epileptic discharges is probably the same. In the same patient with independent bitemporal interictal discharges, the left map can be mathematically mirrored and simply subtracted from the right. A flat topographical map indicates that the sources are probably anatomical “mirror” foci. In a “new” patient, either or both the ictal and interictal maps can be compared to a library of maps obtained from patients with well established and extensively documented etiology, morphology and localization history. Again a flat topographical result probably indicates that the “new” patient has a similar anatomical focus to the known focal patient.