Society proceedings 13P

patients ~18 months old. Ictal EEGs, at all ages, most commonly were generalized slow wave transients followed by decrements, less com- monly diffuse ‘fast’ rhythms. Identifiable etiologies, focal EEG features and partial seizures were more common in patients with hypsarrhyth- mia. Mental/developmental retardation and medical intractability was characteristic of all.

B203: Prediction of lower developmental performance of healthy preterm survivors by neonatal EEG-sleep measures - Mark S, Schera, Doris A. Steppea and David L. Banksb (‘Department of Pediatrics, Children’s Hospital of Pittsburgh and Magee- Womens Hospital, University of Pittsburgh School of Medi- cine, and bDepartment of Statistics, Carnegie Mellon Univer- sity, Pittsburgh, PA 15213)

Developmental assessments were obtained at 12 and 24 months for thirty healthy preterm (~32 weeks) and fullterm cohorts, who received neonatal EEG-sleep studies. Preterm infants had lower scores (adj R2 = 56. P < .OOOl) at 12 months of age than fullterm infants when they were not corrected for prematurity. After correction, significantly lower scores were noted for these healthy preterm infants (adj R2 = .29; P < .02 respectively). At 24 months of age, significantly lower scores were again noted for preterm infants only before correction (adj R2 = 34; P < ,005). Lower spectral EEG energies in the alpha and beta frequency ranges, lower REM counts, and higher spectral EEG correla- tions, which distinguished preterm and fullterm neonatal cohorts at postconceptional term ages later correlated with lower developmental performances. At 24 months of age, socioeconomic class also corre- lated with lower developmental scores in preterm neonates before cor- rection for prematurity. Although this cohort of healthy preterm infants escaped major neonatal illnesses, specific neonatal EEG-sleep measures predicted lower developmental performance compared to a fullterm group. Adjustment for ‘age equivalency’ is still required at least to 24 months of age as predicted by neonatal neurophysiologic measures of brain function. Factors associated with lifestyle (i.e., socioeconomic status) exert an influence at older ages. Supported by NSOI 110, NS.26793, RR00084.

B204: The unusual variants of SREDA (subclinical rhythmic elec- trographic discharge of adults) - Barbara F. Westmoreland and Donald W. Klass (Mayo Clinic, Rochester, MN 55905, USA)

We first described a group of predominantly elderly patients with SREDA in 198 I. Since then, we have collected a total of 108 patients with SREDA and have observed some unusual variants. The character- istic SREDA pattern begins abruptly with rhythmic sharp-contoured components followed by a non-evolving theta rhythm with a wide- spread distribution. maximal over the parietal-posterior regions, and lasts for several seconds or a minute without subjective or objective clinical manifestations. The unusual variants of SREDA that we have observed arc also subclinical and include: predominantly delta fre- quency, notched waveforms, predominant frontal distribution, more localized distribution, more prolonged duration, and occurrence during sleep. Neither typical SREDA or these variants correlate significantly with epileptic seizures, and both need to be distinguished from electro- graphic seizure discharges.

B205: Epileptiform abnormalities in hepatic encephalopathy - David M. Ficker, Frank W. Sharhrough, and Barbara F. Westmoreland (Department of Neurology, Mayo Clinic, Roch- ester, MN 55905 USA)

Epileptiform abnormalities are not very common in patients with hepatic disease; however, In a review of EEGs in patient with a diag- noses of encephalopathy over a IO-year period, I8 (13%) of the patients had epileptiform abnormalities on the EEG. This consisted of focal

spike and sharp wave discharges in 3, bilateral independent discharges in 5, periodic lateralized epileptiform discharges (PLEDs) in 5, and generalized spike and wave discharges in 5. Ten patients had electro- graphic seizure discharges, focal in 6 and generalized in 5. Five patients had electrographic status epilepticus, partial in 2, generalized convul- sive in 2, and generalized nonconvulsive in 1. Twelve of the patients had clinical seizures, partial in 4 (which became secondarily general- ized in 1) and generalized in 8. Two patients presented with convulsive status epilepticus. Ten patients died, 2 patients became worse clinically, 5 patients remained unchanged, and one patient improved. The pres- ence of epileptiform abnormalities when seen in patients with hepatic encephalopathy generally indicates a poor prognosis.

B206: Course of electroencephalographic findings in Hashimoto’s encephalopathy - J. Cibula, R. Henchey, W. Helveston, J. Malone, R. Gilmore (University of Florida, Gainesville, FL 32610; Department of Neurology, College of Medicine, Uni- versity of Florida, Gainesville, FL32610)

Hashimoto’s encephalopathy is a steroid responsive relapsing dis- order frequently presenting with seizures and EEG abnormalities. We report the EEG findings in ten patients with encephalopathy and/or seizure associates with elevated antithyroid antibodies. There were several combinations of EEG findings within the same patient from time to time and from one patient to another. Six patients’ EEGs had generalized slowing or frontal rhythmic slowing; three also had nipha- sic waves. One had periodic sharp waves. Four had bitemporal slowing, left > right. Hashimoto’s encephalopathy is heterogenous both clini- cally and electrographically. A high level of suspicion is necessary to establish the diagnosis. The EEG findings change over the course of the illness and usually improve with appropriate treatment.

ClOl: Aberrant somatosensory evoked fields in patients with arte- riovenous malformations: evidence for cortical reorganization - Howard A. Rowley and Timothy P.J. Roberts (Departments of Radiology and Neurology, University of California, San Francisco, CA 94143)

We studied surgical candidates with hemispheric mass lesions, both congenital and acquired, in order to establish evidence for cortical reorganization. Fifty consecutive patients with frontal or partial mass lesions were recruited: 35 with brain tumors and 15 with arteriovenous malformations (AVMs). All underwent somatosensory evoked field mapping using a large array (37.channel) biomagnetometer (BTI, San Diego.) Signal averaged data were fit using a single equivalent current dipole model and coregistered to magnetic resonance images. Cortical sensory localizations were obtained for both hemispheres in all 35 tumor patients. With large tumors near the central sulcus, there was appropriate displacement of dipoles due to mass effect in some cases. Four of the 1.5 AVM patients showed aberrant displacement of sensory dipoles, and one had no detectable responses in the involved hemi- sphere. One third of our AVM patients, but none of our tumor patients, showed aberrant or absent somatosensory evoked fields. The potential for cortical reorganization must be considered when mapping or trcat- ing patients with congenital brain lesions. Supported by Biomagnetic Technologies. Inc.

C102: Functional magnetic resonance imaging in a patient with continuous occipital seizures - E. Passaro, S.Y. Bookheimer, M.S. Cohen, J. Engel (UCLA School of Medicine, Los Angeles, CA)

M.C. is a 48 year old woman with simple partial occipital seizures since childhood. With eyes closed, she perceives flickering lights which disappear during eye opening. We performed functional MRI using a GE I .5 Tesla scanner with an SPGR sequence. The patient rested with eyes closed for 4 one minute blocks and opened her eyes during 3 inter-