Ivo Drury

Focal Cerebral Magnetic Resonance Changes Associated with Partial Status Epilepticus

Summary: We report 2 patients with transient abnormalities on magnetic resonance imaging (MRI) associated with partial status epilepticus (SE). A man with a 4‐month history of partial seizures had complex partial SE for 9 days, with left temporal maximum on ictal EEG. Left temporal lobe T2 signal was increased on MRI during SE, but cerebral MRI was normal 9 weeks later. A woman with “cryptogenic” temporal lobe epilepsy for 16 years had complex partial SE for 1 week, with right temporal maximum on ictal EEG. T2 Signal was increased over the entire right temporal lobe, extending into the insula, without mass effect, on MRI 1 month after SE ended. Repeat MRI 1 month later showed marked decrease in volume of increased T2 intensity, without gadolinium enhancement, but with mild mass effect over the right anteroinferomesial temporal areas. A gemistocytic astrocytoma was resected. Focal cerebral MRI abnormalities consistent with cerebral edema may be due to partial SE but also may indicate underlying glioma, even in long‐standing partial epilepsy. Focal structural imaging changes consistent with neoplasm should be followed to full resolution after partial SE.

Intracerebral depth electrode monitoring in partial epilepsy: the morbidity and efficacy of placement using magnetic resonance image-guided stereotactic surgery.

OBJECTIVE To determine the indications for, efficacy of, and safety of depth electrode placement using magnetic resonance imaging (MRI)-guided stereotactic surgery in patients with intractable epilepsy. METHODS We analyzed retrospectively the results of depth electrode usage in 50 consecutive patients at the University of Michigan Hospitals studied in the years 1991 through 1994, using MRI-guided stereotactic implantation, in conjunction with simultaneous subdural strip electrode recordings. RESULTS There were no deaths, no infections, and no new neurological deficits. One small subdural hematoma adjacent to a subdural strip electrode was evacuated to prevent interference with ictal recording. Two cylindrical subdural electrodes were found to be intraparenchymal, as revealed by postoperative MRI, and were removed. One patient was unintentionally left alone briefly, and he pulled out the electrodes while confused postictally, requiring a subsequent operation for replacement. Ictal onset zones were successfully localized in 47 patients. CONCLUSION We have found intracerebral electrode placement to be as safe as subdural strip electrode placement and have found combined depth and strip electrode monitoring to be highly effective in localizing the onset zones of complex partial seizures. Intracranial monitoring was particularly useful in the detection of a single ictal onset zone in the absence of neuroimaging abnormality and in the definitive diagnosis of bilateral independent ictal onset zones in the temporal lobe epilepsy syndrome. The specific technical aspects of the procedure that contribute to a successful outcome are reviewed. A comparison with earlier reported series suggests that MRI-guided stereotaxy and pial inspection may reduce complications of depth electrode placement.

The value of pelvic thrusting in the diagnosis of seizures and pseudoseizures

Article abstract We evaluated pelvic thrusting as a potential diagnostic sign and localizing indicator of ictal onset. By reviewing the video-EEG results of patients with temporal lobe epilepsy, frontal lobe epilepsy, generalized epilepsy, and pseudoseizures. Pelvic thrusting occurred in 4% of right and 2% of left temporal lobe epilepsy patients, in 24% of frontal lobe epilepsy patients, and in 17% of patients with pseudoseizures. Pelvic thrusting is relatively common in frontal lobe epilepsy and in pseudoseizures, but also occurs in temporal lobe epilepsy.

INTERICTAL EPILEPTIFORM ACTIVITY IN ELDERLY PATIENTS WITH EPILEPSY

OBJECTIVE To examine the frequency of interictal epileptiform activity (IEA) in elderly patients with epilepsy. DESIGN AND METHODS From a consecutive 13,905 EEGs recorded over 5 years at a university hospital EEG laboratory, 558 studies were performed on outpatients aged 60 years or more. Medical record review identified 125 patients in whom a confident clinical diagnosis of epilepsy was made by a board-certified neurologist. The EEG findings in these patients were reviewed. The effects of various variables on the likelihood of detecting IEA were calculated using Fishers test and chi-square analysis. RESULTS IEA were present on the first EEG in 35% of 55 patients (mean age 65 years) with pre-existing epilepsy, and 26% of 70 patients (mean age 70 years) with seizure onset after 60 years. There were no significant differences in the frequency of IEA in patients with late onset epilepsy in the 7th or in the 8th decades of life. Most IEA were focal. Activation procedures added little additional information. Patients with more than one seizure per month were significantly more likely to have IEA (P = 0.016). There were no major differences in likelihood of IEA detection depending on the underlying cause of the seizures. CONCLUSIONS The frequency of IEA in elderly patients with epilepsy is substantially lower than that reported in epileptic populations as a whole. This low rate of IEA in routine EEG studies must be recognized when considering the diagnosis of an epileptic syndrome for episodic events happening in the elderly.

Postictal nose-rubbing in the diagnosis, lateralization, and localization of seizures

Background: Semiology is very useful in the diagnosis and classification of seizures. Some clinical signs occur primarily with specific localization-related epilepsies. Objective: To evaluate postictal nose-rubbing as a potential diagnostic sign and a potential lateralizing or localizing indicator. Methods: We reviewed presurgical prolonged video-EEG results of 50 consecutive patients with right temporal lobe epilepsy (TLE), 50 consecutive patients with left TLE, 50 consecutive patients with frontal lobe epilepsy, 11 consecutive patients with generalized epilepsy, and 100 consecutive patients with nonepileptic events. Videotapes of all events were reviewed independently by two investigators who were blinded to the results of the monitoring. The episodes of nose-rubbing and the hand with which the patient rubbed the nose were recorded. Results: Nose-rubbing occurred in 25 of 50 (50%) right TLE patients and in 21 of 50 (42%) left TLE patients. Approximately 90% of patients rubbed his or her nose with the ipsilateral hand. Nose-rubbing occurred in 5 of 50 (10%) frontal lobe epilepsy patients. Nose-rubbing was not seen in any patient with generalized epilepsy or nonepileptic events. Postictal nose-rubbing did not occur after secondarily generalized seizures. Conclusions: Nose-rubbing is an easily observed phenomenon, has high interobserver reliability, and provides useful lateralizing information in patients with TLE. It was less frequently seen in extratemporal lobe epilepsy and was not seen after generalized seizures or nonepileptic events.

Variance of interburst intervals in burst suppression

Each EEG performed over a 3 year period at the University of Michigan with a diagnosis of generalized burst-suppression (BS) was reviewed. Ten EEGs from 10 patients with hypoxic-ischemic encephalopathy (HIE-BS) and 21 records from 8 patients with pentobarbital induced burst-suppression for treatment of status epilepticus (SE-BS) were reviewed. For each EEG, the mean duration of 40 interburst intervals (IBIs) as well as their coefficient of variability were calculated. We found that in the SE-BS group the coefficient of variability of IBI duration was highly correlated with the logarithm of mean IBI duration while in the HIE-BS group, there was no significant correlation between these 2 variables. This suggests that the underlying mechanism causing BS is different in the 2 groups and might be related to a uniform and progressive affection of similar brain structures in the SE-BS group and a more patchy and variable pathology in the HIE-BS group.

Non-epileptic seizures in temporal lobectomy candidates with medically refractory seizures

Diagnosis of epileptic seizures is often based on temporal lobe epileptiform abnormalities appearing on interictal EEG, when reported ictal semiologies are consistent with temporal lobe seizures. It is unclear how often such patients have non-epileptic seizures. We studied 145 patients who had temporal interictal EEG spikes and reported ictal semiology characteristic of temporal lobe seizures, with long-term EEG-video-monitoring (LTM) for presurgical evaluation of medically refractory seizures. Nonepileptic seizures were unexpectedly recorded in 12 of these patients (8%). Outcomes after LTM in patients who had both epileptic seizures and nonepileptic seizures demonstrated that the epileptic seizures usually were controlled with medications. Our observations support LTM as useful in diagnosis of non-epileptic seizures in this group of patients. We suggest that ictal recordings always should be performed before epilepsy surgery, in part to avoid unintentional surgical treatment of nonepileptic seizures.

Benign Partial Epilepsy of Childhood with Monomorphic Sharp Waves in Centrotemporal and Other Locations

Summary: We reviewed EEGs from children whose history and clinical course was compatible with benign partial epilepsy of childhood with centrotemporal spikes. In 21% of patients with a single EEG focus, the discharge was outside the centrotemporal area. In 37.5% of patients with more than one focus, one was in the centrotemporal area while the other was not. We suggest that the typical EEG features of this syndrome are the normal background, the stereotypic morphology of the sharp waves, and their activation by drowsiness and sleep, not their exclusive location in the centrotemporal regions. Insistence on a centrotemporal location for the EEG discharges in this syndrome may lead to a misclassification of the type of epilepsy in some children with implications for therapeutic decisions and prognostic statements.

Generalized spike-waves, multiple loci, and clinical course in children with EEG features of benign epilepsy of childhood with centrotemporal spikes.

Summary: In 41 patients with EEG features of benign epilepsy of childhood with centrotemporal spikes (BECCT), we noted associated generalized spike‐wave discharges (GSWD) in 14.6% and multiple independent sharp wave foci in 9.8%. The presence or absence of these EEG features was not predictive of the clinical course. The high incidence of GSWD in children with BECCT suggests a possible relation in the expression of these two EEG traits.

Asymmetric hypsarrhythmia : clinical electroencephalographic and radiological findings

Summary: Twenty‐six children (16 boys and 10 girls) with hypsarrhythmia and infantile spasms (IS) were studied at the University of Michigan EEG Laboratory in a 4‐year period. Six (2 boys, 4 girls), had asymmetric hypsarrhythmia with a preponderance of both slowing and epileptic form activity over one hemisphere. All 6 had the symptomatic form of IS, 4 with dysplastic conditions, 1 with porencephaly from a cerebral infarct, and 1 with hypoxic‐ischemic encephalopathy. Five children had focal abnormalities on either physical examination or imaging studies. Four had the highest amplitude slowing and most epileptiform activity ipsilateral to the lesion, in 1, it was contralateral. Asymmetric hypsarrhythmia constituted 23% of cases with hypsarrhythmia examined at our EEG laboratory. The significant success in surgical therapy for some children with IS indicates the importance of identifying focal hemispheric abnormalities even if they are not apparent clinically. EEG may suggest focal changes not detected clinically or radiologically.