M. Sundaram

Seizures associated with spontaneous subarachnoid hemorrhage.

We analysed the charts of 131 consecutive cases of spontaneous subarachnoid hemorrhage--without arteriovenous malformations--for seizures. Convulsions occurred in 31 patients (24%) and most often within 24 hours of bleeding. Motor manifestations of partial seizures were of no lateralizing value to aneurysm site. Early mortality, rebleeding and intracerebral hematoma were similar in both seizure and non-seizure groups. Late seizures were infrequent in survivors who had suffered seizures in the acute stage--thus questioning the necessity for routine, long term prophylactic anticonvulsants in these patients.

Domoic acid induced seizure activity in rats

Domoic acid, in increasing doses (10-300 pmol), was microinjected into the hippocampal CA3 region of rats. All rats consistently exhibited generalized bilateral electrical seizure discharge activity at 100 pmol of domoic acid. Seizure latency varied inversely with the dose of domoic acid in the range tested. Local hippocampal administration of gamma-aminobutyric acid (GABA) resulted in neuronal recovery from domoic acid-induced seizures. The seizure activity of domoic acid might be the result of decreased GABAergic inhibition.

Factors affecting interictal spike discharges in adults with epilepsy

We investigated various factors affecting interictal spike discharges (ISDs) in standard interictal EEGs of 203 consecutive cases with seizure(s). 94 EEGs (46%) showed ISDs. Yield was maximum (68%) when recordings were done within 2 days of a seizure; beyond this period, incidence of ISD did not change with time from the last seizure. EEGs of patients having greater than 12 seizures/year were more likely to contain ISD (68%) than the records of cases with less than 12 attacks/year (37-41%; P less than 0.001). Age and neurological status at the time of EEG, etiology and anticonvulsants did not influence the frequency of ISD. Analysis of serial EEGs (n = 512) from the study group showed that if initial 3 EEGs lacked ISD, yield from further standard EEGs is small.

Triphasic waves: clinical correlates and morphology.

Twenty-six (41%) of 63 consecutive patients with triphasic waves had various types of metabolic encephalopathies while 37 patients (59%) had non-metabolic encephalopathies, usually senile dementia. Triphasic waves were not found to be specific for any single type of metabolic encephalopathy. Etiology was more closely linked to conscious level at recording than any morphological or distributional feature of the triphasic waves themselves. Thus, all 31 alert patients had non-metabolic encephalopathies while all 13 comatose patients had metabolic encephalopathies. The second, positive, component (Wave II) most often had the highest voltage while equally maximal Waves I and II occurred next most commonly. Triphasic waves were most often maximally expressed anteriorly. Among patients with metabolic encephalopathies, a posterior-anterior delay or lag of the wave II peak occurred more commonly than did the better known anterior-posterior lag. Lags occurred with both metabolic and non-metabolic conditions, but were more common with the former. No difference in quantity or mode of appearance existed between the metabolic and non-metabolic groups when matched for conscious level. Prognosis for patients with either metabolic or non-metabolic encephalopathies was unfavourable. Only 4 of 24 metabolic and one of 35 non-metabolic patients were well at follow-up over 2 years later. Forty percent of EEGs with sharp and slow wave complexes (slow spike waves) had sporadically-appearing triphasic waves. The relative amplitudes of the 3 components differed from triphasic waves in other conditions: equally maximal Waves II and III were the most usual form.

EEG in epilepsy: current perspectives.

The electroencephalogram (EEG) plays an important diagnostic role in epilepsy and provides supporting evidence of a seizure disorder as well as assisting with classification of seizures and epilepsy syndromes. Emerging evidence suggests that the EEG may also provide useful prognostic information regarding seizure recurrence after a single unprovoked attack and following antiepileptic drug withdrawal. Continuous EEG video telemetry monitoring has an established role in the diagnosis of non-epileptic pseudo-seizures and in localizing the seizure focus for epilepsy surgery. Newer tools such as EEG mapping and magneto-encephalogram, although still investigational, appear potentially useful for defining the seizure focus in epilepsy. This review examines the traditional concepts of clinical EEG in the light of newly available data.

Etiology and patterns of seizures in the elderly.

67 consecutive, unselected patients with seizure onset after the age of 60 were studied prospectively in a general hospital with only neurosciences facilities for a population of 500,000. Investigations in most cases included CT scan of the brain and EEG. Etiology could be determined in 44 (66%): tumor- 16 (22%), stroke - 15 (22%) and miscellaneous - 13 (20%). Seizures were partial in 45 (67%) and generalized from onset in 22 (33%). Seizures were exclusively nocturnal in 8 of 23 (35%) cases with unknown etiology.

Polymyositis presenting with distal and asymmetrical weakness.

Reprint requests to: Dr. E.M. Ashenhurst Department of Clinical Neurological Sciences, University Hospital. Saskatoon. Saskatchewan. Canada S7N 0X0. INTRODUCTION Polymyositis presenting with predominantly distal and asymmetrical weakness is rare. Only five patients have been described in detail. We describe a patient who presented with distal weakness and wasting of the left leg. The literature on this unusual form of polymyositis is reviewed.

Treat the patient, not the test

Since the pioneering work of Buchthal and Svensmark1 in 1960 correlating serum phenytoin and phenobarbital level with seizure control and toxicity, drug level measurement has become an important part of epilepsy management. Approximately 9,000 to 10,000 tests for serum anticonvulsant levels are ordered annually in a typical large North American hospital, at a cost of up to

Rhythmic auditory stimulation in generalized epilepsy

90 per test, depending on the drug tested. Drug levels are particularly useful in assessing noncompliance, which is thought to occur in up to 50% of patients with epilepsy at some point.2 Levels are also useful in explaining toxic symptoms when multiple drugs are used and in analyzing interactions due to protein binding or metabolic alterations. The serum levels of anticonvulsants, especially of the older drugs …

Abnormal EEG Patterns and the Effect of Sleep: A Review

Activation of spike-wave discharges by photic stimulations (PS) and rhythmic auditory stimulations (AS) was investigated in 40 patients with generalized epilepsy and 25 controls. PS produced spike-wave discharges in 23 (55%) and AS in 12 (33%) cases. In 4 patients AS activated spike-wave discharges but PS failed to do so. AS may be occasionally used in generalized epilepsy as an activating method when standard procedures such as hyperventilation and PS fail.