Is it time for individualized testing in the electroencephalogram (EEG) laboratory?

BACKGROUND AND PURPOSE: The interictal electroencephalogram (EEG) has an important role in the classification and treatment of epilepsy. In busy EEG laboratories, valuable resources are used in order to comply with current recommendations regarding the length of EEG recordings. Our aim was to examine the time to first interictal epileptiform discharge (IED) in standard and sleep-deprived EEGs. METHODS: Standard and sleep-deprived EEG recordings with IEDs were retrospectively reviewed during a 2-year period. Bedside EEGs and long-term video-EEGs were excluded. IED latency according to EEG type, age group and inpatient/outpatient status was analyzed with the Kaplan-Meier estimator. RESULTS: The study group included 684 patients, 372 (54%) males, aged 0.2-89 years. Standard (n = 316) and sleep-deprived (n = 368) EEGs were performed in 245 inpatients and 439 outpatients. The EEG was requested in 96% of the inpatients following a seizure. Most IEDs were recorded whilst the patients were awake (43%) or drowsy (34%). Ninety percent of the IEDs were recorded within 18.5 min, earlier in standard (14.6 vs. 21.3 min) (P = 0.024) EEGs and in inpatients (14 vs. 21.3 min) (P = 0.002). IED latency was unaffected by age. CONCLUSIONS: Electroencephalogram type and admission status may be used for individual determination of the duration of EEG recording. Reducing the duration of standard and sleep-deprived EEGs may be considered especially in inpatients.

When should a sleep-deprived EEG be performed following a presumed first seizure in adults?

OBJECTIVES: To evaluate the effect of the interval between the seizure and the EEG recording on the yield of early sleep-deprived EEG (SD-EEG) in patients admitted following a presumed first seizure. MATERIALS AND METHODS: We retrospectively reviewed the EEG recordings and medical records of patients admitted to the Neurology Department in Assaf Harofeh Medical Center because of a presumed first seizure during a 3-year period between 2006 and 2009 and who had a SD-EEG following a first routine EEG without epileptiform discharges (EDs). RESULTS: The study group included 78 patients aged 18-78 years (mean 35 ± 17). Previous seizures were recognized through repeated history in 32 (41%) patients. EDs were recorded in the SD-EEG in 16 (21%) patients: 13/46 (28%) with a SD-EEG performed within 3 days following the seizure and 3/32 (9%) with a later SD-EEG (P = 0.042) and in 10/32 (31%) patients in whom previous seizures were recognized and 6/46 (13%) with a first seizure (P = 0.05). CONCLUSIONS: EDs in the SD-EEG following a first diagnosed seizure occur more commonly when the test is performed within 3 days following a first seizure or when previous seizures are recognized.

Electroencephalography findings in adult patients with West Nile virus-associated meningitis and meningoencephalitis.

Eighteen adult patients with serologically confirmed West Nile virus (WNV)-associated meningitis or meningoencephalitis were admitted to our hospital during the 2000 West Nile fever outbreak in Israel. Thirteen of the patients had a more severe and prolonged clinical course, and an electroencephalogram (EEG) was, therefore, requested. A specific EEG pattern was seen in 8 patients, consisting of generalized slowing, which was more prominent over the anterior regions. Generalized slowing that was prominent over the temporal area was seen in 2 patients, and intermittent slowing over the temporal region was seen in 1 patient. Two patients had normal EEG findings. We suggest that WNV meningoencephalitis should be considered in the differential diagnosis of meningitis or meningoencephalitis with a prolonged clinical course and anteriorly predominant slowing on an EEG.

Inhibition of human red blood cell glutathione reductase by valproic acid.

Glutathione reductase (GR) one of the enzymes of the glutathione redox cycle, plays a salient role in maintaining appropriate cellular levels of reduced glutathione. The enzyme in human red blood cells is inhibited in vitro by the anticonvulsant drug valproic acid (VPA). The inhibition is dose-dependent, reversible, uncompetitive and does not depend on the redox state of the enzyme. VPA also inhibits red blood cell GR activity in children being treated with the drug. The level of serum VPA correlates significantly with the suppression of GR activity.

Cimetidine-related cardiac conduction disturbances and confusion.

A 70-year-old woman free of renal or hepatic dysfunction developed reversible mental confusion, sinus bradycardia, and extreme QT interval prolongation following initiation of intravenous cimetidine 1200 mg daily. The association of mental confusion with cardiac conduction impairment in a single patient in the context of cimetidine toxicity is highly unusual. We review this and other reports on potentially fatal cimetidine-related cardiac conduction disturbances to suggest that in patients at risk, in addition to reducing cimetidine dosage, electrocardiogram (ECG) follow-up is indicated to identify dangerous bradycardia and QT interval prolongation.

Folic acid deficiency, megaloblastic anemia and peripheral polyneuropathy due to oral contraceptives.

A 34-year-old woman developed megaloblastic anemia and peripheral polyneuropathy following the use of oral contraceptives for 4 years. Low levels of folic acid and vitamin B12 were found. Both the complete recovery after therapy with the vitamins, and the absence of other causes of vitamin B12 and folate deficiency, suggest that the vitamin deficiencies were caused by the oral contraceptives and resulted in the rare combination of megaloblastic anemia and polyneuropathy. The poor response to vitamin B12 alone, and the development of anemia and polyneuropathy 4 months after cessation of vitamin B12 therapy suggest that folate deficiency was the primary problem.

PIP: A 34-year old woman developed megaloblastic anemia and peripheral polyneuropathy following the use of oral contraceptives (OCs) for 4 years. Low levels of folic acid and vitamin B12 were found. Both the complete recovery after therapy with the vitamins and the absence of other causes of vitamin B12 and folate deficiency suggest that these were caused by OCs and resulted in the rare combination of megaloblastic anemia and polyneuropathy. The poor response to vitamin B12 alone, and the development of anemia and polyneuropathy 4 months after cessation of vitamin B12 therapy suggest that folate deficiency was the primary problem.

Tiapride as treatment for certain patients with idiopathic torsion dystonia.

Five female patients with idiopathic torsion dystonia (ITD) responded to treatment with tiapride, a selective D-2 dopamine antagonist. Previous treatments with various drugs, including anticholinergics, were ineffective. It is suggested that the previously reported genetic subgroups of ITD respond to different drug regimens. The autosomal dominant group responded to anticholinergics, while the autosomal recessive group responded best to a selective D-2 dopamine antagonist.