Electroencephalogram and seizures in chronic alcoholism

Abstract

CNS complications of chronic alcoholism are frequently difficult to assess due to the variety of direct and secondary conditions which can result from alcoholic drinking and lifestyles. The influence of alcoholism and alcohol-related factors on the EEG of patients with chronic alcoholism was studied in 213 patients (15.4% of all adults who had EEGs) using visual analysis. The influence of a variety of alcohol-related factors — drinking history, clinical complications, traumatic head injuries, head CT findings and laboratory results — on the EEG and alcohol-related seizures was studied. The effect of EEG results on the decision to treat alcohol-related seizures was also assessed. 152 of the patients had seizures, mostly (90% of those with defined seizure types) generalized tonic-clonic seizures. 53% of all seizures occurred in the early withdrawal period (8 h to 7 days abstinence). A history of partial seizures was significantly associated with findings of focal EEG abnormalities, a history of head injuries and structural lesions on CT. The clinical significance of these findings was unclear, however, as the majority of patients who had focal EEG abnormalities or structural brain lesions still appeared to have generalized withdrawal seizures. The EEG and CT appeared to be complementary tests: for most patients, focal abnormalities were demonstrated on only one of the two tests. The majority of patients (56%) with normal EEGs had predominantly low voltage recordings (< 25 μV), compared with 13.9% of 1167 patients without a history of alcoholism ( P < 0.001). Other alcoholism-related factors, such as head injuries and structural abnormalities on CT and age, did not influence the occurrence of low voltage recordings. A slight increase in frequency of low voltage records occurred in patients with cortical atrophy identified on CT. These findings were verified in a smaller controlled, prospective study of 24 patients. Several other clinical findings in patients with alcohol-related seizures included hypoglycemia in two patients, and the finding of lower serum magnesium levels in patients with seizures (mean 1.36±0.04 mEq/l) compared with those who had delirium or other diagnosis (mean 1.6±0.10 mEq/l, P < 0.05). Hypomagnesemia did not appear to be a precipitating factor in the development of alcohol-related seizures, as patients in various stages of abstinence had similar magnesium levels. One-half of patients were treated chronically with anticonvulsants and only one maintained therapeutic drug levels and two had overdosages. A history of recurring seizures (and particularly of partial seizures) was a more important factor in the decision to treat with chronic anticonvulsant therapy than was the results of EEG. The finding of low voltage EEG is useful in detecting alcoholism, although this findings is not specific for alcoholism. The role of EEG in chronic alcoholism is more contributory to the clinical evaluation than it is widely assumed.