A Review of the Usefulness of the Standard EEG in Psychiatry

Abstract

The goal of this paper is to draw conclusions about the usefulness of the standard EEG in psychiatry. In general, two thirds of psychiatric referrals for an EEG are expected to provide useful information. The emphasis in schizophrenia is placed on left-sided abnormalities, especially on the left temporal area. In mood disorders the emphasis is on right-sided foci, in addition to the controversial 6/sec spike and wave complexes, small sharp spikes and positive spikes. In the acute stage of alcoholism, a relationship is seen between the degree of intoxication and the amount of slow activity, while in the chronic stage an increase in slow activity is seen, but another change is fast activity on the temporal areas. During withdrawal a low seizure threshold can be seen as irregular bilateral spike and wave complexes. During abstinence 2-4 yr may be required before slow wave sleep is normal in all regards. Among the organic mental syndromes, delirium shows slow activity, except in delirium tremens, which often is associated with a normal record with fast activity. In dementia the prevalence of EEG abnormalities is related to the degree of impairment. After five sessions of ECT diffuse slow waves are often seen. In other conditions, among developmental disorders about one half of autistic children show abnormalities and epileptiform activity is not uncommon. Mild nonspecific abnormalities are seen in about 40% of dyslexics and also in behavior disorders. Anxiety disorders include anorexia nervosa, showing abnormal background activity related to the effect of starvation on cerebral metabolism. In panic attacks paroxysmal activity can be seen. In borderline personality positive spikes have been (again) associated with impulsivity and 6/sec spike and wave complexes with interpersonal problems. Of the drugs of abuse psilocybin and phencyclidine are often associated with generalized epileptiform patterns and with marijuana the alpha shows a decreased frequency with increased amplitude. Typically, an increase in slow activity is seen with psychotropic drugs if there is a change in the level of awareness. Finally, distinctive personality traits are, at times, seen in temporal lobe epilepsy and the phenomenon of "forced normalization" may appear when seizures stop and psychotic symptoms appear.