Serial Electroencephalographic and Clinical Studies in a Case of Prolonged Insulin Coma

Abstract

PROLONGED coma is one of the important complications of insulin shock treatment for schizophrenia. With a normal or elevated blood sugar, induced by administration of dextrose, the patient remains comatose. Temperature becomes elevated, pulse becomes rapid, and there is a shifting neurological picture. Coma may persist from a few hours to several days, and when consciousness is recovered, there are frequently disturbances in the sensorium, memory changes, and other mental alterations of an organic type. The etiology is not clearly understood.1Cases of prolonged coma obviously provide an excellent opportunity to study the brain potential correlates of reversible neurological and mental changes, usually severer and of longer duration than any which may be induced in humans by deliberate experimental manipulation. Since prolonged coma may occur in one-sixth of all patients subjected to a course of insulin coma therapy,2 it is surprising that few EEG studies have so far been reported. The most extensive series are described in the recent papers of Yeager, Simon, Margolis, and Burch 3 on 12 cases and of Revitch * on 5 cases. Single cases have been reported by Proctor and Easton,5 Goldfarb, Laughlin, and Kiene," and Fister.7 The findings of these authors have been relatively uniform. Diffuse slowing of rhythms was found associated with altered sensorium or organic confusion, and the EEG returned to normal as clinical recovery took place. There seemed to be a correlation of length of coma, degree of organic confusion, remission of mental symptoms, and degree of EEG abnormality. EEG changes accompanying neurological complications of insulin have been described by Allan and Crommelin 8 in a juvenile diabetic and by Halle and Ross 9 in four cases undergoing coma therapy. The latter found localized EEG abnormal¬ ities, related to the neurological signs, which disappeared when the signs cleared up. Wyke 10 reported detailed serial studies, correlating clinical, EEG, and blood sugar observations, on a 9-year-old girl with hypoglycemia due to islet cell tumor of the pancreas. Wyke considered that the frequency spectrum of the EEG bore a more direct relation to the clinical picture than did the blood sugar level.The present paper is a report, with serial EEG studies, of a particularly interest¬ ing case of prolonged coma. Most of the important cerebral complications following coma were observed in this case, and it was possible to correlate state of conscious¬ ness with EEG changes.