Theta Pattern Coma, a Variant of Alpha Pattern Coma

Abstract

Electroencephalograms with a dominant rhythmic areactive 5Hz theta activity are reported in two comatose patients with fatal outcome. This pattern was followed by isoelectric EEG and death in the first patient, who suffered multiple injuries including severe cerebral concussion and later tentorial herniation. The second patient died eight hours after the second EEG recording, both EEGs having shown a very rhythmic 5-6 Hz activity which was maximal anteriorly. He died two days after a severe cerebral hypoxic episode due to acute respiratory failure. Both patients were in their late sixties. It is suggested that the dominant areactive theta activity is a variant of malignant "alpha pattern coma".

Observations on comatose survivors of cardiopulmonary resuscitation with generalized myoclonus

“…Such a coexistence seems to be a frequent phenomenon occurring more often than suggested by previous observations in single patients with transitions between alpha-and theta-coma-EEG, and between BS-EEG and alpha-coma-EEG [6,36-40]. …”

Aetiology and prognosis of encephalopathic patterns on electroencephalogram in a general hospital

“…None of these patients was comatose at the time of their EEG, unlike previous cases of ''theta coma", which have been associated with a poor outcome, and which has been suggested as a variant of malignant ''alpha pattern coma" by some authors. 13 The importance of the underlying diagnoses causing the encephalopathy rather than the severity of the ensuing EEG patterns in prognostication cannot be understated. This is exemplified by the prognosis of patients diagnosed with renal or hepatic failure, in which four of the seven (57%) patients with follow-up data had died within 19 months, despite six (86%) having ''mild" encephalopathic changes on EEG.…”

Rhythmic Coma in Children

“…A separate study concerning near-drowning victims reports that only 14% have a good prognosis. tis, and drug overdose),9.10.18-22 beta frequency (secondary to stroke, hypoxic-ischemic encephalopathy, and drug overdose),11.21,23 theta frequency (hypoxicischemic encephalopathy),'-~ and coexisting frequencies over the course of an acute illness (secondary to hypoxic-ischemic encephalopathy and drug overdose).9.11,21,22 Synek in 1984 and proposed an entity of theta coma and suggested its imilarity to alpha coma .24, 25 However, the description of their EEG findings in theta coma suggests a variant of a burst-suppression pattern at times with reactivity, rather than invariant, nonreactive, diffuse activity of a distinct frequency that qualifies as alpha-or other-frequency rhythmic coma. Moreover, their population dealt only with adults with cardiopulmonary arrest or motor vehicle accident victims with head trauma, both of which fit into poor prognostic groups from the adult literature' and as suggested by our data.…”