A clinical study of post-traumatic amnesia.

Abstract

Fifteen consecutive patients with head injuries, admitted to the neurosurgical services of the Winnipeg General and St. Boniface hospitals, were given two memory tests within 24 hours following recovery of consciousness. The first test concerned immediate recall of a series of digits, presented orally. The second was a paired-associates test which involved learning and retaining pairs of stimuli and also required that when one stimulus of the pair is given the subjects correctly respond with the other associated stimulus. Fifteen control subjects admitted to hospital for acute episodes other than head injury were tested. The controls were matched with the head-injured subjects for age and education. During the eight-minute retention interval a distraction stimulus was administered randomly to six of the head-injured subjects and to six matched controls. No defect was found in immediate (a few seconds) memory of the head-injured group. The distracting stimulus had no significant influence on retention. Verbal learning, as defined by the number of trials to reach a criterion score on a memory test, was impaired and verbal retention, tested by recall at one hour after the initial learning period, was also impaired. These findings suggest that head-injured patients have at least a temporarily decreased ability to form lasting memory traces.