Appearances are deceptive? Long-term cognitive and central auditory sequelae from closed head injury

The purpose of the present study was to examine possible signs of long-term cognitive and/or central auditory sequelae seven to eleven years after a closed head injury (CHI) of sufficient severity to cause scull fracture and/or brain contusion. Another purpose was that this investigation should be carried out in a group of recovered trauma victims with, to the individual, no known or minimal sequelae. A computer-based set of five cognitive tests and three central auditory tests were used in a group of formerly brain-injured patients who considered themselves as well recovered. Most of the participants did not report any signs of cognitive or auditory impairment. Tests of working memory capacity, verbal information processing speed, phonological processing and verbal inference-making ability were used. Auditory brain response (ABR), distorted speech audiometry (interrupted speech), and phase audiometry were used to test central auditory function. The initial severity of brain damage, i.e. status when the patient arrived at the emergency ward, was estimated with Swedish Reaction Level Scale (RLS). Cognitive shortcomings after CHI were demonstrated in a high percentage (59%, 13/22) of the cases seven to eleven years after the injury. Central auditory processing disorders (APD) were also demonstrated in a fairly high percentage (58%, 11/19) of the subjects. None of the correlations between RLS and the results on cognitive and central auditory tests reached statistical significance. However, there was a correlation between cognitive performance and the results on the central auditory tests used in this investigation. Eighty percent (8/10) of those participants with pathologies on ABR and/or phase audiometry and/or IS also failed on one or more of the cognitive tasks, compared to 44% (4/9) among those with no signs of APD. It is possible, many years after CHI, to observe cognitive shortcomings and APD in a relatively high percentage of CHI cases that are subjectively considered to be fairly well recovered. The cognitive tasks used in the study have proved to be a sensitive method to discover cognitive impairments. Long-term cognitive sequelae and APD could not be predicted from RLS scores.