Re-examining the concept of severity in traumatic brain injury

This paper re-examines the theoretical concept of severe brain injury focusing on the duration of coma as a precise indicator of the clinical profile. A retrospective hospital chart study of 361 traumatic brain-injured patients was undertaken to determine the homogeneity of the subsample of the severely brain-injured (defined as 2 or more days of coma) with respect to the probability of four types of impairment: ataxia, contractures, paralysis and speech impairment. The current concept of severity assumes homogeneity among the 'severely brain-injured'. However, our results indicate significant differences in impairment within this population. The authors feel strongly that future studies must describe coma duration in finer gradations, and test for homogeneity within samples before inferences are made. Improvements in life-sustaining technologies have resulted in longer coma durations. The need to use coma days as an indicator of impairment rather than a broad category of severity is emphasized.