The study of blink reflexes was carried out to demonstrate the correlations, if there were, between the stage of diffuse axonal injury(DAI) and the abnormality of blink reflexes. The blink reflex was recorded in 20 healthy adult subjects and 22 patients with DAI who were classified according to Adams' classification(DAI I; 7, DAI II; 9 and DAI III; 6). The latencies and amplitudes of R1 and R2 in patients with DAI were compared with those of healthy subjects.

The results were as follows; 1) In 20 subjects of patient group, the latencies of R1 were all within a normal range. In 2 subjects, the difference in latencies between the two sides was above 1.4 msec. 2) In 15 subjects, R2 was absent or delayed, and reduced in the size of amplitude in all. Nine were affected bilaterally, and 4 were unilaterally. 3) Seventy one percent of patients in each stage represented abnormal findings. 4) There were no correlations between the DAI stage and the blink reflex.

This study demonstrated that the polysynaptic R2 was more profoundly suppressed than the oligosynaptic R1 in a diffuse axonal injury because of a loss or decrease of suprapontine facillitation, which influenced the trigeminal spinal complex and the interneuron of lateral reticular formation.