[Auditory brain stem responses of knocked-out boxers]

We studied about ABRs of boxers, who receive repeated impact to the head and are often concussed, immediately after bouts or training in order to reveal the influence of knock-out or repeated mild head injuries. Forty-six male professional boxers ranged from 18 to 28 years old, were examined at the stadium and the boxing gymnasium. 85 recordings were done since some boxers were examined more than once. 27 cases of pre-exertion group (resting: 5, pre-sparing: 10, pre-training: 12) were compared with post-bout group (35 cases). The I-V IPL (interpeak latency) of pre-exertion group was 4.30 +/- 0.18 m sec and that of post-bout group was 4.02 +/- 0.15 m sec. The latter showed significantly shorter (p less than 0.01) IPL. Among 35 cases of post-bout group, the I-V IPL of knocked-out group (14 cases) was 4.04 +/- 0.11 m sec, and that of non-knocked-out group (21 cases) was 4.01 +/- 0.17 m sec. There was no significant difference. The I-V IPL of pre-sparing state was 4.24 +/- 0.15 m sec, and that of post-sparing state was 4.10 +/- 0.13 m sec. The difference was significant between these two groups (p less than 0.01). After training without impacts to the head, I-V IPLs were shortened in all 12 cases. IPL of pre-training state was 4.34 +/- 0.22 m sec, and that of post training state was 4.19 +/- 0.22 m sec. This also showed significant difference (p less than 0.01). On one boxer, we recorded ABRs during disturbance of consciousness. He was knocked-out by a blow to the face in the first round, and was completely unconscious. ABRs were recorded twice immediately after he had been laid on the bed.(ABSTRACT TRUNCATED AT 250 WORDS)