The purpose of this study is to demonstrate normal values and age effect on the Middle Latency Response, and to evaluate the prognostic value of brain-stem auditory evoked potentials and Middle Latency Response in brain injured patients.

The subjects of this study were sixty-three adult volunteers and thirty brain injured patients who were admitted to the Department of Rehabilitation Medicine, Yonsei University College of Medicine, and managed with a comprehensive rehabilitative treatment between March 1, 1988 and Jan. 1, 1989.

The main results are as follows:

1) In the Middle Latency Response, the mean latencies of wave Na and Pa were 21.7±2.50 msec and 32.5±2.14 msec, respectively; and the mean amplitude of Na-Pa was 1.03±0.383㎶.

2) Although no significant effect of sex and site was noted, the mean latencies of wave Na and Pa became significantly prolonged and the mean amplitude of Na-Pa larger with increments of age(p<0.05).

3) Among the 30 brain injured patients, there were 21 males and 9 females. The mean age was 48.3 years.

4) All of the brain injured patients showed normal brain-stem auditory evoked potentials.

5) At discharge, the brain injured patients who showed normal Middle Latency Response at admission had achieved significantly greater improvement in their functinal status compared with those who showed abnormal Middle Latency Response (p<0.01).

According to the above results, the Middle Latency Respense study in the early stage of rehabilitation is helpful in predicting the prognosis of brain injured patients.