抄録
Auditory brainstem evoked potentials (BAEPs) reflect activities of the brainstem auditory pathway and its surrounding structures. It is said that BAEPs are reliable indicators of the prognosis of patients with severe brain damage. We studied the relationship between initial BAEP findings, particularly interpeak latencies of waves I to V and waves III to V, and mortality resulting from severe subarachnoid hemorrhage.
BAEPs were sequentially recorded in 76 cases of severe subarachnoid hemorrhage (Hunt & Kosnik grade IV, V) during the first few days after onset.
BAEPs were graded into four groups based on initial findings. Group A: waves I to V were all recorded (41 cases). Group B: waves IV & V were absent (3 cases). Group C: either wave I or waves I & II only were recorded (12 cases). Group D: all waves absent. Prognosis in Groups B & C was poor, with only one patient surviving in a vegetable state. There were no survivors in Group D.
The relationship between interpeak latencies (I-V ipl, III-V ipl) and prognosis in Group A is discussed in this paper. In cases where severe subarachnoid hemorrhage resulted in death, there was significant prolongation of I-V ipl and III-V ipl over the mean latency of 20 normal subjects plus 2SD. The difference in initial BAEP findings between the dead and survivors was significant (p<0.001). We reasoned that severe subarachnoid hemorrhage cases received primary brainstem damage and secondary brainstem damage due to increased intracranial pressure associated with acute cerebral swelling. We therefore concluded that poor prognosis could be predicted based on initial BAEP findings.
On the other hand, in acute hydrocephalus cases latencies were recovered by ventricular drainage. Continuous BAEP monitoring was therefore considered to be useful for predicting the effect of ventricular drainage in acute hydrocephalus.
BAEP monitoring appears to be a useful clinical indicator of prognosis of severe subarachnoid hemorrhage. Prolonged interpeak latencies of over mean plus 2SD can indicate poor prognosis in severe subarachnoid hemorrhage.
