BRAINSTEM AUDITORY EVOKED POTENTIALS IN POLYNEUROPATHY: A PROSPECTIVE STUDY

In this study, a BAEP study was performed to evaluate acoustic nerve involvement in 39 patients (30 males, 9 females) affected by demyelinating and axonal polyneuropathy with various etiologies. Twenty similarly age–matched healthy volunteers were taken as the control group. Of patients, 16 had demyelinating and 23 had axonal neuropathy. While demyelinating group composed of 5 Hereditary Motor and Sensory Neuropathy (HMSN) type-I, 5 acute inflammatory demyelinating polyneuropathy, 4 chronic inflammatory demyelinating polyneuropathy and 2 uremic neuropathy patients, axonal neuropathy group composed of 2 HMSN type II, 12 diabetic neuropathy, 5 acute sensory motor axonal neuropathy, 3 alcohol-related neuropathy and 1 neuropathy associated with polyarteritis nodosa patients. In overall evaluation, 12 of 39 patients (30.7%) had abnormal BAEP findings, BAEP wave latency changes were prominent in demyelinating neuropathy rather than in axonal neuropathy (7.69% and 23.7%, respectively). While statistically significant prolonged latency in wave I was detected in HMSN type-I patients (p < 0.01, for both ears), belonging to demyelinating group, not only prolonged latency in wave I but also in I-III interpeak latency were observed in acquired demyelinating neuropathic patients (p < 0.01, for both ears). Abnormal BAEP findings showed a correlation only with median motor and sural conduction velocities. There was not any significant difference between the axonal neuropathy group and the control group in terms of BAEP findings.

As a conclusion, this study revealed that demyelinating patients had more frequent and severe acoustic nerve involvement when compared to patients with axonal neuropathy, and both distal and proximal parts of acoustic nerve in patients with demyelinating neuropathy were involved.