AUDITORY BRAIN-STEM RESPONSE TEST BATTERY FOR MULTIPLE-SCLEROSIS PATIENTS - EVALUATION OF TEST FINDINGS AND ASSESSMENT OF DIAGNOSTIC-CRITERIA

A battery of auditory brain stem response (ABR) tests has been used to evaluate 39 multiple sclerosis (MS) subjects (9 with probable, 8 with possible, 6 with suspected and 16 with definite MS, according to conventional classification of the disease). Test battery included evaluation of ABR waveform, latencies and interpeak intervals, test-retest variability, rate-induced ABR changes, binaural increase of wave-V amplitude and effect of ipsilateral masking with broad-band noise. Test results allowed a measure of the sensitivity, specificity and efficiency of each test in the battery. The high efficiency values thus obtained validated each test in the battery when normals were compared with definite MS patients. No single test, however, proved to be sufficient--by itself--to reliably distinguish subjects with earlier stages of the disease, suggesting that a combined evaluation of tests is necessary to fit better the clinical classification. When compared with 'conventional' ABR analysis, 'sensitized' ABR tests--i.e. the measures of test-retest variability, binaural increase of wave-V amplitude and the effect of ipsilateral broad-band noise masking--showed higher percentages of positive results in subjects with no clinical signs of brainstem and midbrain involvement. Sensitized tests therefore appeared more suitable to reveal a brainstem subclinical involvement.