The diagnostic value of earlier and later components of Vestibular Evoked Myogenic Potentials (VEMP) in multiple sclerosis.

AIM OF THE STUDY: To evaluate the ability of VEMP to disclose spatial dissemination of Multiple Sclerosis. MATERIALS AND METHODS: Forty-six MS patients with auditory and/or vestibular symptoms were studied. Patients were divided in two groups. Group 1 included 24 patients with brainstem MRI findings, and Group 2 included 22 patients without MRI findings. VEMP and BAEP have been recorded and assessed. RESULTS: Abnormal p13n23 wave was observed in 50%, while unilateral absence or bilateral delay of the n34p44 in 43% of the patients. The overall diagnostic value considering abnormal cases suggested by both first and second VEMP waves was increased to 71%. Statistically significant differences revealed between patients and controls for p13 latency (p=0.018). The p13n23 was abnormal in 7 patients, although MRI scanning did not reveal brainstem lesions. In 9 out of 18 MS patients suffering from unilateral hearing loss, n34p44 was present in the unaffected ears and absent in the affected side, although p13n23 was normal. CONCLUSION: Abnormal VEMP imply the presence of lesions undetected by MRI neuroimaging, which verifies the diagnostic value of the method. Unilateral absence of n34p44 complex was related with sensorineural hearing loss, supporting the hypothesis that n34p44 is of cochlear origin.

Acoustic stapedial reflex in normal adults: biological behavior and determination of threshold levels.

OBJECTIVE: To record acoustic reflex thresholds for admittance (Y) and its components, susceptance (B) and conductance (G) in healthy subjects and to establish normative data. STUDY DESIGN: Acoustic reflex threshold was determined in 100 healthy persons, divided into 5 age groups of 20 persons each (20-29, 30-39, 40-49, 50-59 and 60-69 years old). Detection was performed for Y, B, and G at 226-, 678- and 1,000-Hz probe tones, using 500-, 1,000-, 2,000- and 4,000-Hz stimuli. RESULTS: Statistically significant differences in acoustic reflex thresholds were revealed between different components, stimuli and tones. The lowest threshold level was recorded for Y at 226 Hz using stimulus 1,000 Hz. Four percent missing values were observed at 226 Hz. Subjects belonging to different age groups had different reflex thresholds. CONCLUSION: Inclusion of acoustic reflex detection for B and G offers more detailed information about the middle ear status compared with Y alone, and appears to be sensitive in detecting subtle diseases.