Sensitivity and Specificity of Clinical and Laboratory Otolith Function Tests.

OBJECTIVE

To evaluate clinic based and laboratory tests of otolith function for their sensitivity and specificity in demarcating unilateral compensated complete vestibular deficit from normal.

STUDY DESIGN

Prospective cross-sectional study.

SETTING

Tertiary care hospital vestibular physiology laboratory.

SUBJECTS

Control group-30 healthy adults, 20-45 years age; Case group-15 subjects post vestibular shwannoma excision or post-labyrinthectomy with compensated unilateral complete audio-vestibular loss.

INTERVENTION

Otolith function evaluation by precise clinical testing (head tilt test-HTT; subjective visual vertical-SVV) and laboratory testing (headroll-eye counterroll-HR-ECR; vesibular evoked myogenic potentials-cVEMP).

MAIN OUTCOME MEASURE

Sensitivity and specificity of clinical and laboratory tests in differentiating case and control subjects.

RESULTS

Measurable test results were universally obtained with clinical otolith tests (SVV; HTT) but not with laboratory tests. The HR-ECR test did not indicate any definitive wave forms in 10% controls and 26% cases. cVEMP responses were absent in 10% controls.HTT test with normative cutoff at 2 degrees deviations from vertical noted as 93.33% sensitive and 100% specific. SVV test with normative cutoff at 1.3 degrees noted as 100% sensitive and 100% specific. Laboratory tests demonstrated poorer specificities owing primarily to significant unresponsiveness in normal controls.

CONCLUSIONS

Clinical otolith function tests, if conducted with precision, demonstrate greater ability than laboratory testing in discriminating normal controls from cases with unilateral complete compensated vestibular dysfunction.