Sensitivity and specificity of mastoid vibration test in detection of effects of vestibular neuritis [Sensibilità e specificità del test della vibrazione mastoidea nella individuazione degli esiti della neurite vestibolare]

Aim of this study was to determine sensitivity and specificity of the mastoid vibration test in patients who had suffered an attack of vestibular neuritis. Results were compared with the caloric test and two bedside tests of vestibular function (head shaking test and head thrust test). Results are reported in 28 patients who had a residual vestibular deficit 6 months after acute neuritis and in 25 healthy subjects. Mastoid vibration nystagmus was evoked in 21 patients but not in controls. In these patients, mastoid vibration test had a sensitivity of 75% and specificity of 100%. Since one patient had inverted mastoid vibration nystagmus, specificity of identification on the pathological side was 95%. Sensitivity of the test increased with increasing severity of the vestibular lesion. Indeed, mastoid vibration nystagmus was induced in 93% of patients with caloric paralysis and in 58% of those with caloric paresis. Nystagmus could usually be modulated or elicited by stimulation of either mastoid. In the few patients in whom mastoid vibration nystagmus was elicited only from one side, or when there was a clear difference in intensity of the nystagmus induced on the two sides, the stimulated side was more often the affected side. Four patients still showed spontaneous nystagmus. The caloric test was abnormal in 26/28 patients (93%) with paralysis in 16 and paresis in 12; 71% of patients had a head shaking induced nystagmus: 64% had an asymmetrical response in head thrust test. In conclusion, mastoid vibration test was overall more sensitive than head thrust test. Mastoid vibration test was slightly less sensitive than head shaking test in patients with severe residual deficit and more sensitive in patients with partial deficit. Mastoid vibration test, a valid, low cost clinical screening test for rapid detection of asymmetrical vestibular function, does not cause patient discomfort. It is suggested that this test be included in the diagnostic workup of all patients with suspected vestibular dysfunction.