We report herein our trial using cervical vestibular evoked myogenic potentials (cVEMP) to screen for acute-onset nystagmus-free patients complaining of “dizziness” and “floating.” Each patient was placed in a supine position with his or her head elevated. Active electrodes were placed bilaterally on the sternocleidomastoid muscle, while the reference electrode was placed on the rostral lateral sternum. The stimulating sounds consisted of a “Click” (95 or 105 dBnHL) transmitted using insert earphones. The stimulation frequency was 5 Hz, 100 sweeps. Bilateral simultaneous stimulation was performed, and the results were recorded. A total of 108 patients ranging in age from 14 to 86 years old (average, 61.1±16.6 years) were examined. None of the patients had conductive hearing loss or spontaneous nystagmus. cVEMP responses are suppressive with an ipsilateral predominance, and neck muscle tension is indispensable for the implementation of this examination. However, muscle tension decreases with aging, as evidenced by an age-associated decrease in amplitudes as well as the prolongation of the latency times. Meanwhile, the VEMP amplitudes are increased to a greater extent by neck rotation than by neck elevation during recording. The advantage of head elevation to obtain better responses was found to burden the patients with continued muscle tension in the neck. Light insert earphones were therefore used to alleviate the patients' load. The number of sweeps was limited to 100 because repetitive stimuli fatigued the muscles, leading to poor responses. Stimulation was provided, and bilateral recordings were simultaneously made. Overall, 30.6% of the patients exhibited unilateral abnormal cVEMP findings, while 2.8% of the patients exhibited bilateral abnormal cVEMP findings; 15.7% of the patients had VEMP findings with a poor reproducibility. When the poor reproducibility group was compared with the normal response group, the average age of the poor reproducibility group was significantly older. In conclusion, abnormal VEMP test results were observed in over 30% of the patients who underwent testing. Bilateral cVEMP is useful as a primary test in patients without nystagmus who complain of dizziness and floating.
