ENG, sinusoidal vertical-axis rotation, and otoacoustic emissions testing in a man whose disabling dizziness had culminated in forced retirement

Ear, Nose & Throat Journal, June, 2007 by Kenneth H. Brookler, Mohamed A. Hamid

A 51-year-old ex-policeman presented with a considerable history of vestibular symptoms. Four years earlier, he had awoken in the middle of the night with rotary vertigo, nausea, and vomiting. For the next 2 weeks, these symptoms occurred on and off with varying severity; between episodes of rotary vertigo, he would experience nausea and dizziness, although these recurrent symptoms were less severe than those at the onset. He sought treatment from a neurologist and was placed on clonazepam.

Treatment allowed the patient to function at a minimal level for intermittent periods, but he was unable to carry out his police work. When he did try to resume some duties 1 year after the onset of symptoms, he found it difficult to drive to work. He also experienced difficulty working out at the gym; while on the treadmill, for example, he needed to hold onto the rails tightly and stare at the TV screen in order to complete his walk. Electrony-stagmography (ENG) and contrast-enhanced magnetic resonance

imaging at that time were negative for any abnormality. Audiometry revealed a mild high-frequency sensorineural hearing loss, although the patient reported no subjective hearing loss.

The patient attempted vestibular rehabilitation therapy with little success. On "bad days," his rotary vertigo, nausea, and vomiting forced him to remain immobilized to minimize his symptoms. On "average days," he still experienced nausea and was unable to drive; at most, he was able to walk from room to room within his home. The patient was advised to retire as a result of his disability, and he did so.

Three years after his retirement, the patient presented to the office of the lead author (K.H.B.) with a 4-month history of tinnitus in addition to his vestibular symptoms. The ringing was binaural, constant, and high in frequency, and it seemed to be louder at night. The tinnitus was accompanied by binaural fullness. The only significant findings on a clinical neurotologic examination were right nuchal tenderness and difficulty performing the sharpened tandem Romberg test.

The patient was taken off the clonazepam to make it possible to obtain vestibular test results that would not be masked by a drug effect, such as the prevention of central vestibular compensation. At follow-up 5 weeks later, he reported that he had felt much better during the previous 2 weeks and was relatively free of symptoms. He had been able to resume driving without difficulty, and he had returned to the gym. The only negative observation he made was that his tinnitus might have been a little louder.

Follow-up ENG showed nystagmus in the right lateral position, and caloric testing elicited no warm or cool responses in the right ear. The simultaneous binaural bithermal caloric test elicited a type 2 response that was consistent with a reduced vestibular response (RVR) right. Sinusoidal vertical-axis rotation testing showed normal gains and phases and no abnormal symmetry. Ocular fixation suppression of rotation-induced nystagmus was observed.

Audiometry detected a mild to moderate, symmetrical, high-frequency hearing loss with normal speech testing. Findings on tympanometry in both ears were normal, and no acoustic stapedial reflexes were produced. Distortion product otoacoustic emissions testing revealed a more robust and wide range of responses, and much less artifact was noted in the left ear than in the right.

This case features several points of interest:

* The first point concerns the long-term use of centrally acting medications. Clonazepam had produced some symptomatic benefit (although no sustained improvement), but it had done so by suppressing the automated mechanisms that facilitate central vestibular compensation. The beneficial effect of discontinuing clonazepam was rapid, and by 5 weeks it was almost complete.

* ENG revealed an RVR right, indicating that the vestibular abnormality had progressed since the patient's normal ENG 3 years earlier.

* The sinusoidal vertical-axis rotation test uncovered evidence of complete central vestibular compensation consistent with the patient's absence of symptoms at the time.

* The audiometric findings, especially the absence of acoustic stapedial reflexes on acoustic immittance testing, were consistent with otosclerosis.

* Distortion product otoacoustic emissions testing revealed lesser findings on the right, which was the side of the vestibular abnormality.

From Neurotologic Associates, PC, New York City (Dr. Brookler), and the Cleveland Hearing and Balance Center, Beachwood, Ohio (Dr. Hamid).