Case report

A 37-year-old man was seen in the authors’ interdisciplinary center for vertigo and balance disorders in 2005. He complained of periods of dizziness that were usually provoked by loud sounds, especially when he had to speak loudly in conferences or in restaurants with a noisy background. He never experienced true rotatory vertigo. These spells of dizziness increased at 34 years of age, after which his sensitivity to noise also increased, to the point where he could even hear his own eye movements in his right ear and other sounds produced by his own body, such as footsteps and his own voice. Dizziness increased with exertion in sport activities until he could not even jog after 35 years of age.

Physical examination showed normal outer ear canals and eardrums with normal Eustachian tube function, but during Valsalva maneuver he felt a slight shift of the visual scene and dizziness. The Weber tuning fork test lateralized to the right ear, and the Rinne test was positive bilaterally. Hennebert’s sign was positive, so that both positive and negative pressure in the right outer ear canal provoked a shifting of the visual scene. When repeating these signs under Frenzel goggles, the authors noted small torsional movements of the eyes toward the left side while positive pressure was applied, which reversed when negative pressure was applied. Vertical and horizontal components could not be seen. This simple investigation alone was sufficient for SCDS to be suspected.

Audiometry supported the clinically suspected air–bone gap at least at 500 Hz, and cervical VEMPs in response to acoustic clicks confirmed a reduced threshold of approximately 46 dB nHL on the right and a normal threshold (82 dB nHL) on the left ( Fig. 1 A). CT of the temporal bones showed dehiscence of the right superior semicircular canal ( Fig. 2 A).

Cervical vestibular evoked myogenic potential thresholds before ( A ) and after ( B ) plugging of the superior canal. The threshold is determined by a linear regression through the amplitudes of the potentials at different stimulus intensities. This technique is a very rough way to determine the threshold, but because the change in amplitude with stimulus intensity is usually linear, the authors often use only two stimulus intensities if the threshold has normal values. As can be seen, even with four intensities used in ( A ) for the threshold of the right sacculus, the amplitudes are close to the linear regression and the threshold is at approximately 46 decibels above normal adult hearing level (dB nHL), which is considerably below normal (75 dB nHL in the authors’ laboratory). After plugging, the vestibular evoked myogenic potential threshold is normal on both sides, between 80 and 90 dB nHL. The amplitude at 90 dB nHL is almost identical on both sides. The value of 176 μV at 95 dB nHL may be a little high, but even taking the value of the first measurement (131 μV) would result in a normal threshold.

( A ) CT reconstruction in the plane of the right superior semicircular canal. A large dehiscence in the upper part of the semicircular canal can be seen. ( B ) The dehiscence intraoperatively. Scale ticks are 1 mm.

In a more detailed history, the authors found that even beginning at approximately 10 years of age, the patient experienced periodic vague dizziness, especially in train stations, shopping centers, and other noisy public places. His symptoms increased with exertion in sporting activities, especially when riding his bicycle uphill. He felt best in quiet environments and when lying in bed. He avoided common social activities with friends, and later also with colleagues, because he found them too noisy; he preferred quiet. He often told his parents that something must be wrong, and was evaluated by several physicians who considered diagnoses such as vitamin deficiencies and even psychogenic causes. Before presenting to the authors’ clinics, the conclusion was simply that he had to live with these symptoms.

The authors saw no indications of panic disorder, depression, or any other psychogenic disturbances. The patient had a good sense of humor, was intelligent and insightful, and was running his own company successfully in a very competitive field. No indication was seen that he was somatizing or overestimating his symptoms. After he learned the diagnosis and the operative treatment option, he chose to wait 3 more years, during which time the symptoms became even stronger and, ultimately, intolerable, at which point he decided to pursue surgical treatment.

The dehiscent canal was plugged using the middle cranial fossa approach without complications. In the immediate postoperative period, air conduction thresholds were almost identical to the preoperative audiogram. Bone conduction thresholds were still slightly better than air-conduction thresholds. In absolute silence he was still able to hear his eyes moving with his right ear, but markedly less so than preoperatively, and it was not bothersome. Vestibular function was reduced only for the plugged superior canal, because he showed evidence of a deficient vestibuloocular reflex for rapid head thrusts exciting the plugged canal but none of the other canals on the ipsilateral side.

Within 48 hours of surgery the patient noted profound changes, even commenting on what seemed like a “new life.” First, he noted that he no longer heard his voice, eye movements, or other body sounds in the affected ear. Second, he noted that ambulation, particularly outdoors, felt more stable. Finally, he found that ambient noise no longer seemed to disturb his equilibrium or sense of well-being. Reflecting on this, he commented that only after surgery did he realize how often since childhood he had altered his routine or environment to avoid noisy situations and the associated disequilibrium. He now enjoys going to social events and restaurants, and has been able to resume sporting activities without feeling dizzy. Loud sounds no longer disturb him, and he has no fear of crowds or busy places.