Methods
A Neurotologist specialist examination revealed no abnormalities. The auditory evaluation confirmed bilateral conductive hearing loss, particularly affecting the airway thresholds between 125 to 1000 Hz frequencies, with ascending curves. Also, the bone conduction study showed thresholds below 0 dB at 250, 500, and 1000 Hz. Video Oculo Nystagmography (VNG) was conducted, including analysis of spontaneous nystagmus with and without ocular fixation and assessment of eye movements such as slow tracking and saccades. The results were within normal limits. Additionally, video head impulse test(v-Hit) testing yielded normal findings. Cervical vestibular myogenic evoked potentials (c-VEMPs) demonstrated a significant decrease in presentation thresholds, even occurring at stimuli below 60 dB bilaterally, with amplitudes well above average values.
Furthermore, spontaneous nystagmus without ocular fixation was observed during pressure stimuli using the Valsalva Maneuver and sound stimulation while pronouncing the phoneme ”M.” In particular, the production of the mentioned phoneme triggered an intense horizontal rotational nystagmus to the left, defined as “fremitus nystagmus”4 . Based on the findings, a diagnosis of bilateral superior semicircular canal dehiscence (B-SCD) is proposed. A high-resolution ear CT scan with cuts smaller than 0.5 mm is recommended to confirm the presence of the bone defect (Figure 1 ).
The diagnosis of B-SCD relies on a combination of characteristic symptoms, audiometric testing, and radiographic findings. Ward et al. established consensus criteria that include air-bone gaps on audiometry and visible dehiscence of the superior canal on high-resolution CT scans. Additional vestibular symptoms may include trigged dizziness or nystagmus in response to loud noises, as noted in the case report. While conservative treatment is reasonable in milder cases, surgery aimed at resurfacing or plugging the dehiscent canal can relieve symptoms4. The described bilateral B-SCD repair surgery improves conductive hearing loss, though vestibular disturbances may persist3-5.