A Case of Bilateral Superior Semicircular Canal Dehiscence Syndrome

Case DesCriptionA 48-year-old male with a past medical history of hypothyroidism on thyroxine tablets presented to the clinic with a 2-year history of intermittent bilateral ear tinnitus.He described it as a ringing sound that is worse in a quiet environment.The tinnitus is associated with decreased hearing mainly in the left ear.He also mentioned episodic dizziness that lasts for a few seconds and is usually triggered by standing up quickly and is not associated with nausea, vomiting, or visual disturbances.No ear pain or discharge.He has a history of chronic rhinosinusitis controlled by nasal sprays.He denied any history of head trauma or previous ear surgeries.He used to work in a steel and iron factory with physical exertion, heavy lifting, and chronic noise exposure, without using hearing protection.The otoscopic findings were normal.The cranial nerves were intact.Fiberoptic nasoendoscopy showed no significant findings.The tympanometry was type A bilaterally, indicating normal middle ear function, and the pure tone audiometry (PTA) revealed a left mixed hearing loss with a right mild air-bone gap (Fig. 1).Temporal bone computed tomography (CT) scans revealed dehiscence of the roofs of both superior semicircular canals (Figs 2 and 3).The cervical vestibular evoked myogenic potential (cVEMP) test showed the following findings (Fig. 4):• Elevated P1-N1 amplitudes in both ears (42.6 µV in the right ear and approximately 39 µV in the left ear at 105 dB), exceeding the normal range (10-25 µV) and aligning with the presence of a third window phenomenon.• Lower than normal cVEMP threshold (100 dB in both ears), supporting increased vestibular sensitivity.• Interaural amplitude ratio (IAR) is only 4.4%, suggesting symmetric bilateral involvement, which indicates bilateral SSCD rather than unilateral disease.