Deficiency of the superior semicircular canal

Deficiency of the superior semicircular canal (SSCD) has been defined as the absence of bone overlying the superior semicircular canal (SSC) toward the middle fossa dura. SSCD has recently been reported to be associated with a syndrome of sound-or pressure-induced vertigo and oscillopsia. The vertical–torsional nystagmus induced by sound in these patients has been identified to correlate with the affected SSC. High-resolution computed tomograph scan and middle fossa exploration have corroborated these findings. Repair or occlusion of the SSC has resulted in resolution or improvement of symptoms. SSCD should be evaluated in patients who have sound-or pressure-induced vertigo and in patients who have been diagnosed with atypical Meniere or perilymphatic fistula.