ONS Advance Access: Minimally Invasive Middle Fossa Keyhole Craniectomy for Repair of Superior Semicircular Canal Dehiscence

Superior semicircular canal dehiscence (SSCD) syndrome was first described by Minor et al. in 1998.1 SSCD occurs when the normal bony covering over the superior semicircular canal is absent.2,3 In some cases, the area of missing bone can be small. The exact mechanism of how this bony covering is lost remains unclear.1,4,5

The clinical presentation of SSCD involves varying degrees of both auditory and vestibular dysfunction.69 Symptoms result from the pathological third window that leads to irregular vestibular stimulation.10,11 The auditory dysfunction experienced in SSCD include aural fullness, hearing loss (sensorineural, mixed, and conductive), and tinnitus (both constant and pulsatile).4 Patients also often describe internal amplification of sounds, such as their own heartbeat, autophony, and other internal noises such as digestive and breathing sounds.1214 Some patients have described hearing their own steps amplified when they walk as well as being able to hear their eyes moving inside of their head.15,16 Vestibular dysfunction includes disequilibrium and vertigo spells.1 Tullio’s phenomenon, composed of pressure- and sound-induced vertigo, disequilibrium, or oscillpsia, is also commonly reported in this disorder.17,18

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