Surgical protocol
All patients were placed under general anesthesia, and facial nerve
monitoring electrodes were put in place. A standard mastoidectomy was
performed through a postauricular incision, with decompression of the
sigmoid sinus. The facial nerve and three semicircular canals were
identified and skeletonized, after which the endolymphatic sac was
identified posterior to the posterior semicircular canal, along the
posterior fossa plate, below Donaldson’s line. The bone over the sac was
widely removed for decompression. A fenestration was made at a spot on
the posterior canal as far as possible away from the ampulla, keeping
the membranous labyrinth intact. Next, a small piece of soft tissue was
filled into the fenestration to tightly block the membranous labyrinth
over a short segment, after which, the fenestration was finally sealed
with bone wax to further safeguard against perilymph leakage.
Thereafter, the superior and horizontal semicircular canals were blocked
using the same method.