Cochlear basal turn patency in unrecognized perilymph gushers.

Objectives: Perilymph gusher (PLG), an uncommon complication of otologic surgery, has been attributed to communication between the cochlea and the internal auditory canal (IAC). Subtle osseous defects may be missed on routine review of computed tomography (CT). This study aimed to quantify cochlear basal turn patency not seen on axial CT in patients with PLG and compare those against patients without intraoperative PLG.

Methods: Ears that underwent cochlear implantation or stapedotomy with preoperative helical CT that was interpreted as "normal" at a tertiary referral center. An otologist and a radiologist independently and in a blinded fashion measured the dimensions of cochlear basal turn patency on CT images in oblique plane and parasagittal planes along the interface of the cochlea and IAC fundus.

Results: Sixty-one ears were reviewed, including 3 with surgically confirmed PLGs and 12 with apparent dehiscence without a PLG. Mean defect width with PLG was 0.83 mm (range 0.75-0.9 mm) and without PLG was 0.43 mm (range 0.3-0.65 mm, p = 0.011). A greater proportion of PLGs occurred in ears with defects (3 of 15) than in ears without (0 of 46, p = 0.013). Using a cutoff of 0.75 mm, a greater proportion of PLGs occurred with defect width >0.75 mm (3 of 3) than in defects <0.75 mm (0 of 12, p = 0.022).

Conclusions: CT dehiscence between the IAC and cochlear basal turn, particularly with a width > 0.75 mm, should be considered a risk for PLG with stapedotomy or cochlear implantation.