Enlarged Cochlear Aqueducts

A Potential Route for CSF Gushers in Patients With Enlarged Vestibular Aqueducts

Abstract

Objective 

We investigated whether the size of the cochlear aqueduct (CA) is increased in patients with enlarged vestibular aqueducts (EVAs) compared with individuals with normal inner ear anatomy. Furthermore, we assessed whether the size of the CA is related to the cerebrospinal fluid (CSF) gusher during cochlear implantation (CI) surgery.

Study Design 

Retrospective study.

Setting 

Tertiary referral center.

Patients 

The medical records for 35 patients with a biallelic SLC26A4 mutation were reviewed. All of the patients were confirmed to have EVA by temporal bone computed tomography (TBCT) and biallelic SLC26A4 mutation by genetic analysis. Thirty-six age- and sex-matched patients without a mutation in the SLC26A4 gene were selected as comparison group.

Main Outcome Measures 

The diameters of the CA and vestibular aqueduct (VA) were measured, and the type of CA was evaluated using TBCT.

Results 

The CA was larger in patients with EVA (2.39 ± 0.99 mm) as compared with controls (1.76 ± 0.87 mm; p < 0.001). The types that could be most easily visualized from the subarachnoid space to the cochlea were more common in patients with EVA. Furthermore, mean CA size was significantly larger in EVA patients with CSF gushers (3.65 ± 1.12 mm) as compared with those without CSF gushers (2.03 ± 0.66 mm; p < 0.001).

Conclusion 

The CA is a potential pathway for CSF gushers between the subarachnoid space and the inner ear. Therefore, we suggest that evaluation of the CA by TBCT may be helpful in predicting intraoperative CSF gushers in patients with EVA.