Cochlear implant outcomes in patients with superior canal dehiscence

To determine whether adult cochlear implant (CI) users with superior canal dehiscence syndrome (SCDS) or asymptomatic superior semicircular canal dehiscence (SCD) have different surgical, vestibular, and audiologic outcomes when compared to CI users with normal temporal bone anatomy.

A retrospective single institution review of CI users with either superior semicircular canal dehiscence syndrome or asymptomatic superior semicircular canal dehiscence identified eight post-lingually deafened adults with unilateral or bilateral cochlear implantation between 2006 and 2010. Preoperative and postoperative speech perception scores as well as medical and epidemiological data were recorded and analyzed.

One patient with superior canal dehiscence syndrome and seven patients with asymptomatic superior semicircular canal dehiscence were identified, representing 7% or 8/113 of CI patients that fulfilled selection criteria. Average dehiscence length was 3.3 mm ± 0.79 SEM. Three patients received bilateral implants and five patients received a unilateral implant. Among asymptomatic superior semicircular canal dehiscence patients, subjective rates of post-operative dizziness were similar to those seen in patients with normal temporal bone anatomy (12.5 % vs. 15.9%, respectively). Speech perception abilities after surgery were poorer in SCD patients compared to the non-SCD cohort (Consonant Nucleus Consonant 33.7 ± 7.78 SEM vs. 56.7 ± 2.15 SEM P = 0.011), although both groups improved substantially relative to pre-operative performance. We also completed detailed analyses of auditory and vestibular outcomes in one patient with SCDS who underwent CI surgery in the symptomatic ear, which demonstrated preservation of vestibular function post-operatively, improved quality-of-life measures, and reduced dizziness symptomatology.

Our data suggest that patients with asymptomatic superior canal dehiscence at the time of CI surgery have similar albeit decreased speech perception scores compared to non-SCD adult CI users. Subjective rate of dizziness or vertigo following CI surgery was similar in both asymptomatic SCD and non-SCD cohorts, with detailed analyses of a single symptomatic SCD patient revealing improved vestibular function and reduced SCD symptoms following CI.