Cochlear Implant Electrode Choice in Challenging Surgical Cases: Malformation, Residual Hearing, Ossification, or Reimplantation

Cochlear Ossification After Vestibular Schwannoma Surgery: A Temporal Bone Study

OBJECTIVE

This study aims to investigate patterns of cochlear ossification (CO) in cadaveric temporal bones of patients who underwent vestibular schwannoma (VS) surgery via the translabyrinthine (TL), middle cranial fossa (MF), or retrosigmoid (RS) approaches.

STUDY DESIGN

Histopathologic analysis of cadaveric temporal bones.

SETTING

Multi-institutional national temporal bone repository.

METHODS

The National Institute of Deafness and Communication Disorders and House Temporal Bone Laboratory at the University of California, Los Angeles and the Massachusetts Eye and Ear Otopathology Laboratory were searched for cadaveric temporal bones with a history of VS for which microsurgery was performed. Exclusion criteria included non-VS and perioperative death within 30 days of surgery. Temporal bones were analyzed histologically for CO of the basal, middle, and apical turns.

RESULTS

Of 92 temporal bones with a history of schwannoma from both databases, 12 of these cases met the inclusion criteria. The approaches for tumor excision included 2 MF, 4 RS, and 6 TL approaches. CO was observed in all temporal bones that had undergone TL surgery. Among temporal bones that had undergone MF or RS surgeries, 5/6 had no CO, and 1/6 had partial ossification. This single case was noted to have intraoperative vestibular violation after RS surgery upon histopathologic and chart review.

CONCLUSION

In this temporal bone series, all temporal bones that had undergone TL demonstrated varying degrees of CO on histological analysis. MF and RS cases did not exhibit CO except in the case of vestibular violation. When cochlear implantation is planned or possible after VS surgery, surgeons may consider using a surgical approach that does not violate the labyrinth.

Cochlear implantation for post-meningitis deafness with cochlear ossification: diagnosis and surgical strategy

BACKGROUND

Cochlear ossification (CO) after meningitis can cause profound sensorineural hearing loss (SNHL). Cochlear implantation (CI) is the ideal treatment strategy for CO.

AIMS

To explore the strategy for CI in patients with CO after meningitis.

MATERIALS AND METHODS

In this retrospective study, the medical records of patients diagnosed with profound SNHL due to CO after meningitis and who underwent CI in our department between September 2010 and September 2021 were collected and reviewed. Their imaging and surgical findings were analyzed.

RESULTS

The data of 26 patients with unilateral CI were reviewed. All patients underwent preoperative temporal high-resolution computed tomography (HRCT) and 22 patients magnetic resonance imaging (MRI). The sensitivity of HRCT was 61.5% (10/26), whereas that of MRI was 81.8% (18/22). Combined HRCT and MRI achieved a detection rate of 92.3% (24/26). Twenty-two and four patients underwent complete and partial electrode implantations, respectively.

CONCLUSIONS AND SIGNIFICANCE

Preoperative temporal bone HRCT and MRI are essential for determining whether a patient is suitable for CI and surgical planning. A false-negative diagnosis is possible when diagnosing CO, but combined HRCT and MRI can improve the positive rate of preoperative diagnosis of CO post meningitis. Early CI is recommended.