Hearing Restoration with Cochlear Implantation in Patients Deafened after Blunt Head Trauma

Postoperative radiological assessment of the mastoid facial canal in cochlear implant patients in correlation with facial nerve stimulation

Objectives

To correlate the radiological assessment of the mastoid facial canal in postoperative cochlear implant (CI) cone-beam CT (CBCT) and other possible contributing clinical or implant-related factors with postoperative facial nerve stimulation (FNS) occurrence.

Methods

Two experienced radiologists evaluated retrospectively 215 postoperative post-CI CBCT examinations. The mastoid facial canal diameter, wall thickness, distance between the electrode cable and mastoid facial canal, and facial-chorda tympani angle were assessed. Additionally, the intracochlear position and the insertion angle and depth of electrodes were evaluated. Clinical data were analyzed for postoperative FNS within 1.5-year follow-up, CI type, onset, and causes for hearing loss such as otosclerosis, meningitis, and history of previous ear surgeries. Postoperative FNS was correlated with the measurements and clinical data using logistic regression.

Results

Within the study population (mean age: 56 ± 18 years), ten patients presented with FNS. The correlations between FNS and facial canal diameter (p = 0.09), wall thickness (p = 0.27), distance to CI cable (p = 0.44), and angle with chorda tympani (p = 0.75) were statistically non-significant. There were statistical significances for previous history of meningitis/encephalitis (p = 0.001), extracochlear-electrode-contacts (p = 0.002), scala-vestibuli position (p = 0.02), younger patients’ age (p = 0.03), lateral-wall-electrode type (p = 0.04), and early/childhood onset hearing loss (p = 0.04). Histories of meningitis/encephalitis and extracochlear-electrode-contacts were included in the first two steps of the multivariate logistic regression.

Conclusion

The mastoid-facial canal radiological assessment and the positional relationship with the CI electrode provide no predictor of postoperative FNS. Histories of meningitis/encephalitis and extracochlear-electrode-contacts are important risk factors.

Key Points

• Post-operative radiological assessment of the mastoid facial canal and the positional relationship with the CI electrode provide no predictor of post-cochlear implant facial nerve stimulation.

• Radiological detection of extracochlear electrode contacts and the previous clinical history of meningitis/encephalitis are two important risk factors for postoperative facial nerve stimulation in cochlear implant patients.

• The presence of scala vestibuli electrode insertion as well as the lateral wall electrode type, the younger patient’s age, and early onset of SNHL can play important role in the prediction of post-cochlear implant facial nerve stimulation.

A Systematic Review of Cochlear Implantation in Temporal Bone Fractures and the Significance of Otic Capsule Involvement

OBJECTIVE

Head trauma can cause deafness in cases with and without a skull base fracture. Anatomic disruption can occur with skull base fractures, but inner ear structures can also be damaged by the concussive forces of the trauma even without fracture. It is thought that negative prognostic indicators for successful cochlear implantation (CI) for hearing rehabilitation include fractures involving the otic capsule or ossification of the cochlea. This review evaluates success of CI in posttrauma patients.

DATA SOURCES

PubMed/MEDLINE, Cochrane, and Embase.

STUDY SELECTION

Search terms used were "cochlear implant" AND ("trauma" OR "fracture"). Studies including preoperative computed tomography or magnetic resonance imaging and patient-level outcome data were included.

DATA EXTRACTION

Study design, perioperative and postoperative outcomes, and complications were reported. Success rates of CI were compared using χ analysis.

DATA SYNTHESIS

Twenty-three studies encompassing 88 patients who experienced posttraumatic deafness and received subsequent CI were included. CI was reported as successful for 28 of 34 patients (82%) with otic capsule-involving fracture, as compared with 17 of 22 (77%) in those who had an otic capsule-sparing temporal bone fracture, and 15 of 17 (88%) of patients without evidence of fracture (i.e., concussive inner ear injury).

CONCLUSIONS

In patients with posttraumatic hearing loss, success rates do not significantly differ between cases that do or do not involve fractures of the otic capsule. CI for posttraumatic hearing loss is generally successful.

Cochlear implantation after traumatic brain injury without otic capsule fracture: A case report and literature review

OBJECTIVE

The aim of this study was to report a case of cochlear implantation (CI) for a patient with an otic capsule-sparing traumatic brain injury (TBI) and to review the relevant literature.

METHODS

A patient with history of TBI received a CI for bilateral profound hearing loss. A systematic review of the literature was performed to identify and compare similar cases.

RESULTS

A 36-year-old male with a history of hearing loss from right acute labyrinthitis was referred for bilateral profound sensorineural hearing loss (SNHL) after a fall with associated injury to the central auditory nervous system (CANS) including the brainstem. On the right, behavioral acoustic threshold measurements were in the profound range with absent OAEs. On the left, testing revealed no measurable behavioral acoustic thresholds and variable physiologic measures. A right unilateral cochlear implant was performed with most recent follow-up demonstrating speech awareness thresholds of 25 dB HL with excellent detection of all 6 Ling sounds. However, the patient also continues to suffer from other neurologic sequelae related to his TBI, which challenge his ability to demonstrate objective and subjective benefit. A systematic review of the literature demonstrates variable outcomes for patients with TBI and SNHL.

CONCLUSIONS

Patients with profound SNHL and TBI present a distinct rehabilitative challenge for clinicians. CI may provide meaningful benefit in this population, though care should be taken in patient selection and counseling.