The Clinical Application Of Cochlear Implantation In Bilateral Total Deafness Following Head Trauma

OBJECTIVEHead trauma often causes loss of auditory and vestibular function. However, cochlear implantation for patients with bilateral severe to profound sensorineural hearing loss following head trauma remains controversial, and there has been disagreement about exactly which should be performed as the initial treatment. The objective of this research is to compare the outcomes of cochlear implantation and auditory brainstem implantation in bilateral severe to profound sensorineural hearing loss following head trauma, determine which should be performed as the initial treatment.MATERIALS AND METHODS(1) A retrospective study of our experience with cochlear implantation in bilateral severe to profound sensorineural hearing loss after head trauma (with or without temporal bone fractures).(2) A systematic review of literatures which reported cases of bilateral hearing loss after head trauma treated by means of cochlear implantation or auditory brainstem implantation. Information was gathered for each study on preoperative audiological assessment, radiological findings, treatments such as cochlear implantation or auditory brainstem implantation, implanted ear, problems encountered during the surgery, postoperative audiological outcomes, and complications after the surgery.RESULTS(1) Four patients with bilateral hearing loss following head trauma who underwent cochlear implantation were reviewed. All patients obtained open-set speech perception, and none of them experienced a decrease in the hearing performance with the passage of time.(2)17articles met the defined criteria and were included in the final data analysis.51patients received cochlear implants, and most achieved satisfactory results.45patients received unilateral cochlear implantation.18patients without temporal bone fractures in the implanted ear achieved the average sentence recognition about80%, ranging from30%to100%.2patients with temporal bone fractures not involving the inner ear scored100%and92%in speech recognition.12patients with temporal bone fractures involving the inner ear in the implanted ear achieved the average sentence recognition about78%, ranging from40%to100%. The detail information of the temporal bones of11patients was not achieved. These patients achieved the average sentence recognition about56.89%, ranging from16%to100%.6patients received bilateral cochlear implantation, and5scored70%,76%,100%,100%and100%in speech recognition respectively. A total of9patients were implanted with auditory brainstem implants after head trauma,3patients failed to achieve satisfactory open set sentence recognition. In the other3patients, auditory-alone-mode open-set sentence recognition was45%,60%, and100%respectively.3patients had been previously treated with auditory brainstem implants, and achieved poor results. Then they underwent cochlear implantation. All3patients obtained better auditory results with the cochlear implant if compared with the auditory brainstem implant.CONCLUSIONCochlear implantation is an effective method for hearing rehabilitation in bilateral severe to profound sensorineural hearing loss after head trauma. Audiologic results of cochlear implantation do not decrease with time. Results of cochlear implantation remain widely superior and more predictable than results of auditory brainstem implantation in these patients. In patients without cochlear nerve damage, cochlear implantation should be performed as the initial treatments to rehabilitate their hearing. The incidence of cochlear ossifications, negative electrophysiologic testing, the higher risk of postoperative facial nerve stimulation, and temporal bone fractures involving inner ear should not be determinant factors that favor auditory brainstem implant placement. If a lesion of the cochlea nerve is suspected, a cochlear implant can be placed on the contralateral side. Auditory brainstem implants may be indicated when cochlear implant insertion was not successful, cochlear implantation has failed to provide satisfactory results, and bilateral cochlear nerves were damaged. Patients who have bilaterally intact cochlear nerves on temporal bone CT scan and MRI should not receive auditory brainstem implantation only depending on the negative electrophysiologic testing.