Abstract
With the emphasis on bilateral hearing nowadays, bilateral cochlear implantation has been tried out for bilateral aural rehabilitation. Bilateral sensorineural hearing loss caused by head trauma can get help from cochlear implantation. We present the case of a 44-year-old man with bilateral otic capsule violating temporal bone fractures due to head trauma. The patient demonstrated much improved audiometric and psychoacoustic performance after bilateral cochlear implantation. We believe bilateral cochlear implantation in such patient can be a very effective tool for rehabilitation.
1
Introduction
Temporal bone fractures often lead to loss of audiovestibular function . Otic capsule violating fractures are associated with higher incidence of sensorineural hearing loss than otic capsule sparing fractures . Transverse fractures can cause direct trauma to the otic capsule resulting in destruction of the organ of Corti and the stria vascularis, hemorrhage into the inner ear, and subsequent labyrinthitis ossificans.
The opportunities to provide optimal aural rehabilitation for patients with bilateral hearing loss have expanded due to modern improvements in cochlear implant techniques. Binaural hearing rehabilitation can enhance the physiological and emotional function of patients who suffer from bilateral sensorineural hearing loss, especially in acutely deaf patients.
We present the case of a 44-year-old man who deafened by bilateral temporal bone fracture and achieved satisfactory aural rehabilitation with bilateral cochlear implantation.
2
Case report
A 44-year-old man presented to the Department of Otolaryngology with bilateral hearing loss. Six weeks prior to presentation, the patient fell and was admitted to the neurosurgery service in a nearby hospital with intracranial and intraventricular hemorrhages. After he recovered from his acute injury, he sought treatment for his hearing loss.
A high resolution temporal bone computed tomogram (CT) taken immediately after the trauma revealed bilateral temporal bone fractures. The fracture lines crossed both otic capsules, and multiple air bubbles were identified in the semicircular canals, vestibules, and cochleae. Ossicular chains and the facial canals were intact on both sides ( Fig. 1 ). On otoscopic examination, both ear drums were intact and there was no evidence of hemotympanum or cerebrospinal fluid leakage.
The patient showed no response to pure tone stimuli at the maximum limits. Immittance audiometry revealed type A tympanograms on both sides. During auditory brain stem response testing, wave Vs were not detected at 90 dB in either ear. The patient also complained of mild dizziness and ataxia. A caloric test showed no response on either side.
Cochlear implantation was considered to be the best option for aural rehabilitation. Prior to implantation, a follow-up temporal bone CT and temporal magnetic resonance imaging (MRI) scan were obtained 45 days after the trauma. On the temporal bone CT, the air bubbles that had been identified on the initial CT had disappeared and labyrinthitis ossificans was not detected. On the temporal MRI, we confirmed an intact vestibulocochlear nerve and a patent cochlear duct ( Fig. 2 ). Seven weeks after the trauma, the patient underwent cochlear implantation in his right ear. During the operation, the fracture line was found to cross the promontory and the oval window niche was covered with dense fibrous tissue. After removal of the fibrous tissue, the oval window membrane was found to be intact. The cochlear duct was patent and there was no resistance during electrode insertion. The device was switched on 24 days after implantation and all electrodes were available for electrical stimulation. The average threshold level was approximately 100 CL (current level) and the comfort level was about 140 CL.
Four weeks after the first mapping, the patient scored 100% on an open set sentence perception test and 80% and 40% on open set word perception tests with bisyllabic and monosyllabic words, respectively. Eight weeks after implantation, aided pure tone audiometry confirmed a threshold level of 25 dB and the patient scored 100% on open set word perception tests with bisyllabic and monosyllabic words. The tinnitus in the right ear that the patient experienced post-trauma eventually disappeared.
During rehabilitation, the patient expressed a desire for additional cochlear implantation because of continuing tinnitus in the left ear and difficulty associated with unilateral hearing. One year after the first surgery, the patient underwent cochlear implantation on the left side. An imaging study confirmed that the cochlear duct was still patent and the electrodes were fully inserted without any difficulties. The first mapping was performed six weeks after the second operation. Following mappings and rehabilitations, the tinnitus in the left ear disappeared. The patient was very satisfied with spatial hearing and hearing in noise, aided pure tone audiometry 7 weeks after the second operation showed similar threshold levels in both ears ( Fig. 3 ).
