Abstract
Purpose
Temporal bone fracture, which involves the otic capsule, can lead to complete loss of auditory and vestibular functions, whereas the patients without fractures may experience profound sensorineural hearing loss due to cochlear concussion. Cochlear implant is indicated in profound sensorineural hearing loss due to cochlear trauma but who still have an intact auditory nerve.
Material and methods
This is a retrospective review study. We report 5 cases of postlingually deafened patients caused by cochlear trauma, who underwent cochlear implantation. Preoperative and postoperative hearing performance will be presented. These patients are cochlear implanted after the cochlear trauma in our department between 2001 and 2006.
Results
All patients performed very well with their implants, obtained open-set speech understanding. They all became good telephone users after implantation. Their performance in speech understanding was comparable to standard postlingual adult patients implanted.
Conclusion
Cochlear implantation is an effective aural rehabilitation in profound sensorineural hearing loss caused by temporal bone trauma. Preoperative temporal bone computed tomography, magnetic resonance imaging, and promontorium stimulation testing are necessary to make decision for the surgery and to determine the side to be implanted. Surgery could be challenging and complicated because of anatomical irregularity. Moreover, fibrosis and partial or total ossification within the cochlea must be expected.
1
Introduction
The cochlear implant is a surgically implanted device that bypasses a nonfunctional cochlea and stimulates the hearing nerves with patterns of electrical currents so that speech and other sounds can be experienced by profoundly deaf people.
Sensorineural hearing loss (SNHL) due to bilateral temporal bone fractures (trauma) is a dramatic consequence for the injured patients. In patients with severe to profound SNHL due to cochlear trauma but who still have an intact auditory nerve, cochlear implant is indicated .
Because of posttraumatic ossification of the cochlea, implantation should be performed early and can be recommended to the patient if bilateral deafness is diagnosed. And also, due to the trauma, surgery can be difficult because of the distorted anatomy. Treatment of SNHL may be various caused by additional damage of auditory nerve fibers and posttraumatic central lesions. In the case of auditory nerve damage and distorted anatomy, brain stem implants may offer new possibilities.
We report 5 cases of postlingually deafened patients caused by cochlear trauma, who underwent cochlear implantation. Preoperative and postoperative hearing performance will be presented.
2
Materials and methods
2.1
Case 1
A 46-year-old male had a severe head injury in a car accident in May 2000. He was operated on 2 times because of intracranial hemorrhage, and he had an intensive care unit (ICU) stay unconsciously for 3 months. After discharge from the ICU, he noticed bilateral hearing loss. Otoscopic examination was normal, and audiological examination revealed bilateral profound SNHL. Temporal bone computed tomographic (CT) scan showed a transverse-type fracture in the right petrous bone involving the vestibule ( Fig. 1 ). Left temporal bone scan revealed fracture line on the squamous part of the temporal bone ( Fig. 2 ). The promontory stimulation test demonstrated good dynamic range as shown by the test frequencies for both ears. A left cochlear implant was performed 14 months after the accident. Two separate fracture lines were noticed at the operation on the mastoid and squamous part of the temporal bone. A simple mastoidectomy, posterior tympanotomy, and round window approach were performed. Free blood was seen in the cochlea through the incision made on the round window membrane and the electrode array of Nucleus 24M (Cochlear Corporation, Inssbruck, Australia) applied with full insertion. Intraoperative electrical stapedius reflex threshold (ESRT) and neural response telemetry tests were positive.
2.2
Case 2
A 40-year-old male presented with sudden onset of complete bilateral hearing loss after being assaulted by others in prison with a wooden stick in 1995. Head trauma caused a skull base fracture and required a craniotomy at that time. After being discharged from the hospital, he complained bilateral hearing loss and vertigo. The patient’s vertigo and postural instability gradually improved over the weeks, but his hearing loss remained unchanged. Audiological evaluation revealed bilateral profound SNHL. Otologic examination revealed retraction of both tympanic membranes. Temporal bone CT scan revealed normal. The promontory stimulation test demonstrated bilateral sufficient neural function. A right ear cochlear implant was performed. A simple mastoidectomy, posterior tympanotomy, and cochleostomy were performed, and all electrodes were inserted using a Medel Combi 40+ device (Med-El, Innsbruck, Austria). Intraoperative ESRT was obtained for all electrodes.
2.3
Case 3
A 44-year-old male presented to the emergency department after falling from the fourth floor in May 2004. He presented with bilateral hearing loss and vertigo after being discharged from the ICU and was referred to our department. Otologic examination revealed normal. His audiological evaluation showed bilateral profound SNHL; no response was obtained from speech reception thresholds. Temporal bone CT scan demonstrated bilateral petrous bone transverse-type fractures involving the vestibule ( Figs. 3 and 4 ). Promontory stimulation test showed good dynamic range for both ears. After 11 months, right ear was implanted by using a Medel Pulsar device (Med-El, Innsbruck, Austria). A simple mastoidectomy, posterior tympanotomy, and standard cochleostomy were performed, with observation of free blood in the cochlea. Full insertion of the electrode array was noted. Intraoperative ESRT was positive.
2.4
Case 4
A 12-year-old boy had a severe head injury in a car accident in September 2005. On physical examination, he had broken right arm and leg. Because of the brain concussion, he was admitted in the ICU for 20 days where he developed progressive hearing loss. Otoscopic ear examination was normal. His audiological examination revealed bilateral profound SNHL. Temporal bone CT scan showed a bilateral petrous bone transverse-type fracture involving the vestibule ( Fig. 5 ). Right ear was implanted in March 2006 using a Medel Pulsar device in 6 months after the accident. A posterior tympanotomy and cochleostomy were performed. The electrode array was fully inserted. Although the intraoperative telemetry was normal, ESRT was not obtained.
2.5
Case 5
A 45-year-old had blunt head injury in July 2003. He was admitted to a nearby hospital, and CT scans demonstrated skull base fracture sparing the temporal bones and brain contusion. One week after the trauma, when he recovered consciousness, he was aware of bilateral hearing loss. He was referred to our hospital 1 month after the trauma. His otologic examination revealed normal results, but his audiogram revealed bilateral profound SNHL ( Fig. 6 ). He also complained about a momentary vertigo. The promontory stimulation test indicated appropriate neural function in both ears. On CT scans, bilateral transverse-type temporal bone fracture passing through otic capsule was noted ( Figs. 7 and 8 ). Right cochlear implantation was carried in August 2004. Incus appeared to be dislocated; granulation tissue and bone chips were observed over the promontorium. Promontorium was appeared as flattened and displaced through facial canal. Oval and round window could not be identified. Cochleostomy was performed, and all electrodes of Medel Combi 40+ device cochlear implant were inserted. C-arm radiography, in the surgical room, confirmed good positioning with positive intraoperative telemetry. A mild facial paresis that responded to steroid therapy at the early postoperative period was noted. Control radiographs confirmed correct positioning. The patient used the cochlear implant for nearly 2 years with decreasing performance in time. With the increase of most comfortable loudness levels over time, the number of electrodes causing nonauditory sensation also observed. The speech perception tests demonstrated disappointing results. Because of limited benefit, reimplantation was planned.
Subsequently, a second surgery was agreed to perform explantation and reimplantation. The implant was explanted from the right ear in February 2007. Cochleostomy window could not be exposed because of fibrous tissues and scarring. At that time, it was decided to perform implantation in the left ear, cochleostomy was performed, and a new Medel Pulsar device cochlear implant was implanted. Electrical stapedius reflex threshold was negative. Intraoperative telemetry indicated the insertion of 8 of 12 electrodes.
All patients postoperative radiograph confirmed correct positioning. Programming and aural rehabilitation were performed 1 month later.
2.6
Audiological data
Auditory performance was measured using a battery of closed- and open-set speech tests. All tests were developed for Turkish language, by the audiology department of Marmara University Medical School (Istanbul, Turkey). The open-set test batteries included 3 syllabic words, phonetically balanced monosyllabic word recognition, and common phrase comprehension. For the closed-set testing, identification for the phonemes at the beginning and the end of monosyllabic word tests was administered. All tests were presented via live voice, at a distance of 1 m with 0° azimuth, and at 70 dB A in sound-treated test booth. During the tests, the patients were asked to set their speech processors’ sensitivity to the most comfortable level. The data on cochlear implant patients were collected preoperatively and at 6 months, 1, 2, 3, 4, 5, and 7 years postoperatively.
2
Materials and methods
2.1
Case 1
A 46-year-old male had a severe head injury in a car accident in May 2000. He was operated on 2 times because of intracranial hemorrhage, and he had an intensive care unit (ICU) stay unconsciously for 3 months. After discharge from the ICU, he noticed bilateral hearing loss. Otoscopic examination was normal, and audiological examination revealed bilateral profound SNHL. Temporal bone computed tomographic (CT) scan showed a transverse-type fracture in the right petrous bone involving the vestibule ( Fig. 1 ). Left temporal bone scan revealed fracture line on the squamous part of the temporal bone ( Fig. 2 ). The promontory stimulation test demonstrated good dynamic range as shown by the test frequencies for both ears. A left cochlear implant was performed 14 months after the accident. Two separate fracture lines were noticed at the operation on the mastoid and squamous part of the temporal bone. A simple mastoidectomy, posterior tympanotomy, and round window approach were performed. Free blood was seen in the cochlea through the incision made on the round window membrane and the electrode array of Nucleus 24M (Cochlear Corporation, Inssbruck, Australia) applied with full insertion. Intraoperative electrical stapedius reflex threshold (ESRT) and neural response telemetry tests were positive.
