Auditory Brainstem Implant in Posttraumatic Cochlear Nerve Avulsion

Abstract

Patients aged over 12 years with neurofibromatosis type 2 are considered candidates for an auditory brainstem implant (ABI). This study extends the indication criteria of ABI to subjects with profound hearing loss due to damaged cochleas and/or cochlear nerves (CNs) following head injuries. In our department, over the period from April 1997 to November 2002, 32 patients, 23 adults and 9 children, were fitted with ABIs. Their ages ranged from 14 months to 70 years. These patients were suffering from a variety of tumor (13 subjects) and nontumor CN or cochlear diseases (19 subjects). Six patients, 5 adults and 1 child, had profound hearing loss following head injury. Their mean age was 25 years (range: 16–48 years). Five were male and 1 female. The retrosigmoid approach was used in all 6 patients. The electrode array was inserted into the lateral recess of the fourth ventricle and correct electrode positioning was monitored with the aid of electrically evoked auditory brainstem responses and neural response telemetry. Correct implantation was achieved in all patients. No complications were observed due to implantation surgery or related to ABI activation and stimulation of the cochlear nuclei. At activation, an average of 9.8 electrodes (range 5–13) were switched on without side effects. One to 6 electrodes were activated in the following sessions after time periods ranging from 2 to 16 months. All patients achieved auditory-alone-mode closed-set word recognition scores ranging from 40 to 100%; 3 had auditory-alone-mode open-set sentence recognition scores of 60–100%; 2 of these even had speech-tracking performance scores of 38 and 43 words, respectively, showing an ability to engage in normal conversation and converse over the phone. The present study demonstrates that the ABI is a useful rehabilitation instrument in subjects with damaged cochleas and/or CN avulsion following head injury who are unamenable or poorly responsive to auditory rehabilitation using cochlear implants.

Satisfação e qualidade de vida em usuários de implante auditivo de tronco cerebral

“…This is usually the case of individuals with Neurofibromatosis type 2 (NF-2), malformation or agenesis of cochlear nerves and/or cochlea, as well as in cases of cochlea ossification following meningitis (1)(2)(3)(4) . The ABI allows access to speech and environmental sounds.…”

Cochlear Implantation in Posttraumatic Bilateral Temporal Bone Fracture

“…If a patient has bilateral fractures through the internal auditory canals disrupting both vestibulocochlear nerves and distorting the anatomy, an auditory brain stem implant may be the only option for auditory rehabilitation. The current results of auditory brain stem implantation do not equal those of multi-channel CIs, but should be considered when the results of the diagnostic workup are inconclusive and when there is radiological evidence of distortion of the cochlear anatomy [25] .…”

Auditory Brainstem Implants in Children: Results Based on a Review of the Literature

“…Twelve (10.0%) of the patients had associated anatomic deformities, and 15 (12.5%) had other associated deficiencies or disabilities, as presented in Tables 1 and 2 [7,[10][11][12][13] . Among the studies, 13 patients [10,14] were fitted with the Pulsar CI100 ABI ® (Med-El Co., Innsbruck, Austria), 5 patients were fitted with a Concerto ABI ® (Med-El Co., Innsbruck, Austria) [10] , 1 patient received a Nucleus 22 Auditory Brainstem Implant System ® (Cochlear Co., Lane Cove, Australia) [15] , and the other 48 [7,13,14,[16][17][18][19] were fitted with the Nucleus 24 Auditory Brainstem Implant System ® (Cochlear Co., Lane Cove, Australia). The Nucleus 24 and 21 ABI ® were activated using the spectral peak coding (SPEAK) strategy [7,13,14,[16][17][18][19] , and the Pulsar CI100 ABI ® was activated using the continuous interleaved sampling (CIS) technique [5] .…”

“…Regarding the surgical procedure, 4 patients [13] were fitted with ABIs with the retrolabyrinthine approach, 8 with the suboccipital approach [14] , 49 with the retrosigmoid approach, [10,18,21] and 2 with the translabyrinthine approach [1,3,6,7,9,[13][14][15][22][23][24] . Both patients with bilateral schwannomas and tumors caused by NF2 received the retrosigmoid and transmeatal combined approaches for tumor removal.…”

“…The hearing and speech evaluation of the implantees has been performed in different ways among authors. Colletti et al [1,6,9,22] and Kalamarides et al [15] tested hearing using the following tests: (1) recognition of environmental sound or sound detection test; (2) closed-set vowel confusion test; (3) closed-set consonant confusion test; (4) closed-set word recognition in the vision-only mode (lip-reading), sound-only mode, and "sound plus-vision mode"; (5) open-set sentence recognition in the vision-only mode, sound-only mode, and sound-plus-vision mode; and (6) speech-tracking test [9,18] . Goffi-Gomez et al [13] and Eisenberg et al [24] used the "Infant Toddler Meaningful Auditory Integration Scale" (IT-MAIS) to evaluate hearing capacity and the "Meaningful Use of Speech Scale" (MUSS) to evaluate speech performance.…”