1/57. Using the CLARION cochlear implant in cochlear ossification. This paper is a retrospective review of 5 patients with various degrees of cochlear ossification who were implanted with the CLARION Multi-Strategy Cochlear Implant. Preoperative computed tomography scans, intraoperative findings, surgical technique, and hearing outcomes are discussed in a case report format. Full implantation was achieved in all cases by a systematic approach that included drill-through of proximal obstruction (2 cases), scala vestibuli insertion (2 cases), and complete drill-out (1 case). The only complication was delayed wound healing in a patient with sickle cell disease, chronic active hepatitis, and steroid dependency on antimetabolite therapy. Early results show that the 4 patients with at least 3 months of experience have a mean open-set sentence recognition score of 55% and a mean open-set word recognition score of 24%. The conclusion is that implantation of the Clarion device in ossified cochleas can be successful in all degrees of ossification and can provide significant hearing benefit. ( info) |
2/57. Implantation of the CLARION cochlear implant in an ossified cochlea. This report describes the successful implantation of the CLARION Multi-Strategy Cochlear Implant electrode in the totally ossified cochlea of a 5-year-old child via a radical mastoidectomy approach. Postoperatively, the child demonstrated responses to auditory stimuli, even though the electrode array contacted only bone and muscle graft tissue with no visible evidence of nerve fibers or cochlear lumen. Responses to sound did not begin to emerge until 10 weeks following initial stimulation and improved slowly over time. Although the child's postoperative auditory performance is more limited than that of most implanted children, she derives substantially more benefit from her implant than she did from conventional hearing aids. ( info) |
3/57. Relationship between cochleovestibular disorders in hemifacial spasm and neurovascular compression. OBJECTIVE: To investigate the evolution of cochleovestibular symptoms before, during, and after microvascular decompression (MVD) of the facial nerve in hemifacial spasm. STUDY DESIGN: Prospective study in patients with hemifacial spasm. Among our 13 patients who underwent MVD of the facial nerve from 1995 to 1997, 6 had associated cochleovestibular disorders confirmed by neurotologic tests. RESULTS: In four of these patients, a concomitant compression of the eighth and facial nerves was found at surgery. Preoperative magnetic resonance angiography studies had shown three cases of this double neurovascular compression. Intraoperative auditory brainstem response monitoring showed that interposition of Teflon between vessel and facial nerve was highly critical to the auditory function. Auditory brainstem response monitoring was used to guide the surgeon during this critical phase. Surgery improved at least one cochleovestibular symptom in each patient. CONCLUSIONS: The authors propose two pathophysiologic hypotheses. First, the concomitant facial and cochleo-vestibular symptoms may be due to a hyperactivity of both the facial and vestibular nuclei. According to theories about cryptogenic hemifacial spasm, the origin of this hyperactivity could be an ectopic excitation focus. However, the two nerves may have different sites of ectopic excitation. According to the second hypothesis, a pulsatile compression of the facial nerve may be transmitted to the eighth nerve. This could take place even if only the facial nerve is in contact with a vascular loop. ( info) |
4/57. Supracochlear approach to the petrous apex: case report and anatomic study. OBJECTIVE: The case of an 11-month old infant with petrous apex abscess drained through the supracochlear air cells prompted an anatomic study of the dimensions of this approach. Of the various approaches to the petrous apex, the supracochlear dissection has been the least described. STUDY DESIGN: Twenty temporal bones were dissected to completely expose the epitympanum. This required mastoidectomy, exenteration of zygomatic root and epitympanic air cells, and removal of the incus. Measurements were taken from three sides of a triangle described by the tegmen tympani (TT), tympanic facial nerve (TFN), and superior semicircular canal (SSCC). Similar measurements were obtained from standard coronal computerized tomographic (CT) scans from a random series of 20 patients. RESULTS: Mean lengths of the sides of the triangle were 7.0 mm (TT), 5.3 mm (TFN), and 4.8 mm (SSCC). The superior petrous apex air cells or marrow space was accessible through the supracochlear exposure in all specimens. Mean lengths from the coronal CT images were 4.2 mm (TT), 3.2 mm (TFN), and 8.45 mm (SSCC). CONCLUSIONS: The authors conclude that the supracochlear approach may provide adequate access to the superior petrous apex for drainage and biopsy in selected cases. ( info) |
5/57. A three-array cochlear implant: a new approach for the ossified cochlea. The ossified cochlea, although rare, represents a challenge for cochlear implantation. While it is no longer considered an absolute contra-indication to implantation, insertion may be technically difficult and the results may be suboptimal. Techniques which have been employed are reviewed. The new Digisonic multi-array implant, which was designed specifically for use in the ossified cochlea is described, along with the technique used for its insertion. In the first patient to be implanted with this new implant, all electrodes lie within the cochlea and are functional. The new Digisonic multi-array implant may have advantages over other solutions for the ossified cochlea. ( info) |
| OBJECTIVE: Auditory neuropathy is a recently described clinical entity characterized by sensorineural hearing loss in which the auditory evoked potential (ABR) is absent but otoacoustic emissions are present. This suggests a central locus for the associated hearing loss. In this study the results observed in a child with auditory neuropathy who received a cochlear implant are presented and compared with those of a matched group of children who were recipients of implants. methods: A single-subject, repeated-measures design, evaluating closed-set and open-set word recognition abilities was used to assess the subject and a control group of matched children with implants who had also experienced a progressive sensorineural hearing loss. RESULTS: The subject demonstrated improvements in vowel recognition (82% correct) by 1 year after implantation, which were only slightly lower than the control group. Consonant recognition and open-set word recognition scores were significantly lower. CONCLUSION: Caution should be exercised when considering cochlear implantation in children with auditory neuropathy. As with conventional hearing aids, less than optimal results may be seen. ( info) |
| Insertion of a sufficient number of electrodes is important for a successful use of cochlear implants. We investigated the results of scala vestibuli insertion for cochlear implantation in cases of obstructed scala tympani. In a series of 200 cochlear implantations, scala vestibuli insertion was successfully performed in 4 cases with obstruction of the scala tympani. Etiologies included a temporal bone fracture, severe otosclerosis and malformations of the cochlea. The maximum insertion depth obtained via the scala vestibuli was 30 mm. Postoperative results were comparable to patients in whom conventional scala tympani insertion was performed. No adverse effects related to the site of insertion were observed. scala vestibuli insertion offers a valuable alternative in cases of obstructed scala tympani that can be employed for a variety of etiologies. ( info) |
8/57. Hearing impairment in 18q deletion syndrome. The 18q-syndrome is associated with hearing impairment in 50-80 per cent of cases. The hearing loss may be sensorineural or conductive. A high proportion of cases are associated with narrow or stenosed external auditory canals. This may be a useful clinical pointer to the syndrome. Two cases with impaired hearing are presented in this paper including one case with complex external ear and middle ear malformations. The clinical and audiological features in each case are described. ( info) |
| BACKGROUND: gadolinium-enhanced magnetic resonance imaging (GdMRI) is routinely used in the evaluation and management of suspected retrocochlear pathology such as vestibular schwannoma. However, its value in the evaluation and diagnosis of cochlear pathology associated with sensorineural hearing loss (SNHL) has been less clear. STUDY DESIGN: Retrospective review of case histories and imaging studies of patients with SNHL and cochlear enhancement on GdMRI diagnosed between 1998 and 2000. RESULTS: Five patients with SNHL who required gadolinium administration to establish the diagnosis of endocochlear disease were identified. Diagnosed lesions included an intralabyrinthine schwannoma, intracochlear hemorrhage, radiation-induced ischemic change, autoimmune labyrinthitis, and meningogenic labyrinthitis. In these illustrative cases, the GdMRI demonstrated intrinsic high signal or contrast enhancement within the cochlea and labyrinth in the absence of a retrocochlear mass. In one patient with meningogenic labyrinthitis, cochlear enhancement on MRI led to prompt cochlear implantation before the potential development of cochlear ossification. CONCLUSION: Our experience suggests that GdMRI plays a crucial role in the diagnosis of cochlear pathology associated with sensorineural hearing loss and may directly impact patient management. ( info) |
| We present three cases of acquired deafness, associated with obliterated cochleas, in which the apparently radiologically more favourable side was chosen for implantation. In the first case, because of unexpected obliteration, only a partial insertion was possible. Deteriorating performance and non-auditory stimulation of the facial nerve led to removal of the implant and a contralateral implantation with full insertion under the same anaesthetic gave a good postoperative result. In the second case, CT scanning indicated minimal obliteration, but extensive obliteration was encountered at surgery, which required double-array insertion with a delayed but satisfactory outcome. In the third case, extensive unexpected obliteration was noted at surgery and, in light of the experience gained with the first two cases, it was decided not to proceed but to explore the contralateral side. At surgery on the contralateral side, a patent cochlea was noted with full electrode insertion and an excellent outcome. These cases demonstrate a learning curve for this department and our philosophy now is to explore the contralateral ear rather than accept a partial insertion. ( info) |