Cochlear patency problems in cochlear implantation

Abstract

Sensory deafness may be associated with partial or total obliteration of the cochlear scalae. Before undertaking cochlear implant surgery, a preoperative assessment of cochlear patency with high‐resolution computed tomography (CT) is indicated. To determine the accuracy of pre‐implant CT, a review of the radiographic and surgical findings in 36 implanted ears was performed. An abnormal CT scan was found to be a reliable predictor of compromised cochlear patency at operation. These findings help the surgeon to select the side most favorable for implantation and to anticipate problems that may be encountered during device insertion. A normal pre‐implant CT scan, however, does not exclude the possibility of compromised cochlear patency. A 46% false negative rate was encountered, presumably because subtle degrees of osseous or fibrous obliteration of the cochlea are beyond the resolution by current generation CT scanners. In our opinion, the radiographic finding of cochlear ossification is not a contraindication to an attempt at cochlear implantation. The only assured way of determining the extent of cochlear patency is by performing an ‘exploratory cochleostomy’ with fenestration of the basal cochlear turn. Drilling anteriorly through an ossified basal scala tympani will often expose an adequate lumen and permit insertion of even a long multichannel electrode into a partially ossified cochlea. Nevertheless, it is essential that the implant team be prepared with devices appropriate for whatever existing or surgically created lumen may be available.

Flexible fiberoptic endoscopy and laser surgery in obliterated cochleas: Human temporal bone studies

“…Partial or complete ossification of the cochlear scalae is a common occurrence in patients with nonspecific congenital deafness and profound deafness resulting from meningitis, temporal bone fracture, otosclerosis, autoimmune diseases, MeniBre's disease, or ototoxicity [2,3]. The scala tympani, particularly in the basal turn region, is the segment of the cochlea most commonly affected by fibrosis and new bone formation [4].…”

Método para medida do comprimento da cóclea por meio de ressonância magnética

“…Himi et al 15 have stated that 3D MRI is superior compared to CT for assessing the patency of the perilymphatic space. Jackler et al 2 and Nikolopoulos et al 3 have stated that a normal preoperative CT does not exclude the possibility of finding an obstructed cochlea during surgery. MRI has thus been used as the imaging method of choice for assessing spiral canal obstructions, especially in candidates for cochlear implants.…”

“…Computed tomography (CT) and magnetic resonance imaging (MRI) are currently used for this evaluation. [2][3][4][5][6][7][8][9][10][11][12][13] Jackler et al 2 found a 46% rate of false negative results when comparing the results of high resolution CT with surgical findings in 36 ears with implants. Nikolopoulos et al 3 concluded that the sensitivity rate was about 62.5% in a study of 108 children.…”

Complicações em 550 cirurgias consecutivas de implante coclear

“…Care in making the flap is important to minimize complications; we suggest some shapes which improve blood supply. In the anterior base flap, the blood supply comes from the superficial temporal artery and the dermal plexus; in the inferior base flap this blood supply comes from retroauricular and occipital branches of the external carotid artery [18][19][20][21] . Cholesteatoma is a rare and late complication which affected 1.2% of our patients with a mean time of onset 45 months after the procedure.…”