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To report device failures, audiological signs and other reasons for revision cochlear implant surgery, and discuss indications for revision surgery.
Revision procedures between November 1997 and August 2017 were retrospectively analysed. Over 20 years, 2181 cochlear implant operations were performed, and 114 patients underwent 127 revision operations.
The revision rate was 4.67 per cent. The full insertion rate for revision cochlear implant surgery was 88.2 per cent. The most frequent reasons for revision surgery were: device failure (59 per cent), wound breakdown (9.4 per cent) and electrode malposition (8.7 per cent). The device failure rate was: 2.78 per cent for Advanced Bionics, 1.82 per cent for Cochlear and 5.25 per cent for Med-El systems. The number of active electrodes was significantly increased only for Med-El devices after revision surgery. The most common complaints among 61 patients were: gradually decreased auditory performance, sudden internal device shutdown and headaches.
The most common reason for revision surgery was device failure. Patients should be evaluated for device failure in cases of: no hearing despite appropriate follow up, side effects such as facial nerve stimulation, and rejection of speech processor use in paediatrics. After revision surgery, most patients have successful outcomes.
To determine cochlear duct mid-scalar length in normal cochleae and its role in selecting the correct peri-modiolar and mid-scalar implant length.
The study included 40 patients with chronic otitis media who underwent high-resolution computed tomography of the temporal bone. The length and height of the basal turn, mid-modiolar height of the cochlea, mid-scalar and lateral wall length of the cochlear duct, and the ‘X’ line (the largest distance from mid-point of the round window to the mid-scalar point of the cochlear canal) were measured.
Cochlear duct lateral wall length (28.88 mm) was higher than cochlear duct mid-scalar length (20.08 mm) (p < 0.001). The simple linear regression equation for estimating complete cochlear duct length was: cochlear duct length = 0.2 + 2.85 × X line.
Using the mid-scalar point as the reference point (rather than the lateral wall) for measuring cochlear duct mid-scalar length, when deciding on the length of mid-scalar or peri-modiolar electrode, increases measurement accuracy. Mean cochlear duct mid-scalar length was compatible with peri-modiolar and mid-scalar implant lengths. The measurement method described herein may be useful for pre-operative peri-modiolar or mid-scalar implant selection.
This study aimed to determine the effect of the subperiosteal tight pocket technique versus the bone recess with suture fixation technique on the revision cochlear implantation rate and complications.
This retrospective study included 1514 patients who underwent cochlear implantation by 2 senior surgeons between October 2002 and January 2016. Revision cases were identified and analysed.
In all, 52 patients (3.34 per cent) underwent revision cochlear implantation. The revision rate was 7.18 per cent in the subperiosteal tight pocket group versus 2.37 per cent in the bone recess with suture fixation group (p < 0.001). Device failure was the most common reason for revision surgery in both groups. There was a significant difference in the device failure rate between the bone recess with suture fixation group (2.11 per cent) and subperiosteal tight pocket group (6.88 per cent) (p < 0.001).
Accurate fixation of the cochlear implant receiver/stimulator is crucial for successful cochlear implantation. As the bone recess with suture fixation technique is associated with a lower revision rate and a similar complication rate as the subperiosteal tight pocket technique, it should be the preferred fixation technique for cochlear implantation.
The bony cochlear nerve canal is the space between the fundus of the internal auditory canal and the base of the cochlear modiolus that carries cochlear nerve fibres. This study aimed to determine the distribution of bony labyrinth anomalies and cochlear nerve anomalies in patients with bony cochlear nerve canal and internal auditory canal atresia and stenosis, and then to compare the diameter of the bony cochlear nerve canal and internal auditory canal with cochlear nerve status.
The study included 38 sensorineural hearing loss patients (59 ears) in whom the bony cochlear nerve canal diameter at the mid-modiolus was 1.5 mm or less. Atretic and stenotic bony cochlear nerve canals were examined separately, and internal auditory canals with a mid-point diameter of less than 2 mm were considered stenotic. Temporal bone computed tomography and magnetic resonance imaging scans were reviewed to determine cochlear nerve status.
Cochlear hypoplasia was noted in 44 out of 59 ears (75 per cent) with a bony cochlear nerve canal diameter at the mid-modiolus of 1.5 mm or less. Approximately 33 per cent of ears with bony cochlear nerve canal stenosis also had a stenotic internal auditory canal and 84 per cent had a hypoplastic or aplastic cochlear nerve. All patients with bony cochlear nerve canal atresia had cochlear nerve deficiency. The cochlear nerve was hypoplastic or aplastic when the diameter of the bony cochlear nerve canal was less than 1.5 mm and the diameter of the internal auditory canal was less than 2 mm.
The cochlear nerve may be aplastic or hypoplastic even if temporal bone computed tomography findings indicate a normal cochlea. If possible, patients scheduled to receive a cochlear implant should undergo both computed tomography and magnetic resonance imaging of the temporal bone. The bony cochlear nerve canal and internal auditory canal are complementary structures, and both should be assessed to determine cochlear nerve status.
This study investigated the performance of a cartilage slicer device referred to as the ‘Hacettepe cartilage slicer’.
Forty-one cartilage pieces were harvested from eight fresh frozen human ears and measured in thickness with a digital micrometer. These pieces were randomly sliced using four different thickness settings and two different types of blades. The thicknesses of the slices and remaining pieces were measured also. Scanning electron microscopy was utilised to determine the surface smoothness of the slices.
Thickness results showed a proportional increase with the increasing thickness setting, with a ±0.1 mm margin of error. The measurements showed that over 95 per cent of the slices’ structural integrity was preserved. Although both blades provided satisfactory results, scanning electron microscopy revealed that the slices cut with a single bevel blade had superior surface smoothness.
To our knowledge, the current study is the first to evaluate the performance of a cartilage slicer device. Based on the thickness results, the Hacettepe cartilage slicer fulfilled its design goals: to consistently produce slices at the intended thickness with a ±0.1 mm tolerance, and to preserve over 95.3 per cent of cartilage thickness thereby ensuring undamaged, strong cartilage slices.
This paper reports the authors' technique of manubrio-stapedioplasty using glass ionomer cement for malleus and incus fixation due to tympanosclerosis.
A retrospective case review was conducted of five patients with conductive hearing loss (mean pre-operative air–bone gap of 42.75 dB) treated in a tertiary referral centre. The hearing results of a manubrio-stapedial bone cement ossiculoplasty technique, utilised on the five patients, were analysed. All cases were Wielinga and Kerr tympanosclerosis classification type 2 (attic fixation of the malleus-incus complex with a mobile stapes). The incus and head of the malleus were removed in all patients, and the manubrium was directly connected to the head of the mobile stapes using glass ionomer cement. Patients were evaluated in terms of pre- and post-operative audiometric results; hearing gain and post-operative air–bone gap were the main outcome measures.
Mean post-operative air–bone gap was 5.25 dB. Four patients had an air–bone gap of less than 10 dB; the remaining patient had an air–bone of 12.50 dB.
Manubrio-stapedioplasty is an effective method for ossicular reconstruction in cases of malleus and incus fixation due to tympanosclerosis.
We aimed to study the influence of age, in normal hearing individuals, on: the masking level difference test, the speech recognition in noise test, the transient evoked otoacoustic emissions test, and the contralateral transient evoked otoacoustic emission suppression test. We also aimed to research the effect of age when using these tests to evaluate the central auditory nervous system.
Transient evoked otoacoustic emissions and contralateral transient evoked otoacoustic emission suppression were measured in all subjects. Subjects also underwent masking level difference and speech recognition in noise tests.
We found a decrease in transient evoked otoacoustic emission amplitudes, speech recognition in noise scores and hearing thresholds with age. We also found that higher masking level difference values were associated with lower speech recognition in noise scores and contralateral transient evoked otoacoustic emission suppression values.
We conclude that decreasing speech recognition in noise scores are associated with decreasing contralateral transient evoked otoacoustic emission supression values. This effect may be related to medial efferent system dysfunction.
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