Monitoring Cochlear Health With Intracochlear Electrocochleography During Cochlear Implantation: Findings From an International Clinical Investigation

OBJECTIVES

Electrocochleography (ECochG) is emerging as a tool for monitoring cochlear function during cochlear implant (CI) surgery. ECochG may be recorded directly from electrodes on the implant array intraoperatively. For low-frequency stimulation, its amplitude tends to rise or may plateau as the electrode is inserted. The aim of this study was to explore whether compromise of the ECochG signal, defined as a fall in its amplitude of 30% or more during insertion, whether transient or permanent, is associated with poorer postoperative acoustic hearing, and to examine how preoperative hearing levels may influence the ability to record ECochG. The specific hypotheses tested were threefold: (a) deterioration in the pure-tone average of low-frequency hearing at the first postoperative follow-up interval (follow-up visit 1 [FUV1], 4 to 6 weeks) will be associated with compromise of the cochlear microphonic (CM) amplitude during electrode insertion (primary hypothesis); (b) an association is observed at the second postoperative follow-up interval (FUV2, 3 months) (secondary hypothesis 1); and (c) the CM response will be recorded earlier during electrode array insertion when the preoperative high-frequency hearing is better (secondary hypothesis 2).

DESIGN

International, multi-site prospective, observational, between groups design, targeting 41 adult participants in each of two groups, (compromised CM versus preserved CM). Adult CI candidates who were scheduled to receive a Cochlear Nucleus CI with a Slim Straight or a Slim Modiolar electrode array and had a preoperative audiometric low-frequency average thresholds of ≤80 dB HL at 500, 750, and 1000 Hz in the ear to be implanted, were recruited from eight international implant sites. Pure tone audiometry was measured preoperatively and at postoperative visits (FUV1 and follow-up visit 2 [FUV2]). ECochG was measured during and immediately after the implantation of the array.

RESULTS

From a total of 78 enrolled individuals (80 ears), 77 participants (79 ears) underwent surgery. Due to protocol deviations, 18 ears (23%) were excluded. Of the 61 ears with ECochG responses, amplitudes were < 1 µV throughout implantation for 18 ears (23%) and deemed "unclear" for classification. EcochG responses >1 µV in 43 ears (55%) were stable throughout implantation for 8 ears and compromised in 35 ears. For the primary endpoint at FUV1, 7/41 ears (17%) with preserved CM had a median hearing loss of 12.6 dB versus 34/41 ears (83%) with compromised CM and a median hearing loss of 26.9 dB ( p < 0.014). In assessing the practicalities of measuring intraoperative ECochG, the presence of a measurable CM (>1 µV) during implantation was dependent on preoperative, low-frequency thresholds, particularly at the stimulus frequency (0.5 kHz). High-frequency, preoperative thresholds were also associated with a measurable CM > 1 µV during surgery.

CONCLUSIONS

Our data shows that CM drops occurring during electrode insertion were correlated with significantly poorer hearing preservation postoperatively compared to CMs that remained stable throughout the electrode insertion. The practicality of measuring ECochG in a large cohort is discussed, regarding the suggested optimal preoperative low-frequency hearing levels ( < 80 dB HL) considered necessary to obtain a CM signal >1 µV.

Multi-electrode sequential versus single electrode stimulation to elicit the stapedial reflex during cochlear implantation: Correlation with maximum comfort level

OBJECTIVES

To assess whether electrical stimulation sequentially delivered through 4 electrodes located in different cochlear areas may elicit the stapedial reflex at lower levels compared to single electrode stimulation and to correlate the sequentially obtained values with the maximum comfort level (C-level).

PATIENTS AND METHODS

A retrospective study was performed on 35 post-verbal adult patients (age 19-80 years) consecutively implanted in 2 cochlear implant centers, evaluating the level of stimulation (pulse width) necessary to electrically evoke the stapedial reflex with two different stimulation modalities: single electrode versus sequential 4 electrode stimulation. Threshold values were compared with C-level obtained at activation.

RESULTS

The average differences of pulse width and C-level were significantly smaller (P<0.0001) when the stapedial reflex was obtained with the sequential stimulation modality and reached statistical significance for every single electrode (P<0.0001).

CONCLUSIONS

Stapedial reflex thresholds obtained with sequential stimulation through 4 different electrodes significantly correlate to the C-level obtained at the first setting and may be helpful in defining the upper limit of the dynamic field during initial CI mapping.

Bilateral congenital cholesteatoma: report of an emblematic case

OBJECTIVES

To describe a case of bilateral congenital cholesteatoma (CC) of the middle ear with a focus on diagnostic clues, treatment and a review of the pertinent literature.

PATIENT AND METHODS

An 8-year-old child was incidentally noted to have whitish bilateral retrotympanic masses with normal hearing and referred to our department in January 2005. Microscopic examination of the ears and CT scan of the temporal bones led to a presumptive diagnosis of bilateral CC. The lesion on the right side was surgically removed, followed by that on the left side after 6 months; a retroauricular transcanal approach was adopted in both ears.

RESULTS

Anatomic integrity of the middle ear was achieved with preservation of pre-operative hearing. No signs of recurrence were evident 20 months after the last surgery.

CONCLUSIONS

Bilateral CC is a rare finding but otologists must be aware of it. Surgery must be planned early in order to achieve radical removal of the pathology and the preservation of middle ear structures.

Gynecomastia and the complete circumareolar approach in the surgical management of skin redundancy

Gynecomastia is a benign enlargement of the male breast due to a physiological or pathological factor that interferes with the balance between estrogens and androgens in the serum. Gynecomastia itself requires no treatment unless the persistent enlargement of the male breast is a source of embarrassment and/or distress for the adolescent or adult man. The indications for the surgical treatment of gynecomastia are founded on two main objectives: (1) the restoration of male chest shape and (2) diagnostic evaluation of suspected breast lesions. The diagnostic evaluation begins with an adequate history and a thorough breast examination helped by laboratory tests and instrumental research. Several approaches for surgical treatment have been described in the literature. Some problems arise in patients who have significant enlargement and ptosis of the breast that will require skin reduction and in some patients requiring nipple-areola complex reduction. The authors believe that the complete circumareolar technique with purse-string suture creates the best aesthetic results, with fewer complications, in patients with moderate and severe ptotic glandular breast enlargements that have skin redundancy combined with areolar enlargement. From 1995 through 1999, a total of 10 male patients with moderate to severe gynecomastia were treated surgically using a complete circumareolar approach. All patients achieved a good aesthetic contour of the chest. Only two patients required a revision of the circumareolar scar to correct postoperative enlargement.