Non-sutured fixation of cochlear implants using a minimally-invasive approach.

The minimal invasive techniques have become the main stay of the surgical approach for the cochlear implant. Securing the implant with sutures can be challenging due to the limited access and awkward operating angle. We have developed a non-sutured technique to secure the implant by placing and securing the proximal end of the electrode into a bony groove. Our series supports the notion that the technique is suitable for implant cases in which the patient's age is older than 18 months.

Metastatic carcinoma mimicking a facial nerve schwannoma: the role of computerized tomography in diagnosis.

Secondary deposits in the temporal bone are uncommon but well recognized. Such tumours may involve the facial nerve by direct extension of the destructive process into the fallopian canal. We present a rare case of metastasis from a breast carcinoma in the facial nerve itself, involving the nerve in the internal acoustic meatus with extension into the labyrinthine segment, the first genu and into the middle-ear segment. The rest of the temporal bone was not involved. The lesion resembled a facial schwannoma on a routine magnetic resonance (MR) image. The diagnosis was confirmed after a post-operative computed tomography (CT) scan showed another separate secondary deposit in the basisphenoid. Histology was consistent with secondary tumour from a breast carcinoma. The case highlights the importance of keeping a high degree of suspicion for metastatic tumours in patients with a previous history of malignancy and the usefulness of CT scan in the evaluation of such cases.

Cochlear efferent neurons projecting to both ears in the chicken, Gallus domesticus.

Different retrograde neuroanatomical tracers were injected into each cochlea of adult chicken. The number of cells labeled in the cochlear efferent cell group found bilaterally within the caudal pontine reticular formation depended upon the tracer, with True Blue and Fluoro Gold yielding maximal average counts of 332 efferent neurons per injection. Double labeling of less than 1% of these cells was possible with the combination of True Blue and Diamidino Yellow. Thus the contribution of efferent neurons with axon collaterals projecting to both ears is not fundamentally different in birds and other vertebrates.

Frequency selectivity of central auditory neurons without inner ear.

A group of neurons in the inferior colliculus (IC) of the chicken displayed frequency selectivity after surgical removal of both cochleae. Characteristic neuronal frequencies were evident in the following three measures. i) The cells fired spontaneously with discrete preferred interspike intervals; ii) Impulse responses of these neurons to electrical stimuli of cochlear nerves displayed oscillations at the preferred frequencies; iii) When the cochlear nerves were stimulated with a random pulse sequence, a reverse correlation analysis showed that the cells preferred the same frequencies in the stimulus input. Preferred frequencies observed thus far covered over 4 octaves of the auditory range. These "oscillating cells" were found only in a small rostromedial area in the IC. Neuronal frequency selectivity may serve a temporal analysis of sound and underlie sound identification with certain cochlear implants. It may also support interaural crosscorrelation necessary for directional hearing.

Bilobed pharyngeal pouch: a very rare finding.

A bilobed pharyngeal pouch is a very rare finding. One such case is reported here, and is the first to be treated successfully by endoscopic division and stapling.

Post-aural ache: an unusual presentation of a metastatic temporal bone lesion from a primary adenocarcinoma of the lung.

OBJECTIVE: We report a rare case of temporal bone metastasis from a lung primary, presenting only as post-aural tenderness. CASE REPORT: A 57-year-old man presented to our out-patient department with left post-aural pain of four months' duration. Clinical examination revealed tenderness in the left post-aural region; the ear, nose and throat examination was otherwise unremarkable. Computed tomography and contrast-enhanced magnetic resonance imaging showed erosion of the left petrous temporal bone. Incisional biopsy was carried out. Histopathological and immunohistochemical analysis showed infiltrative metastatic adenocarcinoma of the lung. Further imaging with positron emission tomography confirmed increased uptake from the right lower lobe of the lung, suggesting the site of the primary lesion. The patient was treated with chemo-radiotherapy. CONCLUSION: Post-aural pain is a non-specific symptom, and, with normal clinical and audiometric test results, rare lesions such as the one presented could be easily missed. A thorough clinical examination must be performed to identify genuine signs, and appropriate imaging undertaken to exclude rare causes, such as this metastatic lesion of the temporal bone.

A survey of auditory brainstem nuclei in the chicken (Gallus domesticus) with cytochrome oxidase histochemistry.

The chicken's auditory brainstem nuclei from the cochlear nuclei to the nuclei of the lateral leminiscus were studied with cytochrome oxidase histochemistry. A strong reactivity in the cochlear and laminar nuclei was confirmed. Additional structures displaying high activity levels include the superior olive and both partitions of the nucleus intermedius lemnisci lateralis. Unilateral cochlea removal led to a strong reduction of activity in the cochlear nuclei and the nucleus laminaris, whereas there was no remarkable effect in higher brainstem centers. After bilateral cochlea extirpation auditory structures still displayed higher enzyme levels than most other nuclei. These observations point to the extraordinary metabolic activity in the ascending auditory pathway which is largely independent of sensory input from the auditory nerve.

A survey of the auditory midbrain, thalamus and forebrain in the chicken (Gallus domesticus) with cytochrome oxidase histochemistry.

The chicken's central auditory nuclei from the inferior colliculus to field L in the forebrain were studied with cytochrome oxidase histochemistry. All stations of the ascending pathway displayed high activity levels, including the inferior colliculus, the nucleus ovoidalis of the thalamus, and field L1 to L3 and the hyperstriatum ventrale caudale which correspond to primary and secondary auditory cortex. In the inferior colliculus a moderately active external nucleus could be distinguished from a more intensely stained central and superficial nucleus. In the central nucleus there was a lateral shell displaying stronger neuropil reactivity than a central core. Unilateral cochlea removal caused no remarkable effect in tectum and thalamus. The auditory forebrain contralateral to the lesion displayed reduced CO reactivity compared with the ipsilateral side. After bilateral cochlea extirpation auditory structures still displayed higher enzyme levels than most other nuclei.

Retrograde labelling of auditory brainstem neurons following tritiated glycine injection into the inferior colliculus of the chicken, Gallus domesticus.

We investigated retrograde labelling with tritiated glycine injected into the inferior colliculus of the chicken. Tracer deposits were placed in the central nucleus of the inferior colliculus at positions yielding unit activity with best frequencies between 0.4 and 4 kHz. Most neuron systems known to project to the inferior colliculus in birds were unlabelled, whereas strongly labelled cells were found in three nuclei, only on the ipsilateral side. The nucleus lemnisci lateralis pars ventralis contained numerous small glycine-transporting cells. The superior olivary nucleus contained few such cells of similar size in its peripheral region. The nucleus of the trapezoid body contained a group of larger labelled neurons. The observed specificity suggests that we labelled glycinergic neurons projecting to the inferior colliculus.