Age as a Factor of Growth in Mastoid Thickness and Skull Width.

OBJECTIVES: To understand the growth rate of mastoid thickness and skull width associated with the age for both normal and malformed inner-ear anatomy groups. Also, to determine if there is any mathematical relation between cochlear size as measured by the "A" value against the age, mastoid thickness, and skull width. METHODS: Ninety-two computed tomography image datasets of human temporal bone were made available that contained normal (n = 44) and malformed inner-ear (n = 48) anatomies. The age of the subjects ranged from 6 months to 79 years. CE marked OTOPLAN preplanning otology software was used to load the patient's preoperative images for making all the measurements including mastoid thickness, skull width, and the cochlear size as measured by the "A" value. Mastoid thickness was measured both in axial and coronal planes starting from the cochlear entrance to the skull surface, with the line in plane with the basal turn of the cochlea. Skull width was measured from side to side in both axial and coronal planes from the image slice that gave the highest width. The cochlear size in terms of basal turn diameter "A" was measured from "Cochlear View" in the oblique coronal plane. RESULTS: Mastoid thickness and skull width increased with age in a logarithmic manner. The mastoid thickness increased from a minimum of 17 mm to around 34 mm and the skull width increased from 105 mm to around 146 mm as the age increased from 6 months to 20 years. At the age of around 20, both the mastoid thickness and skull width reached the plateau and thereafter with a very little growth. The skull width was linearly correlated with the mastoid thickness conveying the fact that bigger the head size is, thicker will be the mastoid. The size of the cochlea as measured by the "A" value did not have any meaningful correlation with the age, mastoid thickness, and skull width. This conveys the message that the cochlear size is independent of the overall size of head and the age of patient. CONCLUSIONS: Mastoid thickness and skull width increased with age, while the cochlear size was independent of age, mastoid thickness, and the size of the skull.

Trans-aditus approach: an alternative technique for cochlear implantation.

The objective of this study was to report our preliminary experience with an alternative technique for cochlear implantation. Twenty patients underwent cochlear implantation via a trans-aditus ad antrum approach to the round window. The main steps involved in the surgical procedure are cortical mastoidectomy, elevation of tympanomeatal flap, incudostapedial joint dislocation, incus removal, preparation of a bed for the implant, cochleostomy via the external auditory canal, and finally insertion of the electrode into the cochlea via the aditus. Twenty-five implants were performed on 20 patients, 18 children (mean age of 3.2 years) and 2 adults. Twelve patients were males and eight were females. All the children were pre-lingual while the adults were post-lingual. Nucleus freedom cochlear implant system (Cochlear, Lane Cover, NSW, Australia) was used in four patients and a cochlear Nucleus 5 was used in six patients. A Med-el SONATA implant (MED-EL, Innsbruck, Austria) was used in 15 patients. The minimum follow-up was 5 months. Here, we describe a new alternative technique for cochlear implantation and report our preliminary results. The procedure has advantages over the existing techniques and avoids the potential complications of posterior tympanotomy, transcanal, and transmeatal techniques.

Conservative management of acoustic neuroma.

AIM OF STUDY: To identify those patients with vestibular schwannoma (acoustic neuroma) in whom treatment becomes necessary. METHOD: Retrospective chart review. RESULT: A total of 205 patients with small tumors were followed for a mean of 40.8 months. The longest follow-up was 180 months. One hundred and ninety-seven patients had a follow-up of more than 12 months. Eight patients with a follow-up of less than 12 months were excluded from the study. In 136 patients (66.3%) the tumor did not grow. Forty-seven patients (23.9%) showed some evidence of slow growth. Eight of 197 patients (4%) had rapid growth and 6 patients (3%) had radiological evidence of tumor regression. Fifteen patients came to surgery. Five of these showed rapid growth, four developed ataxia in whom tumor growth was slow, three had ataxia without tumor growth, two patients developed brainstem compression, and one patient elected to proceed to surgery, although there were no tumor growth or symptoms. CONCLUSION: Few patients with small tumors will come to surgery in the short term. Perhaps the majority of patients with such small tumors will not need surgery. Long-term follow-up studies of 20 years or more are required to be come more confident about the natural history of these tumors. This study continues.