Translabyrinthine Surgical Approach to the Internal Acoustic Meatus

Abstract

A good surgical approach should offer adequate access to manage the pathology and possible complications; it should be capable of modification to suit the circumstances; and it should be relatively devoid of risk. This versatility is to be found in the translabyrinthine approach to the internal acoustic meatus and cerebellopontine angle if combined, when necessary, with a modified transtentorial dissection.Acoustic neuroma surgery The translabyrinthine approach was first suggested by Panse (1904) and it was performed in 1912 by Quix and later by others. Though Cushing (1917) foresaw combined surgical attacks on this area, he condemned the translabyrinthine operation (Cushing 1921) and it fell into disrepute. For the next forty years the suboccipital operation described by Dandy (1925) was predominantly used, and even today it is preferred by many neurosurgeons. Ironically it is returning to favour with neurosurgeons and otologists since, in the management of smaller vestibular schwannomas, it offers the prospect of preservation of hearing as well as of facial nerve function following total tumour removal (Smith 1977). Regrettably, however, many patients when first seen have large tumours which are not amenable to such preservation, and even among the group with smaller tumours the hearing loss is frequently so severe that there would be little point in attempting to maintain it. Furthermore, Morrison et al. (1976) have drawn attention to the fact that some schwannomas, whatever their nerve or origin, are surgically inseparable from the cochlear division of the VIII cranial nerve; this applied to nearly one in four.House (1964) and Hitselberger & House (1966) pioneered the modern revival of the translabyrinthine operation which, assisted by microsurgical dissection, antibiotics, steroids and by good anaesthesia, is now practised by teams of otologists and neurosurgeons in many centres throughout the world. With increasing experience, surprisingly large tumours can be removed totally by the translabyrinthine approach. The principal advantage is in the surgical management of small and medium-sized tumours when there is very little risk of mortality or morbidity even to the facial nerve (Table I). When the otologist becomes involved in the surgical treatment of these lesions, his searching for smaller tumours is likely to be more enthusiastic and persevering. The advent of computerized axial tomography, while revolutionizing the comfort and safety of diagnosis, has not yet solved this problem. There is still a need for tomographic contrast radiology of the type described by Morris & Wylie (1974) for the demonstration of intracanalicular and smaller angle filling defects.When we come to consider large tumours which have distorted or displaced the brain-stem and which are frequently associated with raised intracranial pressure, the translabyrinthine 1 Paper read to Sectionof Otology at Brighton, 2SJune 1977 0141.0768/78

Facial Nerve Function after Surgery for Removal of Acoustic Neuroma by the Extended Middle Cranial Fossa Approach

“…In a study in which the suboccipital approach was combined with the translabyrinthine approach, the anatom ical facial nerve preservation rate was found to be 84% [2], Large discrepancies are seen in the results obtained by different investiga tors on the functional preservation rate, es pecially in patients with large tumors, for whom rates of 14.5 [6], 77 [8], and 75-92% [10] have been reported. Although func tional preservation is more important than anatomical preservation, there are few de tailed reports on this subject.…”

“…At institu tions that have performed 100 or more oper ations by the translabyrinthine approach, the anatomical preservation rate in patients with small or medium-sized tumors has been found to be excellent, with reported rates of 81.4-100 [6] and 98-99% [9]. Reported ana tomical preservation rates vary widely for patients with large tumors, ranging from 14.5 [6] to 84% [9], We obtained anatomical preservation rates in initial surgery of 85.2% of 27 patients with medium-sized tumors. For those with large tumors, we found a pres ervation rate of 62.2% of 45 patients, mid way between the two values reported above.…”

“…Although several investigators have re ported on facial nerve function after AN sur gery by the suboccipital approach [1], there have been few reports on the results of sur gery by a lateral approach [6,7], and even fewer that have taken the above-mentioned factors into consideration.…”

Misleading auditory brainstem responses in a case of acoustic neuroma

“…There is an inverse relationship between the detectability and the operability of acoustic neuroma (Selters and Brackmann, 1977) and this is enhanced by the morbidity and mortality rates for small as opposed to large tumours (House, 1978;Morrison, 1978). It is therefore of great importance to diagnose tumours as early as possible in order to preserve facial nerve, and occasionally cochlear nerve, function.…”

A stepwise illustration of the translabyrinthine approach to a large cystic vestibular schwannoma

“…Surgical series of translabyrinthine resections often include meningiomas of the cerebellopontine angle as well as the internal acoustic meatus, schwannomas of the facial and trigeminal nerves, and cholesteatomas, neurinomas, and chordomas – illustrating the multiple uses of this approach 3 . In this paper, the translabyrinthine approach for resection of a large, cystic vestibular schwannoma (figure 1) is illustrated in a stepwise manner using a narrated video and still images.…”