Total removal of large acoustic neuromas. A modification of the McKenzie operation with special emphasis on saving the facial nerve

[Results of 110 microsurgical acoustic neuroma operations]

We report our experiences in 110 cases of microsurgical removal of acoustic neurinomas. The historic development, the chances of preservation of the facial nerve and hearing function and the mortality risks are described in detail, hereby stressing the advantages of the lateral suboccipital approach in microneurosurgery.

Operative treatment of lesions in the region of the tentorial notch

After a description of the topographic anatomy, the different approaches to the tentorial notch and the details of technique are illustrated by a few examples. The pterional approach permits surgical treatment of lesions in the supratentorial region of the anterior and middle third of the tentorial opening. Any approach to the infratentorial region can be enlarged and improved by incising and stitching back the free margin of the tentorium. The medial occipital approach is appropriate for space-occupying lesions situated medially in the ascending portion, that is in the posterior third of the free margin of the tentorium. Infratentorial tumours in the cerebello-pontine angle and in the prepontine region, with extension into the tentorial notch, are best treated through the lateral suboccipital approach. A subfrontal infrachiasmatic procedure is indicated in the case of suprasellar lesions with parasellar extension into the tentorial notch, if the anatomy of the optic chiasm allows it. The location of any particular lesion may call for a combination of different approaches.

Total one-stage suboccipital microsurgical removal of acoustic neuromas of all sizes: with emphasis on arachnoid planes and on saving the facial nerve

Clinical suspicion is essential for early diagnosis of acoustic neuroma. No absolutely characteristic pattern of hearing loss occurs, and atypical presentations are the rule. The diagnosis of acoustic neuroma is possible by tests that can be performed on an outpatient basis. A hearing loss for high tones with impaired speech discrimination is frequently seen. Testing of the acoustic reflexes and particularly the brain stem auditory-evoked responses (BAER) are becoming the most reliable methods of defining hearing loss in patients suspected of having an acoustic neuroma. High-resolution, thin-sectioning, overlapping-cut CT scanning including CT pneumography when necessary and polytomography of the internal auditory meatus are the mainstays of radiologic evaluation. Complete removal of the tumor at one operation is usually possible by the suboccipital retromastoid route with preservation or restoration of normal brain stem function and preservation of facial nerve function. Preservation of hearing has occasionally been accomplished, and the potential occasionally exists for restoration of hearing in patients with favorable smaller tumors, which have not acquired extensive arterial supply in common with the cochlea. The two factors that most influence results are early diagnosis and gentleness of surgical manipulation of the tissues that is made possible by magnification and illumination with the operating microscope.

The two-stage excision of huge acoustic neurinomas

Total removal of huge acoustic neurinomas was carried out in 23 patients by means of a two-stage suboccipital transmeatal approach with microsurgical technique. There was no operative mortality. Good results were obtained in 18 (78%) of the patients who have returned to normal activities or full-time employment. Five patients (22%) have residual preoperative neurological deficits causing a reduced level of activity. All of these, except one, are able to care for themselves. None of the patients has had any further significant neurological deficit caused by the operative procedures. Anatomical integrity of the facial nerve was maintained in 17 patients (74%). Surgical technique, operative morbidity, and results are thoroughly discussed. The potential advantages of this technique are stressed.

The suboccipital approach to removal of acoustic neuromas

This article reviews the author's technique for removing acoustic neuromas by the suboccipital approach. Also discussed are various considerations regarding the selection and use of instruments for this operation. The anatomy of the internal acoustic meatus and the principles involved in facial- and cochlear-nerve preservation are described. A guide is provided for stepwise dissection of the internal acoustic meatus in the laboratory.

Total removal of acoustic neurinomas

The authors analyze the results of total removal of acoustic neurinomas in 120 patients operated on between January, 1967, and January, 1976. The facial nerve was preserved after surgery in 65 patients (54.2%). The use of microsurgical techniques in the last 3 years of study permitted preservation of the seventh nerve in 26 of 35 operated patients (74.3%). Of 103 patients examined postoperatively, 96 retained their full or partial capacity for work (93.2%). Ten patients (8.3%) died after surgery. In the last 3 years, 35 patients were operated on without a single death.

Facial nerve function after suboccipital removal of acoustic neurinoma

The recovery of facial nerve function after suboccipital removal of 91 acoustic neurinomas is presented. The results after anatomical preservation of the nerve (60 cases), direct anastomosis of the nerve (7 cases), nerve grafting (16 cases), and facial hypoglossal anastomosis (8 cases) are presented after a follow-up period of 31.2 months. A simplified classification was used to describe motor function. The results are compared to those in the literature.