Between March 1966 and September 1992, 1400 acoustic neuromas were treated in Paris, France, by surgical excision. The findings over the last 7 years are presented. The translabyrinthine approach has been used in more than 85% of cases. Where hearing preservation is attempted, the middle fossa approach has been adapted for intracanilicular tumors and the retrosigmoid approach for small tumors extending into the cerebellopontine angle, in which the fundus of the internal meatus is free of tumor. The main goal is to achieve a grade I or II result in facial function within 1 month of surgery. Results improved during 1991 after the introduction of continuous facial nerve monitoring and the use of the Beaver mini-blade for dissection of tumor from nerve. With these techniques, facial function of grade I or II at 1 month improved from 20% to 52% for large tumors (larger than 3 cm), from 42% to 81% for medium tumors (2 to 3 cm). and from 70% to 92% for small tumors (up to and including 2 cm extracanalicular). The facial nerve was at greater risk using the retrosigmoid or middle fossa approaches than by the translabyrinthine route. Since 1985, success in hearing preservation has changed little, with useful hearing being preserved in 38.2% of cases operated on by means of the retrosigmoid route and a 36.4% of cases after the middle fossa approach. In older patients with good hearing and small tumors, observation with periodic MRI scanning is recommended. Despite earlier diagnosis, the number of patients suitable for hearing preservation surgery remains very limited and careful selection is required. Trigeminal nerve signs were present in 20% of cases preoperatively, in 10% postoperatively, and recovered spontaneously. Palsies of the other cranial nerves after surgery were much rarer and were as follows: sixth nerve (abducens), 0.5%; ninth nerve (glossopharyngeal), 1.4%; and tenth nerve (vagus), 0.7%. The importance of preservation of function of the nervus intermedius of Wrisberg is stressed. These results emphasize the advantages of the translabyrinthine approach, offering greater security to the facial nerve and lower morbidity.

The combination of electrophysiologic intensities and tumor size are reproducible and better predictors of initial facial nerve function than any individual parameter, but long-term facial nerve function is more likely to have a better outcome if the nerve is left intact and a per-operative graft repair is not performed. The study suggests that although the best available predictor of overall long-term facial nerve outcome is the level of early postoperative function, this factor is not useful in surgical rehabilitation decision making.

A series of 238 consecutive patients with acoustic neuromas, operated on in Paris has been studied to identify unusual presentations and varied symptomatology. The most common history was that of a progressive unilateral hearing loss (in 68.1%), with tinnitus (in 49.1%) or disequilibrium (in 49.1%) or both. Sudden hearing loss (in 14.7%) or fluctuating hearing loss (in 6.3%), and a single or repeated episodes of acute vertigo (in 8.8%) were seen less commonly. Headaches occurred as an associated symptom in 10.5%, tinnitus was the sole symptom in 2.8% and other uncommon symptoms included otalgia, facial nerve palsy, facial or ocular pain, altered sensation in the face or eye, or tingling of the tongue. Some 11.3% of patients presented with normal pure tone auditory thresholds and a 100% speech discrimination score and of these patients acoustic reflex thresholds were normal in 53% and brainstem auditory evoked responses were suggestive of the retro-cochlear abnormality in only 76.2%. Amongst the less common presentations, the initial symptoms mimicked such diagnoses as Meniére's disease, benign positional vertigo, vertebro-basilar migraine, vertebro-basilar insufficiency, Bell's palsy and Trigeminal neuralgia. Overall, 20.6% of patients had unusual initial presenting symptoms, 36.5% of the symptoms were unusual and these were found in isolation in 11.8% of patients. An awareness of the spectrum of more subtle symptoms of acoustic tumours may lead to the correct diagnosis at an earlier stage.

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We report the use of MRI in the diagnosis, follow-up and therapeutic management of three cases of intralabyrinthine Schwannoma. The diagnosis was based on the history and initial and follow-up MRI findings. The main feature suggesting the diagnosis was a nodular intralabyrinthine mass of low signal intensity on T2-weighted images, and high or isointense signal on T1-weighted images (relative to cerebrospinal fluid), which showed contrast enhancement. Follow-up imaging showed growth of the tumour in one patient. One patient underwent surgery for severe tinnitus. To detect these lesions, MRI should be focussed on the inner ear, using thin-section T2-weighted and T1-weighted images before and after contrast medium. MRI allowed informed surgical planning.