Preservation of facial, cochlear, and other nerve functions in acoustic neuroma treatment

Abstract

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.

Long-term facial nerve clinical evaluation following vestibular schwannoma surgery

“…Since the first successful resection of a VS occurred in 1894 2 , surgical techniques have been continuously refined to reduce patient morbidity and mortality rates 3,4 . over the last century, treatment of VS has undergone immense changes and the focus of surgery has improved from prolongation of patient's life towards preservation of cranial nerve function 5 , specially the seventh nerve.…”

“…Harvey cushing improved surgical techniques and brought the mortality rate down to approximately 20% 3 performing sub-total removal of the tumors. Improvement in surgical techniques and development of new technological devices had brought the mortality rate to under 2% 4,5 . The advances and improvements in microsurgical techniques have changed the actual goals of surgery, being facial nerve preservation an utmost concern 3 .…”

Fractionated Stereotactic Radiotherapy for Acoustic Neuromas

“…Other studies have corroborated this inverse relationship between the size of the tumor and preservation of the facial nerve function [20]. With continuous intraoperative monitoring of the facial nerve, however, Sterkers et al [21] reported that the percentage of preserved facial function (grade I or II) improved from 20 to 52% for large tumors (1 3 cm), from 42 to 81% for medium tumors (2-3 cm in diameter) and from 70 to 92% for small tumors (!2 cm in diameter). These results demonstrate the challenge for preservation of facial nerve function during resection of the acoustic neuroma and illustrate the need for techniques for treatment that will preserve function.…”

“…Hearing was not preserved in that series in any of the 3 patients with large tumors in whom hearing preservation was attempted. Sterkers et al [21] report that hearing was preserved in 38.2% of cases Williams operated on by means of the retrosigmoid route and 36.4% of cases after the middle fossa approach. Cerullo et al [23] showed that, for the 64 patients with functional preoperative hearing, 13 patients retained hearing postoperatively: 5 had normal hearing (PTA !…”

Late-onset facial nerve degeneration after vestibular schwannoma surgery: incidence, putative mechanisms, and prevention

“…[1,2,11,[14][15][16][17]19] Given the medical, psychological, and functional sequelae of facial nerve weakness, [13,23] close attention has been paid to factors that influence facial nerve outcome, and a number of authors have reported on their experience with these complex tumors. [1,11,17,18,21] In recent years, the phenomenon of delayed facial nerve palsy has become evident. [10,12,22] This condition, characterized by spontaneous deterioration of facial nerve function in a patient who has otherwise normal or near-normal facial function in the immediate postoperative period, has been reported to occur in 15 to 29% of patients who underwent microsurgical resection of vestibular schwannomas.…”