Endoscope-Assisted Microsurgery of Large Vestibular Schwannomas

Abstract

Aims: The application of endoscope-assisted microsurgery in the treatment of small or medium-sized vestibular schwannomas is of proven value. The goal of our study is to evaluate its usefulness in cases of large schwannomas. Patients and Methods: Eighteen patients were included in this prospective study. Their average tumor diameter was 3.9 cm. The retrosigmoid approach was used in all cases. The endoscope was applied during all stages of tumor removal. Results: The facial nerve was visualized endoscopically at early stages of surgery in 9 patients and the abducent nerve in 7 patients. The source of bleeding was identified in 1 case. Tumor remnants in the region of the fundus of the internal auditory canal after apparently total removal were identified in 2 cases. Exposed and unobliterated temporal bone air cells were not observed. Discussion: Even in cases of large schwannomas, the location of the facial nerve can be determined endoscopically early in the procedure. The application of endoscope-assisted microsurgery increases the rate of cranial nerve preservation and of total tumor removal. Although the application of the endoscope did not provide useful information in some cases, it is a safe procedure that did not lead to any complications and/or to considerable prolongation of the operative time. Its application is justified in all cases.

Vestibular schwannoma - endoscope-assisted neurosurgery - facial nerve - tumor remnant

References

• 1 Slattery W H III, Francis S, House K C. Perioperative morbidity of acoustic neuroma surgery.  Otol Neurotol. 2001;  22 895-902
• 2 Ebersold M J, Harner S G, Beatty C W, Harper Jr C M, Quast L M. Current results of the retrosigmoid approach to acoustic neuroma.  J Neurosurg. 1992;  76 901-909
• 3 Brennan J W, Rowed D W, Nedzelski J M, Chen J M. Cerebrospinal leak after acoustic neuroma surgery: influence of tumor size and surgical approach on incidence and response to treatment.  J Neurosurg. 2001;  94 9-17
• 4 Samii M, Matthies C. Management of 1000 vestibular schwannomas (acoustic neuromas): the facial nerve-preservation and restitution of function.  Neurosurgery. 1997;  40 684-694
• 5 Comey C H, Jannetta P J, Sheptak P E. Staged removal of acoustic tumors: techniques and lessons from a series of 83 patients.  Neurosurgery. 1997;  37 915-921
• 6 Yates P D, Jackler R K, Satar B. Is it worthwhile to attempt hearing preservation in larger acoustic neuromas?.  Otol Neurotol. 2003;  24 460-464
• 7 Briggs R J, Fabinyi G, Kaye A H. Current management of acoustic neuromas: review of surgical approaches and outcomes.  J Clin Neurosci. 2000;  7 521-526
• 8 Ojemann R G. Management of acoustic neuroma (vestibular schwannoma).  Clin Neurosurg. 1993;  40 498-533
• 9 Iwai Y, Yamanaka K, Ishiguro T. Surgery combined with radiosurgery of large acoustic neuromas.  Surg Neurol. 2003;  59 283-289
• 10 Fries G, Perneczky A. Endoscope- assisted brain surgery: Part 2 - Analysis of 380 procedures.  Neurosurgery. 1998;  42 226-232
• 11 Perneczky A, Fries G. Endoscope-assisted brain surgery: Part 1 - Evolution, basic concept and current technique.  Neurosurgery. 1998;  42 219-225
• 12 Schroeder H W, Gaab M R. Intracranial endoscopy. Neurosurg Focus 1999 6 (4) Article 1
• 13 McKennan K X. Endoscopy of the internal auditory canal during hearing conservation acoustic tumor surgery.  Am J Otol. 1993;  14 259-262
• 14 Magnan J, Chays A, Cohen J M, Caces F, Locatelli P. Endoscopy of the cerebellopontine angle.  Laryngol Otol Rhinol. 1995;  116 115-118
• 15 Magnan J, Barbieri M, Mora R, Murphy S, Meller R, Bruzzo M, Chays A. Retrosigmoid approach for small and medium-sized acoustic neuromas.  Otol Neurotol. 2002;  23 141-145
• 16 King W A, Wackym P A. Endoscope-assisted surgery for acoustic neuromas (vestibular schwannomas): early experience using the rigid Hopkins telescope.  Neurosurgery. 1999;  44 1095-1100
• 17 Rosenberg S I. Endoscopic otologic surgery.  Otolaryngol Clin North Am. 1996;  29 291-300
• 18 Rosenberg S I, Silverstein H, Willcox T O, Gordon M A. Endoscopy in otology and neurotology.  Am J Otol. 1994;  15 168-172
• 19 Tatagiba M, Matthies C, Samii M. Microendoscopy of the internal auditory canal in vestibular schwannoma surgery.  Neurosurgery. 1996;  38 737-740
• 20 Valtonen H J, Poe D S, Heilman C B, Tarlov E C. Endoscopically assisted prevention of cerebrospinal fluid leak in suboccipital acoustic neuroma surgery.  Am J Otol. 1997;  18 381-385
• 21 Wackym P A, King W A, Poe D S, Meyer G A, Ojemann R G, Barker F G, Walsh P R, Staecker H. Adjunctive use of endoscopy during acoustic neuroma surgery.  Laryngoscope. 1999;  109 1193-1201
• 22 Samii M, Matthies C. Management of 1000 vestibular schwannomas (acoustic neuromas): surgical management and results with an emphasis on complications and how to avoid them.  Neurosurgery. 1997;  40 11-21
• 23 Yasargil M G. Management of Accoustic Neuromas. In: Microneurosurgery, Vol. IV B. Stuttgart: Thieme Verlag 1996: 100-123
• 24 Goksu N, Bayazit Y, Kemaloglu Y. Endoscopy of the posterior fossa and dissection of acoustic neuroma.  J Neurosurg. 1999;  91 776-780
• 25 Matula C, Tschabitscher M, Day J D, Reinprecht A, Koos W T. Endoscopically assisted microneurosurgery.  Acta Neurochir. 1995;  134 190-195
• 26 Wackym P A, King W A, Meyer G A, Poe D S. Endoscopy in neuro-otologic surgery.  Otolaryngol Clin North Am. 2002;  35 297-323
• 27 Sampath P, Rini D, Long D M. Microanatomical variations in the cerebellopontine angle associated with vestibular schwannomas (acoustic neuromas): a retrospective study of 1006 consecutive cases.  J Neurosurg. 2000;  92 70-77