Endoscope-Controlled Removal of Intrameatal Vestibular Schwannomas

Abstract

The use of endoscopes for surgery of the cerebellopontine angle tumors is steadily obtaining widespread acceptance. The objective of the present study was a laboratory and clinical evaluation of the safety of the endoscope-controlled microneurosurgical removal of the intrameatal vestibular schwannomas through a retrosigmoid approach. The anatomical investigation was done on formalin-fixed cadaver heads and dry temporal bones. Clinical series included 33 consecutive patients (23 women and 10 men; mean age 50 ± 15 years). A bayonet-style rigid endoscope with 70 ° angle of view and 4 mm outer diameter was found to be optimal for observation of the internal auditory canal. Its insertion in the cerebellopontine cistern should be preferably done under control through an operating microscope. Endoscope-controlled manipulations necessitate the use of a special holder system, which provides a stable position of the device and allows bimanual manipulations by the surgeon. A thermographic evaluation did not reveal a significant increase of the local temperature due to use of the endoscope. Use of the endoscope permitted removal of the neoplasm from the most lateral part of the internal auditory canal and identification of the nerve of tumor origin. In total, 28 tumors underwent total removal, and anatomical preservation of the facial nerve was attained in 31 cases. Damage of the facial nerve by the endoscope was met once. In 8 out of 16 patients, who showed serviceable hearing before surgery, this was preserved after tumor removal. In conclusion, endoscope-controlled removal of the intrameatal vestibular schwannomas seems to be a technically feasible, effective and safe procedure. Nevertheless, good equipment and special training are absolutely necessary for attainment of optimal results.

Key words

Vestibular schwannoma - endoscope-controlled removal - neuroendoscopy - internal acoustic meatus

References

• 1 Chernov M, DeMonte F. Skull base tumors. In: Levin VA (ed). Cancer in the nervous system, 2nd edn. Oxford: Oxford University Press 2002: 300-319
• 2 Yamakami I, Uchino Y, Kobayashi E, Yamaura A. Conservative management, gamma-knife radiosurgery, and microsurgery for acoustic neurinomas: a systematic review of outcome and risk of three therapeutic options.  Neurol Res. 2003;  25 682-690
• 3 McKennan K X. Endoscopy of the internal auditory canal during hearing conservation acoustic tumor surgery.  Am J Otol. 1993;  14 259-262
• 4 Magnan J, Chays A, Lepetre C, Pencroffi E, Locatelli P. Surgical perspectives of endoscopy of the cerebellopontine angle.  Am J Otol. 1994;  15 366-370
• 5 Rosenberg S I, Silverstein H, Willcox T O, Gordon M A. Endoscopy in otology and neurootology.  Am J Otol. 1994;  15 168-172
• 6 Matula C, Tschabitscher M, Diaz Day J, Reinprecht A, Koos W T. Endoscopically assisted microneurosurgery.  Acta Neurochir (Wien). 1995;  134 190-195
• 7 Tatagiba M, Matthies C, Samii M. Microendoscopy of the internal auditory canal in vestibular schwannoma surgery: technique application.  Neurosurgery. 1996;  38 737-740
• 8 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
• 9 Jennings C R, O'Donoghue G M. Posterior fossa endoscopy.  J Laryngol Otol. 1998;  112 227-229
• 10 Goksu N, Bayazit Y, Kemaloglu Y. Endoscopy of the posterior fossa and dissection of acoustic neuroma.  J Neurosurg. 1999;  91 776-780
• 11 King W A, Wackym P A. Endoscope-assisted surgery for acoustic neuromas (vestibular schwannomas): early experience using the rigid Hopkins telescope.  Neurosurgery. 1999;  44 1095-1102
• 12 Low W K. Enhancing hearing preservation in endoscopic-assisted excision of acoustic neuroma via the retrosigmoid approach.  J Laryngol Otol. 1999;  113 973-977
• 13 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
• 14 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
• 15 Gerganov V M, Romansky K V, Bussarsky V A, Noutchev L T, Iliev I N. Endoscope-assisted microsurgery of large vestibular schwannomas.  Minim Invas Neurosurg. 2005;  48 39-43
• 16 Morita A, Okada Y, Kitano M, Hori T, Taneda M, Kirino T. Development of hybrid integrated endoscope-holder system for endoscopic microneurosurgery.  Neurosurgery. 2004;  55 926-932
• 17 House W F, Brackmann D E. Facial nerve grading system.  Otolaryngol Head Neck Surg. 1985;  93 184-193
• 18 Gardner G, Robertson J H. Hearing preservation in unilateral acoustic neuroma surgery.  Ann Otol Rhinol Laryngol. 1988;  97 55-66
• 19 Ojemann R G. Retrosigmoid approach to acoustic neuroma (vestibular schwannoma).  Neurosurgery. 2001;  48 553-558
• 20 Ciric I, Zhao J-C, Rosenblatt S, Wiet R, O'Shaughnessy B. Suboccipital retrosigmoid approach for removal of vestibular schwannomas: facial nerve function and hearing preservation.  Neurosurgery. 2005;  56 560-570
• 21 Perneczky A, Fries G. Endoscope-assisted brain surgery: Part 1 - evolution, basic concept, and current technique.  Neurosurgery. 1998;  42 219-225
• 22 Fries G, Perneczky A. Endoscope-assisted brain surgery: Part 2 - analysis of 380 procedures.  Neurosurgery. 1998;  42 226-232
• 23 Teo C. Endoscopic-assisted tumor and neurovascular procedures.  Clin Neurosurg. 2000;  46 515-525
• 24 Boor S, Maurer J, Mann W, Stoeter P. Virtual endoscopy of the inner ear and the auditory canal.  Neuroradiology. 2000;  42 543-547
• 25 Vrabec J T, Briggs R D, Rodriguez S C, Johnson Jr R F. Evaluation of the internal auditory canal with virtual endoscopy.  Otolaryngol Head Neck Surg. 2002;  127 145-152