Skip to main content

Advertisement

SpringerLink
Log in

Dorsal displacement of the facial nerve in acoustic neuroma surgery: clinical features and surgical outcomes of 21 consecutive dorsal pattern cases

  • Original Article
  • Published:
Neurosurgical Review Aims and scope Submit manuscript

Abstract

In acoustic neuroma surgery, the facial nerve (FN) course varies among patients, but a dorsal pattern is rarely observed. We retrospectively reviewed and classified 556 acoustic neuromas operated on via a lateral suboccipital retrosigmoid (LSO) approach into two groups: dorsal (group D) and non-dorsal (group ND). The clinical features and outcomes including functional preservation of the FN, the extent of tumor resection, and the retreatment rate were compared. Among 556 cases, 21 (3.8 %) patients with dorsal patterns were identified. No significant differences in clinical features or preoperative status were noted between groups D and ND. No significant differences in functional FN preservation were found between groups D and ND in the immediate postoperative period (90.5 and 83.0 %, respectively) or 1-year postoperatively (95.2 and 97.0 %, respectively). Compared with group ND, the extent of tumor resection was significantly less (p < 0.0001) and the retreatment rate was significantly higher in group D (hazard ratio, 33.6; 95 % confidence interval [CI], 11.7–96.1; p < 0.0001). In one dorsal pattern case, surgical resection was abandoned based on the intraoperative findings. Dorsal displacement of the FN was accurately predicted with preoperative imaging evaluations in just two cases. Functional preservation of the FN during acoustic neuroma surgery is achievable if the FN runs along the dorsal side of the tumor. However, a dorsal pattern, especially when the FN is broadened, is clearly associated with less complete tumor removal and a higher rate of retreatment than typical pattern cases.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7

Similar content being viewed by others

References

  1. Amano M, Kohno M, Nagata O, Taniguchi M, Sora S, Sato H (2011) Intraoperative continuous monitoring of evoked facial nerve electromyograms in acoustic neuroma surgery. Acta Neurochir (Wien) 153:1059–1067

    Article  Google Scholar 

  2. Bae CW, Cho YH, Hong SH, Kim JH, Lee J-K, Kim CJ (2007) The anatomical location and course of the facial nerve in vestibular schwannomas: a study of 163 surgically treated cases. J Korean Neurosurg Soc 42:450–454

    Article  PubMed  PubMed Central  Google Scholar 

  3. Carlson ML, Van Abel KM, Driscoll CL, Neff BA, Beatty CW, Lane JI, Castner ML, Lohse CM, Link MJ (2012) Magnetic resonance imaging surveillance following vestibular schwannoma resection. Laryngoscope 122:378–388

    Article  PubMed  Google Scholar 

  4. Chen DQ, Quan J, Guha A, Tymianski M, Mikulis D, Hodaie M (2011) Three-dimensional in vivo modeling of vestibular schwannomas and surrounding cranial nerves with diffusion imaging tractography. Neurosurgery 68:1077–1083

    Article  PubMed  Google Scholar 

  5. Committee on Hearing and Equilibrium (1995) Committee on Hearing and Equilibrium guidelines for the evaluation of hearing preservation in acoustic neuroma (vestibular schwannoma). Otolaryngol Head Neck Surg 113:179–180

    Article  Google Scholar 

  6. Ebersold MJ, Harner SG, Beatty CW, Harper CM, Quast LM (1992) Current results of the retrosigmoid approach to acoustic neurinoma. J Neurosurg 76:901–909

    Article  CAS  PubMed  Google Scholar 

  7. El-Kashlan HK, Zeitoun H, Arts HA, Hoff JT, Telian SA (2000) Recurrence of acoustic neuroma after incomplete resection. Am J Otol 21:389–392

    Article  CAS  PubMed  Google Scholar 

  8. Esquia-Medina GN, Grayeli AB, Ferrary E, Tubach F, Bernat I, Zhang Z, Bianchi C, Kalamarides M, Sterkers O (2009) Do facial nerve displacement pattern and tumor adhesion influence the facial nerve outcome in vestibular schwannoma surgery? Otol Neurotol 30:392–397

    Article  PubMed  Google Scholar 

  9. Gerganov VM, Giordano M, Samii M, Samii A (2011) Diffusion tensor imaging-based fiber tracking for prediction of the position of the facial nerve in relation to large vestibular schwannomas. J Neurosurg 115:1087–1093

    Article  PubMed  Google Scholar 

  10. Gurgel RK, Dogru S, Amdur RL, Monfared A (2012) Facial nerve outcomes after surgery for large vestibular schwannomas: do surgical approach and extent of resection matter? Neurosurg Focus 33(3):E16

    Article  PubMed  Google Scholar 

  11. Haque R, Wojtasiewicz TJ, Gigante PR, Attiah MA, Huang B, Isaacson SR, Sisti MB (2011) Efficacy of facial nerve-sparing approach in patients with vestibular schwannomas. J Neurosurg 115:917–923

    Article  PubMed  Google Scholar 

  12. House JW, Brackmann DE (1985) Facial nerve grading system. Otolaryngol Head Neck Surg 93:146–147

    CAS  PubMed  Google Scholar 

  13. House WF (1968) Acoustic neuroma. Case summaries. Arch Otolaryngol 88:586–591

    Article  CAS  PubMed  Google Scholar 

  14. Kemink JL, Langman AW, Niparko JK, Graham MD (1991) Operative management of acoustic neuromas: the priority of neurologic function over complete resection. Otolaryngol Head Neck Surg 104:96–99

    Article  CAS  PubMed  Google Scholar 

  15. Kim HS, Kim DI, Chung IH, Lee WS, Kim KY (1998) Topographical relationship of the facial and vestibulocochlear nerves in the subarachnoid space and internal auditory canal. AJNR Am J Neuroradiol 19:1155–1161

    CAS  PubMed  Google Scholar 

  16. Kin T, Oyama H, Kamada K, Aoki S, Ohtomo K, Saito N (2009) Prediction of surgical view of neurovascular decompression using interactive computer graphics. Neurosurgery 65:121–128

    Article  PubMed  Google Scholar 

  17. Kohno M, Shinogami M, Yoneyama H, Nagata O (2014) Prognosis of tinnitus after acoustic neuroma surgery—surgical management of postoperative tinnitus. World Neurosurg 81:357–367

    Article  PubMed  Google Scholar 

  18. Kohno M, Taniguchi M (2011) Intraoperative real-time continuous facial nerve monitoring in acoustic neuroma surgery. Acta Neurochir (Wien) 153:2273–2274

    Article  Google Scholar 

  19. Kohno M, Sato H, Sora S, Miwa H, Yokoyama M (2011) Is an acoustic neuroma an epiarachnoid or subarachnoid tumor? Neurosurgery 68:1006–1016

    PubMed  Google Scholar 

  20. Koos WT, Day JD, Matula C, Levy DI (1998) Neurotopographic considerations in the microsurgical treatment of small acoustic neurinomas. J Neurosurg 88:506–512

    Article  CAS  PubMed  Google Scholar 

  21. Koos WT, Matula C, Lang J (2002) Microanatomy of the cerebellopontine angle. In: Color atlas of microneurosurgery of acoustic neurinomas. George Thieme Verlag, Stuttgurt, pp 5–58

    Google Scholar 

  22. McElveen JT, Belmonte RG, Fukushima T, Bullard DE (2000) A review of facial nerve outcome in 100 consecutive cases of acoustic tumor surgery. Laryngoscope 110:1667–1672

    Article  PubMed  Google Scholar 

  23. Morita A, Fukushima T, Miyazaki S, Tamagawa T (1988) Operative results in 45 cases of acoustic neurinoma: technical comments on the preservation of the facial nerve and hearing function. No Shinkei Geka 16:811–818, Japanese article with English abstract

    CAS  PubMed  Google Scholar 

  24. Nonaka Y, Fukushima T, Watanabe K, Friedman AH, Sampson JH, Mcelveen JT Jr, Cunningham CD III, Zomorodi AR (2013) Contemporary surgical management of vestibular schwannomas. Neurosurgery 72:ons103–ons115

    PubMed  Google Scholar 

  25. Oishi M, Fukuda M, Ishida G, Saito A, Hiraishi T, Fujii Y (2011) Presurgical simulation with advanced 3-dimensional multifusion volumetric imaging in patients with skull base tumors. Neurosurgery 68:188–199

    Article  PubMed  Google Scholar 

  26. Ojemann RG (1993) Management of acoustic neuromas (vestibular schwannomas) (honored guest presentation). Clin Neurosurg 40:498–535

    CAS  PubMed  Google Scholar 

  27. Ojemann RG (2001) Retrosigmoid approach to acoustic neuroma (vestibular schwannoma). Neurosurgery 48:553–558

    Article  CAS  PubMed  Google Scholar 

  28. Sameshima T, Mastronardi L, Friedman AH, Fukushima T (2004) Inner petrosa anatomy for retrosigmoid transmeatal approach. In: Microanatomy and dissection of the temporal bone, 2nd edn. AF-Neurovideo, Inc., Raleigh, NC, pp 25–50

    Google Scholar 

  29. Sameshima T, Morita A, Tanikawa R, Fukushima T, Friedman AH, Zenga F, Ducati A, Mastronardi L (2013) Evaluation of variation in the course of the facial nerve, nerve adhesion to tumors, and postoperative facial palsy in acoustic neuroma. J Neurol Surg B Skull Base 74:39–43

    PubMed  PubMed Central  Google Scholar 

  30. Samii M, Matthies C (1997) Management of 1000 vestibular schwannomas (acoustic neuromas): surgical management and results with an emphasis on complications and how to avoid them. Neurosurgery 40:11–23

    CAS  PubMed  Google Scholar 

  31. Samii M, Gerganov VM, Samii A (2010) Functional outcome after complete surgical removal of giant vestibular schwannomas. J Neurosurg 112:860–867

    Article  PubMed  Google Scholar 

  32. Sampath P, Rini D, Long DM (2000) Microanatomical variations in the cerebellopontine angle associated with vestibular schwannomas (acoustic neuromas): a retrospective study of 1006 consecutive cases. J Neurosurg 92:70–78

    Article  CAS  PubMed  Google Scholar 

  33. Sartoretti-Schefer S, Kollias S, Valavanis A (2000) Spatial relationship between vestibular schwannoma and facial nerve on three-dimensional T2-weighted fast spin-echo MR images. AJNR Am J Neuroradiol 21:810–816

    CAS  PubMed  Google Scholar 

  34. Sasaki T, Shono T, Hashiguchi K, Yoshida F, Suzuki SO (2009) Histological considerations of the cleavage plane for preservation of facial and cochlear nerve functions in vestibular schwannoma surgery. J Neurosurg 110:648–655

    Article  PubMed  Google Scholar 

  35. Seol HJ, Kim C-H, Park C-K, Kim CH, Kim DG, Chung Y-S, Jung H-W (2006) Optimal extent of resection in vestibular schwannoma surgery: relationship to recurrence and facial nerve preservation. Neurol Med Chir (Tokyo) 46:176–180

    Article  Google Scholar 

  36. Sughrue ME, Kaur R, Rutkowski MJ, Kane AJ, Kaur G, Yang I, Pitts LH, Parsa AT (2011) Extent of resection and the long-term durability of vestibular schwannoma surgery. J Neurosurg 114:1218–1223

    PubMed  Google Scholar 

  37. Taoka T, Hirabayashi H, Nakagawa H, Sakamoto M, Myochin K, Hirohashi S, Iwasaki S, Sakaki T, Kichikawa K (2006) Displacement of the facial nerve course by vestibular schwannoma: preoperative visualization using diffusion tensor tractography. J Magn Reson Imaging 24:1005–1010

    Article  PubMed  Google Scholar 

  38. Yamakami I, Kobayashi E, Iwadate Y, Saeki N (2002) Hypervascular vestibular schwannomas. Surg Neurol 57:105–112

    Article  PubMed  Google Scholar 

  39. Yoshino M, Kin T, Ito A, Saito T, Nakagawa D, Kamada K, Mori H, Kunimatsu A, Nakatomi H, Oyama H, Saito N (2014) Diffusion tensor tractography of normal facial and vestibulocochlear nerves. Int J Comput Assist Radiol Surg. doi:10.1007/s11548-014-1129-2

    PubMed  Google Scholar 

  40. Zhang Y, Chen Y, Zou Y, Zhang W, Zhang R, Liu X, Lv Z, Yang K, Hu X, Xiao C, Liu W, Liu H (2013) Facial nerve preservation with preoperative identification and intraoperative monitoring in large vestibular schwannoma surgery. Acta Neurochir (Wien) 155:1857–1862

    Article  Google Scholar 

  41. Zhao X, Wang Z, Ji Y, Wang C, Yu R, Ding X, Wei S (2010) Long-term facial nerve function evaluation following surgery for large acoustic neuromas via retrosigmoid transmeatal approach. Acta Neurochir (Wien) 152:1647–1652

    Article  Google Scholar 

Download references

Acknowledgments

The authors thank the neurosurgeons, medical engineers, and medical technologists at Tokyo Metropolitan Police Hospital for their assistance with acoustic neuroma surgeries. We also would like to thank Editage (www.editage.jp) for English language editing.

Authors’ contributions

Nejo, T. contributed to the study concept, designed the study, performed data collection and analysis, and wrote the manuscript; Kohno, M. contributed to the study concept, collected data, and revised the manuscript; Nagata, O. performed the statistical analysis; and Sora, S. and Sato, H. both contributed to the study concept and revised the manuscript.

Author information

Authors and Affiliations

  1. Department of Neurosurgery and Stroke Center, Tokyo Metropolitan Police Hospital, 4-22-1, Nakano, Nakano-ku, Tokyo, 164−8541, Japan

    Takahide Nejo, Michihiro Kohno, Shigeo Sora & Hiroaki Sato

  2. Department of Anesthesiology, The Cancer Institute Hospital of Japanese Foundation for Cancer Research, Tokyo, Japan

    Osamu Nagata

Authors
  1. Takahide Nejo
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Michihiro Kohno
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Osamu Nagata
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Shigeo Sora
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Hiroaki Sato
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Takahide Nejo.

Ethics declarations

Disclosure

The authors have no personal financial or institutional interest in any of the drugs, materials, or devices described in this article.

Conflict of interest

The authors declare that they have no competing interests.

Additional information

Comments

Kenji Ohata, Osaka, Japan

The therapeutic goal of acoustic neuroma surgery is total tumor excision, with preservation of facial nerve and hearing function. Owing to current advancement in surgical technique, disease-specific mortality now approaches zero. To date, the majority of studies comparing treatment modalities have focused on technical outcomes including facial function, hearing status, and tumor control.

This study described the incidence, clinical features, and surgical outcomes of acoustic neuroma cases with the dorsally displaced facial nerves. Dorsal facial nerve displacement is very rare, and there are major limitations in the preoperative prediction of facial nerve course. Thus, intraoperative facial nerve monitoring is essential, and surgeons must make decisions of management strategies including microsurgical resection, stereotactic radiosurgery, or observation based on intraoperative findings of facial nerve course.

Ali Tayebi Meybodi, Arnau Benet, San Francisco, USA

The preservation of facial nerve function is a major priority of surgical intervention for acoustic neuromas and may even surpass the goal of total tumor extirpation. Intraoperative facial nerve monitoring can help in identification of the course of the facial nerve. While most acoustic neuromas push the facial nerve anteriorly and superiorly, a position stemming from the anatomical relationship of the VII–VIII in the cerebellopontine cistern and the internal acoustic canal, there exists a group with the facial nerve displaced posteriorly. In the latter group, the trajectory of the retrosigmoid approach intersects with VII before the tumor is accessed. This surgical trajectory (posterior and superior) requires constant nerve manipulation while resecting the tumor. This surgical scenario resembles that of a petroclival meningioma, which typically exists beyond the nerve complexes of the posterior fossa, when approached from a posterolateral point of view.

Nejo et al. have provided a nice clinical study of this challenging situation. In their retrospective study of 556 acoustic neuroma cases, they have determined the cases in which the facial nerve ran dorsal to the tumor and have compared the surgical results with the more conventional form of tumor pushing the nerve anteromedially. Their results are surprising. A minority of cases (<4 %) presented a facial nerve located dorsally, which required to either abort the surgery (because of an unusually broadened facial nerve on the dorsal aspect of the tumor) or to settle to a subtotal resection. Moreover, magnetic resonance (MR) imaging did not help them identify this difficult situation in most of the cases, although they were able to avoid facial nerve injury by intraoperative monitoring.

The information provided in this paper is quite resourceful for the surgeons practicing acoustic neuroma surgery. First, it is noted that the current imaging techniques, emphasizing on pure anatomical aspects (MR and computed tomography), cannot provide enough information for surgical planning.1 Second, fused functional and anatomical imaging techniques (diffusion tensor imaging MRI) may appear promising in this arena.2–4 Third, effective identification of these challenging cases preoperatively helps sparing the patient a suboptimal surgical procedure. The last important point would be selection of the optimal surgical approach. Radiosurgery is a promising choice but is not effective in large tumors. While the retrosigmoid approach may not provide an optimal trajectory, the middle fossa exposure seems to be a better choice in these cases. However, with large tumors that sit mostly in the cerebellopontine angle, the middle fossa approach may not provide an optimal view. On the other hand, the extended endoscopic endonasal approaches provide full access to the anterior brainstem. Exposing the lateral cisterns around the brainstem requires progressive drilling around the internal carotid canal and the jugular foramen, which carry increased risk and complexity. However, studies are showing the competency of this approach in reaching the most lateral aspect of the posterior fossa.5,6 The anatomical route from an endonasal perspective is rather straightforward, using the natural opening of the nasal cavity and drilling the clivus. After completing an endoscopic anterior petrosectomy and a lateral transclival approach, the cranial nerves 6 to 12 are exposed. The advantage of this surgical trajectory is that it provides an exposure and manipulation of the tumor before any cranial nerve (if lying dorsal to the tumor) is manipulated and does not require cerebellar retraction. Also, the origin of the cranial nerves is identified more easily which is a critical point for preserving the facial nerve. In the other hand, the expanded endoscopic endonasal approaches require a steep learning curve and very experienced surgical teams. This area of research is currently evolving and may open new frontiers for resection of these complex tumors.

References

1. Sartoretti-Schefer S, Kollias S, Valavanis A. Spatial relationship between vestibular schwannoma and facial nerve on three-dimensional T2-weighted fast spin-echo MR images. AJNR Am J Neuroradiol. 2000;21(5):810–816.

2. Chen DQ, Quan J, Guha A, Tymianski M, Mikulis D, Hodaie M. Three-dimensional in vivo modeling of vestibular schwannomas and surrounding cranial nerves with diffusion imaging tractography. Neurosurgery. 2011;68(4):1077–1083.

3. Gerganov VM, Giordano M, Samii M, Samii A. Diffusion tensor imaging-based fiber tracking for prediction of the position of the facial nerve in relation to large vestibular schwannomas. J Neurosurg. 2011;115(6):1087–1093.

4. Taoka T, Hirabayashi H, Nakagawa H, et al. Displacement of the facial nerve course by vestibular schwannoma: preoperative visualization using diffusion tensor tractography. J Magn Reson Imaging. 2006;24(5):1005–1010.

5. Benet A, Prevedello DM, Carrau RL, et al. Comparative analysis of the transcranial “far lateral” and endoscopic endonasal “far medial” approaches: surgical anatomy and clinical illustration. World Neurosurg. 2014;81(2):385–396.

6. Morera VA, Fernandez-Miranda JC, Prevedello DM, et al. “Far-medial” expanded endonasal approach to the inferior third of the clivus: the transcondylar and transjugular tubercle approaches. Neurosurgery. 2010;66(6 Suppl Operative):211–219; discussion 219–220.

Figure legend: Endoscopic endonasal view of the anterolateral brainstem as seen through an expanded trans-clival approach. The cranial nerves 6–12 are exposed

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Nejo, T., Kohno, M., Nagata, O. et al. Dorsal displacement of the facial nerve in acoustic neuroma surgery: clinical features and surgical outcomes of 21 consecutive dorsal pattern cases. Neurosurg Rev 39, 277–288 (2016). https://doi.org/10.1007/s10143-015-0681-8

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10143-015-0681-8

Keywords

Search

Navigation