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NI FEATURE: THE EDITORIAL DEBATE-- PROS AND CONS
Year : 2016  |  Volume : 64  |  Issue : 3  |  Page : 376-379

Giant vestibular schwannoma – an alternative perspective by the translabyrinthine approach


1 Department of Otorhinolaryngology, Nanavati Superspeciality Hospital, Fortis Hiranandani Hospital, Mumbai and Hinduja Healthcare and Surgical Hospital, Mumbai, Maharashtra, India
2 Department of Otorhinolaryngology, Jindal Hospital, Hissar, Haryana, India

Date of Web Publication3-May-2016

Correspondence Address:
K P Morwani
Department of Otorhinolaryngology, Nanavati Superspeciality Hospital, Fortis Hiranandani Hospital, Mumbai and Hinduja Healthcare and Surgical Hospital, Mumbai, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.181573

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How to cite this article:
Arsiwala Z, Patil A, Mehta M, Morwani K P. Giant vestibular schwannoma – an alternative perspective by the translabyrinthine approach. Neurol India 2016;64:376-9

How to cite this URL:
Arsiwala Z, Patil A, Mehta M, Morwani K P. Giant vestibular schwannoma – an alternative perspective by the translabyrinthine approach. Neurol India [serial online] 2016 [cited 2020 Feb 26];64:376-9. Available from: http://www.neurologyindia.com/text.asp?2016/64/3/376/181573


We have come a long way in vestibular schwannoma surgery. In the present era, the incidence of morbidity, mortality, meningitis, facial nerve damage, and the incidence of residual tumours have decreased tremendously in every training centre. We congratulate the author for managing such a large number of giant vestibular schwannomas.[1]

In this series, as all the cases of acoustic neuromas had no serviceable hearing, there was no contraindication in operating upon the tumor via the translabyrinthine approach.[2] In any tumour of more than 4cm in size with the patient having a residual hearing, preservation of postoperative serviceable hearing in the best of hands is rarely possible.[2],[3] The translabyrinthine approach to the cerebellopontine (CP) angle is an excellent approach for a tumour mass that extends towards the midline or is partially located anterior to the pons. Using this approach, although hearing is sacrificed, the facial nerve function is generally preserved.[3] The greatest advantage of this approach is in being able to identify the facial nerve from the labyrinthine portion, which is difficult when approaching the internal auditory meatus by the retrosigmoid approach [Figure 1]. The other advantage of the approach is in obviating the need for any cerebellar retraction using this approach (whereas, in the retrosigmoid approach, the cerebellar retraction is usually needed, as mentioned by the author) [Figure 2]. Thus, post-operatively, there is negligible cerebellar odema and hence, the mobilization of these patients is much earlier.[2]
Figure 1: Tumour exposure without cerebellar retraction. JB: Jugular bulb; T-IAM: Tumor in the internal auditory meatus; T-CPA: Tumor in the cerebellopontine angle; FN:Facial Nerve; FC:  Fallopian canal More Details; PFD: Posterior fossa dura

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Figure 2: Preoperative and postoperative magnetic resonance images showing negligible cerebellar oedema

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We agree with the authors in not performing a pre-operative cerebrospinal fluid diversion procedure unless the rapid progression of neurological symptoms demanded it, and development of acute hydrocephalus was an not indication for it. However, we do agree with the philosophy of Dr. Misra of avoiding tumour removal in elderly moribund patients, and performing solely a ventriculoperitoneal shunt procedure in them.[4]

Intraoperative facial nerve monitoring does improve facial nerve identification (particularly at the brainstem level) in trained hands [Figure 3] and [Figure 4].[5] However, in our opinion, it can never replace the knowledge of proper facial nerve anatomy and the surgeons' experience in identifying the nerve in relation to the tumour. Facial nerve preservation definitely improves with experience and increase in the surgical expertise.[1],[2],[3] We endorse the method described by the author of the use of facial nerve monitor.[1] We also agree with their observations regarding the significance of preservation of the continuity of the cochlear nerve along with the facial nerve. It is important to preserve the cochlear nerve particularly in the younger group of patients. In the eventuality that they subsequently develop any other pathology including a vestibular schwannoma on the contralateral side, the preservation of the cochlear nerve on the side of lesion, permits the possibility of performing a cochlear implant surgery on that side, if required. Bone anchored hearing aid (BAHA) can be implanted during surgery or anytime after surgery. House Ear Institute has one of the largest series with 300 cases reported 10 year ago; similarly, California Ear Institute has reported their results with 400 cases with good results.
Figure 3: Preservation of facial nerve (FN) and cochlear nerve (CN)

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Figure 4: (a) Preoperative; (b) Postoperative contrast magnetic resonance image; and, (c) Postoperative patient image showing the facial nerve preservation

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An endoscope is an effective tool that helps in identifying the location of all cranial nerves at the level of the brain stem. It is more helpful in larger tumours where the surgeon's vision is almost totally obscured by the tumour. It is also helpful in identifying the residual tumours in certain inaccessible areas.[5],[6]

As far as the rehabilitation of the facial nerve is concerned, the author has only mentioned about tarsorraphy, which is an inferior procedure. A gold implant is cosmetically more acceptable and does not reduce the field of vision [Figure 5].
Figure 5: A gold implant performed at follow up in a patient operated for a vestibular schwannoma who developed facial nerve palsy in the postoperative period. The eyelid gold implant enables him to close his affected eye adequately

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At our institute, as well as at most centres internationally, an intraoperative facial nerve grafting is advocated whenever the proximal end of the facial nerve is accessible.[6],[7]

In the cases where the proximal end is not accessible, we have always recommended the performance of a facial-hypoglossal nerve anastomosis along with a gold implant, as has also been practiced internationally [Figure 6].[5],[7] In the cases where the anatomical continuity of the facial nerve is presumed to be intact on the operating table and the patients do not show any clinical improvement after 9 months of surgery, a facial-hypoglossal anastomosis along with a gold implant is also recommended [Figure 7].
Figure 6: (a) Facial nerve grafting in the cerebellopontine angle; and, (b) facial nerve grafting from the middle cranial fossa to the cerebellopontine angle. Br: Brain; Co: Cochlea; SSC: Superior semicircular canal

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Figure 7: Facial-Hypoglossal nerve anastomosis performed 3-and-a-half years after surgery for the vestibular schwannoma. A nerve is anastomosed end-to-end to the cut end of facial nerve (a) and end-to-side to the hypoglossal nerve (b). (c) Post operative picture of the patient following the facio-hypoglossal nerve anastomosis

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Our excellent results with the facial-hypoglossal anastomosis dispels the myth that there is no improvement in the facial nerve function when reanimation is performed even after more than 2 years of the development of facial palsy.

The author has excellent results with the preservation of lower cranial nerve (LCN) function for the size of tumours operated.[1] However, as far as the management of LCN palsies is concerned, they have not utilised the procedure of thyroplasty type 1 with a cricopharyngeal myotomy [Figure 8], which can be performed when the patient cannot be weaned off the Ryle's tube and the tracheostomy, even after 3-4 months following surgery.
Figure 8: (a) Thyroplasty type 1; and, (b) Cricopharyngeal myotomy

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The rate of cerebrospinal fluid leak in this series is higher than that seen in other Indian and international series.[8],[9] To reduce the incidence of cerebrospinal fluid rhinorrhea, it is preferable to obliterate all the mastoid air cells with bone dust supplemented by bone wax, instead of using the bone wax alone [Figure 9].
Figure 9: Obliteration of all the mastoid air cells with bone dust supplemented by bone wax, instead of using the bone wax alone

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The dural closure is equally important with utilization of alternate methods which helps the surgeon in attaining an airtight seal. The skin and musculoperiosteal incision are given in different planes to reduce the incidence of cerebrospinal fluid leak from the wound [Figure 10]. Use of fibrin glue also reduces the incidence of cerebrospinal fluid leak.
Figure 10: (a) A residual tumour after the retrosigmoid approach; and, (b) The residual tumor removed by the translabyrinthine approach

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Most of the centres perform a postoperative computed tomographic (CT) scan on the day of surgery or within 24 hours of the surgery. We agree with the author that the CT scan be performed on the 7th post-operative day or at the day of discharge unless the neurological status demands that it be performed earlier.

In the cases of residual tumours (which is higher in this series (seen in case numbers 1, 4, 6, 7, 8), those tumours showing evidence of growth are often treated with stereotactic radiosurgery at many institutes worldwide. In our opinion, if a residual tumour is left in the internal auditory meatus, which is often the case when surgery is performed by the retrosigmoid approach, then these tumours may be removed using the translabyrinthine approach in the subsequent stage [Figure 10].

When the tumour is adherent to the facial nerve, we agree with the author that every effort should be made to preserve the facial nerve function, and at times, leave behind residual tumour (which should be in mm and not in cm.

The average time taken for surgery is more when compared to that reported by other institutes but is comparable to the time taken by us by in performing the translabyrinthine approach.

We agree with the author that extubation of the patient may be performed immediately following surgery when the surgical time is shorter, and keeping the patient intubated when the surgical time is longer. The mortality rate in the study in focus is slightly higher compared to that reported in the international data .[7] There is a future for the use of coblators in the removal of vestibular neuromas.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

 
  References Top

1.
Lanman TH, Brackmann DE, Hitselberger WE, Subin B. Report of 190 consecutive cases of large acoustic tumors (vestibular schwannoma) removed via the translabyrinthine approach. J Neurosurg 1999;90:617-23.  Back to cited text no. 1
[PUBMED]    
2.
Nickele CM, Akture E, Gubbels SP, Başkaya MK. A stepwise illustration of the translabyrinthine approach to a large cystic vestibular schwannoma. Neurosurgical Focus 2012;33:3, E11.  Back to cited text no. 2
    
3.
Misra BK, Purandare HR, Ved RS, Bagdia AA, Mare PB. Current treatment strategy in the management of vestibular schwannoma. Neurol India 2009;57:257.  Back to cited text no. 3
[PUBMED]  Medknow Journal  
4.
Sluyter S, Graamans K, Tulleken CA, Van Veelen CW. Analysis of the results obtained in 120 patients with large acoustic neuromas surgically treated via the translabyrinthine-transtentorial approach. J Neurosurgery 2001;94:61-6.  Back to cited text no. 4
    
5.
Régis J, Roche PH, editors. Modern management of acoustic neuroma. Karger Medical and Scientific Publishers; 2008.  Back to cited text no. 5
    
6.
Tos M, Thomsen J. The translabyrinthine approach for the removal of large acoustic neuromas. Archives of oto-rhino-laryngology. 1989;246:292-6.  Back to cited text no. 6
    
7.
Jain VK, Mehrotra N, Sahu RN, Behari S, Banerji D, Chhabra DK. Surgery of vestibular schwannomas: An institutional experience. Neurol India 2005;53:41.  Back to cited text no. 7
[PUBMED]  Medknow Journal  
8.
Angeli RD, Piccirillo E, Di Trapani G, Sequino G, Taibah A, Sanna M. Enlarged translabyrinthine approach with transapical extension in the management of giant vestibular schwannomas: Personal experience and review of literature. Otology and Neurotology. 2011;32:125-31.  Back to cited text no. 8
    
9.
Régis J, Roche PH, editors. Modern management of acoustic neuroma. Karger Medical and Scientific Publishers; 2008.  Back to cited text no. 9
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]



 

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