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Journal of Craniovertebral Junction and Spine
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EDITORIAL
Year : 2016  |  Volume : 7  |  Issue : 3  |  Page : 131-132  

Is “total” tumor resection and facial nerve functional preservation possible in large acoustic neurinoma?


Department of Neurosurgery, K.E.M. Hospital and Seth G.S. Medical College, Mumbai, Maharashtra, India

Date of Web Publication16-Aug-2016

Correspondence Address:
Atul Goel
Department of Neurosurgery, K.E.M. Hospital and Seth G.S. Medical College, Parel, Mumbai - 400 012, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0974-8237.188421

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How to cite this article:
Goel A. Is “total” tumor resection and facial nerve functional preservation possible in large acoustic neurinoma?. J Craniovert Jun Spine 2016;7:131-2

How to cite this URL:
Goel A. Is “total” tumor resection and facial nerve functional preservation possible in large acoustic neurinoma?. J Craniovert Jun Spine [serial online] 2016 [cited 2018 May 25];7:131-2. Available from: http://www.jcvjs.com/text.asp?2016/7/3/131/188421

Acoustic neurinoma surgery is a frequently performed neurosurgical procedure. The art of surgical resection of an acoustic neurinoma has to be learnt and perfected over years of training, after operations on several tumors and an in-depth understanding of nuances of the entire spectrum of the subject. Saving of seventh cranial nerve forms the most crucial and challenging surgical issues. The outcome of surgical treatment is evaluated by the outcome of facial nerve function. The high probability of facial nerve dysfunction after surgery has gradually, but surely made surgical treatment of acoustic neurinoma lose its “numero uno” position in the treatment. Gamma knife radiation is emerging as a favored option, particularly for small- and medium-sized acoustic neurinomas. The net effect is that the surgeons are getting less experienced in acoustic neurinoma surgery and considering the potential of facial dysfunction are themselves shying away from taking the risk.

It is crucial to understand the relationship of the facial nerve with the acoustic neurinoma before executing the surgical procedure. More important is to philosophically understand the potential of recurrence of acoustic neurinomas. Furthermore, it has to be realized that gamma knife is a strong and effective tool and has been reported on several occasions to successfully control the growth pattern of an acoustic neurinoma. The issue in discussion is not about the effectiveness or potential of side effects of gamma knife or even regarding the indications of its possible use in acoustic neurinoma surgery but is to identify the possible issues that can make surgery a viable and preferred option for all sizes of acoustic neurinomas.

Acoustic neurinoma is no different than a subcutaneous neurinoma or a neurioma that is, visible or palpated in the neck. It is the “malignant” location, profile of the neighboring neural structures and the compressive consequences that make surgical treatment a highly debated and discussed issue. The general principal of surgery for all tumors, benign or malignant, is “lumpectomy.” Resect the lump and make space and wait with folded hands for its recurrence. While benign tumors take several years or decades to recur, malignant tumors recur relatively early. It will help if the surgeons realize that “once an acoustic neurinoma always an acoustic neurinoma.” “Curing” is a nonissue in the treatment. It is important to understand that surgery is a space creating solution for a space occupying lesion. The quality of surgery is evaluated by the extent of space created and by the nature of functional preservation. While radical surgery, maximal space creation and “total” tumor resection is the goal of surgery, any neurological dysfunction, particularly of the most visible region of the body that determines the identity of an individual can be considered to be a surgical failure. Over the several years of our experience with acoustic neurinoma surgery, we have realized that recurrence of an acoustic neurinoma is independent of the extent of its resection. This fact emphasizes the point that the surgeons goal of treatment is to preserve the function and within this solo premise the tumor resection has to be carried out. During the entire surgical procedure, the surgeon has to worry more about the clinical outcome after surgery and less about the long-term possibility of recurrence.

The author does not wish to argue or discuss the issue of the extent of functional preservation of facial nerve that is possible in cases undergoing surgery on large acoustic neurinoma surgery. The issue is the extent of the radicality of tumor resection that is necessary and possible in these cases. After an experience with more than 1000 acoustic neurinoma surgery, the author has come to a conclusion that “total” microscopic resection of a large (more than 3.5 cm) acoustic neurinoma is compatible with anatomical and functional preservation of the facial nerve in < 5% of cases. The facial nerve is remarkably stretched and on occasion, its fibers are inseparably merged in the capsule of the tumor. While facial nerve is physically strong, dissection that will lead to stretch and manipulation of the nerve can lead to damage to its integrity or vascularity, both of these events can lead to functional loss. Moreover, considering the nature of consequences that are at stake, the surgeon has to be aware of his skills and the morphological situation at hand and determine the extent of tumor resection that would be possible without affecting the safety of the nerve. It should not happen that the attempts of heroics and showmanship during surgery lands the patient with a face that spells misery.

Careful, controlled, and tailored surgery of acoustic neurinoma is effective for all sizes of acoustic neurinomas. The risk to the facial nerve has to be considered paramount during the entire surgical procedure for all sizes of acoustic neurinomas. In small- or medium-sized tumors, the facial nerve is relatively safely and completely separable from the tumor. However, even in these cases, facial nerve function can be affected during dissection, manipulation, and traction.

Surgery for large acoustic neurinomas forms one of the most challenging neurosurgical issues. Patients present with disabling symptoms of headache and ataxia, apart from hearing loss. Radical surgery should be planned and done, as the aim of partial or subtotal resection can be associated with “small” tumor resections that is, ineffective in control of presenting symptoms. Radical tumor resection is not always an easy or a safe operation in cases with large acoustic neurinomas. Tumor debulking and resection and dissection of the tumor from the adjoining cranial nerves, cerebellum, and brain stem have to be gentle and calculated. Special surgical skills are necessary for treating a vascular tumor, solid tumors, cystic tumor, and tumors associated with nodular borders. In general, it requires considerable surgical experience to be able to perform a successful resection of a large acoustic neurinoma. Although other consequences like lower cranial nerve paresis and even mortality are possible following surgery, such complications are becoming less frequent in contemporary neurosurgery. Not many decades ago, saving of life was the goal of surgery for large acoustic neurinomas.

There are several publications on the subject that mention a high “total” resection rate and “high” facial function preservation for small-, medium-, and large-sized acoustic neurinomas. The authors of future publications must present a definition of “total” tumor resection. They should clearly present to the readers as to the number of cases wherein total tumor resection that bared facial nerve completely free was possible in large acoustic neurinomas. The authors experience suggests that these results can divert surgeons from the real issue at stake. The issue of preservation of anatomical and functional integrity of facial nerve should be paramount. The surgeon has to understand that the relationship of facial nerve with the tumor capsule is intense and total baring of the nerve may not even be attempted more particularly in large tumors. If facial demolition or destruction continues, surgery for acoustic neurinoma will soon be put on the waitlist.




 

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