|Year : 2017 | Volume
| Issue : 1 | Page : 31-33
A novel technique for surgery of extracranial schwannoma to preserve neurological function
Jyoti Dabholkar1, Ameya Bihani2
1 Department of ENT and HNS, KEM Hospital, Mumbai, Maharashtra, India
2 Department of ENT, KEM Hospital, Mumbai, Maharashtra, India
|Date of Web Publication||27-Jul-2017|
Department of ENT, KEM Hospital, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
Schwannomas are benign encapsulated tumor arising from Schwann cells of the nerve sheath. Large schwannomas of the neck present as neck mass and arise from major nerve such as vagus and cervical sympathetic chain. Surgical excision is the standard of management of such tumors but result in permanent nerve damage. Here, we present a case of 35-year-old female with schwannoma arising from vagus nerve with the intact neurological function of the nerve. We removed the tumor by intracapsular dissection, leaving behind the capsule, preserving the function of the nerve.
Keywords: Intra-capsular dissection, parapharyngeal space, schwannoma
|How to cite this article:|
Dabholkar J, Bihani A. A novel technique for surgery of extracranial schwannoma to preserve neurological function. J Head Neck Physicians Surg 2017;5:31-3
|How to cite this URL:|
Dabholkar J, Bihani A. A novel technique for surgery of extracranial schwannoma to preserve neurological function. J Head Neck Physicians Surg [serial online] 2017 [cited 2021 Mar 2];5:31-3. Available from: https://www.jhnps.org/text.asp?2017/5/1/31/211733
| Introduction|| |
Schawnnomas are slow growing benign encapsulated tumors which arise from the sheath cells of the nerves. They do not cause any neurological deficit when small but may present with such deficits with an increase in size. Surgical excision is accepted the line of management in large schwannomas but results incomplete neurological deficit postoperatively which hampers the quality of life. Hence, we have adapted the technique for intra-capsular dissection of schwannomas which will prevent the injury to nerve axons and will also serve the purpose of removal of the tumor.
| Case Report|| |
A 35-year-old female patient presents with foreign body sensation in throat for the past 5 years. She occasionally experiences difficulty in swallowing. There was no history of change in voice or aspiration. The gag was present but reduced. There was no obvious swelling in the neck. On indirect laryngoscopy, both the vocal cords were mobile, and there was no pharyngeal or laryngeal bulge.
Cords were in normal position with no sagging. Ultrasonography of the neck was done at private hospital as routine investigation which revealed a mass in the neck close to great vessels.
Computed tomography was done to reveal the exact site and extent of the lesion. It revealed that there was 4 cm diameter lesion on the left side in the neck which enhancement on the administration of contrast uniformly but not brilliantly. The mass had displaced internal jugular vein anterolaterally and splayed the carotid arteries away from internal jugular vein suggestive of its origin from vagal nerve [Figure 1].
|Figure 1: Contrast enhance computed tomography showing the mass which enhances on contrast with splaying of internal jugular vein from carotid artery|
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Magnetic resonance imaging (MRI) of the neck revealed that the mass was isodense to hypodense on T1 and enhance nearly uniformly on gadolinium contrast and was heterogeneously hyperintense showing occasional areas of degeneration or necrosis. The mass was asising from carotid sheath with splaying the internal jugular vein from the carotid artery. These features were suggestive of schwannoma of vagal origin. The upper limit of this swelling was less than a centimeter from the skull base. The therapeutic options were discussed with the patient and opted for surgery (a) T1 (b) T1 with contrast (c) T2 [Figure 2].
|Figure 2: Magnetic resonance imaging neck (a and b) T1 hypointense mass with homogenous enhancement on contrast (c) T2 - hyperintense mass with focal areas of degeneration|
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The patient was taken under general anesthesia. The incision was taken in the upper cervical cutaneous crease about two finger breath below the mandible so as to prevent injury to the marginal mandibular nerve. The submandibular gland was removed classically so as to get an access to high parapharyngeal space. The tumor was identified present n carotid sheath reaching up to skull base. The hypoglossal and glossopharyngeal nerves were visualized and preserved The capsule of the tumor was incised, and the tumor was removed with intra-capsular dissection by the blunt method. The capsule was left without dissecting it off the nerve. The lymph nodes were sampled to rule out any metastasis for round cell tumor [Figure 3].
|Figure 3: (a) Encapsulated tumor. (b) Intracapsular extraction of schwannoma done with capsule left behind|
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Immediate postoperatively, the patient had left-sided vocal cord which recovered by on starting pulse therapy of systemic steroids. On day 3 postoperatively, the patient had regained complete mobility of left vocal cord and had normal voice with the normal gag reflex.
| Discussion|| |
Schwannoma is the benign tumor of nerve sheath cells. Twenty-five to forty percentage of schwannomas of the body are seen in head and neck region. They were first described by Verocay in 1910. These are slow growing, smooth, and regular benign masses.
Fine-needle aspiration cytology (FNAC) has been standard in diagnosing the nature of neck swelling, but in cases of schwannoma, FNAC may not be helpful in giving a diagnosis. The other limitation of FNAC is accessibility of tumors deep-seated in parapharygeal space in close relation to great vessels.
Hence in such scenarios, MRI is the gold standard of imaging which will not only reveal the extent of swelling but also its nature of pathology as well as organ/site of origin. Anatomically, vagus lies in the carotid sheath and hence, tumors arising from the vagus will shift the internal jugular vein laterally and internal carotid artery medially. The cervical sympathetic chain lies postero-medial to carotid sheath, and hence, the tumors arising from cervical sympathetic chain will push the great vessel anteriorly and not splay them., The accepted lines of surgical management are complete excision of the schwannoma, but the major drawback of this approach is unrepairable neurological damage of the concerned nerve of origin. In cases of the vagus nerve, this will lead to vocal cord paralysis, loss of movement of palate and ipsilateral pharynx leading to hoarseness of voice and aspiration. In cases with involvement of cervical sympathetic chain, postoperatively patient develops Horner's syndrome. In both scenarios, there is a permanent neurological deficit which compromises the quality of life severely. Hence, we decided to use a different technique of management of schwannomas arising from the nerves whose neurological function are intact preoperatively. The technique is based on the principle that the tumor arises from the Schwann sheath cells and not the neurones themselves and hence if the tumor is removed by intra-capsular dissection and the capsule is left behind without tackling the nerve fibers, the functioning of the nerves can be maintained.
According to the study by Valentino et al., intracapsular enucleat ion while preserving the nerve fibers preserved its function by more than 30% when compared to tumor resection with primary anastomosis. Kim et al. concluded that intracapsular enucleation have led to the maintaining of 86% of their nerve function, but the drawback of the study was the small sample size (seven cases). A series of five cases described by de Araujo et al. using the enucleation technique showed a 60% success rate in preserving nerve function postoperatively. Torossian et al. reviewed postoperative neurological outcomes in 15 head and neck schwannomas undergoing enucleation with nerve preservation. Only two tumors recurred, and these recurrences were attributed to the lack of microscopic dissection. Hence, the success of this technique has varied results ranging from 30% to 86% successful preservation of neurological function. Further studies with larger sample sizes and with long-term follow-ups have to be undertaken to establish the success and drawback of this technique, but till then, this technique should be resorted to as an option in managing schwannomas with no preoperative neurological deficits.
| Conclusion|| |
Management of schwannomas has always been a great challenge. Complete surgical excision has been the gold standard for management of schwannoma in the neck but results into a complete neurological functional deficit of the nerve of origin. We have tried an intracapsular technique of extraction of schwannoma in a case of vagal schwannoma and preserved its functioning postoperatively.
The long-term result of this techniques have not been yet evaluated and will require a long-term prospective study due to the absence of substantial literature related to this approach but till then, this approach can be used of the approach of choice in schwannomas presenting without any neurological compromise.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]