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CASE REPORT
Year : 2019  |  Volume : 46  |  Issue : 2  |  Page : 67-69

Surgical removal of peripheral nerve schwannoma with intraoperative neurophysiological monitoring


1 Department of Neuroanaesthesiology, Siddhagiri Advanced Neuroscience Centre and Research Unit, Kolhapur, Maharashtra, India
2 Department of Neurosurgery, Siddhagiri Advanced Neuroscience Centre and Research Unit, Kolhapur, Maharashtra, India

Date of Web Publication28-Jan-2020

Correspondence Address:
Dr. Prakash Chandragouda Bharamagoudar
Department of Neuroanaesthesiology, Siddhagiri Advanced Neuroscience Centre and Research Unit, Karveer, Kolhapur -416 234, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jss.JSS_31_19

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  Abstract 


Schwannomas are the most common peripheral nerve tumors arising from neural sheath. They account for <8% of soft-tissue neoplasm. Surgical excision is the only option when patients present with complaints such as paresis, palsy, paresthesia, and pain. The essential goal of surgery will be complete excision of tumor with preserving nerve function. Intraoperative neurophysiological monitoring (INM) gives basic, reliable, and real-time information on the functionality of explored nerve, which helps the surgical team in microscopic dissection of tumor and complete removal without damaging the normal nerve fasciculi. We present a case of complete surgical excision of radial nerve schwannoma in a 48-year-old male, with INM and without any postoperative neurodeficits.

Keywords: Intraoperative neurophysiological monitoring, peripheral nerve, schwannoma


How to cite this article:
Bharamagoudar PC, Marajakke S. Surgical removal of peripheral nerve schwannoma with intraoperative neurophysiological monitoring. J Sci Soc 2019;46:67-9

How to cite this URL:
Bharamagoudar PC, Marajakke S. Surgical removal of peripheral nerve schwannoma with intraoperative neurophysiological monitoring. J Sci Soc [serial online] 2019 [cited 2022 Aug 15];46:67-9. Available from: https://www.jscisociety.com/text.asp?2019/46/2/67/276980




  Introduction Top


Schwannomas are the most common peripheral nerve tumors, first described by Verocay in 1908.[1] They arise from Schwann cells. They are benign, slow growing, solitary, and account for <8% of all soft-tissue tumors.[2] They are mostly asymptomatic initially, but when increased in size may present with paresis, palsy, paresthesia, and pain. After surgical excision, 10% of the patients develop neurodeficits.[3] Intraoperative neurophysiological monitoring (INM) helps the surgical team in microscopic dissection of tumor, identifying uninvolved fascicles and complete excision with real-time, precise monitoring of nerve function. We present a case of complete surgical excision of radial nerve schwannoma in a 48-year-old male, with INM and without any postoperative neurodeficits.


  Case Report Top


A 48-year-old male patient came to us with complaints of swelling over the left arm for 7 years. It was gradually progressing in size and was initially painless, but for the last 1 year, it was associated with severe pain on touch. There was no history of similar swellings anywhere else in the body. There was no history of loss of weight, loss of appetite, and trauma. There was no comorbid conditions and no family history of any similar complaints. There was no history of limb weakness or any paresthesia. On clinical examination, the swelling was globular around 3 cm × 2 cm × 2 cm in size, was soft, and was noncompressible with tenderness.

Magnetic resonance imaging (MRI) showed a well-defined ovoid focal lesion measuring about 40 mm × 28 mm × 26 mm within the intermuscular plane along the distal portion of the left arm, which was predominantly hypointense on T1 and predominantly hyperintense on T2 [Figure 1]. A well-defined peripheral hypointense rim was seen on T2 with few hypodense septa and a few prominent flow voids. The lesion was closely related to and/or probably arising from the left radial nerve.
Figure 1: Magnetic resonance imaging showing a well-defined, ovoid, focal lesion measuring about 40 mm × 28 mm × 26 mm within the intermuscular plane along the distal portion of the left arm which is predominantly hypointense on T1 and predominantly hyperintense on T2-weighted images

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A provisional diagnosis of radial nerve schwannoma was done, and the patient was posted for surgical excision after explaining the risks of limb paresis and paresthesia postoperatively. The patient was American Society of Anesthesiologists I, with all investigations being normal. Radial nerve monitoring was planned with the help of NIM (Medtronic, Jacksonville, Florida USA) nerve monitoring system.

In the operation theater, the patient was premedicated with injection midazolam 1 mg and injection fentanyl 100 μg. Preoxygenated with 100% O2 for 3 min, anesthesia was induced with injection propofol 2 mg/kg intravenously. Supreme™ LMA ® no. 4 was inserted. The position was confirmed with end-tidal carbon dioxide (ETCO2) and auscultation. The patient was mechanically ventilated with O2+ N2O+ sevoflurane minimum alveolar concentration 1. Standard monitoring was done with SpO2, noninvasive blood pressure, electrocardiogram, ETCO2, and anesthesia gas monitoring.

After induction, electrodes were placed over the extensor carpi radialis longus, bravis, and extensor digitorum. The tumor was pedunculated and seen to be arising from one of the fascicles of the radial nerve. With a bipolar stimulation (0.5–1 ms, 0.7 mA), the nerve was traced to the inferior and medial aspects of the tumor [Figure 2] and [Figure 3]. The capsule over the tumor was dissected all around and the tumor was excised in toto [Figure 4] with preservation of uninvolved radial nerve fasciculi. After complete excision, bipolar stimulation (0.5–1 ms, 0.5 mA) was given proximally directly on the nerve, and electromyography activity was noted and documented.
Figure 2: Intraoperative dissection of schwannoma

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Figure 3: Intraoperative photographs showing evoked electromyography responses. Note all the three muscles (extensor carpi radialis longus, bravis, and extensor digitorum) showing electromyography activity in the last picture

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Figure 4: Intraoperative and postoperative photographs of schwannoma

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After surgery and complete awakening of the patient, the LMA was removed. There were no postoperative deficits in the left upper limb and no paresthesia. Injection paracetamol 1 g was given for postoperative pain relief. The patient was observed in the ward for 1 day and discharged on the 2nd postoperative day. On follow-up after a week, the patient was completely asymptomatic with Grade 5/5 power in the left upper limb.

Histopathology report confirmed it to be schwannoma.


  Discussion Top


Schwannomas of peripheral nerves are mainly solitary tumors, are well capsulated, are slow growing, and are noninfiltrating in nature.[4],[5] They gradually displace and/or compress nerve fascicles, which develops clinical symptoms.[6] Malignant transformation in solitary schwannoma is rare. MRI is the investigation of choice which shows well-defined fusiform mass isointense on T1-weighted and hyperintense on T2-weighted images.[7]

Surgical excision is the treatment of choice.[4] Complete removal of tumor with no neural deficit is the main purpose of surgery. In literature, postoperative neurological deficit varies from 1.5% to 80%.[4],[8],[9],[10],[11] Higher percentage of complications occurred in short-term observations. In a retrospective study of 76 patients with schwannoma, the function was preserved in 89% of cases.[12] In a study by Kline et al.,10.5% of patients developed postoperative motor weakness.[13]

Atraumatic removal of tumor does not eliminate postoperative neurological deficit. Compression, irritation, and damage to fascicles encircling the tumor during incision will lead to deficits.[10] Some of the fascicles entering the tumor are usually nonfunctional.[11] INM helps the team in identifying and preserving nerve fascicles.

Here, in our case with a typical presentation of schwannoma, we used INM and with minimally invasive and careful dissection, we could remove the tumor and preserve the nerve fascicles functionally. INM is precise, is accurate, and is of real time. There are limitations in predicting postoperative pain or paresthesia, but we can monitor motor function. We need more studies on the use of INM in peripheral nerve tumor surgeries.


  Conclusion Top


INM and nerve stimulation is an important tool in the complete surgical excision of peripheral nerve tumors and preserving nerve function.

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.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Zhou J, Man XY, Zheng M, Cai SQ. Multiple plexiform schwannoma of a finger. Eur J Dermatol 2012;22:149-50.  Back to cited text no. 1
    
2.
Kransdorf MJ. Benign soft-tissue tumors in a large referral population: Distribution of specific diagnoses by age, sex, and location. AJR Am J Roentgenol 1995;164:395-402.  Back to cited text no. 2
    
3.
Barbour JR, Boyd KU. Tumors of the peripheral nervous system. In: Mackinnon SE, Yee A editors. Nerve Surgery. New York: Thieme; 2015. p. 530-71.  Back to cited text no. 3
    
4.
Adani R, Baccarani A, Guidi E, Tarallo L. Schwannomas of the upper extremity: Diagnosis and treatment. Chir Organi Mov 2008;92:85-8.  Back to cited text no. 4
    
5.
Kehoe NJ, Reid RP, Semple JC. Solitary benign peripheral nerve tumors. J Bone Joint Surg B 1995;77;497-500.  Back to cited text no. 5
    
6.
Rockwell GM, Thoma A, Salama S. Schwannoma of the hand and wrist. Plast Reconstr Surg 2003;111:1227-32.  Back to cited text no. 6
    
7.
Thawait SK, Chaudhry V, Thawait GK, Wang KC, Belzberg A, Carrino JA, et al. High-resolution MR neurography of diffuse peripheral nerve lesions. AJNR Am J Neuroradiol 2011;32:1365-72.  Back to cited text no. 7
    
8.
Kang HJ, Shin SJ, Kang ES. Schwannomas of the upper extremity. J Hand Surg 2000;25:604-7.  Back to cited text no. 8
    
9.
Kim SM, Seo SW, Lee JY, Sung KS. Surgical outcome of schwannomas arising from major peripheral nerves in the lower limb. Int Orthop 2012;36:1721-5.  Back to cited text no. 9
    
10.
Park MJ, Seo KN, Kang HJ. Neurological deficit after surgical enucleation of schwannomas of the upper limb. J Bone Joint Surg Br 2009;91:1482-6.  Back to cited text no. 10
    
11.
Donner TR, Voorhies RM, Kline DG. Neural sheath tumors of major nerves. J Neurosurg 1994;81:362-73.  Back to cited text no. 11
    
12.
Kim DH, Murovic JA, Tiel RL, Moes G, Kline DG. A series of 397 peripheral neural sheath tumors: 30-year experience at Louisiana State University Health Sciences Center. J Neurosurg 2005;102:246-55.  Back to cited text no. 12
    
13.
Kline DG, Hudson AR, Tiel RL, Guha A. Management of peripheral nerve tumors. In: Winn HR, editor. Youmans Neurological Surgery. 5th ed. Philadelphia: Saunders; 2004. p. 3941-57.  Back to cited text no. 13
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]



 

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