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Table of Contents    
Year : 2021  |  Volume : 69  |  Issue : 3  |  Page : 757-758

Hemimasticatory Spasm: Does Microvascular Decompression of Trigeminal Motor Root Work?

1 Department of Neurosurgery, Cancer Center, Integrated Hospital of Traditional Chinese Medicine, Southern Medical University, Guangzhou, P. R. China
2 Department of Neurosurgery, Zhongda Hospital Southeast University, Nanjing, P. R. China
3 Department of Neurosurgery, NASA Neuro Care, Jalandhar, Punjab, India

Date of Submission18-Nov-2017
Date of Decision07-Jan-2018
Date of Acceptance29-Dec-2019
Date of Web Publication24-Jun-2021

Correspondence Address:
Dr. Naveen Chitkara
Department of Neurosurgery, NASA Neuro Care, Jalandhar, Punjab 144001
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0028-3886.319198

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How to cite this article:
Chen L, Wu G, Wang H, Guo X, Chitkara N. Hemimasticatory Spasm: Does Microvascular Decompression of Trigeminal Motor Root Work?. Neurol India 2021;69:757-8

How to cite this URL:
Chen L, Wu G, Wang H, Guo X, Chitkara N. Hemimasticatory Spasm: Does Microvascular Decompression of Trigeminal Motor Root Work?. Neurol India [serial online] 2021 [cited 2021 Oct 17];69:757-8. Available from:

Hemimasticatory spasm (HMS) is a very rare disorder characterized by paroxysmal brief twitches or spasms of unilateral chewing muscles, which mainly include the masseter and temporalis muscles. The primary cause of HMS is not known fully; however, the vascular compression is one of the most important theories accepted.[1],[2] In recent years, HMS has been considered a disorder of the motor root of the trigeminal nerve, which is compressed or attached by surrounding blood vessels. The onset of HMS, its pathogenesis, and electrophysiological performance are similar to that of hemifacial spasm (HFS). Since 2012, neurosurgeons have begun to perform microvascular decompression (MVD) for the treatment of HMS, and achieved favorable outcomes [Table 1]. There have been very few case reports so far, and only nine patients worldwide have finally accepted MVD till now.[1],[3], [4,[5] In the past five years, we successfully performed MVD of trigeminal nerve via retrosigmoid approach for six patients suffering HMS, and achieved good outcomes in the period of follow up. The offending vessels and the motor root of trigeminal nerve were detached and separated by Teflon graft during the surgery [Figure 1]. In five of our cases, we found the branch of SCA offending the motor root of trigeminal nerve, while in the last case, the offending vessels included pontine perforating artery and superficial lateral pontine vein; in addition, a petrosal vein was closely related to trigeminal nerve. All of the patients felt relief in symptoms after MVD, and the preoperative trismus disappeared immediately after the surgery. However, the worm-like movements of the chewing muscles in the last case were still present, while biting within three months after the surgery. Although several cases have already been reported previously, we believe that because of their uniqueness, our cases will be quite helpful for neurosurgeons, especially when they have to make decisions for the management of HMS. Offending arteries were usually found near the motor root of trigeminal nerve in all of the cases reported before, while in one of our cases, there were venous compression, severe arachnoid adhesions, and non-typical artery-to-nerve compression. Hence, MVD of trigeminal nerve may be a considerable treatment for HMS when the pharmacological management does not give relief [Figure 2] and [Figure 3].
Table 1: Summary of the patients with HMS treated by MVD

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Figure 1: Preoperative brain MRI 3D-CISS scans showed a suspicious small vascular (arrow) compression of the trigeminal nerve. b The motor root of trigeminal nerve was compressed by SCA, and there was an artery impression on the nerve. c SCA was detached away from the trigeminal nerve, while the nourishing vessels remained intact. d The vasculature and the nerve were separated by Teflon graft

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Figure 2: Needle electromyography showed the bursts of action potential units of the left masseter muscles(a) and temporalis muscles(c) during the period of spasm. b and d showed potentials of the right masseter muscles and temporalis muscles corresponding to the left.

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Figure 3: The motor root and sensory root of trigeminal nerve were attached together as one unit, and the motor root was on the ventral side. The pontine perforating artery was close to the nerve. b After the dissection of arachnoid adhesions, the superficial lateral pontine vein was found to compress the motor root of trigeminal nerve. c Pontine perforating artery was detached away from the nerve. d All of the offending vessels were separated from the nerve by Teflon graft.

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We have a few clinical cases at present, which need to be followed up for a longer term. In future, more surgical cases should be reviewed carefully to confirm the exact outcome of MVD in treatment of HMS.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Chon KH, Lee JM, Koh EJ, Choi HY. Hemimasticatory spasm treated with microvascular decompression of the trigeminal nerve. Acta Neurochir (Wien) 2012;154:1635-9.  Back to cited text no. 1
Cruccu G, Inghilleri M, Berardelli A, Pauletti G, Casali C, Coratti P, et al. Pathophysiology of hemimasticatory spasm. J Neurol Neurosurg Psychiatry 1994;57:43-50.  Back to cited text no. 2
Dou NN, Zhong J, Zhou QM, Zhu J, Wang YN, Li ST. Microvascular decompression of trigeminal nerve root for treatment of a patient with hemimasticatory spasm. J Craniofac Surg 2014;25:916-8.  Back to cited text no. 3
Sun H, Wei Z, Wang Y, Liu C, Chen M, Diao Y. Microvascular decompression for hemimasticatory spasm: A case report and review of the literature. World Neurosurg 2016;90:703-5.  Back to cited text no. 4
Wang YN, Dou NN, Zhou QM, Jiao W, Zhu J, Zhong J, et al. Treatment of hemimasticatory spasm with microvascular decompression. J Craniofac Surg 2013;24:1753-5.  Back to cited text no. 5


  [Figure 1], [Figure 2], [Figure 3]

  [Table 1]


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