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Table of Contents    
Year : 2021  |  Volume : 69  |  Issue : 4  |  Page : 1063-1064

Foramen Magnum Decompression in Hemifacial Spasm Associated with Chiari 1 Malformation

Department of Neurosurgery, Government Medical College and Hospital, Trivandrum, Kerala, India

Date of Submission23-Jan-2018
Date of Decision01-Apr-2018
Date of Acceptance22-Mar-2021
Date of Web Publication2-Sep-2021

Correspondence Address:
Sourabh Kumar Jain
Department of Neurosurgery, Medical College and Hospital, Trivandrum - 695 011, Kerala
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0028-3886.325351

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How to cite this article:
Jain SK, Jyothish L S, Peethambaran A, Sunil Kumar B S, Asher P, Kutty RK, Sharma S. Foramen Magnum Decompression in Hemifacial Spasm Associated with Chiari 1 Malformation. Neurol India 2021;69:1063-4

How to cite this URL:
Jain SK, Jyothish L S, Peethambaran A, Sunil Kumar B S, Asher P, Kutty RK, Sharma S. Foramen Magnum Decompression in Hemifacial Spasm Associated with Chiari 1 Malformation. Neurol India [serial online] 2021 [cited 2021 Oct 23];69:1063-4. Available from:


Type I  Chiari malformation More Details (CIM) is a caudal displacement of cerebellar tonsils through the foramen magnum and into the cervical canal. CIM is also seldom associated with hemifacial spasm (HFS). Current evidence supports the narrowing of posterior fossa being one of the mechanisms responsible for HFS.[1]

A 28-year-old female patient complaining of twitching in right eyelid since six months that initially occurred twice daily, gradually increased leading to HFS. It precipitated on talking and gradually involved the right cheek along with the angle of mouth. On examination, bilateral knee jerk was exaggerated and bilateral ankle clonus was present. Magnetic resonance imaging (MRI) of brain with contrast suggestive of AICA compressing Right VII-VIII complex at cisternal and intracanalicular portions without any hydrocephalus [Figure 1]. MRI whole spine suggestive of syringomyelia (C2-T11) tonsillar descent of 5.5 mm into cervical spinal canal noted s/o CIM [Figure 2]. It was diagnosed as right HFS with CIM with Syringomyelia (C2-T11). The patient was not responding to conservative treatment. Hence, foramen magnum decompression with duraplasty was done and symptomatic improvement was observed postoperatively.
Figure 1: On MRI brain with contrast was suggestive of AICA compressing VII-VIII complex at cisternal junction and intracanalicular position

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Figure 2: On MRI whole spine was suggestive of Syringomyelia (C2-T11) and tonsillar descent of 5.5 mm in to the cervical spinal canal noted s/o Chiari malformation type1

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There is no medical treatment that is consistently effective for HFS. Botulinum toxin injections are ineffective in producing long-term control of spasm and results in varying degrees of facial weakness. McLaughlin et al. standardized the procedure of microvascular decompression of facial nerve to relieve HFS with very good results.[2]

Several mechanisms have been proposed regarding neural irritation in CIM; first, direct neural compression by malformed anatomic structures, causing neural dysfunction or irritation in a facial nerve pathway. Second, the traction of extra-axial facial nerve due to downward displacement of the hindbrain. Third, a microcirculatory disorder resulting from vascular compression due to CIM. Vascular compression of anatomic structures such as vertebra-basilar system by odontoid retro-flexion has been hypothesized causing micro-ischemic events that could change facial nerve function and result in symptoms of HFS.[3] Lastly, the theory regarding trigeminal neuralgia could be due to compression of the spinal trigeminal pathway by cerebellar herniation, which could explain both pain and progressive regression after decompression by surgery. The facial motor nucleus is located in the lower third of the pons beneath the fourth ventricle. It is possible that compression of the nucleus in the pons may be responsible for HFS.[4]

The surgery for HFS is aimed at the decompression of neural structures and cerebrospinal fluid (CSF) pathways when associated with CIM. Hence, foramen magnum decompression is the ideal choice as a primary procedure because it may relieve the symptoms by relieving the traction or compression on the facial nerve.

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 othe r 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.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Meadows J, Guarnieri M, Miller K, Haroun R, Kraut M, Carson BS. Type I Chiari malformation: A review of the literature. Neurosurg Quart 2001;11.  Back to cited text no. 1
McLaughlin MR, Jannetta PJ, Clyde BL, Subach BR, Comey CH, Resnick DK. Microvascular decompression of cranial nerves: Lessons learned after 4400 operations. J Neurosurg 1999;90:1-8.  Back to cited text no. 2
Moller AR. The cranial nerve vascular compression syndrome, I: a review of treatment. Acta Neurochir (Wien) 1991;113:18-23.  Back to cited text no. 3
Cheng J, Meng J, Lei D, Hui X, Zhang H. Surgical management of hemifacial spasm associated with Chiari I malformation: analysis of 28 cases. World Neurosurg 2017;107:464-70.  Back to cited text no. 4


  [Figure 1], [Figure 2]


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