Objective: To describe a case of secondary hemifacial spasm with atypical features.

Background: Hemifacial spasm (HS) is a peripherally induced movement disorder involving involuntary unilateral contraction of facial muscles [1]. Epidermoid cysts are rare benign tumors that account for less than 1% of intracranial neoplasms [2] and have been rarely associated with HS [3,4]. Unlike primary HS, secondary HS often presents with simultaneous upper and lower face involvement at onset [5].

Method: We present a case of a 31-year-old male patient with no known diseases and under no medication who presented with HS caused by an epidermoid cyst of the left cerebellopontine angle, summarizing his clinical history, neurological findings, and laboratory, imagiological and anatomopathological work-up.

Results: Our patient presented with paroxysmal involuntary left-sided facial spasms with left jaw deviation beginning 1 month before he sought medical help. It happened several times a day, with increasing frequency, usually after laughing or eating, lasted less than 1 minute, and worsened with sleep deprivation and stress. Neurological examination revealed the described features upon volitional contraction of facial muscles, with no other abnormalities. Trial with clonazepam and especially carbamazepine led to symptom improvement, with almost total relief after botulinum toxin administration in his face and neck. Laboratory tests ruled out infectious and auto-immune disorders, electrolyte disturbances, thyroid function abnormalities, and copper metabolism impairment. Brain MRI showed a mass with 3.2×2.8 cm in left cerebellopontine angle suggesting an epidermoid cyst with ipsilateral III to VIII cranial nerves compression. The anatomopathological examination confirmed the diagnosis. The surgical treatment took place 3 months following symptom onset. After surgery, the patient remains asymptomatic under no medication.

Conclusion: Even in patients with no previous neurological disease, the presence of atypical clinical features of HS must compel physicians to extensively rule out secondary causes.

References: 1. Wang A, Jankovic J. Hemifacial spasm: clinical findings and treatment. Muscle Nerve 1998 Dec;21(12):1740-7 2. Hasegawa M et al. Cerebellopontine angle epidermoid cysts: clinical presentations and surgical outcome. Neurosurg Ver 2016 Apr;39(2):259-66; discussion 266-7 3. Auger RG, Piepgras DG. Hemifacial spasm associated with epidermoid tumors of the cerebellopontine angle. Neurology 1989 Apr;39(4):577-80 4. Alemdar M. Epidermoid cyst causing hemifacial spasm epidermoid cyst in cerebellopontine angle presenting with hemifacial spasm. J Neurosci Rural Pract 2012 Sep;3(3):344-6 5. Colosimo C et al. A comparative study of primary and secondary hemifacial spasm. Arch Neurol 2006 Mar;63(3):441-4

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