Long-Term Outcome of Hemimasticatory Spasm

Abstract

ObjectiveaaThis study aims to identify the demographic, clinical, and therapeutic characteristics of four patients with hemimasticatory spasm (HMS) seen in our outpatient department over a period of 20 years.MethodsaaWe performed a retrospective chart review of four patients with HMS who visited outpatient services in the Department of Neurology from 2001 to 2020.ResultsaaThe follow-up for all patients ranged from 2 years to 9 years. Three patients had facial or bucco-oral morphea. Two patients maintained long-term improvements in symptoms after being treated with botulinum toxin for 4-7 years, while one patient reported improvement in symptoms with treatment of carbamazepine that subsequently remitted after pregnancy.ConclusionaaThis report highlights the long-term outcome of HMS in our patients. Our patients reported a significant reduction or complete resolution of symptoms after treatment, and eventually, two patients were asymptomatic while off treatment.

Hemimasticatory Spasm Treated With Muscle Afferent Block Therapy and Occlusal Splint

“…Hemimasticatory spasm (HMS) manifests as unilateral, paroxysmal contractions of the jaw-closing muscles, resulting in brief twitches and/or spasms. [1][2][3] HMS can be treated with oral medication, botulinum toxin therapy, and microvascular decompression surgery. Although botulinum toxin injection into the affected muscles is believed to be the most effective option, [1][2][3] possible side effects include hemifacial asymmetry due to atrophy of the injected muscle and masticatory disturbance related to a reduction in bite force.…”

“…[1][2][3] HMS can be treated with oral medication, botulinum toxin therapy, and microvascular decompression surgery. Although botulinum toxin injection into the affected muscles is believed to be the most effective option, [1][2][3] possible side effects include hemifacial asymmetry due to atrophy of the injected muscle and masticatory disturbance related to a reduction in bite force. 4 Muscle afferent block (MAB) therapy involving the injection of a local anesthetic is effective for relieving muscle pain without reducing muscle strength.…”

“…HMS is a rare unilateral movement disorder caused by dysfunction of the motor trigeminal nerve and is characterized by paroxysmal contractions of the jaw-closing muscles, mainly the masseter and/or temporalis. [1][2][3] A neurologist may diagnose a patient with HMS with hemifacial spasm or unilateral oromandibular dystonia. Dentists and oral surgeons may diagnose temporomandibular joint disorders or bruxism.…”

“…EMG may provide important information about the loss of the silent period and irregular bursts of high-frequency motor units. [1][2][3] Botulinum toxin therapy is believed to be the most effective treatment option for HMS. [1][2][3] However, in the present case, mild muscle atrophy and a significant reduction in bite force were observed on the affected side.…”

Peripherally-induced Movement Disorders: An Update

“…Much less common than HFS, HMS is characterized by unilateral, involuntary, intermittent contractions of the jaw-closing muscles, resulting in brief twitches and/or spasms without actual jaw deviation [30,31]. Patients with HMS may have additional features such as facial hemiatrophy, connective tissue disorders such as scleroderma, and skin changes such as morphea [32][33][34].…”