Unilateral spastic trismus in brain stem stroke: A hindrance to oral care, mastication, and speech

Abstract

Spastic trismus (ST) is a rare manifestation of stroke-induced spasticity, characterised by sustained contraction of the masticatory muscles, resulting in restricted jaw opening. It can severely impact oral hygiene, feeding, speech, and access to dental procedures, and may complicate emergency airway management. ST is more commonly observed in bilateral cerebral cortical lesions, while isolated unilateral ST following a brainstem stroke is exceedingly rare. We report a case of unilateral ST in a 57-year-old man with a history of diabetes mellitus and dyslipidaemia who suffered a brainstem stroke affecting the pontomedullary junction and medulla. He developed severe limb incoordination, dysphagia, and dependence on nasogastric tube feeding but remained cognitively intact. He was referred to us two years post-stroke, presenting with severe trismus (interincisal distance of 11 mm) and right jaw hypertrophy. Conservative treatments, including warm compresses and stretching exercises, failed. Botulinum toxin injection was offered, but declined. He was started on oral baclofen (10 mg twice daily), which was later reduced due to drowsiness. After two weeks, his interincisal distance improved to 22 mm, facilitating oral hygiene and speech articulation. Baclofen was discontinued after four weeks as no further improvement was observed, but gains were maintained at three, six, and 12 months post-discharge. This case highlights the challenges in managing post-stroke ST, particularly in a unilateral brainstem lesion. While botulinum toxin remains the treatment of choice, oral antispasmodics may serve as viable alternatives when injections are contraindicated or declined. Further research is needed to establish evidence-based rehabilitation strategies to improve long-term outcomes for ST.