Effect of Botulinum Toxin A on Trismus after Pons Infarction: A case report

ABSTRACT

We report a 77-year-old woman with bilateral pons infarction who presented with severe trismus, which was responsive to botulinum toxin-A injection. She was unable to open her mouth and showed anterior displacement of her temporo-mandibular (TM) joint on MRI findings. She was fed via nasogastric tube because of mouth opening limitation. There was no improvement of her mouth opening after range of motion exercise. She underwent closed reduction of the TM joints under general anesthesia but there was no significant improvement. Electromyography studies revealed continuous muscle activities on masseter and temporalis muscles during mouth opening. Botulinum toxin-A (Botox(R)) was injected into both the masseter and left temporalis muscles under ultrasonographic guidance. There was some improvement in mouth opening at post-injection 5 days. The inter-incisal distance improved gradually, and she could start oral feeding after 18 days. She could maintain an inter-incisal distance of 1.8 cm with favorable response during post-injection 4 months.