The tongue muscles: Clinical applications in lingual dystonia

Lingual dystonia, a type of oromandibular focal dystonia, involves sustained tongue contractions, often causing protrusion during actions such as speaking or chewing. It is classified as either primary or secondary, depending on the underlying cause. Botulinum neurotoxin (BoNT) is a recognized treatment for focal dystonias, including lingual dystonia. However, precise administration of BoNT can be challenging, limiting its efficacy and potentially causing adverse effects. This review focuses on selecting target muscles and using ultrasound guidance for accurate BoNT administration. Using ultrasound, with or without electromyography, a submental injection approach is employed to target the genioglossus and hyoglossus muscles, which are most affected in lingual dystonia. The suprahyoid muscles are critical anatomical considerations during submental injections to avoid aspiration. Additionally, as drooling is a common symptom of lingual dystonia, BoNT injections into the submandibular glands are also discussed. A case series with X-linked dystonia-parkinsonism was our way to clinically demonstrate BoNT injections in those with severe lingual dystonias.