Oromandibular Dystonia as a Side Effect of Methotrexate

Oromandibular dystonia is a focal dystonia characterized by involuntary movements of the jaw, oropharynx, lips, and tongue. The diagnosis of oromandibular dystonia is clinical and can be complex. For effective treatment, it is essential to understand its underlying etiology. A 70-year-old man was referred to our center with a diagnosis of Meige's syndrome, which had been present for five and a half years, for receiving botulinum toxin-A (BoNT-A) injections. Upon physical examination, he exhibited oromandibular dystonia, with a score of 177 points on the Oromandibular Dystonia Rating Scale (OMDRS). He had a history of taking methotrexate for six years, as he was diagnosed with psoriatic arthritis during that time. The possibility of methotrexate-induced dystonia was considered. A switch from methotrexate to sulfasalazine was initiated. Subsequently, the patient showed progressive improvement in his symptoms, as reflected by an OMDRS score of 103 points. After eight weeks, the medical team decided to supplement the treatment with BoNT-A injections, resulting in an OMDRS score of 75. While there is currently no definitive evidence linking the use of methotrexate to the development of dystonia, it is advisable to consider oromandibular dystonia as a potential side effect of methotrexate until more robust evidence becomes available.