Lingual Dyskinesia Developing after the First Dose of Methylphenidate Treatment in a Child with Neurodevelopmental Disorders: Genetic Predispositions.

Methylphenidate is generally well tolerated, but it often causes sleep disturbances, less commonly suppresses appetite, and may lead to neurological and movement disorders such as tics, dyskinesia, and psychosis. Among movement disorders, acute dyskinesias are particularly rare but clinically significant, as highlighted in recent pharmacovigilance data. Dopamine receptor hypersensitivity and excessive dopamine signaling, disturbances in other neurotransmitter systems, and genetic predisposition are some of the mechanisms thought to contribute to dyskinesia. In the literature, most cases of dyskinesia reported with methylphenidate consist of orofacial and limb dyskinesias or a combination of these. Additionally, acute cases of dyskinesia have been reported following the combined use of methylphenidate and sodium valproate in childhood. To our knowledge, our case is the first case of isolated lingual dyskinesia in which similar drug-related movement disorders are also identified in the family. It is known that the patient's mother also experienced acute movement disorders after taking psychotropic drugs. Furthermore, the presence of epilepsy diagnosis, sodium valproate use, and multiple neurodevelopmental disorders in our case is noteworthy. While our case demonstrates that dyskinesia can occur even at standard low treatment doses after the first dose, it emphasizes the importance of considering dyskinesia as a potential side effect in cases with a family history of similar drug-related side effects and epilepsy comorbidity.