Treatment of dystonia using trihexyphenidyl in costello syndrome

Costello syndrome (CS), a rare syndrome with multisystemic involvement inherited as a dominant trait, is characterized by developmental delay, coarse facial appearance, cardiac defects including hypertrophic cardiomyopathy, skin abnormalities, brain complications, and a predisposition to certain malignancies. The musculoskeletal system is particularly affected in CS, with peculiar orthopedic anomalies that impact posture and gait. Dystonia has been recently documented to contribute to abnormal postures and musculoskeletal anomalies characterizing CS, suggesting the possible use of pharmacological treatments to treat these complications. We report the case of a child affected by CS displaying a particularly severe musculoskeletal involvement with dystonic posture especially in the arms and legs. The Movement Disorder‐Childhood Rating Scale (MD‐CRS) and a gait analysis were used to assess clinical patterns of hyperkinetic movement disorder and dystonia. The child was further treated with trihexyphenidyl for six months with a final dosage of 14 mg. MD‐CRS and gait analysis assessments provided evidence for a significant improvement of posture and the related musculoskeletal problems with no side effects. Our preliminary study report provides first evidence that pharmacological anti‐dystonia treatment significantly improves movement and posture disorders in patients with CS. Further studies enrolling larger cohorts of patients should be performed to validate these preliminary observations.