Childhood Hypertonia of Central Origin: A Trial of Anticholinergic Treatment Effects

Inclusion Criteria:

* Dystonia in the dominant upper extremity

Exclusion Criteria:

* Complete absence of voluntary movement in the affected hands, wrists, and elbows
* Severe weakness in the dominant upper extremity (MRC grade \< 4)
* Passive range of motion at the hand, wrist or elbow less than 80% of normal
* Current use of medications for dystonia (anticholinergics, L-dopa, baclofen, diazepam, tizanidine, tetrabenazine, reserpine, and others)
* Changes in the subject's physical therapy regimen for the duration of the 15-week study
* Prior use of trihexyphenidyl or other anticholinergic therapy for dystonia.
* History of surgery on the dominant upper extremity or cervical spine
* Botulinum toxin injection in the dominant upper extremity within the previous 6 months
* Current or prior implantation of an intrathecal baclofen pump, deep brain stimulator, or other device to treat dystonia or spasticity
* Concurrent acute or chronic medical condition (such as frequent seizures, heart disease, or asthma) that could adversely affect motor performance or the safety of testing
* Presence of diurnal fluctuations or other clinical signs and symptoms suggesting an inborn error of metabolism, a family history of dystonia suggesting a genetic dystonia, or dystonia due to injury after the neonatal period (including toxin exposure, trauma, or medication-induced)
* History of allergic or adverse reaction to trihexyphenidyl or other anticholinergic medications
* Current complaint of urinary retention requiring treatment.
* History of glaucoma, or family history of glaucoma with onset before age 40