Pharmacogenomic Contributions to Trihexyphenidyl Biotransformation and Response in Children With Dystonic Cerebral Palsy

Number of participants with at least one adverse event as measured by the Safety Monitoring Uniform Report Form (SMURF)

Adverse events will only include those that are determined to be related to the study drug.

Time frame: Through study completion, an average of 2 years

Change from baseline in dystonia duration as measured by the Dyskinesia Impairment Scale (exploratory)

Duration of dystonia using subscale DIS-D are measured in 12 body regions during activity and rest. Dystonia duration scores are measured on a 4-point scale from 0 to 4 with 0 being dystonia is absent and 4 being dystonia is always present (≥90%).

Time frame: Baseline, 16 weeks

Change from baseline in dystonia amplitude as measured by the Dyskinesia Impairment Scale (exploratory)

Amplitude of dystonia using subscale DIS-D are measured in 12 body regions during activity and rest. Dystonia amplitude scores are measured on a 4-point scale from 0 to 4 with 0 being dystonia is absent and 4 being dystonia in maximal range of motion (≥90%).

Time frame: Baseline, 16 weeks

Change from baseline in dystonia as measured by the Quality of Upper Extremity Skills Test (QUEST) (exploratory)

Upper extremity function in 1 domain; grasp. 13 activities with item-level scores and three items for the tester to rate: hand function, spasticity, and cooperativeness. All scores are summed, and formulas are used to calculate percentages for this domain. Domain percentage is summed with a minimum score less than 0, and the maximum score is 100.

Time frame: Baseline, 16 weeks

Change in functional impact from baseline as measured by the Dyskinetic Cerebral Palsy Functional Impact Scale (D-FIS) (exploratory)

Functional impact scores are measured on a 5-point scale from 0 to 4 with 0 being dyskinesia may be present but has no impact on the named activity, and 4 being dyskinesia is present and prevents child from doing a named activity, even with help. An "NA" option indicates the activity is difficult but NOT due to dyskinesia.

Time frame: Baseline, 16 weeks

Change in priority scores in functional impact from baseline as measured by the Dyskinetic Cerebral Palsy Functional Impact Scale (D-FIS) (exploratory)

Priority scores are measured on a 4-point scale from 1 to 4 with 1 being an activity is not a priority and 4 being an activity is highest priority.

Time frame: Baseline, 16 weeks

Change in patient-driven performance from baseline as measured by the Canadian Occupational Performance Measure (exploratory)

Performance scores are measured on a 10-point scale with 1 being not able to do an activity at all and 10 being able to do an activity extremely well.

Time frame: Baseline, 16 weeks

Change in patient-driven goal satisfaction from baseline as measured by the Canadian Occupational Performance Measure (exploratory)

Satisfaction scores are measured on a 10-point scale with 1 being not satisfied at all with the way they do an activity to 10 being extremely satisfied with the way they do an activity.

Time frame: Baseline, 16 weeks

Change in caregiver's perspective about their child in 4 domains: health status, comfort, wellbeing, functional abilities, and ease of caregiving from baseline as measured by Caregiver Priorities and Child Health Index of Life with Disabilities

Scores for each domain and for the total survey are standardized and range from 0 to 100 with 0 being the worst and 100 being the best.

Time frame: Baseline, 16 weeks

Measure the acceptability of outcome measures at 16 weeks as measured by the Acceptability of Intervention Measure

Scores are measured on a 5-point scale from Completely Disagree to Completely Agree for items 1) The outcome measure meets my approval. 2) The outcome measure is appealing to me. 3) I like the outcome measure. 4) I welcome the outcome measure

Time frame: 16 weeks