A handheld surface electromyography device will be tested by clinicians on children with limb hypertonia, and inter-rater reliability will be assessed with and without the device.

Hypothesis:

Qualitative surface EMG measurement during passive movement will increase the inter-rater reliability of clinicians for diagnosis of spasticity and dystonia in children with hypertonia.

Specific Aims:

1. Develop a handheld surface EMG device with auditory output that can be used similarly to a stethoscope to listen non-invasively to the activity of muscles.
2. Provide clinicians at 5 different institutions with a device to test for 2 months in their own clinics.
3. Bring all 5 clinicians to Stanford University for a single-day exercise in which each clinician will examine 10 children with hypertonia. Each clinician will rate the children without using the device, and then again with the device. Intra-class correlations and kappa statistics will be used to assess whether the use of the device leads to improved inter-rater reliability.

Inclusion Criteria:

• Age 6-18
• hypertonia in at least one limb due to spasticity

Exclusion Criteria:

• any condition that would increase the risk of participation