Imaging of 3D Innervation Zone Distribution in Spastic Muscles From High-density Surface EMG Recordings

Each patient will receive BTX injections in 2 sites. 100 units at double dilution will be injected at each site.

Standard physical therapy will be ordered to both groups as part of standard of care for patients after BTX injections to maximize the outcomes.

For standard injection procedures, target muscles will be visualized under ultrasound imaging which is operated by an experienced and dedicated technician. Position of needle tip within the target muscle is visualized prior to injection. Ultrasound guidance can help ensure depth of needle tip location, i.e., to make sure the needle tip is within the muscle, but it is not able to tell where it is located with reference to the innervation zones (IZs) of the entire muscle.

Simultaneous surface EMG and intramuscular EMG measurements will be acquired from the spastic biceps of the patients. Patients will be seated comfortably on a height-adjustable chair. The arm to be tested will be secured firmly on a customized apparatus with the elbow joint at approximately 90° of flexion and the shoulder at approximately 45° of abduction and 30° of flexion. The 128-channel unipolar surface EMG signals will be recorded with 2 flexible 2-dimensional 64-channel surface electrode array. A coating fine wire electrode will be inserted into the mid-axial section of the biceps to record bipolar intramuscular EMG signals. Ultrasound scan will be performed on the biceps to identify the location of the inserted wire electrode. Patients will be asked to contract their impaired biceps to perform maximum voluntary contraction of elbow flexion against the vertical plates 3 times.