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

Inclusion Criteria:

• a history of not more than one stroke which occurred at least 6 months prior to studyenrollment;
• elbow flexor spasticity rated at 2 or 3 on Modified Ashworth scale (MAS);
• receiving repeated botulinum toxin injection every 3-4 months;
• absence of excessive pain in the paretic upper limb;
• capacity to provide informed consent, with Mini-Mental State Examination (MMSE) mustbe 25 or higher; The following modified Ashworth scale (MAS) will be used for spasticity assessment:

0 -No increase in muscle tone; 1 -Slight increase in muscle tone, manifested by a catch andrelease or by minimal resistance at the end of the range of motion when the affectedpart(s) is moved in flexion or extension; 1+ -Slight increase in muscle tone, manifested bya catch, followed by minimal resistance throughout the remainder (less than half) of theROM; 2 -More marked increase in muscle tone through most of the ROM, but affected part(s)easily moved; 3 -Considerable increase in muscle tone, passive movement difficult; 4 -Affected part(s) rigid in flexion or extension.

Exclusion Criteria:

• recent botulinum toxin injection < 4 months;
• recent changes in antispastic medications <3 weeks (i.e., the antispastic medicationregime is not stable;
• Changes in antispastic medications (such as baclofen, tizanidine, dantrolene etc)during the followup research visits. (NOTE: it is clinically rare for patients whoreceive repeated injections to change their antispastic medications);
• history of spinal cord injury or traumatic brain damage;
• history of serious medical illness such as cardiovascular or pulmonary complications;
• any condition that, in the judgment of a physician, would prevent the person fromparticipating.