Can we Train Patients With Chronic Stroke Out of Abnormal Hand Synergy?

The aim of the current study is to investigate whether non-invasive brain stimulation
(intervention) applied during motor training in chronic stroke patients can change their
abnormal flexion synergy. The investigators will study chronic stroke patients , who are
defined as patients that sustained a stroke at least 6 months prior to our testing date.

Three functional aspects of each finger will be tested: maximal voluntary contraction (MVC),
finger dexterity, and hand posture.

Prior to intervention, participants will have a baseline assessment including clinical tests,
MVC, the individuation task, and the configuration task. Following the baseline assessment
patients will receive intervention, training on the configuration task paired with concurrent
transcranial Direct Current Stimulation (tDCS) for 5 consecutive days. On the sixth day and
as a one week follow-up after, subjects will have a post-intervention assessment containing
the same tests performed in baseline.

This design will allow us to determine speed and accuracy during the configuration task, the
individuation index, and possible changes in abnormal flexion synergy.

Inclusion Criteria:

- Age 21 and older

- Ischemic stroke greater than six months ago, confirmed by CT or MRI

- Residuals unilateral upper extremity weakness

- Ability to give informed consent and understand the tasks involved.

- Appearance of Flexion synergy in hand.

- Ability to extent finger at least for 5 degrees.

Exclusion Criteria:

- Cognitive impairment, with score on Montreal Cognitive assessment (MoCA) ≤ 20

- History of physical or neurological condition that interferes with study procedures or
assessment of motor function (e.g. severe arthritis, severe neuropathy, Parkinson's
disease)

- Contraindication to tDCS (deep brain stimulators or other metal in the head, skull
defect, pacemaker)

- Inability to sit in a chair and perform upper limb exercises for one hour at a time

- Participation in another upper extremity rehabilitative therapy study or tDCS study
during the study period

- Terminal illness

- Social and/or personal circumstances that interfere with ability to return for therapy
sessions and follow up assessments

- Pregnancy

- Severe Neglect