Upper-limb Active Function and Botulinum Toxin a

This study looks at the effects of botulinum toxin type A (Botox) injections on upper limb function in people who have had a stroke. After a stroke, many people develop spasticity — a muscle stiffness in the arm that limits movement and makes everyday activities difficult. Botox is used to relax overactive muscles, but this study specifically looks at whether it also improves active elbow extension (the ability to straighten the arm) and how this relates to brain changes visible on MRI. The study includes a stroke group (receiving Botox injections as part of their standard care) and a healthy control group. For stroke patients, there are detailed criteria about elbow function and Botox history to ensure the right participants are included. You may be eligible if: - You are 18 or older and have had an ischemic or hemorrhagic stroke at least 6 months ago - Your doctor recommends a Botox injection into your elbow flexor muscles - You have at least 20 degrees of active elbow extension - You have limited elbow extension due to spasticity You may NOT be eligible if: - You have severe passive limitation of elbow extension (more than 30 degrees) - You have pain during elbow movement - You have significant cognitive impairment - You are on anticoagulant therapy that prevents intramuscular injections - You are pregnant, breastfeeding, or planning pregnancy within 18 months - You have a history of conditions like myasthenia gravis or Lambert-Eaton syndrome Talk to your doctor to see if this trial is right for you.