The purpose of this study is to investigate if a person with weakness or paralysis in one or both arms, can use the NuroSleeve combined powered arm brace (orthosis) and muscle stimulation system to help restore movement in one arm sufficient to perform daily activities. This study could lead to the development of a product that could allow people with arm weakness or arm paralysis to use the NuroSleeve and similar devices to improve arm health and independent function.

People can develop arm weakness due to stroke and other neurological conditions. Portable powered braces and functional electrical stimulation can help restore functional arm movement in these individuals. Powered braces and muscle stimulation may be triggered by detecting movement or electrical activity of proximal muscles that the person still can control. The overall objective of this study is to establish that children and adults with chronic, stable neurological motor impairment can achieve voluntary control over the NuroSleeve upper extremity orthosis and functional electrical stimulation system, and that they can use this voluntary control to perform functionally beneficial tasks to enhance independence, mental and physical health. While myoelectric prostheses have been studied for decades in children with limb loss, it is necessary to gather pilot data on the use of orthoses with optional electrical stimulation in people with intact yet paralyzed limbs. These adults and children have persistent motor deficits even after intensive physical and occupational therapy. The NuroSleeve and similar devices could help all people who have arm weakness.

Inclusion Criteria:• Must be 4 years or older

• Must have weakness in one or both arms such that flexion or extension of the wrist, elbow or shoulder are 3/5 or less on the Manual Muscle Testing Scale
• The etiology of weakness is due to a neurological disease or injury or orthopedic condition that occurred 6 or more months ago
• Participant is willing to comply with trial instructions
• Adult participant is able to provide informed consent prior to enrollment in the study, and for children, child is able to provide assent and designated caregiver (parent or guardian) is able to provide informed consent
• The participant is fluent in English and, if the participant were a child, at least one parent/guardian were fluent in English
• Medically stable and living at home in the community.
• No joint contracture, spasticity or other limitations to range of motion in the affected lower limb(s) precluding the operation of a wearable, powered orthotic device on the arm
• Sufficient sitting balance to sit in a chair
• No condition (e.g., severe arthritis, central pain) that would interfere with movement of the legs, ability to understand verbal commands and cooperate with test procedures.
• No condition that would pose a risk to the application of electrical current to the body (e.g., skin conditions or skin breakdown)

Exclusion Criteria:• Visual impairment such that following visually-guided instructions would be challenging even with ordinary corrective lenses

• Orthopedic conditions of either arm that would affect performance on study
• Untreated psychiatric or neurologic disturbances that would affect motivation and trial participation
• Excessive pain in one or both of the arms (> 5 on a 10-point visual analog scale)
• Excessive spasticity at one or both arms, as defined as a score of > 2 on the Modified Ashworth Spasticity Scale
• Advice from any of the participant's health providers that upper extremity powered orthotics or electrical stimulation were contra-indicated
• Presence of an implanted medical device in the body (such as cardiac pacemaker, implanted defibrillator, metallic device)
• Metal implants or exposed metal in the weak or paralyzed arm
• Lack of access to internet or wireless coverage to enable telemedicine-guided sessions
• Any history of seizure or epilepsy (only an exclusion criterion for those seeking to undergo optional transcranial magnetic stimulation)
• Currently taking the medication bupropion (only an exclusion criterion for those seeking to undergo optional transcranial magnetic stimulation)
• Any history of prior neurosurgical procedure (only an exclusion criterion for those seeking to undergo optional transcranial magnetic stimulation)
• Known or suspected skull defect (only an exclusion criterion for those seeking to undergo optional transcranial magnetic stimulation)
• Any history of alcohol or other substance use
• Other conditions or circumstances that, in the opinion of the investigators, would preclude safe and/or effective participation, including severe skin conditions, and/or other sequelae that may be contraindicated for using a powered orthotic or using electrical stimulation, as well as personal circumstances