Hand motor impairments are commonly observed after stroke due to deficits in motor execution and higher-order processes (motor planning and motor learning). These deficits lead to impaired one-handed motor control in stroke victims, which can be detected by examining movements during natural movements and the coordination of fingertip forces. Due to damage to the certain parts of the brain that control fine motor movement, the victim experiences loosened grip that negatively affects his interest in performing activities of daily living (ADL).
Interesting, little is known about the types of motor learning impairments that occur after stroke and how lesion location may affect motor relearning. Also, the relationship between hand motor impairment and hand function has also been unclear. A better understanding of how stroke affects the formation and consolidation of motor memory would be useful in designing rehabilitation protocols to improve motor execution and higher-order processes.
Treatment of stroke-led hand motor impairment
Despite the scarcity of research on motor learning impairments post stroke, a number of therapeutic methods are available that leverage principles of motor learning. These treatment approaches focus on strengthening the weak muscle groups and reducing the spasticity in spastic muscles. The ultimate objective is restoring the balance between agonist and antagonist muscle groups.
The most commonly used therapy for stroke-led hand motor impairment is Constraint Induced Therapy (CIT), which focuses on limiting the movement of non-affected areas and using the affected areas more commonly and strongly.
Certain parts of the brain can be damaged after stroke. Neuroplasticity allows the brain to rewire motor planning and execution functions that were once stored in these areas. To stimulate Neuroplasticity in the injured parts of the brain, more repetition and task specific intervention are needed to forge and strengthen new neural pathways. Bimanual exercises, physical therapy and robot assisted therapy are among some of the most prescribed Neuroplasticity based interventions that attempt to resolve hand motor difficulties.
An emerging visualization technique, Motor Imagery (MI) can also be used to rehabilitate motor deficits after stroke. Widely used in sports training as the mental practice of action, MI initiates internal imagery (or first person perspective) in stroke victims for neurological rehabilitation. When paired with physical practice, mental rehearsal can mentally simulate a given action as the subject (in this case a stroke survivor) feels himself performing the action. This mental practice of action seems to improve motor execution and higher-order processes, as supported by various studies.