Paresis is a neurological problem that is characterized by partial or complete paralysis of a muscle or group of muscles. It is usually caused by damage to the nervous system, such as a stroke or traumatic brain injury. Paresis can also be caused by diseases such as multiple sclerosis, cerebral palsy, and Parkinson's disease. Symptoms of paresis include weakness, numbness, and loss of coordination. Treatment for paresis depends on the underlying cause and may include physical therapy, medications, and surgery.