A spasm is a sudden, involuntary contraction of a muscle, a group of muscles, or a hollow organ, or a similarly sudden contraction of an orifice. It is sometimes accompanied by a sudden burst of pain, but is usually harmless and ceases after a few minutes. Spasmodic muscle contraction may also be due to a large number of medical conditions, however, including the dystonias.
In very severe cases, the spasm can induce muscular contractions that are more forceful than the sufferer could generate under normal circumstances. This can lead to torn tendons and ligaments.
Spasticity or muscular hypertonicity is a disorder of the body motor system, and especially the central nervous system (CNS), in which certain muscles are continuously contracted. This contraction causes stiffness or tightness of the muscles and may interfere with gait, movement, and speech. Depending on severity, the person with the spastic muscles may or may not feel it. However, it can often be severely disabling . The human motor system is not always linked with the sensory systems, nor the voluntary-muscle systems.
Symptoms may include hypertonia (increased muscle tone), clonus (a series of rapid muscle contractions), exaggerated deep tendon reflexes, muscle spasms, scissoring (involuntary crossing of the legs), and fixed joints (contractures). The degree of spasticity varies from mild muscle stiffness to severe, painful, and uncontrollable muscle spasms.
If the cause is fatigue, the first remedy is rest. Massage seems to not be helpful. Stretching or relaxing the muscles involved may also work. Chronic spasms can lead to shortening of the muscles and ligaments. Regular (daily) exercises over the years ahead of these ligaments and muscles are needed to prevent the pain and the crippling of movement.
Treatment may include such medications as baclofen, diazepam, dantrolene, or clonazepam; muscle stretching, range of motion exercises, and other occupational therapy or physical therapy regimens to help prevent joint contractures (shrinkage or shortening of a muscle) and reduce the severity of symptoms; or surgery for tendon release or to block the connection between nerve and muscle, so that the muscle does not contract. The connection between nerve and muscle may also be blocked temporarily, without surgery, by injecting botulinum toxin into the muscle.
taken from wikipedia.