Spasticity
Spasticity is defined as a "velocity-dependent increase in muscle stretch reflex."  It 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 activities of daily living, gait, movement, and speech. The person with the spastic muscles may or may not feel it, know about it or want to do something about it.  The human motor system is not always linked with the sensory systems, nor the voluntary-muscle systems.

# Causes
Voluntary movement is controlled by several interacting systems within the nervous system.  Primary control is through the upper motor neurons in the motor cortex of the brain, which send their axons via the cortico-spinal tract to connect to lower motor neurons in the spinal cord.   Spasticity is caused by damage to upper motor neurons or to the cortico-spinal tract. It may occur in association with spinal cord injury, multiple sclerosis, cerebral palsy (see Spastic Diplegia), anoxic brain damage, brain trauma, severe head injury, some metabolic diseases such as adrenoleukodystrophy, and phenylketonuria.

# Presentation
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. The degree of spasticity varies from mild muscle stiffness to severe, painful, and uncontrollable muscle spasms.
The condition can interfere with rehabilitation in patients with certain disorders, and often interferes with daily activities.  Over the years, it may increase in its effect, so more severe treatments may be needed later.  Cold weather and fatigue can trigger spasms more severely  than other times.  Multi-tasking (such as walking, talking, eating and other activities) can also trigger more severe spasticity.

# Possible benefits
- May help some patients to ambulate, stand or transfer (e.g., stand pivot transfers)
- May assist in maintaining muscle bulk
- May assist in preventing DVTs
- May assist in preventing osteoporosis pressure ulcer formation over bony prominences
- Can be used as diagnostic tool (with increased spasticity being a sign of exposure to a noxious stimuliinfection, bowel impaction, urinary retention, etc)

# Treatment
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.
Some USA states have also issued medical marijuana to help treat spasticity.

# Prognosis
The prognosis for those with spasticity depends on the severity of the spasticity and the associated disorder(s). To a small degree spasticity performs the helpful role of exercise, but it is usually bothersome to normal activities in life.