Symptoms of MS: Spasm

Spasticity can be described as stiff muscles that resist passive movement. It is part of the upper motor neurone syndrome, which is damage to the nerves in the central nervous system that are carrying messages instructing muscles how to move. This can either lead to a lack of movement or to uncontrolled movements.
Other symptoms related to the upper motor neurone syndrome include:

Spasms - powerful uncontrollable muscle contractions which can be extremely painful and can be triggered in many ways eg coughing, sneezing or a full bladder
Clonus - a repetitive movement, such as a constant tapping of the ball of the foot
Contracture - when muscles become shortened and fix a limb in one position

Spasticity is a condition in which muscle tone becomes greatly increased. Muscle tone is what enables people to move limbs or hold a position. The term refers to the level of tension or resistance to movement in a muscle. For instance, to bend your arm, you must shorten or contract the biceps muscle at the front of the arm (increasing the tone) and at the same time lengthen or relax the triceps muscle at the back of the arm (reducing the tone).
When someone has spasticity in a limb, the signals from the brain are interrupted and the muscle remains in its shortened, contracted state. This causes the affected limb to feel stiff or tight and to be resistant to movement.
The instruction to contract a muscle can be triggered by sensory signals from peripheral nerves in the limb, which causes an automatic, reflex response initiated by the spinal cord. The message is also sent along the spinal cord to the brain, which then sends a message back to the muscle telling it when it is appropriate to relax again.
In MS, spasticity occurs if read more