Donna Schmidt, age 16, of Miami, Fla., for her question:

WHAT CAUSES SPASTIC PARALYSIS?

Spastic paralysis is a type of cerebral palsy, a condition in which damage to the brain has resulted in poor control over the muscles. The brain damage usually happens at birth, although it can happen before birth.

Spastic paralysis can also develop after birth if an infection such as meningitis damages the brain, or if damage results from strokes, skull fractures or other injuries.

The part of the brain that is damaged and the amount of damage done determine which muscles are affected and how severely. Sometimes the damage is so slight that the individual may have only a little clumsiness, a slight loss of balance or perhaps a slight speech difficulty.

In severe cases, the individual cannot walk. Or he may walk on his toes with his feet turned inward, his knees together and with one leg crossing over in front of the other, in a typical "scissors gait."

Spastic paralysis can affect all the muscles.