Spastic cerebral palsy is usually the result of an upper motor neuron lesion in the brain (often through injury or damage inflicted in the womb or during birth), though the motor cortex and corticospinal tract may also be affected. The lesion impairs the brain’s ability to send signals to the nerve receptors housed in the spine, which in turn limits the nerves’ ability to receive gamma amino butyric acid. Gamma amino butyric acid normally triggers the nerves to send messages to the muscles that cause them to work together; when one group of muscles contracts, another relaxes. The lack of this important organic compound in these damaged nerves instead causes them to send a signal to the connected muscles to tense up, or become hypertonic. In people with spastic diplegia, the nerve receptors that control the legs are damaged, making the legs rigid and weak. Premature infants are at an increased risk of developing spastic diplegia.
Spastic diplegia causes the legs to be overly stiff. Usually, people with spastic diplegia have a distinct, scissored walk. The legs cross over in a scissoring motion and the toes are pointed upwards due to the contractions in the muscles. People with spastic diplegia may also have some symptoms in their hands, though not nearly as pronounced as the symptoms in the legs and feet.
Spastic diplegia can cause deformities in the legs, so braces are commonly used to help support the legs of children with the condition. Most cases are diagnosed by the age of three. Physical therapy is also affective in helping people with spastic diplegia strengthen their muscle tone and increase their range of motion. Massage, yoga and chiropractic therapy can also help loosen the rigidity in the legs.
The degree of disability and level of functioning are dependent on how extensive the brain and nerve receptors are. Many people with spastic diplegia lead independent, productive lives, while others require assistance or the use of a wheelchair for mobility.