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. This means that entire groups of muscles contract at once, causing uncontrollable movement and limiting a person’s range of motion.
As with other forms of cerebral palsy, spasticity-dominant cases are non-progressive. The damage to the cerebral cortex and related nerve receptors does not worsen with time, though a person with spastic cerebral palsy will often find their symptoms become more prominent as they age. Over time, the stiffness in the muscles can continue to increase along with muscle tone, leading to more inhibited mobility and in some cases, pain.
Spastic cerebral palsy can also limit protein synthesis in muscle cells and cause fatigue. People with spastic cerebral palsy often find their symptoms become worse or flare up when they are agitated or otherwise under stress. It is important to note that deformities in the muscles and joints are rarely present at birth; they develop over time as stretching and normal range of motion are inhibited. Children with spastic cerebral palsy often experience slowed growth.
Each person with spastic cerebral palsy is unique, and the severity of the condition varies greatly from one person to another. Some people with spastic cerebral palsy experience minimal involuntary muscle movement, while others suffering from spastic cerebral palsy deal with constant tensing of their muscles. Some people have only one limb or part of the body affected, while others experience symptoms in all of their limbs.
When determining the level of affliction, doctors consider the amount of tensing in the muscles in relation to what degree the hypertonia is affecting a person’s life. Symptoms of spastic cerebral palsy may be classified as:
When further classifying spastic cerebral palsy, physicians consider how much of the body is affected by the uncontrollable movement and muscle contraction. Spastic cerebral palsy may be further classified as:
• Spastic Monoplegia (one limb is affected)
• Spastic Diplegia (the legs are affected more than the arms)
• Spastic Hemiplegia (one side of the body is affected more than the other)
• Spastic Paraplegia (only the legs are affected)
• Spastic Triplegia (three limbs are affected)
• Spastic Double Hemiplegia (all four limbs are affected, but one side of the body is more affected than the other)
• Spastic Tetraplegia (all four limbs are affected, but three are more affected than the fourth)
• Spastic Quadriplegia (all four limbs are affected equally)
• Spastic Pentaplegia (all four limbs are affected, as well as the head and neck)