About Cerebral Palsy Spasticity
Cerebral Palsy (CP)
Cerebral palsy affects movement and posture and is caused by brain damage before, during, or after birth. The brain damage underlying CP cannot be reversed and produces life-long disabilities. Despite remarkable medical advances, the incidence of cerebral palsy has not decreased, with one out of 500 children being afflicted with the disorder.
Treatment of cerebral palsy varies with the age of patients and many options are available. It is important for parents and patients to consult with their treatment team, which includes a physical therapist, pediatrician, rehabilitation medicine specialist, neurologist, neurosurgeon and orthopedic surgeon.
Cause of Spasticity
Spasticity refers to increased tone, or tension, in a muscle. Normally, muscles must have enough tone to maintain posture or movement against the force of gravity while at the same time providing flexibility and speed of movement.
The command to tense, or increase muscle tone, goes to the spinal cord via nerves from the muscle itself. Since these nerves tell the spinal cord just how much tone the muscle has, they are called "sensory nerve fibers." The command to be flexible, or reduce muscle tone, comes to the spinal cord from nerves in the brain. These two commands must be well coordinated in the spinal cord for muscles to work smoothly and easily while maintaining strength.
In a person with cerebral palsy, damage to the brain has occurred. For reasons that are still unclear, the damage tends to be in the area of the brain that controls muscle tone and movement of the arms and legs. The brain of the individual with cerebral palsy is therefore unable to influence the amount of flexibility a muscle should have. The command from the muscle itself dominates the spinal cord and, as a result, the muscle is too tense, or spastic.
Prevalence of Spasticity
Approximately 80 out of 100 patients with cerebral palsy have varying degrees of spasticity. Spasticity can be associated with diplegic, quadriplegic or hemiplegic cerebral palsy. Spasticity can be evident during the first year of life in relatively severe CP, but most often it is detected later. It is important to note that once spasticity has developed with cerebral palsy, it never resolves spontaneously.
Effects of Spasticity
There is no way in which spasticity is of benefit to children or adults with CP. Spasticity adversely affects muscles and joints of the extremities, causing abnormal movements, and is especially harmful in growing children. The known adverse effects of spasticity include:
- Inhibition of movement
- Inhibition of longitudinal muscle growth
- Inhibition of protein synthesis in muscle cells
- Limited stretching of muscles in daily activities
- Development of muscle and joint deformities
- Patients with cerebral palsy do not have deformities of the extremities at birth but develop them over time. Spasticity of muscles, along with the limitations on stretching and use of muscles in daily activities, is a major cause of deformities.
Current Treatments for Cerebral Palsy Spasticity
Currently, oral medication, Botox (botulinum A toxin) injection, baclofen infusion, orthopedic surgery, selective dorsal rhizotomy surgery, physical therapy, and braces are employed to treat CP spasticity and related problems.
Oral medications, such as valium and baclofen, are still tried, but the consensus is that they do not reduce spasticity.
Injections of Botox into muscles have been used widely in recent years. Botox weakens muscles for up to 3-4 months after injection, reducing spasticity in a limited group of muscles. Most important, the effect is only temporary. Side effects appear to be minimal.
Baclofen infusion, using a pump implanted in the abdominal wall, is clearly effective in reducing spasticity in spinal cord injury and can also reduce CP spasticity. However, baclofen infusion is not effective permanently; when it is stopped, spasticity recurs. Also, the baclofen infusion carries risks of overdose, meningitis, and other complications that may require repeated hospitalization, and since it has been used for CP for only several years, long-term consequences are not known.
Orthopedic operations, including muscle release and tendon-lengthening procedures, are also used to treat deformities associated with spastic cerebral palsy. Orthopaedic surgery improves range of motion of the joints and makes it easier for children to move the lower extremities. A major side effect is permanent muscle weakness and resulting abnormal postures and deformities. Also, orthopaedic surgery does not reduce spasticity directly but treats only the consequences of spasticity.