Cerebral palsy (CP) is a group of disorders that affect a person’s ability to move and maintain balance and posture. Spasticity, which affects the majority of individuals with CP, is a specific type of hypertonia, or increased muscle tone. This condition manifests as involuntary muscle stiffness and tightness that is velocity-dependent, meaning the faster a muscle is stretched, the more it resists. Reducing spasticity is a primary goal in managing CP because the persistent muscle resistance severely limits mobility, interferes with function, and often leads to pain and secondary complications like fixed joint contractures.
Physical and Rehabilitative Management
Physical therapy (PT) and occupational therapy (OT) are typically the first line of defense against muscle spasticity and its resulting functional limitations. Physical therapists utilize sustained stretching and passive range-of-motion exercises to counteract the tendency of spastic muscles to shorten and resist movement. These techniques aim to maintain existing muscle length and joint flexibility, which helps prevent the development of permanent contractures over time.
Strengthening exercises are also incorporated, specifically targeting muscle groups that oppose the spastic muscles to improve muscle balance and motor control. For example, strengthening the quadriceps can help counterbalance overly tight hamstrings that pull the knee into a flexed position. This approach enhances the individual’s ability to recruit muscles with better precision and timing, leading to improvements in posture and gait.
Orthotics and bracing play a supportive role by maintaining a stretched position for spastic muscles and joints. Devices such as ankle-foot orthoses (AFOs) are worn to hold the ankle in a neutral position, which prevents the calf muscles from shortening and reduces resting muscle tone. Occupational therapy focuses on adapting daily activities and recommending assistive equipment to maximize independence, addressing the practical challenges posed by spasticity in the upper extremities and during fine motor tasks.
Oral Medications for Systemic Relief
When spasticity is generalized, affecting multiple muscle groups across the body, oral medications are often introduced for systemic relief. These drugs circulate to reduce the overall level of excessive muscle tone. Baclofen is a commonly prescribed agent that acts as an agonist at the GABA-B receptor, which helps decrease the release of excitatory neurotransmitters in the spinal cord.
Tizanidine is another centrally-acting muscle relaxant that works by stimulating alpha-2 adrenergic receptors, inhibiting motor neurons that contribute to muscle tightness. Diazepam, a benzodiazepine, enhances the effect of the inhibitory neurotransmitter GABA, leading to muscle relaxation and reduced spasticity.
The effectiveness of these oral medications comes with a trade-off, as their systemic action can lead to generalized side effects. Common adverse effects include drowsiness, sedation, and a reduction in overall muscle strength, which can sometimes limit their usefulness for individuals who are ambulatory. Dosage must be carefully managed to achieve optimal muscle relaxation without causing unacceptable lethargy or generalized weakness.
Targeted Injections and Pump Therapy
For spasticity concentrated in specific muscle groups, Botulinum Toxin (BoNT) injections offer a targeted treatment. BoNT is injected directly into the affected muscle, where it blocks the release of acetylcholine at the neuromuscular junction, causing temporary muscle paralysis and relaxation. This focal reduction in spasticity typically lasts between three to six months before the nerve function begins to recover, after which the injection can be repeated.
Botulinum toxin is particularly useful for improving gait patterns and function in specific limbs, often used in conjunction with stretching or casting to maximize the effect. The localized nature of the injection minimizes systemic side effects, although transient weakness in the targeted muscle is expected.
For individuals suffering from severe, generalized spasticity that affects all four limbs, an Intrathecal Baclofen (ITB) pump may be considered. This treatment involves surgically implanting a pump under the skin of the abdomen, connected by a thin catheter to the spinal fluid. The pump delivers liquid baclofen directly into the cerebrospinal fluid, bypassing the blood-brain barrier. This delivery method allows for a much lower and more potent dose compared to oral baclofen, often up to 1,000 times less, effectively reducing spasticity while minimizing systemic side effects like sedation.
Surgical Interventions
Surgical options are typically reserved for individuals whose spasticity is unmanageable by less invasive methods or when long-term spasticity has led to fixed structural issues. Selective Dorsal Rhizotomy (SDR) is a neurosurgical procedure aimed at permanently reducing spasticity in the lower extremities. During the procedure, the surgeon identifies and selectively cuts a portion of the sensory nerve rootlets in the spinal cord that transmit the abnormal signals causing spasticity.
SDR requires an intensive, prolonged course of post-operative physical therapy, often lasting six to twelve months, to achieve the maximum functional benefit. The goal is to eliminate the excessive muscle tone so the individual can then work on strengthening the underlying muscles and improving motor function and walking ability.
Orthopedic surgery addresses the consequences of chronic spasticity rather than the neurological root cause itself.
Common Orthopedic Procedures
Common procedures include tendon lengthening to correct contractures that limit joint movement and function. Tendon transfers may also be performed to rebalance the pull of muscles around a joint. Osteotomies involve cutting and realigning bone to correct deformities like hip dysplasia or torsional issues caused by years of abnormal muscle forces.