You can feel the tightness when you dress your child, when you try to straighten their arm, when you put on their shoes and their feet are pointed and resistant. Spasticity is the daily reality of most families living with cerebral palsy, and understanding it is the first step toward managing it effectively. This guide explains what spasticity is, why it matters, and the full range of treatments available, from daily stretching to surgery.
What Spasticity Is
Spasticity is a type of muscle overactivity in which muscles are abnormally stiff and resist being stretched. It is the defining feature of spastic cerebral palsy, which accounts for approximately 80 percent of all CP cases. The stiffness is velocity-dependent: the faster you try to move the affected limb, the more the muscle fights back. A slow, gentle stretch meets less resistance than a quick movement.
In a normally functioning nervous system, the brain sends signals down the spinal cord to activate muscles, and also sends inhibitory signals that keep muscles relaxed when they are not needed. In CP, the brain damage disrupts these inhibitory signals. Without the “relax” message, the muscles stay in a constant state of heightened activity. They are always partially contracted, always pulling, always tight.
Spasticity is not the same as rigidity (constant stiffness regardless of speed) or dystonia (involuntary sustained or intermittent muscle contractions that cause twisting). Some children with CP have pure spasticity, while others have a mix of spasticity, dystonia, and other movement abnormalities. Distinguishing between these is important because they respond to different treatments.
Why CP Causes Spasticity
Spasticity in CP results from damage to the upper motor neurons, the nerve cells in the brain that control voluntary movement. When these neurons are injured by HIE, PVL, stroke, or other brain injuries, the balance between excitatory and inhibitory signals to the muscles is disrupted. The excitatory signals dominate, and the muscles become overactive.
The specific pattern of spasticity depends on which areas of the brain are damaged. Damage to the motor cortex on one side of the brain produces spasticity on the opposite side of the body (hemiplegic CP). Damage to the areas controlling the legs bilaterally produces spasticity in both legs (diplegic CP). Widespread damage produces spasticity throughout the body (quadriplegic CP).
The severity of spasticity ranges from mild (the muscles feel slightly tight but the child can still move through a full range of motion) to severe (the limbs are rigid and cannot be moved passively without significant force). The Ashworth Scale and the Modified Tardieu Scale are clinical tools used to measure and track spasticity severity over time.
How Spasticity Affects Movement and Growth
Spasticity is not just uncomfortable. It has cascading effects on every aspect of your child’s physical development.
Movement. Spastic muscles oppose the very movements your child is trying to make. A child trying to reach forward is fighting their own tight biceps. A child trying to walk is working against tight calf muscles that pull their feet into a toe-walking pattern. Spasticity creates abnormal movement patterns that become habitual, and these patterns consume enormous energy.
Contractures. A muscle that is held in a shortened position by spasticity gradually loses its ability to stretch. The muscle fibers shorten permanently, and the joint can no longer move through its full range. This is a contracture, and once established, it requires surgical lengthening to correct. The most common contractures in CP affect the hip flexors, hamstrings, calf muscles (leading to equinus), and forearm and wrist flexors.
Bone and joint development. Growing bones are shaped by the forces acting on them. When spastic muscles pull unevenly across a joint, the joint develops abnormally. Hip displacement (where the femoral head migrates out of the hip socket) is directly caused by spastic hip adductor and flexor muscles. Scoliosis can develop from asymmetric trunk spasticity.
Pain. Chronic spasticity causes muscle pain, joint pain from abnormal positioning, and nerve pain from compression. Many children with CP who cannot verbally report pain show pain through increased irritability, sleep disturbance, and decreased participation in activities. Pain also increases spasticity, creating a vicious cycle.
If medical errors contributed to your child’s brain injury and spasticity, your family may have legal options.
Treatments: Therapy, Botox, Baclofen, and Surgery
Spasticity treatment follows a stepped approach, starting with the least invasive options and escalating as needed. Most children use a combination of treatments simultaneously.
| Treatment Level | Options | Best For |
|---|---|---|
| First Line | Physical therapy, OT, stretching, orthoses (AFOs, splints), positioning | All children with spasticity, ongoing foundation |
| Second Line – Focal | Botulinum toxin (Botox) injections into specific muscles | Spasticity in specific muscle groups causing functional problems |
| Second Line – Generalized | Oral baclofen, diazepam, tizanidine, dantrolene | Widespread spasticity affecting comfort and care |
| Third Line – Surgical | Intrathecal baclofen pump (ITB), selective dorsal rhizotomy (SDR), orthopedic surgery | Severe spasticity not controlled by other treatments, or select candidates for SDR |
Physical therapy and orthoses are the foundation. Daily stretching maintains range of motion and slows contracture development. Ankle-foot orthoses (AFOs), hand splints, and standing frames provide sustained stretch and maintain joint alignment. These are not optional extras. They are essential prevention.
Oral medications reduce spasticity throughout the body but come with systemic side effects. Baclofen is the most commonly used, but it causes drowsiness. Diazepam reduces tone effectively but causes sedation and can be habit-forming. Tizanidine and dantrolene are alternatives with different side effect profiles. Oral medications are most useful when spasticity is widespread and affecting comfort, positioning, or caregiving.
Botox Injections for CP Children: What to Expect
Botulinum toxin type A (Botox, Dysport, or Xeomin) is injected directly into specific spastic muscles to temporarily weaken them. It works by blocking the nerve signal that tells the muscle to contract, reducing tone in the injected muscle for approximately 3 to 6 months.
The procedure. Botox injections are typically done under sedation or brief general anesthesia in young children. The doctor uses ultrasound guidance or electrical stimulation to ensure accurate placement in the target muscle. The entire procedure takes 15 to 30 minutes. Your child may have mild soreness at the injection sites for a day or two.
Timeline of effects. The Botox begins working within 3 to 7 days, with peak effect at 4 to 6 weeks. This peak period is the critical therapy window: your child’s physical therapist should increase session frequency and intensity during this time to maximize gains in range of motion, strength, and new movement patterns while the spasticity is at its lowest. Effects gradually wear off over 3 to 6 months, and injections are typically repeated on a regular cycle.
Common injection targets include the calf muscles (gastrocnemius and soleus) for toe-walking, the hip adductors for scissoring gait, the hamstrings for crouched posture, the biceps for bent elbow, and the forearm flexors for fisted hand. Multiple muscles can be injected in a single session.
If your child’s CP was caused by a birth injury, a case review can help you access the resources your family needs.
Selective Dorsal Rhizotomy (SDR)
SDR is a neurosurgical procedure that permanently reduces spasticity in the legs by selectively cutting sensory nerve rootlets in the lower spinal cord that are contributing to abnormal muscle tone. It is the only treatment that addresses spasticity at its source in the nervous system and produces permanent results.
How it works. The surgeon exposes the nerve rootlets at the base of the spinal cord. Each rootlet is tested with electrical stimulation to determine whether it produces a normal or abnormal response. Rootlets producing abnormal responses (contributing to spasticity) are cut. Those producing normal responses are preserved. Typically, 50 to 70 percent of the tested rootlets are cut. The procedure takes approximately 4 to 6 hours.
Who is a candidate. According to research published in Developmental Medicine and Child Neurology, the best outcomes are seen in children with spastic diplegia (legs more affected than arms), GMFCS Level II or III, good underlying muscle strength beneath the spasticity, age 3 to 8 years (though older children and adults can also benefit), MRI findings consistent with PVL, and no significant dystonia (which does not respond to SDR). Careful candidate selection is critical because SDR permanently changes the nervous system.
Post-operative rehabilitation. SDR requires intensive rehabilitation for 6 to 12 months after surgery. With the spasticity removed, the child must rebuild strength and learn new movement patterns. This is the most demanding phase: the surgery reduces tone, but the rehabilitation builds function. Families should plan for daily therapy sessions in the initial months and ongoing intensive therapy for at least a year.
Managing Spasticity at Home
Medical treatments reduce spasticity. Daily home management maintains the gains and prevents deterioration between treatments. This is where your consistency makes the biggest difference.
Daily stretching. Your physical therapist will teach you a stretching program targeting your child’s tightest muscles. Stretch at least twice daily, holding each stretch for 30 to 60 seconds. Gentle, sustained stretches are more effective than brief, forceful ones. A warm bath before stretching temporarily reduces tone and makes stretching easier and more comfortable.
Positioning. How your child is positioned throughout the day and night matters enormously. Use adapted seating that promotes symmetry and provides trunk support. Use a standing frame daily to provide weight-bearing through extended hips and knees. Use a sleep positioning system that maintains alignment overnight (8 hours of sleep in a poor position can undo a day of good stretching).
Orthoses. Wear prescribed AFOs, hand splints, and other orthoses consistently as directed. These devices provide sustained low-load stretch that prevents contracture. Inconsistent wear reduces effectiveness dramatically.
Manage triggers. Spasticity is worsened by pain (including dental pain, ear infections, constipation), cold temperatures, skin irritation (tight clothing, wet diapers), urinary tract infections, stress, fatigue, and poor sleep. When your child’s spasticity suddenly increases, look for a trigger. Treating the underlying cause often reduces the tone more effectively than any medication.
If your child’s cerebral palsy was caused by a birth injury such as HIE from medical errors during delivery, your family may have legal options that can provide the financial resources to fund Botox treatments, SDR surgery, intensive therapy, equipment, and a lifetime of care.
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