The brain injuries that cause cerebral palsy also commonly cause muscle spasticity, which can limit patients’ mobility and control over their movements. Spasticity that is mild or limited in scope may respond to conservative treatments such as physical therapy, oral medications or injections of botulinum toxin (botox).
But children with severe spasticity, or spasticity that does not respond to these treatments, should be considered for neurosurgery.
In properly selected patients, therapy directed at the underlying nervous system abnormalities can markedly improve function and quality of life. According to Boston Children’s Hospital’s Shenandoah Robinson, MD, neurosurgery can also reduce bone deformation and joint damage, decreasing the need for orthopedic surgery.
Common neurosurgical options
Intrathecal baclofen (ITB) therapy. Baclofen relaxes muscle movement by mimicking the effects of the inhibitory neurotransmitter GABA, and is thought to act at both the brain and spinal cord level. In ITB, a pump implanted in the abdomen delivers baclofen directly into the cerebrospinal fluid (CSF), via a catheter inserted into the spinal canal.
ITB therapy is especially helpful for patients whose spasticity affects all their limbs or one side of the body, as well as those with both spasticity and secondary dystonia. Over time, ITB can improve a child’s gait, mobility, functioning and ease of care, and decrease pain and fatigue.
To be eligible for ITB, patients often undergo a screening test in which a single baclofen injection is given via lumbar puncture. A physical therapist evaluates the child before and after the injection. Once the pump is implanted—requiring an inpatient stay of two to five days—baclofen delivery can be adjusted with a remote programming device.
A few children will show symptom relief almost immediately, but major improvements typically take at least a few months. Patients must come to clinic every two to six months for refills (done via a small needle into a port on the pump), dose adjustments and pump maintenance. Surgery is required to replace the pump roughly every seven years.
While complications are uncommon, there is a small risk of infection, pump malfunction, CSF leakage or breakage, kinking or disconnection of the catheter.
Selective dorsal rhizotomy (SDR). This minimally invasive, one-time spinal operation can permanently reduce leg spasticity and encourage independent walking in children with cerebral palsy. It is most effective in children whose spasticity mainly affects the legs (spastic diplegia) and whose cerebral palsy is the result of premature birth (as opposed to traumatic brain injury or lack of oxygen). The ideal age for SDR is 3 to 12 years old, when the central nervous system has the most plasticity, though some older children (and even adults) can also benefit.
SDR works by selectively severing abnormal sensory nerves in a feedback loop that continuously signals the leg muscles to contract and prevents signals to relax from getting through. It typically requires a hospital stay of four to five days.
Not every child with spastic diplegia is a good candidate for SDR. The patients most likely to benefit can walk independently (or with a walker or cane) and have enough trunk strength to sit on their own.
Equally important, patients must be physically and mentally prepared to cooperate with intensive postoperative physical therapy (PT)—five or more sessions a week for at least six weeks (ideally 12). This requires being motivated and able to follow instructions.
“Participating in intensive physical therapy requires a certain level of cognition and a certain amount of stamina and attitude,” notes Robinson.
With good adherence to PT, most patients return to their baseline level of mobility within 1 to 2 weeks after SDR. Because the operation releases tone in the muscles, spasticity noticeably decreases almost immediately. This exposes the underlying muscle weakness (children tend to rely on taut muscles as a substitute for strength), so patients will need to gradually regain muscle strength. “If children and families can stick to physical therapy faithfully, most children will have greatly improved strength and gait within six months,” says Robinson.
Many children are able to transition from walkers to crutches or a cane after SDR surgery, and many, especially younger children, can avoid orthopedic surgery. Follow-up studies have shown greater mobility 5 to 10 years after SDR and long-term improvement in muscle tone 10 to 15 years after the operation, greater than the improvements seen with intensive PT alone. Complication rates are generally less than 1 percent. (See: Bolster EA et al.; Josenby AL et al.; and Langerak NG et al.)
Window of opportunity
Although families and clinicians often want to postpone surgery as long as possible, it is important to consider neurosurgical options early in a child’s life, for both physical and developmental reasons.
“It’s important for children with cerebral palsy to be able to do things and not see themselves as disabled,” says Robinson. “The earlier children are treated, the more normally their muscles and limbs will develop, the less stigma they will experience in school and the more independence they can enjoy.”
If you have questions about cerebral palsy spasticity or wish to refer a patient for evaluation, contact the Department of Neurosurgery at 617-355-6008.