Spasticity is defined as a disorder of movement characterized by a rate dependent increase in tone, where tone is the resistance to movement. Put simply, children who have spasticity have the resistance set much higher than people without it. As such, when a patient with spasticity wants to use an arm or a leg, the underlying increase in tone will cause them to work harder than normal, as they need to overcome the spasticity in order to accomplish any task.
Treatment of spasticity is geared towards attempting to create a better balance in the control of the motor neurons in the spinal cord. Possible treatments include physical and/or occupational therapy, oral medications, botulism toxin injections, orthopedic surgery, selective dorsal rhizotomy (surgery where some of the sensory nerves are cut) and the delivery of intrathecal baclofen through an implanted pump.
Physical or Occupational Therapy
Therapy is geared towards improving range of motion through stretching and by improving strength. To maximize their benefit, exercise programs need to be done at home as well as during therapy sessions. The therapist will often assist in making sure the braces, crutches, walkers or other assistive devices are best suited for the child.
Medications taken by mouth can help to reduce spasticity by either inhibiting the effects of the reflex arch or acting on the muscle itself to relax it. Although sometimes effective, the problem with these medications is that the dose required to achieve the desired result may lead to intolerable side effects. Because the medication is taken orally, it must pass through the bloodstream. Thus, the whole body is exposed to the medication, and the resulting effects on other parts of the body often outweigh the beneficial effect in reducing spasticity.
Botulinum Toxin Injection
Botulinum injected directly into the disordered muscle group blocks the impulses from the nerve to the muscle, thus reducing stiffness in patients with spasticity. The downside of this therapy is that its effects are temporary (typically lasting 1-6 months). The injections can be repeated, but the tendency is that over time, the beneficial effects of the injection lessen. Botox injections can be useful in allowing us to see how a child will react to a reduction in spasticity. Furthermore, it can allow us to better measure the strength of the extremity and potentially focus therapy to enhance strength in the period where spasticity is reduced. In essence, in some situations it can give us insight as to how a child will look after a more permanent procedure.
Selective Dorsal Rhizotomy (SDR)
This is a surgical procedure where some of the sensory nerves (nerves that supply input to the reflex circuit) are cut. The goal is to reduce the volume of electrical activity being carried by the reflex arch, thereby restoring a more appropriate balance in the control of the motor neuron in the spinal cord. The surgery is done in the lower back. The spine is accessed, the bone is partially removed temporarily, and the spinal sac is open exposing the nerves that connect the legs and the spinal cord. Each nerve has two components. The first is the motor root which transmits the impulse from the spinal motor neuron to the muscles which causes it to contract. The second is the sensory root which carries information from the skin and other tissues back to the spinal cord. Only portions of the sensory root are cut during this procedure. The percentage of each nerve cut depends upon its location and the results of electrical stimulation applied to the nerve during surgery.
After surgery, pediatric patients typically lie in the fetal position. A catheter that is implanted during surgery helps to control pain. This catheter is usually removed 48-hours after surgery. By the third or fourth day, the children become more mobile and start to sit up, can get out of bed, and can begin physical therapy. After five to seven days, the children are transferred to an inpatient rehabilitation service for intensive therapy. This often lasts for four to six weeks and is followed by intensive outpatient therapy for six to twelve months. The focus of therapy is to retrain the child to use his or her legs. To maximize outcome, the surgery and therapy regimen after surgery must go hand-in-hand.
There are two groups of patients that seem to benefit the most from SDR. The first group is those children with spastic diplegia (spasticity in the legs only) or spastic quadriplegia (with only mild involvement of the arms), who have good cognition and are mobile. Treatment in this group is geared towards maximizing functional ability. The second group is comprised of children with severe spastic quadriplegia where the spasticity is hampering the ability of caretakers to provide for the patient’s daily care needs, such as bathing, getting dressed or sitting in a chair. In these cases, treatment is offered to allow the children to receive the necessary care with more comfort and ease.
Intrathecal Baclofen (ITB)
Certain patients can be considered for implantation of a pump that delivers baclofen directly to the spinal fluid, allowing for delivery of a much higher concentration of the drug to the desired site (spinal motor neuron), without having to go through the bloodstream first. By doing this, the potential for undesirable side effects is dramatically reduced. Before the pump is implanted, the child is brought into the hospital to receive a spinal tap at which time a small dose of baclofen is given. We monitor the children afterwards to see whether or not there is enough reduction in the spasticity as a result of the dose given. If the response is adequate, a pump can be implanted. If not, the next day a second higher dose is given. Again, if the patient responds appropriately a pump is implanted. However, if an adequate response is not achieved, this form of treatment is not likely to be effective and the child will no longer be considered a good candidate for this procedure.
The pump is implanted by placing the generator in the wall of the abdominal cavity, underneath the skin and sometimes underneath the muscles. The generator is connected to a catheter that is placed into the spinal sac through a small incision in the lower back. The catheter can be guided into the upper part of the lower back if we wish the effects of the drug to be focused on the legs. A second option would be to thread the catheter higher so that the tip would lie between the shoulder blades if we wish to have an effect on both the arms and the legs. The pump can be programmed to deliver baclofen 24-hours a day at any rate we choose. Thus, if the patient is too spastic we can increase the dose or if they are too loose we can lower the dose. The pump can only hold a certain amount of drug and needs to be refilled every 30-90 days. This is accomplished by putting a needle into the pump and filling its reservoir with new medication. Over time the pump battery wears out and will need to be replaced every three to six years.
UBNS recommends that children with spasticity that are being considered for any interventional treatment should first be evaluated at the Comprehensive Spasticity Clinic at The Women & Children’s Hospital of Buffalo. This clinic is staffed by neurosurgeons, physiatrist (doctors in rehabilitative medicine), and physical and occupational therapists. All care providers are specially trained in the care of pediatric patients and specifically in the unique elements of spasticity that are seen in children. Furthermore, pediatric orthopedists are available for consultation.