Persons with cerebral palsy often experience muscle spasticity that limits their mobility. Clinical approaches to the control of spasticity include drug therapy, surgery and/or physical therapy.
Drug therapies for the treatment of spasticity have had limited clinical success. New drug therapies are under study, as are new methods of using older therapies. One such new method is the use of baclofen administered by means of a pump implanted under the skin of the abdomen.
Baclofen is a muscle relaxant and antispasmodic that works by inhibiting the nervous system. Its precise mechanism of action is unknown although it is thought to inhibit the transmission of impulses between nerve cells. Since it is a nervous system inhibitor, it can affect the action of nerve cells in the brain and cause confusion, drowsiness, dizziness, and difficulties with gait and balance. In high doses, it is reported to have caused problems with breathing and with heart and kidney function.
Baclofen has been used clinically for the relief of muscle spasticity in the limbs, through its action of inhibiting nerve cell transmission in the spinal cord. It is reported that baclofen is of value in diminishing muscle spasticity in persons with injury to the spinal cord and diseases of the spinal cord. However, its usefulness in muscle spasticity associated with cerebral palsy has not been established; also, it is not recommended for use in children under 12 years of age.
One reason for the adverse side effects associated with baclofen is a result of its oral administration. In order to act on the nerve cells in the spinal cord, baclofen first enters the fluid surrounding the spinal cord (the cerebral spinal fluid) and then the spinal cord. When taken by mouth and in order to obtain therapeutic levels the cerebrospinal fluid, relatively large amounts of the drug are needed. However, in high oral doses, the drug also enters the cerebrospinal fluid surrounding the brain and affects brain function, causing lethargy and difficulties with balance. In order to offset the effects of high oral doses, a technique has been developed that uses a pump about the size of a hockey puck. The pump is implanted under the skin of the abdomen, and a tube from the pump is placed into the fluid chamber surrounding the spinal cord. The pump has a reservoir in which baclofen is stored. The pump is programmed to discharge specified amounts of baclofen into the cerebrospinal fluid at a predetermined rate. This method of delivery can more precisely control how much of the drug is administered and where the drug is introduced into the cerebrospinal fluid.
Thus, with the use of the pump there may be better control of baclofen's antispasmodic effect and a decrease in its undesirable side effects. A number of physicians and surgeons are considering the use of the "baclofen pump" for the treatment of muscle spasticity in selected persons with cerebral palsy. As with other methods for the control of spasticity, functional improvement, (for example improved walking) may continue to be dependent on the associated use of other therapies such as physical therapy, orthotic devices, etc.
The issues remaining include: " how successful is baclofen delivered by a pump for the control of spasticity in persons with cerebral palsy?  " what are its side effects on other functions of the spinal cord and brain?  " if spasticity is diminished, is there functional improvement (e.g.: improved walking)?  " does the degree of functional improvement warrant the relatively high cost of the pump and the surgical-medical costs required for its implantation and maintenance? " what is the comparative usefulness of pump-administered baclofen to other available therapies and to other methods now being developed for the control of spasticity?