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Baclofen is a medicine used to treat spasticity (involuntary muscle tightness). It is most often given by mouth, but when spasticity is severe, or oral medications cause side effects, it may be given directly into the space around the spinal cord. It is delivered through a pump placed under the skin. The delivery system consists of three parts:
- The pump itself
- A catheter that brings the medicine from the pump to the spinal canal (space around the spinal cord)
- Baclofen medication which is placed in the pump.
The pump itself is about the size of a hockey puck and is surgically placed under the skin in the mid or lower abdomen. It is easily felt below the skin; whether it can be seen depends on the surrounding fat tissue. Thin people often notice the pump is more visible. In people with more fat, the pump is likely to be less visible. Your doctor may be able to estimate for you how much it will be seen. There are two pump sizes and smaller pumps are generally used in children.
The catheter is connected to the pump, tunneled under the skin around to the spine, and then inserted directly into the spinal column. This catheter delivers medicine into the fluid that surrounds the spinal cord, so that the medicine can act directly at the place where it is needed. This means that often the baclofen pump is as effective as taking medicines by mouth, but with fewer side effects, like drowsiness. Delivering the medication this way also may be more effective for decreasing spasticity in the legs.
The surgery to place the pump usually takes about 90 minutes, and then patients are monitored after the surgery. Patients must come to a clinic that is able to refill the pump with baclofen at least every six months and depending on the dose, may need to be refilled more often. For patients on a very high dose, this can be as often as monthly.
There is a refill port in the center of the catheter that is used to replace the medication. A needle is inserted through the skin and into the pump. Any leftover medicine is removed, and then the new medicine is injected. In most cases this involves a single needle stick, which feels like any needle stick. Since the needle then goes into the pump, some of the usual discomfort of feeling the needle below the skin is not present.
The pump battery lasts up to seven years. Unfortunately, the battery cannot be replaced alone, so the entire pump must be removed and replaced though surgery before the battery runs out. The catheter does not need to be replaced on a regular basis. It is only replaced if problems develop with the catheter.
Who will benefit from a baclofen pump?
Doctors evaluate many factors when considering use of a pump to treat a patient. Generally, the reason to get a pump is when other measures to control spasms have failed, or the side effects of oral medications are unacceptable. Also, the baclofen pump has its greatest effect in the legs, with a weaker effect in the arms. For spasticity in the neck or face, the pump is of limited use.
Patients being considered for a pump must have demonstrated their ability to keep appointments; missed refill appointments can result in baclofen withdrawal which is dangerous.
Doctors typically use a “trial” to determine whether the intrathecal baclofen therapy will be useful. Patients considering a pump come to the hospital for a day and start with an evaluation of spasticity in the morning. Then a test dose of baclofen is injected into the spinal canal and symptoms are evaluated through the day to check for the drug’s effectiveness. Patients who do not respond to this dose may undergo more injections with increasing doses, but generally these injections cannot be done sooner than 24 hours after the last injection. Some centers insert a temporary catheter into the spinal canal so that the medication infusion can be adjusted up or down. Those who do not respond at a high dose will not benefit from a baclofen pump.
Is this experimental?
This is not an experimental treatment. Baclofen pumps are used in many healthcare centers around the world. The first studies for giving baclofen within the spinal canal were completed in persons with spinal cord injury and multiple sclerosis in 1984. Since then, studies have also been completed in traumatic brain injury, cerebral palsy, and stroke.
Side effects
Proper, controlled delivery of baclofen by the pump is not dangerous. However, if the pump fails, or you miss an appointment to refill the pump, baclofen withdrawal can occur. Withdrawal generally causes discomfort and spasticity, but can also be serious and even life-threatening. Rarely infections of the pump or the catheter can occur.
An overdose of baclofen from a pump malfunction can also be serious. Although pump failures are very rare, misprogramming at a refill can induce an overdose.
Despite these concerns, people with a baclofen pump rarely have serious problems. Most side effects are related to effective spasticity control. Some people notice a loss of muscle mass in their legs. Others gain weight as muscle activity decreases. These effects can be lessened by adjusting the dose to allow some spasms. The pump medicine will also relax the bladder, so patients who void spontaneously may have problems with retaining urine. Constipation and, in men, decreased erectile function, sometimes occur with high doses.
Costs
Insurance usually covers the expenses of baclofen pump therapy which may be recommended after less invasive and less expensive options have been tried, but did not control spasticity or pain.
References
Brashear, Allison and Elovic, Elie (2010). Spasticity: Diagnosis and Management. Demos Medical Publishing: New York, New York.
This content is for informational purposes only and may not be comprehensive. Information contained does not imply an endorsement from Shirley Ryan 嫩B研究院, and does not replace the advice of a qualified healthcare professional. See here for further details. ? Shirley Ryan 嫩B研究院 (formerly Rehabilitation Institute of Chicago). Henry B. Betts LIFE Center – (312) 238-5433 – /lifecenter.
