Intrathecal Baclofen Pump System

What is baclofen?
Spasticity is a motor disorder characterized by tight or stiff muscles that may interfere with voluntary muscle movements. Baclofen is a muscle relaxant medication. It is commonly used in adults to decrease spasticity related to spinal cord injuries or multiple sclerosis. Baclofen is also used to treat children who have cerebral palsy.

How does baclofen work?
Spasticity is caused by an imbalance of excitatory and inhibitory input in the spinal cord. This imbalance causes hyperactive muscle stretch reflexes. These reflexes result in involuntary spasms and increased muscle tone.

Baclofen works by blocking the release of excitatory neurotransmitters in the spinal cord. Ideally, baclofen restores the balance of excitatory and inhibitory input to reduce muscle hyperactivity. In this way, it also allows more normal motor movements.

Why is intrathecal baclofen preferred over oral baclofen?
Baclofen can be taken orally (by mouth in pill form) or delivered intrathecally (as an injection in the spine). Oral baclofen causes side effects that may limit its usefulness, especially when prescribed for children. Of the oral baclofen delivered throughout the body, only a small portion goes to the spinal fluid where it is needed to work.

With an intrathecal delivery system, baclofen is delivered right to the target site in the spinal cord. Because the intrathecal system continuously delivers baclofen in small doses directly into the spinal fluid, there are fewer and less severe side effects than that seen with the oral medication.

What is the baclofen pump system?
The baclofen pump system is the intrathecal (directly into the spinal fluid) method of delivering the medication. The system consists of a catheter (a small, flexible tube) and a pump. The pump--a round metal disc, about one inch thick and three inches in diameter--is surgically placed under the skin at the level of the abdomen.

The pump stores and releases prescribed amounts of medication through the catheter. The pump has a 10-mL fluid capacity and can be refilled by inserting a needle through the skin into a filling port (called the diaphragm) in the center of the pump.

Who is a candidate for the pump system?
Anyone who has spasticity and weighs over 30 pounds can be considered for the baclofen pump system. The pump system is appropriate when adjustable and potentially reversible treatment is desired, but cannot be achieved with oral medication.

How will my doctor know if the baclofen pump system will work?
If your doctor recommends the baclofen pump system, you will have a trial of the intraspinal therapy to test the potential effectiveness of the medication. During the medication trial, a small needle is placed near the spinal cord in the lower back. The medication is injected into the spinal canal and you are assessed over 8 to 10 hours to determine how well the medication treats the spasticity. If your muscles don't relax during the first trial, a larger dose may be given the next day to determine its effectiveness.

This procedure causes minor discomfort. You may experience temporary muscle weakness due to the relaxing effect of the medication. This is caused by receiving a large dose of medication all at once during the trial.

Patients who experience positive results with the intrathecal medication can decide with their doctor if they should have a baclofen pump system implanted.

How is the pump system implanted?
The pump is surgically placed just underneath the skin, usually in the lower abdominal area. The procedure to place the pump lasts from 1 to 2 hours.

The procedure may be performed under local anesthesia (pain-relieving medication that numbs the area while you remain awake) or general anesthesia (medication given by an anesthesiologist that induces sleep). Children are most often given general anesthesia and are asleep for the entire procedure.

The catheter is inserted through a needle and guided into the spinal canal, close to where pain pathways enter the spinal cord.

The other end of the catheter is tunneled under the skin to the abdomen, where a pocket is created. There, the pump is implanted through an incision in the abdomen, anchored to surrounding tissue, and connected to the catheter. Once the incision is closed, the pump reservoir is filled with the dosage of baclofen prescribed by the physician.

How is the medication dispensed?
With a programmable pump, a tiny motor moves the medication from the pump reservoir through the catheter. Baclofen flows freely through the spinal fluid, affecting the nerves to control muscle hyperactivity.

Adjustments in the dose, rate, and timing of the medication can be made by your doctor, using an external programmer. The pump system can be set to dispense medication continuously or at certain times of the day. The pump can also be easily reprogrammed if necessary.

Patients must return to their doctor's office for pump refills and medication adjustments, typically every 2 to 3 months. The pump system is taken out and replaced at the end of the battery's life span (which is usually 3 to 5 years).

What are the side effects of baclofen?
Some side effects of baclofen include dizziness, drowsiness, headache, nausea and weakness. Problems with the infusion pump can cause either overdose or sudden withdrawal of baclofen.

What are the potential advantages of the baclofen pump system?
Typically, the intrathecal baclofen pump:

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. For additional health information, please contact the Center for Consumer Health Information at the Cleveland Clinic (216) 444-3771 or toll-free (800) 223-2273 extension 43771. If you prefer, you may visit www.clevelandclinic.org/health/ or www.clevelandclinicflorida.org. This document was last reviewed on: 3/29/2002

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