ITB Therapy

Baclofen can be delivered directly into the thecal space with a three-part system made up of a programmable pump with a reservoir or storage area for the drug; a clear, flexible silicone tube or catheter; and a programming device. This delivery method is called ITB Therapy. Because the drug is administered directly to its site of action—within the spinal cord—much less baclofen is needed than if the drug were taken by mouth and more of the drug actually reaches the nerve cells where it is needed. Because less of the medication is needed (often 100 times less), the side effects of ITB Therapy, including drowsiness and sedation, are much milder than when baclofen is taken by mouth. ITB Therapy is usually combined with physical therapy and other forms of rehabilitation.

ITB Therapy is used to treat severe spasticity that is caused by damage to the brain or spinal cord. It is especially useful for treating spasticity in people with cerebral palsy and is most effective for spasticity of the lower limbs. Candidates for ITB Therapy have disabling spasticity that does not respond to conservative treatment with medications or have intolerable side effects at therapeutic doses. Pharmacotherapy should include, but need not be limited to, a trial of oral baclofen. Most physicians agree that a reduction in the Ashworth scale of two points shows a good response to therapy.

To determine whether ITB Therapy is expected to produce a helpful response, the patient undergoes an ITB Therapy screening test. The screening test for ITB Therapy requires the administration of a test dose of baclofen (typically with 50 mcg, usually not to exceed 100 mcg) via lumbar puncture into the thecal space. Peak effect of the drug usually occurs within four hours. Patients who respond positively to the test dose can be considered for chronic ITB Therapy. During screening, patients must be monitored closely in a fully equipped and staffed setting, due to the rare risk of life-threatening side effects.

Once it has been determined that ITB Therapy is likely to be effective in treating spasticity, a surgeon performs an operation to place a permanent battery-powered pump into place. The first style of pump that was used for ITB was about the size of a hockey puck; a recently approved pump, called the SynchroMed II or SynchroMed EL, is smaller but has a larger storage area (reservoir) that holds the baclofen. An even smaller pump is available for use in very young children. The pump implantation requires two incisions: one in the lower abdomen to make a pocket for the pump under the skin, and another, smaller, incision in the lumbar region to insert the catheter. Exact placement of the pump differs with each patient, but it is generally implanted near the waistline, about one inch below the skin.

implanted, programmable pump

The surgeon inserts one end of the catheter into the intrathecal space using a spinal introducer. A myelogram is often used to confirm catheter placement. The catheter is then tunneled under the skin and the other end is connected to the pump. The pump is sewn into place under the skin in the pocket, and the incision is stitched closed. The tip of the catheter rests between the first and second lumbar vertebrae. The procedure typically lasts about 1 hour.

The entire hospital stay is usually 4 to 7 days, during which time the pump is programmed to deliver the best possible dose of baclofen to reduce muscle tone. There is some tenderness or soreness for several days after the operation, which can usually be controlled with pain medications. The implantable pump may cause a slight bulge in the abdominal wall, but many people report that they stop noticing this after several weeks. A notable decrease in the tone of spastic muscles is usually noticeable within several days of the operation, but significant improvements in function may take longer to be evident.

computer wand

The dose of baclofen can be adjusted whenever necessary by reprogramming the pump in the doctor's office. The pump also contains a programmable alarm that beeps softly when the reservoir is low or the batteries need replacing. The reservoir is refilled by injection as needed, usually every 1 to 3 months. When the batteries run low, about every 4 to 5 years, the entire pump is replaced.

The side effects of ITB Therapy are the same as those for baclofen given by mouth but, as mentioned previously, are milder because of the lower dose of medicine that is required with ITB Therapy. About 5% of people with ITB Therapy develop infections that require temporary removal of the pump. Other equipment-related risks include pump failure, tube kinking or breakage, or movement of the catheter (dislodgement) so that the baclofen no longer reaches the intrathecal space. Mechanical defects or failure to refill the pump reservoir can lead to sudden interruption of baclofen treatment. This can cause a life-threatening withdrawal syndrome. To prevent this, families must be educated about the signs of baclofen withdrawal and are usually encouraged to keep a supply of oral baclofen on hand for such possible emergencies.

Although it rarely happens, it is possible for the person receiving ITB Therapy to receive too much medication (overdose). A baclofen overdose may cause drowsiness, lightheadedness, slowed or difficulty breathing, seizures, loss of consciousness, and coma. In the event of an overdose, it is very important for the patient or caregiver to immediately contact the patient's physician.

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