What is multiple sclerosis (MS)?
Multiple sclerosis (MS) is a disease that causes demyelination of the brain and spinal cord, or a loss of the protective covering around nerve fibers called axons. When this occurs, the axons (the parts of the nerve cells that transmit impulses to other cells) don't work well. As more areas are affected by the loss of myelin, different symptoms develop. The specific symptoms seen in MS are related to the area of injury in the brain or spinal cord. Patients might experience or describe numbness, tingling, or weakness. The weakness might be mild or severe enough to cause paralysis of one side of the body. In some cases, patients may develop loss of control of their bladder or an inability to empty their bladder. As MS progresses, some patients are left with muscle spasticity, which is an involuntary painful contraction of some muscles.
What is spasticity?
Spasticity is a condition in which muscles are exhibiting almost constant contracture or activity, leading to loss of range of motion, decreased function, and even pain. Spasticity occurs after an area of the brain or spinal cord has been injured, leading to weakness and increased tone. When an arm or leg that is affected by spasticity is moved by a health-care professional, there is involuntary resistance to that movement. Often, this spasticity is made worse when the speed (or velocity) of the movement increases. Spasticity is often seen in association with a brain injury, such as after:
- a stroke,
- traumatic damage to the brain or spinal cord, or
- in cases of MS.
What is baclofen, and what are its side effects?
Baclofen is a medication that works in the brain to decrease uninhibited signals that start in an injured area of the brain and cause spasticity. By decreasing these signals, the affected muscle can relax somewhat, and the symptoms of spasticity can be reduced. When taken in pill form baclofen can be effective, but can lead to side effects such as:
- headache, or
These side effects can limit the amount of medication that can be used to decrease the symptoms of spasticity. However, the medication can also be injected around the spinal cord, directly into the cerebral spinal fluid. When used in this way, only small amounts of the medication are needed, and side effects may be reduced.
How is an intrathecal baclofen pump used to treat multiple sclerosis (MS)?
Baclofen can't treat MS itself. However, this medication can be effective in reducing the symptoms associated with severe spasticity caused by MS.
Who is a good candidate for an intrathecal baclofen pump?
There are various selection criteria used to determine if someone with MS is a candidate for an intrathecal baclofen pump. The primary consideration is the presence of spasticity that interferes with the individual's daily activities or care. If someone with MS has primary weakness, then the intrathecal baclofen pump is not an option. Other considerations include limited response to oral baclofen or intolerable side effects at the doses that are required to control the spasticity as well as a good response to a screening test of intrathecal baclofen administered into the cerebrospinal fluid. Prior to implantation of the pump, there must not be any sign of infection.
How does an intrathecal baclofen pump work?
The pump is implanted under the skin and is connected to a catheter (tube) that ends in the spinal fluid. The specific area of placement of the tubing is dependent on each patient and their associated symptoms. The pump has a small reservoir where the medication (baclofen) is placed and is programmed to deliver a specific amount of medication on a regular basis to the cerebrospinal fluid. The exact amount of medication delivered is unique to each patient and can be adjusted based upon symptoms. The programming is initially performed each month after the pump is implanted; once a patient has reached a stable dose, then the pump is checked and refilled every two to three months.
How can I expect to feel after having an intrathecal baclofen pump implanted?
Implanting a pump is a surgical procedure, and many patients experience some soreness around the surgical site after the pump is implanted. The pump is typically located in the abdomen, and some patients find that clothing that rubs over the area is uncomfortable. Some surgeons may fill the pump during the implantation, so that it starts working right away, while others wait a short time after the surgery is completed prior to filling the reservoir with medication. Once medication is flowing, benefits may be identified in six to eight hours.