An intrathecal pump is one way doctors can provide pain medication directly to the spinal cord. The pump is placed beneath the skin of the abdomen and is programmed to deliver a specific amount of pain drug to the spinal cord. The pump itself is attached to a catheter similar to the one used on women during childbirth.
The catheter goes into the back and is inserted into the intrathecal space around the spinal cord itself. Because the spinal cord is given the medicine directly, there are fewer generalized symptoms and less medication needs to be given. One needs only about 1/300 of the medication necessary when given by intravenous means.
The intrathecal pump in the abdomen is a round metallic device about 3-4 inches in diameter that is implanted through surgery just beneath the skin of the abdomen. It is attached to a tube that is, in turn, attached to the catheter in the intrathecal space around the spinal cord. The pump has an empty cavity called the reservoir which contains the medication. The pump is programmed to release medication slowly at the same rate or at different rates, depending on the time of day. When the reservoir is empty, a healthcare provider uses a needle to inject more medication into the reservoir through a port.
Those who might be good candidates for the intrathecal pump include those who fail conservative therapies, those who are dependent on pain medication, those who are not candidates for surgery, those who are good medical candidates to have the surgery and those who have responded positively in the past to medications that are used in these intrathecal pumps.
An intrathecal pump is useful in the following chronic pain syndromes:
- Failure of previous back surgery
- Pain due to cancer pushing on spinal nerves
- Scar tissue due to radiation around the spinal cord
- Pain and inflammation of the meninges of the spinal cord (called arachnoiditis)
- Causalgia, a burning sensation from peripheral nerve problems
- Chronic pancreatitis
- Reflex sympathetic dystrophy, which is a disease of the nervous system
- Spasticity caused by cerebral palsy, MS, stroke, spinal cord injury or brain injury
Doctors perform screening tests to see who is a good candidate for pain relief by means of an intrathecal pump. These screening tests involve getting a single injection of morphine or baclofen into the intrathecal space. The medicine used depends on the use of the intrathecal injection. If one injection works, the doctor may try multiple injections over several days to see if the medication works. Continuous relief is attempted by means of an external pump, which allows the doctor time to see which dosage of medication might work in the intrathecal pump. If this works, the patient will be scheduled to have the intrathecal pump placed.