An implanted intrathecal pump is a little device similar in size to a pacemaker. It is surgically placed under the skin, usually in the lower abdomen, with a catheter or tube that extends from the pump into your spine to deliver a consistent flow of medication. The medication is most often for pain relief, although it may also deliver anti-spasmodic medication such as Baclofen.
The intrathecal pump is sort of like a long term epidural. The people who are candidates for this device have severe chronic pain syndromes like failed back syndrome or post-trauma pain. Sometimes cancer patients are candidates, but it depends on the prognosis because it is a delicate surgery with serious possible complications and the risk vs. benefit may not be enough. Other candidates have problems with spasticity, like that in multiple sclerosis or post-nervous system trauma or disease.
This intervention is most often a last resort. The patient who is appropriate for the pump likely has already had physical therapy, alternative therapies like acupuncture along with long-term narcotics that do not control the pain, or anti-spasmodics that do not provide adequate relief of symptoms. They have had a trial with the device prior to implantation to be sure it helps them prior to going through with the surgery.
The thecal sac is at the bottom of the spinal cord. It is an area with many nerves and circulation of cerebral spinal fluid, and is surrounded by tissue called the meninges. While the pump is implanted in the lower abdomen, the catheter that comes out of the pump is tunneled under the skin and pumps medication into the thecal sac. This usually allows a lower dose of medication than is needed when taken via oral, patch or other route. The medication may be delivered in regular boluses or a steady flow around the clock.
Possible complications of implanted intrathecal pumps include but are not limited to: infection, spinal abscess or hematoma, leaking spinal fluid, bleeding, inflammatory mass at the catheter tip, neurologic injury and endocrine dysfunction.
While all of this sounds a little scary, implanted pumps can be a real godsend for the right patients. Once the medication dose has been titrated appropriately, the consistent and direct medication delivery allows patients to regain some function and independence.
Sources:
American Chronic Pain Association Consumer Guide to Pain Medication and Treatment, 2010 Edition.
http://www.theacpa.org/documents/ACPA%20Consumer%20Guide%202010%20010410.pdf
Croat Med J. 2007 February; 48(1): 22–34.roat Med J. 2007 February; 48(1): 22–34. Via National Center for Biotechnology Information.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2080496/