SpU: Would you please explain the term "interventional pain medicine"? In what ways is this type of care different from the treatment that perhaps a primary care physician or radiologist might offer a patient with low back pain?

Dr. Bennett: Interventional pain medicine is a sub-specialty of medicine, which uses injections and minimally invasive techniques to diagnose and treat painful conditions. The role is not that of a mere technician (that is only one part), but a member of a diagnostic team. The interventional pain medicine physician conducts a full history and physical examination and correlates all interventional diagnostics with that examination and history, assisting the other members of your health care team in determining what is causing a patient's pain. This is quite distinct from the old days when patients were referred to the hospital, showed up for a procedure done by a physician they never met before, and then returned to their family doctor's office having had a procedure with no exam or follow-up.

Furthermore, if your diagnosis is one that does not require surgery, say, a facet joint that is painful, then the interventional pain physician has interventional treatments that can be quite effective (like rhizotomy). Interventional pain medicine performs a whole range of diagnostic injections such as epidural injections and facet joint blocks; minimally invasive treatments such as intradiscal thermal therapy; as well as palliative treatments such as spinal cord stimulation, nerve root stimulation, and intrathecal medication delivery.

When your primary care physician cannot pinpoint the source of your pain, it may be best to seek the care of a pain specialist such as an interventional pain medicine physician. This physician can then help you determine whether you have a carpentry or electrical problem and assist you in obtaining the proper treatment.

SpU: Are drug infusion pumps or spinal cord stimulators appropriate treatment for chronic back pain?

Dr. Bennett: Neuromodulation is the term associated with treatment using spinal cord (or nerve root) stimulation or intrathecal (spinal) drug infusion pumps. In general, neuromodulation in the form of spinal cord stimulation and/or nerve root stimulation can be used when there is neuropathic pain of the neck, thorax, low back, or extremities. We previously believed that spinal cord stimulation was ineffective for neuropathic low back pain. However, recent data has shown that with the appropriate electrode arrays (complex arrays usually requiring a 16-electrode configuration), low back pain can be controlled with a success rate approaching 80%. There are some pain management centers that are using spinal cord stimulation with good success in multilevel discogenic pain, where surgical (fusion) options are not feasible.

Intrathecal (spinal) drug infusion pumps are another option in the treatment of chronic back pain. This mode of treatment is more invasive - it utilizes a catheter that is placed into the cerebral spinal fluid (in the compartment with the spinal cord). The treatment is also medication dependent -- therefore, side effects must be anticipated and considered when making this choice for therapy. What is unknown is the exact incidence of catheter granulomas (benign tumors which form at the tip of the catheter and can compress the spinal cord); these are estimated to occur with a 2% incidence.

SpU: Thank you Dr. Bennett. We appreciate your time and especially your expertise on this important topic.

Dr. Bennett: You are welcome.