January 10, 2006

Neuroscience Insights for Health Care Professionals

The physicians and staff of The Neuroscience Group are providing this physician and provider communication to help you stay abreast of issues and updates in the dynamic field of neurosciences, with the goal of helping you provide better overall healthcare services to your patients. Based on the level of urgency, future emails will take the form of Alerts (urgent news within the neurosciences that may impact your practice), Bulletins (important information), or Updates (more general news) and will be noted as such in the topic headline. Please note that we have options for you at the end of this email as well as helpful links within the right hand margin that can provide additional information. We encourage you to contact us with any questions or suggestions.

Topic: Providers Managing Chronic Pain - Spinal Cord Stimulation and Intrathecal

Chronic pain patients are often difficult to manage in the primary care setting because they require a huge investment of office time and resources to effectively manage their care. Establishing a collaborative approach with a specialist provides additional therapeutic options for the patient. The first step in caring for chronic pain patients is establishing a diagnosis that most effectively predicts the type of treatment needed. Differentiating between nociceptive pain and neuropathic pain is important, as each type of pain responds to different treatment modalities. Pharmacologic treatment (analgesics and prophylactic medication), anesthetic options, surgical and behavioral therapeutic options need to be explored with all chronic, intractable pain patients. Two of the mechanism-based treatments that can be used for chronic pain that is not responding to the previous treatment options are spinal cord stimulation and intraspinal (intrathecal) (IT) drug delivery.

Spinal Chord Stimulation

Pain relief resulting from spinal cord stimulation is thought to occur because of the “gate control theory” of Malzack and Wall, which posits that stimulating large diameter nerve fibers inhibits small fiber input to the brain. Spinal cord stimulation requires implanting an electrode which connects to a pacemaker. The electrode is inserted percutaneously through a mini-laminotomy under local anesthesia. Positioning is advanced with the patient awake to guide the surgeon for “best pain coverage”. Patients can control the intensity of stimulation by regulating the voltage and rate of stimulation. Programming is controlled through a radiotelemetry console programmer. Spinal cord stimulation works best for those patients with lower extremity (radicular) pain. Indications for spinal cord stimulation include:

1. failed back pain syndrome 2. phantom limb and stump pain 3. ischemic pain 4. back and lower extremity pain related to adhesive arachnoiditis 5. causalgia (Hudson, 1998)

Spinal cord stimulation is usually considered before IT. Complications are rare but do include spinal cord injury and infection.

Intrathecal (IT) drug delivery therapy is indicated for those patients who have:

1. a definable cause for their pain 2. no surgically-correctable pathology 3. risk of surgery outweighing the potential benefit 4. no serious untreated drug habit 5. pain that is intractable to less complex, less invasive therapies 6. no medical issues that would preclude doing surgery 7. successfully completed a psychological evaluation 8. no contraindications to implantation

IT therapy should be considered when the pain intensity is unacceptable despite optimized adjunvants, opioid dose escalation or when side effects from oral medications are intolerable. The correct pharmaceutical agent, spinal level for catheter tip placement and method of delivery are guided by the character, pattern and intensity of the patient’s pain. IT therapy is an evolving process, which requires consistent monitoring and repeated assessments. The implantable pump is reprogrammed with each refill. The newer pumps typically hold 20cc or 40cc of drug solution. Delivery of opioids and other adjuncts through the IT system allows for significantly lower doses of morphine and hydropmorphone. Clonidine is sometimes used as an adjuvant, especially with neuropathic pain. IT Clonidine, hydromorphone and Bupivicaine have not been FDA approved but is sometimes given for compassionate off-label purposes.

While side effect profiles are often diminished with IT therapy, nausea, constipation, urinary retention and pruritis are still potential problems. Benign granuloma formations at the tip of the catheter are most often associated with higher morphine concentrations. Myclonus is most often related to the dose of drug administered. Sudden withdrawal of medications, such as Clonidine, can result in life-threatening rebound hypertension. Careful monitoring and in-depth patient education are necessary to successfully manage chronic pain patients with IT delivery systems.

If you have any questions related to spinal cord stimulation or IT therapy, feel free to contact Dr. Phil Yazbak Philip.yazbak@thedacare.org Dr. Randall Johnson. Randall.Johnson@thedacare.org Diane Vanderlin, APNP diane.vanderlin@thedacare.org

Upcoming Events: Patient Education Program, Tuesday 1/24/06, 6:30 p.m. - 8:00 p.m. at the Holiday Inn Select - Appleton. Topic: "Treament Options if Drugs Don't Work for Your Seizures". Presentor: Kristine Towmey, RN