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11 Articles in Volume 13, Issue #8
Ask the Expert: Intranasal Ketamine for Migraine Therapy
Assessment and Treatment of Neuropathic Pain
Diabetes & PAD: Diagnosis, Prevention, and Treatment Paradigms
Editor's Memo: Chronic Low Back Pain: Bringing Back A Forgotten Treatment
Evaluation and Treatment of Chemo- or Radiation-Induced Painful Complications
Guide to Implantable Devices for Intrathecal Therapy
Is Buprenorphine a ‘Partial Agonist’? Preclinical and Clinical Evidence
Letters to the Editor: Hormones and Genetic Testing
Pain Management in Kenya: A Team Experience
PROP versus PROMPT: FDA Speaks
Use of Ultrasound in Detection Of Rotator Cuff Tears

Guide to Implantable Devices for Intrathecal Therapy

Opioid intrathecal therapy offers the advantage of delivering medication directly to the dorsal horn of the spinal cord—increasing potency and reducing the systemic exposure—thus reducing side effects.
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Indications

The indications for intrathecal therapy include chronic intractable pain, which has failed conservative medical care. Conservative care strategies include physical therapy, pharmacotherapy (oral, transdermal, intravenous, or intramuscular), and lesser interventional care. Please refer to Table 5, for a list of indications for intrathecal therapy. With the advances in neurostimulation therapies, intrathecal therapy has been positioned commonly after these strategies, or as an alternative therapy if a patient has relative contraindications to the procedure. In nonmalignant pain patients, this therapy is less often positioned as a salvage therapy to treat patients on high-dose opioid medications. For example, elderly patients who suffers from axial back pain and whom are unresponsive to more conservative therapy or have analgesic benefit with pharmacotherapy but with intolerable side effects, should be considered candidates for intrathecal therapy. In the cancer population, intrathecal therapy has been shown to reduce side effects and improve treatment outcomes, whether curative or palliative in nature, with improvement by Karnofsky Performance Index.1,25

Efficacy

Intrathecal therapy has been demonstrated in many studies to improve pain control and function in both cancer and noncancer patients.26 Intrathecal therapy had level II-2 evidence based for cancer pain and level II-3 evidence for noncancer pain, as described by the United States Preventative Services Task Force criteria for evidence-based medicine,26,27 with a recommendation strength of moderate based on Guayatt’s criteria.28

Risks

Adverse consequences of long term opioid therapy are not averted with intrathecal therapy, as endocrinopathic and immunologic sequelae occur.29 Opioid-related side effects specific to intrathecal delivery include endocrinopathy, urinary retention, pruritis, and fluid retention.29 As the device is an implanted therapy, typical perioperative risks are present and should be addressed prior to proceeding. The importance of having a communicative patient during needle placement within the intrathecal space and catheter deployment and positioning is paramount. Common device-related side effects include catheter malfunction, although there have been recent advancements in catheter design that likely will largely eliminate this challenge, and rarely pump “flipping,” which prevents reservoir refill. Biologic-related side effects include infection and seroma.26

As noted, much of the reported morbidity and mortality associated with intrathecal therapy centers on the refill procedure, where medication is deposited within the reservoir and reprogramming occurs.30 Further, depositing the medication inadvertently outside of the reservoir can cause overdose and requires admission and vigilant care. Some experts advocate ultrasound guidance with needle placement to better qualify appropriate needle position when reservoir membrane localization is difficult to determine.31

When concentrations of medications are elevated outside of the PACC recommendations, granulomas may form. A granuloma is a noninfectious collection of cells found at the catheter tip that can progress to be compressive in nature. Granulomagenic medications include all of the commonly employed intrathecal medications, and are commonly associated with opioid strategies.32 There have been no reports of granuloma formation with monotherapy with either ziconotide or fentanyl. If granuloma is suspected secondary to loss of therapy efficacy or new neurologic findings, a plain radiograph should document catheter tip and then a MRI should be performed at that level. Further, a catheter evaluation should be performed prior to revision. Treatment includes cessation of the granulomagenic medication and replacement of catheter. Very rarely is formal neurosurgical decompression required.

Case Examples

Case 1

A 76-year-old woman presented with axial low back pain that was unresponsive to facet joint treatments. An MRI demonstrated spinals stenosis and lumbar spondylosis with facet arthropathy. Her back pain was most exacerbated when she was laying down flat while trying to sleep. She rated her pain as 9 out of 10 on a numerical rating scale. She had tried a course of hydrocodone (Norco, 5 mg hydrocodone/325 mg acetaminophen up to 4 times daily), and although she reported improvement, she stopped taking the medication due to constipation. The patient also failed other neuropathic pain therapies, including gabapentin at a dose of 100 mg given at night and duloxetine (Cymbalta) 20 mg, because of unsteadiness and sedation. Other oral opioid formulations were tried but stopped due to constipation. She then underwent a trial of morphine—total dose of 0.1 mg/day—and experienced 80% pain relief lasting over 18 hours. She elected to proceed with the implant. Her intrathecal dose is now 0.15 mg/day with no opioid-related side effects; pain score is now 1-2 out of 10.

Case 2

A 38-year-old woman presented with a history of multiple sclerosis and a cerebrovascular accident with continued right-sided sequelae. She is confined to a wheel chair with pain in her axial back, with upper and lower extremity pain on her right side. She reported minimal pain control, and described her pain as aching, burning. She had failed multiple neuropathic pain medications with an attempt to titrate to effect, including gabapentin at 300 mg three times daily, amitriptyline 100 mg at night, oxcarbazepine (Trileptal) 150 mg twice daily, duloxetine 90 mg daily, and topiramate (Topamax) 200 mg at night, along with multiple short-acting opioid regimens with upward titration to daily dose of 300 morphine equivalents. She underwent a trial with ziconotide 2 mcg, and her pain went from 8 out of 10 to 1 out of 10. She subsequently underwent intrathecal implant and flex dosed with bolus delivery of ziconotide per day to dose of 2 mcg/day. The patient continues to report minimal pain (on the order of 1-2/10) with very infrequent pain exacerbations.

Summary

Intrathecal therapy is an important component of the armamentarium to treat pain in patients who that continue to have intractable pain despite conservative efforts. When employed vigilantly and selectively, intrathecal therapy is overwhelmingly helpful. Indications include those patients who cannot tolerate systemic opioid delivery despite analgesic benefit, and in those with uncontrolled pain despite appropriate systemic dosing attempts.

Last updated on: September 25, 2013
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