Intrathecal Trial

Abstract

Intrathecal (IT) drug administration has been shown to be an effective treatment for many chronic pain conditions (Hayek and Hanes, Curr Pain Headache Rep 18(1):388, 2014; Sanford, CNS Drugs 27(11):989–1002, 2013). These conditions include cancer-related pain, neuropathic pain, and nociceptive pain syndromes such as post laminectomy syndrome, spinal stenosis, chronic compression fractures, spondylosis, complex regional pain syndrome, and rheumatoid arthritis (Deer et al., Neuromodulation 20(2):96–132, 2017; Smith et al., J Clin Oncol 20(19):4040–9, 2002). A trial of IT medication is recommended prior to IT pump placement to assess efficacy and side effect profiles (Deer et al., Pain Med 20(4):784–798, 2019). Currently, morphine and ziconotide are the only two agents approved for intrathecal administration for pain, with ziconotide being the only non-opioid agents (McDowell and Pope, Neuromodulation 19(5):522–32, 2016). There are two basic methods to conduct a trial of intrathecal drug delivery systems. The first is a bolus injection, which allows for a quicker trial and for monitor of side effects. The second method is a continuous infusion via a catheter, which allows for dose titration and which may increase success (McDowell and Pope, Neuromodulation 19(5):522–32, 2016). Currently, there is no data to suggest that one method is more advantageous or efficacious than the other (McDowell and Pope, Neuromodulation 19(5):522–32, 2016). The decision on the type of trial to use and the medication to use depends on many factors, including patient’s clinical status, diagnoses, physician preference/facility capabilities. IT morphine administration may be associated with serious side effects such as respiratory depression and hypotension, and may cause dependence over time (Deer et al., Pain Med 20(4):784–798, 2019). IT ziconotide has a narrow therapeutic window requiring careful dose titrations and is contraindicated in patients with a history of psychosis, but is especially useful in patients for whom intrathecal opioid side effects are unbearable (Deer et al., Pain Med 20(4):784–798, 2019).