1. 2011;14;343-351Patient Selection and Outcomes Using a Low-Dose Intrathecal Opioid Trialing Method for Chronic Nonmalignant Pain
   Retrospective Evaluation
   Michael E. Harned, MD, Jay S. Grider, DO, PhD, and Mark A. Etscheidt, PhD.

BACKGROUND: Various methods exist for trialing patients for intrathecal drug delivery.  Currently no standards exist regarding  “best practices” for trialing techniques.

OBJECTIVES: The specific aim of the current study is to report results of patients trialed using a low-dose intrathecal morphine technique in the treatment of chronic noncancer pain.

SETTING: academic pain medicine practice

STUDY DESIGN: Retrospective Review

METHOD: Visual analog pain scores (VAS) were obtained at the initial visit, after a 6 week opioid-free interval prior to trial, at intrathecal doses of 25, 50, 100, 200 and 400 µg of intrathecal morphine during the trial, at one month post-implant, and current VAS.  Additionally, intrathecal opioid doses at implant and current state are reported.

RESULTS: VAS scores at the initial visit and after 6 weeks of opioid cessation were identical.  There was a significant improvement in VAS after the trial, which was sustained over the course of therapy.  Additionally, the use of the protocol described in this article suggests that the dose-response relationship following opioid cessation is in the 50-400 µg/d range for intrathecal morphine and that tolerance may be reversed during the 6 week opioid-free period.

LIMITATIONS: Small trialing study

CONCLUSIONS: Opioid taper and a 6 week opioid-free period may 1) improve long-term analgesia versus a combination of oral/ intrathecal drug delivery system therapy 2) it may be possible to maintain analgesia at microgram doses and 3) opioid tolerance may be reversible in 6 weeks.  Further it appears that a dose response relationship for effective analgesia may be less than 400 µg of intrathecal morphine.