Movement-evoked breakthrough cancer pain despite intrathecal analgesia: a prospective series.

BACKGROUND: Intrathecal analgesia (ITA) is a valuable treatment option for intractable cancer-related pain. However, the issue of movement-evoked breakthrough pain (BTP) has not been specifically investigated in the ITA setting. The aim of the study was to evaluate the effect of ITA on spontaneous resting pain intensity (SRPI), doses of non-ITA opioids, and specifically on movement-evoked pain intensity (MEPI). METHODS: We prospectively studied 28 consecutive patients who graded SRPI and MEPI on a 0-10 numerical rating scale (NRS) at the time of ITA procedure, after 1 week, and after 1 month. Mild pain was defined as NRS ≤ 3 and severe pain as NRS ≥ 7. Concomitant doses of opioids were registered. RESULTS: After 1 week, no patient had severe SRPI compared with 31% before ITA, and the proportion of patients with mild SRPI had increased from 27% to 76%. Meanwhile, the median daily dose of non-ITA opioids decreased from 575 to 120 mg of oral morphine equivalents. The effect on SRPI and on doses of non-ITA opioids remained essentially unchanged during the study month, but the proportion of patients having severe MEPI did not change significantly: 44% still had severe MEPI after 1 week and 40% after 1 month. CONCLUSION: Movement-evoked BTP was a major clinical problem throughout the study month despite otherwise successful ITA. Improving the quality of life of patients with intractable cancer-related pain should include developing strategies to better deal with movement-evoked BTP.

Do the potential benefits outweigh the risks? An update on the use of ziconotide in clinical practice.

Ziconotide is a selective and potent blocker of N-type voltage-gated calcium channels. It was approved by the Food and Drug Administration in 2004 and by the European Medicines Agency in 2005 for the treatment of severe chronic pain in patients needing intrathecal analgesia (ITA). The aim of this paper is to provide a practitioner-oriented, educational, narrative, up-to-date review on the use of ziconotide in clinical pain medicine. Of special concern regarding safety is the partial incongruity between dosing statements in the Summary of Product Characteristics and novel low-dosage, slow uptitration recommendations. Even though ziconotide has obvious advantages compared to opioids, pain practitioners pondering the use of ziconotide nonetheless have to balance its proved potential analgesic effect against its neurological side effects, with special consideration being given to dosing and neuropsychiatric dangers. Using a seesaw analogy, the paper discusses what factors pain physicians should weigh in when considering ziconotide as ITA drug, the non-opioid advantages of ziconotide being counterbalanced by its potential psychiatric side effects. Ziconotide is an important part of the armamentarium of modern interventional pain medicine. If ITA is deemed necessary, ziconotide is a rational alternative, at least in chronic (neuropathic) non-cancer pain. However, in many European countries, ziconotide treatment is only available in a few (if any) centres. The safety profile of ziconotide is not fundamentally more worrying than that of opioids or cannabinoids; it is just different. This paper provides a concise, up-to-date and clinically-oriented summary of the use of ziconotide in clinical practice, not least concerning safety and dosage issues.

Intramuscular pain modulatory substances before and after exercise in women with chronic neck pain.

BACKGROUND: In peripheral tissue, several substances influence pain and pain modulation. Exercise has been found to decrease pain and improve function for chronic pain conditions, but how and why exercise produces beneficial effects remains unclear. This study investigates whether aspects of pain and concentrations of substances with algesic, analgesic and metabolic functions differ between women with chronic neck shoulder pain (CNSP) and healthy women (CON) and whether changes are found after an exercise intervention for CNSP. METHODS: Forty-one women with CNSP and 24 CON subjects were included. The participants attended two microdialysis sessions with 4-6 months between the experiments. During this period, the CNSP subjects underwent an exercise intervention. Expression levels of substance P, beta-endorphin, cortisol, glutamate, lactate and pyruvate as well as pain intensity and pressure pain thresholds were analysed. RESULTS: At baseline, higher concentrations of glutamate and beta-endorphin and lower concentrations of cortisol in CNSP than CON were found. After exercise, decreased levels of substance P and possibly of glutamate, increased levels of beta-endorphin and cortisol as well as decreased pain intensity and increased pain pressure thresholds were found for CNSP. CONCLUSIONS: The findings at baseline indicated algesic and analgesic alterations in the painful trapezius muscles. The findings for CNSP after the exercise intervention, with changes in peripheral substances and decreased pain intensity and sensitivity, could reflect a long-term physiological effect of the exercise.