350: Opiate Tolerance in Long-Term Intrathecal Analgesia

350: Opiate Tolerance in Long-Term Intrathecal Analgesia

20 Free Papers • Chronic Pain Management Chronic Pain Management 44. Quantitative and selective evaluation of the sensory nerve functions in RHE p...

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Chronic Pain Management

Chronic Pain Management 44. Quantitative and selective evaluation of the sensory nerve functions in RHE patients with chronic sciatica T. Sakai, K. Sumikawa Nagasaki University School of Medicine, Anesthesiology, Nagasaki, Japan Background and Aims: Sciatica is frequently associated with lumbar degenerative disorder which cause damage of the nerve fibers. It is known that current perception threshold (CPT) testing can evaluate sensory nerve fibers in both a quantitative and selective manner: CPTs at 2000-, 250- and 5-Hz stimuli directly represent the functions of A␤, A␦ and C fibers, respectively. This study was carried out to compare the sensory nerve functions of the leg between patients with chronic sciatica and healthy volunteers using CPT testing. Methods: After obtaining institutional approval and written informed consent, 17 patients with unilateral sciatica (L5 or S1) and 21 healthy volunteers who had no history of sciatica were studied. The CPT testing (2000, 250, and 5 Hz) was performed at the midpoint of the leg below the knee corresponding to the distribution of the ipsilateral or contralateral nerve root. In healthy volunteers, CPT testing was performed at the L5 dermatome in both legs. Data were compared using Student’s paired or no paired t-test. Results: The CPT values in the ipsilateral legs in the patients with sciatica were significantly higher than those in the healthy volunteers at all frequencies. The CPT values at 2000 and 250 Hz in the contralateral legs were significantly higher than those in healthy volunteers. Conclusions: The results show that the functions of A␤, A␦ and C fibers of the ipsilateral legs in patients with chronic sciatica are damaged, and that the functions of A␤ and A␦ fibers of contralateral legs are also affected.

2000 Hz 250 Hz 5 Hz

Ipsilateral leg in patiens with sciatica

Contralateral leg in patients with sciatica

Left leg in healthy volunteers

Right leg in healthy volunteers

322.5 ⫾ 200.4ⴱ 97.1 ⫾ 91.9ⴱ 61.2 ⫾ 54.9ⴱ

227.7 ⫾ 131.4ⴱ 56.8 ⫾ 34.8ⴱ 37.8 ⫾ 35.7

129.8 ⫾ 51.8 37.2 ⫾ 20.6 31.9 ⫾ 23.0

129.3 ⫾ 52.0 33.2 ⫾ 16.6 27.2 ⫾ 18.0

350. Opiate tolerance in long-term intrathecal analgesia L. Radhakrishnan1, R. Duarte2, H. Mutagi1, S. Kapur1, J. Raphael2 1Russel Hall Hospital, Pain Management, Dudley, UK, 2Birmingham City University, Faculty of Health, Birmingham, UK Introduction: Continuous intrathecal analgesia using opiates for the management of chronic non-malignant pain is a recognized therapy that has been undertaken for around 20 years. There⬘s limited long-term data on opiate tolerance by this route. Aim: To investigate the variance and tolerance to opiates in longterm intrathecal analgesia administration for the management of chronic non-malignant pain. Method: Using medical records, a longitudinal retrospective review of the doses of 47 patients receiving intrathecal morphine or diamorphine was performed. The average yearly equivalent dose since implant date was computed for consecutive years with greater than 10 subjects per year. Results: The mean age of the patients was 60 ⫾ 9 years (range 38-77). The mean opiate dose was 2.66 ⫾ 2.39 mg/day (range 0.3-14.2) and the mean duration of treatment was 6 ⫾ 3 years (range 1-10). There was a gradual increase in opiate dose with time to reach 5.23 mg/day (range 0.75-14.2) at 10 years. Conclusion: This study of intrathecal opiate therapy, with one of the longest follow-up time spans, has shown that opiate dose increases with time, however, the increase is modest. We found patients who did not show any tolerance and only one patient who very rapidly showed dose escalation reaching ⬎10 mg/day within 4 years. Key Words/Subject of Abstract: Intrathecal Spinal Analgesia, long-term administration, opiates.

ⴱp ⬍ 0.05 vs. healthy volunteers (left or right leg). Results were expressed as mean ⫾ SD.

Fig. 1 Daily intrathecal morphine dose equivalent