Ziconotide intrathecal delivery as treatment for secondary therapeutic failure of motor cortex stimulation after 6 years.

INTRODUCTION: Motor cortex stimulation is a well-known treatment modality for refractory neuropathic pain. Nevertheless, some cases of therapeutic failure have been described but alternative therapies for these cases are rarely reported.

CASE REPORT: The patient presented with neuropathic pain in his right arm due to a cervical syrinx which was surgically treated by a shunt in 2003 with no clinical improvement. As alternative therapy, after an evaluation by repetitive magnetic transcranial stimulation with significant benefit, motor cortex stimulation was successfully implanted in 2004. In 2010, a similar pain occurred in the same territory. Local mean pain visual analogical scale (VAS) increased to 82/100. A newer generation stimulation device was then implanted and, within a period of 8months, different stimulation parameter settings were tested, without any pain relief. An intrathecal drug delivery pump was then implanted in 2011, and the upper extremity catheter was located at the cervicothoracic junction. There was no postoperative complication. A bitherapy was initiated at a daily dosage of 0.2mg morphine and 1.3μg ziconotide, not modified since August 2013. At 43months follow-up, mean VAS was 21/100 with improvement of daily life and spare-time activities, anxiety and depression, quality of life (as measured by the SF-36 survey and EQ5D-3L questionnaire).

DISCUSSION: Refractory neuropathic pain treated by motor cortex stimulation may be considered in palliative situations, and secondary therapeutic failure offers only a few perspectives. Intrathecal ziconotide, indicated as a first-line drug in non-cancer pain, could be proposed in such cases.

CONCLUSION: Intrathecal drug delivery including ziconotide in refractory neuropathic pain represents a reasonable option with a good clinical tolerance.