Ziconotide for spinal cord injury-related pain.

Background: Central neuropathic pain related to spinal cord injury is notoriously difficult to treat. So far most pharmacological and surgical options have shown but poor results. Recently ziconotide has been approved for use both neuropathic and non-neuropathic pain. In this cohort study, we assessed responder rate and long-term efficacy of intrathecal ziconotide in patients with pain related to spinal cord injury.

Methods: Patients presenting chronic neuropathic related to spinal cord lesions that was refractory to medical pain management were considered for inclusion. Those accepting were tested by lumbar puncture injection of ziconotide or continuous intrathecal infusion and if a significant decrease in pain scores (>40%) was noted they were implanted with a continuous infusion pump. They were then followed up for at least 1 year with constant assessment of the evolution of pain and side effects.

Results: Out of the 20 patients tested 14 had a decrease in pain scores of more than 40% but only 11 (55%) were implanted with permanent pumps due to side effects and patient choice. These were followed up on average for 3.59 years (±1.94) and in eight patients an above threshold decrease in pain scores was maintained. Overall in patients that responded to the test baseline VAS was 7.91 and 4.31 at last follow-up with an average dose of 7.2 μg of ziconotide per day. Six patients (30%) did not respond to any test and in three patients side effects precluded pump implantation. No significant long-term effects of the molecule were noted.

Conclusion: This study shows response to intrathecal ziconotide test in 40% of the patients of a very specific population in whom other therapeutic options are not available. This data justifies the development further studies such as a long-term randomized controlled trial.

Significance: Intrathecal Ziconotide is a posible alternative for the treatment of pain in patients with spinal cord injury and below level neuropathic pain.