Differential Target Multiplexed Spinal Cord Stimulation for the Treatment of Chronic Intractable Upper Limb Pain: 12-Month Results From a Prospective, Multicenter Study.

OBJECTIVES: This prospective, open-label, single-arm, multicenter study evaluated the use of differential target multiplexed (DTM) spinal cord stimulation (SCS) therapy for chronic upper limb pain (ULP). MATERIALS AND METHODS: A total of 58 candidates for SCS who had chronic ULP were enrolled at 11 sites in the USA. The safety and effectiveness of DTM SCS for treating chronic intractable ULP were evaluated over 12 months. The primary end point was the percentage of responders (≥50% ULP relief versus baseline) to treatment at three months after device activation. This study also evaluated the extent of disability, patient satisfaction, and patient global impression of change with DTM SCS therapy. RESULTS: The mean baseline pain score (10-cm visual analog scale [VAS-10]) for ULP was 7.2 cm, with a mean age of 56 years and mean ULP duration of ten years; 47 subjects were assessed at the primary end point. The percentage of ULP responders was 92% at three months, which was consistent at six (91%) and 12 months (86%). Significant ULP relief (81% reduction in VAS-10) was observed at the primary end point and sustained throughout the study duration. Significant improvements in disability in addition to high levels (>95%) of satisfaction and feelings of improvement were reported. Frequency of study-related anticipated adverse events was in line with expectations of SCS therapy. CONCLUSION: In this patient population with difficult-to-treat conditions with limited clinical evidence of the effectiveness of SCS, subjects reported significant reduction in chronic ULP in response to treatment with DTM SCS.

Chronic pain syndromes, mechanisms, and current treatments.

Although acute pain is a physiological response warning the human body of possible harm, chronic pain can be a pathological state associated with various diseases or a disease in itself. In the United States alone, around one-third of the population has experienced a chronic pain condition and annual cost to the society is in the range of 500-600 billion dollars.(1) It should be noted that if at all this is a very modest estimate, it surpasses the costs associated with cancer, heart disease, and diabetes combined.(1) Unfortunately, despite these humongous costs, the treatment of chronic pain is inadequate.(1) Chronic pain affects individuals in a variety of forms, and below we highlight some of the most common chronic pain conditions seen in a pain clinic. Most of these disorders are difficult to treat and typically require multimodal therapy including pharmacotherapy, behavioral modification, and targeted interventions. We have summarized the scope of each disorder, clinical features, proposed mechanisms, and current therapies for them (Table 1).