BACKGROUND
Spinal cord stimulation (SCS) activates the dorsal column fibers using electrical stimuli. Current SCS systems function in fixed-output mode, delivering the same stimulus regardless of spinal cord (SC) activation.
OBJECTIVE
To present long-term outcomes of a novel closed-loop SCS system that aims to maintain the SC activation near a set target level and within a therapeutic window for each patient. SC activation is measured through the evoked compound action potential (ECAP) generated by each stimulus pulse.
METHODS
Fifty patients with lower back and/or leg pain who were successfully trialed received a permanent system (Evoke; Saluda Medical, Sydney, Australia). Ratings of pain (visual analog scale), quality of life, function, sleep, and medication use were collected at baseline and at each visit. SC activation levels were reported in summary statistics. The therapeutic window for each individual patient was defined as the range of ECAP amplitudes between sensation threshold and uncomfortably strong stimulation.
RESULTS
At 12 mo, the proportion of patients with ≥50% relief was 76.9% (back), 79.3% (leg), and 81.4% (overall), and the proportion with ≥80% pain relief was 56.4% (back), 58.6% (leg), and 53.5% (overall). Patients spent a median of 84.9% of their time with stimulation in their therapeutic window, and 68.8% (22/32) eliminated or reduced their opioid intake. Statistically significant improvements in secondary outcomes were observed.
CONCLUSION
The majority of patients experienced more than 80% pain relief with stable SC activation, as measured by ECAP amplitude at 12 mo, providing evidence for the long-term effectiveness of the Evoke closed-loop SCS system.
The addition of IE to behavioural exposure did not improve outcomes. However, higher adherence to either attentional strategy was associated with larger effect sizes on all measures, suggesting factors shared by the two treatments could have contributed to the outcomes. Taken as a whole, the results suggest that increasing adherence to treatment strategies, possibly by motivational measures, would improve the overall outcomes of these interventions.
Introduction: Chronic pain is a major public health concern, as is the associated use of opioid medications, highlighting the importance of alternative treatments, such as spinal cord stimulation (SCS). Here, we present the final 24-month results of the Avalon study, which investigated the use of the first closed-loop SCS system in patients with chronic pain. The system measures the evoked compound action potentials (ECAPs) elicited by each stimulus pulse and drives a feedback loop to maintain the ECAP amplitude near constant. Methods: Fifty patients were implanted with the Evoke system (Saluda Medical) and followed over 24-months. Pain, quality of life (QOL), function, sleep, and medication use were collected at baseline and each scheduled visit. ECAP amplitudes and programming adjustments were also monitored. Results: At 24 months, responder rates (≥ 50% pain reduction) and high responder rates (≥ 80% pain reduction) for overall pain were 89.5% and 68.4%, respectively, the latter up from 42.2% at 3 months. Significant improvements from baseline were observed in QOL, function, and sleep over the 24 months, including ≥ 80% experiencing a minimally important difference in QOL and > 50% experiencing a clinically significant improvement in sleep. At 24 months, 82.8% of
The TPM/oxycodone patch delivered oxycodone to the site of perceived pain in subjects suffering from PHN, but did not provide analgesia for the broad PHN indication.
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