Chronic pain: promising multizone spinal cord stimulation, but no established superiority

A programming trial before permanent implantation

The study involved patients with refractory chronic pain in the back, trunk or limbs who had no previous experience with neurostimulation. It was conducted at a single center, with one physician responsible for the stimulation trials.

Participants were randomly assigned to passive-recharge burst spinal cord stimulation targeting one zone or programming targeting two zones. Both the patient and the physician were initially blinded to the assignment.

At the midpoint, programming could be adjusted to optimize relief, targeting up to four zones. This adaptation matters: the settings received at the end did not necessarily match those initially assigned. The exact duration of the trial phase is not specified in the abstract.

Less pain, but mostly pooled results

All 30 participants completed the planned follow-up. The mean pain score on a visual analog scale fell from 70.2 at baseline to 22.2 at the end of the trial. The abstract does not specify the scale used, which limits the interpretation of these values.

Mean reported pain relief was 53% at the midpoint and 67% at the end of the trial, following adjustments to multizone programming. By the end, 83% of patients were receiving this programming. The rate of progression to permanent implantation was 87%.

The authors also report improvements in pain interference with daily life, physical function, sleep and anxiety. The magnitude of these improvements is not detailed in the abstract.

What this trial actually tells us

The observed reduction is encouraging for this population, but it does not, on its own, measure the benefit of stimulating several zones. The abstract provides neither separate results for the initially randomized groups nor the uncertainty surrounding the difference between them.

The programming changes at the midpoint also prevent the final improvement from being straightforwardly attributed to multizone stimulation. Finally, proceeding to permanent implantation does not demonstrate that pain relief will persist afterward.

What we can take away

Multizone programming appears to be an option worth studying during spinal cord stimulation trials. These results demonstrate neither superiority over a single zone nor lasting benefit after implantation.