Painful diabetic neuropathy: spinal cord stimulation improves symptoms, without evidence of lasting repair

A device compared with usual care alone

This multicenter randomized trial assigned 91 participants to two groups: 41 were to receive high-frequency spinal cord stimulation alongside usual medical care, and 50 usual care alone.

The primary endpoint was a reduction of at least 50% in lower-limb pain. The study also assessed sensation using a modified clinical score, the mTCNS, as well as intraepidermal nerve fiber density, sleep and quality of life.

A pain benefit, with a denominator worth watching

In the main analysis reported, 27 of the 34 participants in the stimulation group who underwent a temporary trial phase reached the pain-relief threshold, compared with 2 of the 50 participants receiving usual care alone.

The difference is substantial, but the 34 participants analyzed do not represent all 41 people initially assigned to stimulation. The abstract describes a modified intention-to-treat analysis under a worst-case assumption, without providing the details needed to fully assess the consequences of this selection.

Encouraging sensory results, not proof of regeneration

Among participants with six-month data, a sensory improvement of at least three mTCNS points occurred in 16 of 29 people in the stimulation group, or 55.2%, compared with 12 of 48 in the control group, or 25.0%. These results therefore apply to participants who could be evaluated at that time point.

The mean change in nerve fiber density in the skin of the lower calf was 0.58 fiber/mm with stimulation, compared with −0.07 with usual care alone. Assessments of this density and the mTCNS were performed blinded to group assignment, which adds to their value.

However, this biological difference is not enough to establish lasting nerve repair. The authors suggest a possible disease-modifying effect but note that longer-term confirmation is still needed. Favorable results for sleep and quality of life are also reported, without detailed effect sizes in the abstract.

What we can take away

This trial supports a six-month benefit for pain and certain sensory measures in people with painful diabetic neuropathy. It does not yet establish that spinal cord stimulation provides lasting nerve repair or changes the course of the disease.