10-kHz spinal cord stimulation relieved pain and improved sensation in diabetic neuropathy

Design

Multicentre randomised controlled trial, blinded sensory and biopsy assessment

Population

91 adults with painful diabetic neuropathy

Primary outcome

At least 50% lower-limb pain relief

Effect

27/34 vs 2/50 responders; sensory improvement 55.2% vs 25.0%

PDN-Sensory randomised 91 people with painful diabetic neuropathy to high-frequency (10-kHz) spinal cord stimulation plus conventional medical management or conventional management alone. Sensory scoring and skin biopsies were assessed by staff blind to allocation.

In a worst-case modified intention-to-treat analysis, 27 of 34 who underwent a temporary stimulator trial reached at least 50% pain relief, against 2 of 50 on medical management. At six months, sensory scores improved by three points or more in 55% with stimulation and 25% without. Intraepidermal nerve fibre density rose by 0.58 fibres/mm with stimulation and fell by 0.07 without. Eight of ten hierarchical secondary endpoints, including sleep and quality of life, were met.

The pain result repeats earlier trials. The sensory and nerve-fibre gains are new but modest, run to six months, and need longer follow-up before anyone calls this disease-modifying. The procedure is invasive, costly and available at few centres in India.

• Consider referral for a spinal cord stimulation assessment when neuropathic pain persists despite adequate trials of first-line drugs.
• Document an adequate trial of duloxetine, pregabalin or gabapentin, or amitriptyline, with doses and duration, before referral.
• Explain that a temporary trial comes first, and only responders go on to a permanent implant.
• Keep optimising glucose control and foot care; stimulation does not replace either.

Why it matters

It gives refractory neuropathic pain a tested option beyond adding another centrally acting drug.

Don't overread it

Six months of nerve-fibre data cannot show that stimulation changes the course of the neuropathy.

The statistics, in plain English

The pain result is large: about four in five of those who underwent a temporary trial (27 of 34) responded with stimulation, against one in 25 (2 of 50) on medical management. The sensory result (55% vs 25%) is counted only among those with six-month data, which makes it less certain. The trial was not blinded for pain, which patients rate themselves, so part of the pain effect may reflect expectation; the biopsy and sensory scores were blinded and are harder to explain that way.

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