Chemotherapy-induced peripheral neuropathy (CIPN) is a frequent and debilitating side effect of many cancer treatments. It affects 28 to 48% of patients receiving chemotherapy. Symptoms include tingling, numbness, burning sensations, and pain mainly in the hands and feet. While CIPN often improves after chemotherapy ends, in some patients the pain persists and becomes chronic, severely impairing quality of life, sleep, and daily functioning.

Currently, no treatment has been shown to prevent CIPN. For patients with chronic pain, duloxetine is the only recommended drug, but its efficacy is limited. When standard medications fail, patients have very few options.

Spinal cord stimulation (SCS) is a well-established neurosurgical technique used to treat various forms of chronic neuropathic pain, including pain after surgery, trauma, or diabetes. In this procedure, thin electrodes are placed in the epidural space near the spinal cord and connected to a small implantable pulse generator. The electrical impulses delivered by the device modulate pain signals in the nervous system.

Preliminary case reports suggest that SCS may be effective in patients with CIPN, but no randomized controlled trial has yet established its value in this specific indication. The CHEMOSTIM study aims to fill this gap.

CHEMOSTIM is a multicenter, prospective, randomized crossover trial. All enrolled patients will undergo SCS implantation. Participants will then be randomized to receive either active stimulation first followed by sham stimulation, or sham stimulation first followed by active stimulation. In the sham phase, the device is implanted but switched off following a simulated programming session, so patients cannot tell which phase they are in.

The primary outcome is the proportion of patients achieving more than 50% pain reduction on a Visual Analog Scale (VAS) during the active stimulation phase compared to the sham stimulation phase, assessed at 4 months.

Secondary outcomes include changes in quality of life, anxiety and depression, sleep quality, medication use, individualized goal attainment, neurological examination, and nerve conduction studies. The study will also evaluate post-stimulation effects and complications.

Eligible patients are adults with chronic CIPN evolving for at least one year, with pain greater than 5/10 in the lower limbs, who have failed at least two lines of pharmacological treatment (antidepressants, anticonvulsants, topical agents, etc.) and whose indication for SCS has been validated by a multidisciplinary team following SFETD/SFNM guidelines.

Inclusion Criteria:

1. Adult patient with chemotherapy-induced painful neuropathy (platinum salts, vincristine, taxanes, alkaloids, epothilone, thalidomide, etc.) evolving for at least 1 year
2. Indication for spinal cord stimulation validated by a multidisciplinary team meeting according to SFETD/SFNM guidelines
3. Resistance to pharmacological or topical treatment (failure of at least two therapeutic lines or intolerable side effects: anticonvulsants, antidepressants, capsaicin, etc.)
4. Pain score > 5/10 on numerical scale in the lower limbs
5. Patient able to understand and give informed consent to the protocol
6. Patient affiliated to the French Social Security system
7. Patient able to complete follow-up questionnaires

Exclusion Criteria:

• 1. Contraindication to spinal cord stimulation:

• Extensive laminectomy

• Coagulopathy

• Intercurrent infections

• Psychiatric disorders

  2. Body Mass Index (BMI) > 40

  3. Life expectancy < 1 year

  4. Ongoing pregnancy

  5. Patient under guardianship or curatorship

  6. Patient already implanted with a spinal cord stimulation device

Participants are blinded to the stimulation sequence (active vs. sham). Blinding is maintained through a simulated programming session at the start of the sham phase, making it impossible for participants to determine whether stimulation is active or inactive. The surgeon and clinical team are not blinded. The outcome assessor performing pain and functional evaluations is blinded to the sequence allocation.