LUNA Explains : Treatments For Neuropathic Pain

Neuropathic pain is, by definition, pain caused by injury or dysfunction of the nerves, spinal cord or brain.

It can be caused by:

• Compression of a nerve (e.g., carpal tunnel syndrome due to compression of the median nerve in the wrist)
• Injury (e.g., peripheral nerve injury due to diabetes)
• An abnormality in the processing of the pain message by the spinal cord or brain (e.g., phantom limb pain after amputation or mastectomy)

In France, neuropathic pain affects 7% of the general population.

The diagnosis of neuropathic pain is clinical, i.e., it is the patient’s description of the pain that leads to the diagnosis.

It is a particular type of pain, the patient describes “strange” sensations which can be spontaneous (burning, sensation of a vice, discharges, stabbing) and/or provoked (tingling, numbness, itching).

On clinical examination, one often finds :

• hypoesthesia (decreased sensitivity) or anesthesia (loss of sensitivity)
• allodynia (pain induced by normally painless stimulation)
• hyperalgesia (excessive pain in response to a painful stimulus)

Neuropathic pain responds poorly to the painkillers usually used, including morphine.

The therapeutic arsenal will therefore be very different from that used for “classic” pain.

When neuropathic pain is located, local treatments can be used:

Lidocaine is a local anesthetic available, among other things, as a plaster.

This treatment is particularly effective for allodynia.

Lidocaine works by preventing the propagation of the electrical signal along the nerves.

The patient places the patch on the painful area. He can use 1 to 3 patches, depending on the extent of the painful area, for up to 12 hours a day.

Capsaicin (the active compound in chili peppers) is present in the patch in high concentration: 8%.

The patch acts by desensitizing the small epidermal nerve fibers in a reversible manner.

The patch is applied in a hospital by doctors or pain nurses trained in the technique.

The patch is applied for 30 to 60 minutes depending on the areas to be treated. A maximum of 4 patches can be applied at one time. The patch is reapplied every 2–3 months.

The capsaicin patches allow a reduction in pain equal to or greater than 30% in 42 to 70% of patients, with a reduction or even a cessation of medical treatments.

Botulinum toxin has two interesting properties for the treatment of pain:

• A paralyzing action by blocking the release of acetylcholine
• An analgesic action by blocking the neurotransmitters involved in pain (glutamate, substance P…)

Botulinum toxin is administered subcutaneously or intradermally to the painful area.

This is a non-medicinal, non-invasive, scientifically validated pain treatment that is reimbursed by social security when prescribed by an algologist (pain doctor).

The principle of the treatment is based on the stimulation of peripheral nerve fibers using electrodes glued to the skin and connected to an external box which generates an electric current.

rTMS is a recent and rapidly developing neurostimulation technique that can relieve chronic intractable pain, particularly neuropathic pain.

rTMS is a non-invasive technique that acts on the electrical activity of the brain and its functioning thanks to a coil placed in contact with the patient’s skull which induces an electromagnetic field.

It reduces the perception of the painful message.

The rTMS sessions take place in a hospital ward, by a qualified technician, under the supervision of a doctor. The effect is prolonged if the sessions are repeated, each session lasting 20 to 30 minutes.

This technique is used in several fields: pain, tinnitus, depression resistant to drug treatments, etc.

This is an invasive neurostimulation technique which consists of implanting a stimulation electrode in the spinal cord. The electrode is connected to an external neurostimulation box.

This technique is recommended for treating chronic pain that is resistant to any treatment. The indication for the technique is subject to a multidisciplinary assessment.

The decision is taken after studying the medical file in a multidisciplinary consultation meeting.