Chronic pain

Chronic pain has the following characteristics:

• Persistence or recurrence, especially after 3 months,
• A functional impact on the acts of daily life.

A doctor must make a precise diagnosis. In certain situations, he or she will rely on specialists, such as an approved Chronic Pain Structure.

Chronic neuropathic pain initiated or caused by an injury or dysfunction of the nervous system. It usually occurs as a result of an illness (such as multiple sclerosis, diabetes, shingles, etc.) or injury to the nervous system (e.g. after surgery, trauma, stroke, etc.). It can appear several months after the injury.

Neuropathic pain is characterised by continuous spontaneous painful sensations of burning, intense cold, compression or cramping. There may also be a paroxysmal component such as intense sensations of electric shocks or stabbing.

Associated with these spontaneous pains are painful sensations inappropriately provoked by a normally non-painful stimulus, such as friction or exposure to cold (this is called allodynia). The patient may also experience non-painful sensations such as tingling, pins and needles, itching or numbness in the painful area.

Consequences: About 20% of the population suffers from chronic pain of moderate to severe intensity, and 5% from moderate to severe neuropathic pain¹. Neuropathic pain has a significant impact on quality of life, with psychiatric (depression, anxiety, sleep disorders, etc.) and social (impact on employment, more frequent visits to the doctor, etc.) consequences².

The usual painkillers (paracetamol, aspirin, ibuprofen, etc.) are often not very effective for neuropathic pain.

Depending on the causes of the pain, the symptoms and the individual, the doctor generally uses drugs used elsewhere for other indications, such as antidepressants or antiepileptics. This is because the mode of action of these drugs also has analgesic properties.

It is this analgesic property that is sought with this type of medication.

These treatments must be taken systematically for several months. Their effectiveness sometimes only appears after several weeks, sometimes only on part of the symptoms.

Depending on the results obtained, the doctor will propose new solutions, which may be medicinal or non-medicinal. Transcranial Magnetic Stimulation TMS is one of these solutions.

Transcranial Magnetic Stimulation TMS has been shown to be effective in the treatment of chronic pain, particularly neuropathic pain^{3, 4}. It is recommended as a third-line treatment.

The treatment of chronic pain by Transcranial Magnetic Stimulation TMS generally consists of daily sessions of about twenty minutes repeated for at least two weeks. Because TMS is minimally invasive, these sessions are often performed on an outpatient basis.

During the session, the doctor will select a specific target in the primary motor cortex opposite the location of the pain. This target will be determined precisely according to the symptoms, their location, and the anatomy of each patient. The stimulation of this target will lead to the modulation of the neuronal activity of a cerebral network involved in the regulation of pain.

An initial evaluation after 6 to 8 sessions will allow the doctor to judge the effectiveness and possibly propose an evolution of the stimulated target⁵.

The most frequent side effects of TMS in the treatment of chronic pain are headaches experienced by a third of patients, or discomfort at the stimulation site for 10% of patients⁴ , especially during the first sessions. These side effects generally disappear spontaneously after the session.

Transcranial Magnetic Stimulation TMS reduces pain by 30% for half of the patients, and by 50% for a third of the patients³.