In emergency departments and at the general practitioner, pain is the primary reason for consultation. A distinction is made between acute pain, which is short-lived, and chronic pain, which develops over time (generally more than 3 months). “Among the latter, neuropathic pain is certainly less common, but it still concerns 7% of the population (1), with a peak between 50 and 64 years old “, says Professor Nadine Attal, neurologist at the pain assessment and treatment center at the Ambroise Paré hospital in Boulogne-Billancourt.
What is neuropathic pain?
“Neuropathic pain arises from a lesion or disease of the nervous system,” explains Professor Nadine Attal. “It can manifest itself both at the level of the peripheral nervous system with, for example, surgical trauma to a nerve, as well as at the level of the central nervous system (spinal cord and brain) which carries pain signals.”
Damaged nerve fibers are likely to transmit erroneous information. In seemingly normal areas of the body, the “misinformed” person may then feel very real pain. Another characteristic is that neuropathic pain can affect a very limited area of the body, such as a finger, or extend to an area as large as half the body.
Diagnosis is based primarily on questioning and clinical examination. Further examinations are sometimes necessary to confirm the nature of the nerve damage. Long considered an enigmaneuropathic pain is now better understood, underlines Professor Attal. The use of increasingly developed “patient” questionnaires also constitutes a valuable aid to a diagnosis that is not always clear or easy to make.
What could be the causes?
“There are a multitude of causes that can lead to neuropathic pain,” says Professor Attal. “And sometimes the cause is not found, as in certain neuropathies.” So-called peripheral neuropathies can appear following a sciaticaand areaand diabetescancer or even skin trauma (scar, damaged or even severed nerve) after surgery.
Thus, operations for inguinal hernias (in the groin) or disc hernias (in the back) can generate this type of pain. They can also appear after breast removal (mastectomy) or lung surgery (thoracotomy). In the case of surgery for amputation of a limb or organ, the pain is then located at the level of the stump or in the ” phantom limb » (something-hallucinose).
At the level of the central nervous system, the lesions can be consecutive to a stroke (AVC), multiple sclerosisspinal cord injury as in paraplegia, severe head trauma. Depending on the case, the duration of these pains, unrelated to the severity of the disease, can vary greatly over time.
Symptoms common to all neuropathic pain
“Neuropathic pain presents very specific and fairly similar symptoms, whether they are of peripheral or central origin,” describes Professor Attal. Patients describe burning, tingling, prickling, numbness sensationsbut also of vice, of compression. When this reaches its paroxysm, they even speak of electric shocks and of stab wounds. » On examination, there is often a decrease in sensitivity in the area of pain, and sometimes even a complete loss of sensitivity. This is called painful anesthesia.
These pains, which appear spontaneously, are often increased by cold, heat, or the simple friction of clothing. They can also be increased by fatigue, stress, or negative emotions. They are accompanied by sleep and mood disorders. Social, family, and professional life are frequently affected, with fewer leisure activities, more time off work, and progressive isolation.
Drug treatments to relieve pain
“It is important to treat pain as soon as it appears, even in the absence of a clearly established cause or while waiting to find its origin,” observes Professor Attal. And to insist with patients on the absolute necessity, alongside drug or other treatments, of practice a physical activityknowing that all studies have shown that physical activity improves pain.”
Neuropathic pain do not respond to conventional painkillerssuch as aspirin, ibuprofen or paracetamol. Some molecules used to treat other diseases have shown, in use, an analgesic action. Pain specialists thus prescribe antidepressantsespecially from the tricyclic family and other antidepressants such as duloxetine. They also rely on antiepileptics, such as gabapentin and pregabalin. All of these drugs modulate nervous hyperexcitability and calm the transmission of the pain message. But they also cause side effects (drowsiness, weight gain, decreased libido, etc.) that are often dissuasive.
“When neuropathic pain is peripheral and localized, local treatments can be used with much fewer side effects, such as lidocaine plasters,” notes Professor Attal. “This is also the case for capsaicin, the active component of chili pepper, applied in the form of high-concentration skin patches. But since this treatment first causes a burn, it is only offered in hospital.”
Innovative treatments and complementary therapies
“The most severe cases require specific care in centers specialized in pain treatment,” concludes Professor Attal. “These structures can offer innovative treatments such as botulinum toxin or transcutaneous electrical stimulation (TENS), or even in some structures repetitive transcranial magnetic stimulation (rTMS). These neurostimulation techniques offer the advantage of absolute safety, but the waiting times are often too long for rTMS for patients who are sometimes in great pain.”
Finally, spinal cord stimulation, a more invasive technique which consists of installing an electrode at the level of the spinal cord connected to an implanted stimulator, offers good results in some of these pains, notably those linked to chronic sciatica.
Psychocorporeal approaches such as physiotherapy, often in association with the aforementioned treatments, can also be interesting ways to help the patient modify the relationship they have with pain.
