Chronic pain, regardless of its origin, represents a major challenge for individuals who suffer from it on a daily basis. This is pain that lasts over time, impacts the quality of life of patients and can lead to significant psychological, social and professional consequences. In this context, the search for effective therapeutic solutions is essential. Could neurostimulation offer an effective solution against chronic pain? What exactly do we mean by neurostimulation?
Transcutaneous electrical nerve stimulation (TENS)
Transcutaneous electrical nerve stimulation (TENS) is a method of non-drug analgesia used for more than 30 years to treat chronic pain, particularly recognized in the management of localized peripheral neuropathic pain. Used appropriately, its success rate exceeds 60%.
This approach, supported by scientific evidence, uses low-intensity electrical current to influence pain transmission pathways in the nervous system, providing symptomatic relief. It is carried out using a portable device equipped with adhesive electrodes applied to the skin, thus targeting specific points on the body.
TENS is often considered as a complement or alternative to drug treatments for chronic pain, with main indications including peripheral neuropathic pain, chronic low back pain, fibromyalgia syndrome and migraines . This technique thus offers a versatile therapeutic option in the management of various forms of chronic pain.
Action mechanisms
The mechanisms of action of TENS rely on two key neurophysiological processes aimed at attenuating the sensation of pain. First, it stimulates large diameter nerve fibers (A-beta fibers), responsible for transmitting tactile signals to the brain. This stimulation inhibits the transmission of pain signals carried by small nerve fibers (C and A-delta fibers), thus modifying the perception of pain. At the same time, TENS promotes the secretion of neurotransmitters which block pain receptors . Complementarily, this method also encourages the release of endorphins , natural substances produced by the body that act as natural painkillers. Thus, TENS orchestrates a complex modulation of pain transmission pathways, providing effective and multidimensional relief.
Advantages of this technique
TENS has several significant advantages in the treatment of pain:
- It can help reduce medication use , providing an effective and potentially safer alternative for pain relief.
- It offers flexibility in its application depending on the patient's needs, since it can be used during each painful episode.
- It makes the patient independent in the management of their pain. By promoting a more active and participatory approach, this method allows individuals to better control their own well-being and adjust treatment according to the intensity of the pain.
- It is also distinguished by its ease of administration as well as its low cost . This technique can sometimes even be reimbursed by social security under certain conditions, such as the obligation to be trained by a health professional with a university degree in pain.
- It also has no major side effects . The rare adverse reactions reported are generally minor, often limited to mild skin irritation at the electrode placement site.
However, it is important to note certain contraindications to transcutaneous electrical nerve stimulation. It is not recommended to apply TENS to an injured or numb skin region. Likewise, application to specific regions such as the anterior cervical, thoracic region, carotid sinuses, or abdomen in pregnant women should be avoided. TENS should also not be used in the presence of an active implantable medical device, while an electrocardiogram or electroencephalogram is being performed, and in cases of venous or arterial thrombosis or thrombophlebitis. These contraindications highlight the importance of a thorough medical evaluation before initiating transcutaneous electrical neurostimulation.
Spinal cord neurostimulation
Spinal cord neurostimulation is another medical device that also helps fight chronic pain. Its principle is quite similar to TENS, since it aims to modulate the activity of the nervous system using low intensity electrical impulses.
However , its method of administration is much more invasive . Electrical stimulation is delivered through electrodes surgically implanted in the upper cords of the spinal cord. This technique helps relieve pain in 50 to 80% of cases.
Although the exact mechanisms of action of spinal cord neurostimulation remain partially understood, the predominant hypothesis suggests that it causes the release of inhibitory neurotransmitters, thereby blocking the brain's perception of pain . The current emitted would thus replace the pain. Additionally, this stimulation could influence neural circuits to attenuate the neuronal hyperactivity associated with chronic pain.
When to use spinal cord neurostimulation?
Regarding pain management, neurostimulation is considered as a last resort for the management of chronic pain, particularly in situations where drug treatments or non-interventional techniques have not provided satisfactory results. It is therefore considered as an option when other methods of pain control have failed.
The High Authority of Health has also established specific indications for spinal cord neurostimulation:
- Chronic pain of neuropathic origin persisting for at least one year, after the failure of therapeutic alternatives (resulting from a chronic radicular or truncal pain syndrome of diabetic, herpetic, traumatic or surgical origin).
- Chronic pain of ischemic origin, after the failure of therapeutic alternatives (resulting from Buerger's disease).
- Complex regional pain syndromes type I or II persisting for at least six months.
A treatment to be considered with caution
Neurostimulation remains a treatment that is far from trivial and requires a certain number of precautions. A thorough assessment of the patient and additional tests are therefore necessary before recommending any treatment.
Before considering spinal cord neurostimulation, carrying out a preimplantation assessment is an obligatory step. This assessment includes a pain assessment, a psychosocial assessment, as well as an assessment of quality of life. It must be carried out within a structure specialized in the treatment of chronic pain, requiring the collaboration of a multidisciplinary team including at least an algologist and a psychologist or psychiatrist. A spinal cord MRI must also be available.
To complete this procedure, a neurological assessment must be carried out. Finally, temporary stimulation tests must be carried out prior to implantation to evaluate the patient's individual response to this therapeutic modality.
It is essential to note that there is a significant likelihood of reintervention , given potential risks such as electrode displacement, electrode fracture, or infection. And, although the implantation is reversible, it is designed to be maintained for life.
In short, neurostimulation offers promising solutions to alleviate chronic pain. Both transcutaneous electrical nerve stimulation and spinal cord neurostimulation have significant advantages in pain management, although their mechanisms and applications differ. TENS, less invasive and more flexible, proves effective in many cases, while spinal cord neurostimulation is reserved for the most severe situations. These techniques, although they do not remove the source of pain, provide valuable relief, thus highlighting the importance of their integration into chronic pain treatment protocols.
References :
French Society for the Study and Treatment of Pain. (February 26, 2021). Transcutaneous electrical neurostimulation, a non-drug analgesic therapy.
Dr M. Lévêque, pain surgery. TENS.
High Authority of Health. (March 2014). Implantable spinal cord neurostimulators: a technique of last resort .
Vidal. (April 27, 2023). Spinal cord neurostimulation to tackle chronic neuropathic pain.
