Peripheral neuropathy can have many causes. These include traumatic injury, infection, metabolic, neurotoxic, genetic, and often poorly regulated diabetes. The variety of causes and symptoms sometimes leads to a delay in the diagnosis and therefore in the effective management of the condition.

1. Definition of peripheral neuropathy

In the nervous system, a distinction is made between the central nervous system and the peripheral nervous system. The central nervous system includes the spinal cord and the brain, while the peripheral nervous system refers to the nerves located outside the spinal cord and the brain. In other words, the peripheral nervous system includes the cranial nerves, the spinal nerves and the billions of nerve cells in the body. The damage to or dysfunction of one or more peripheral nerves is called peripheral neuropathy. When only one nerve is affected, it is called mononeuritis. When several nerves are affected, it is called polyneuropathy or polyneuritis. The causes are very varied, as are the symptoms, which sometimes make the diagnosis difficult. However, this condition is far from rare. According to the journal Pain, in its article entitled "Neuropathic pain in the general population: A systematic review of epidemiological studies", neuropathy affects 7-10% of the population.

2. Symptoms of peripheral neuropathy

The symptoms of peripheral neuropathy form a varied picture depending on the location of the nerve damage, but also on its severity. According to the High Authority for Health, the main symptoms are:

Sensory symptoms: paresthesias (tingling, pins and needles, numbness...), dysesthesias (painful sensations) as well as hypoesthesias (loss of sensitivity) can be observed in the lower limbs, most often, but also moderate or intense pain (burning, a sensation of being held in a vice...), especially at night, and sometimes, balance disorders.
Motor symptoms: motor disorders mainly affect the legs and result in muscle weakness in these limbs, or even paralysis. They are often accompanied by a loss of reflexes.
Neurovegetative symptoms: malaise due to falls in orthostatic tension, erectile and ejaculation disorders, difficulty in urinating, abnormal sweating, diarrhoea or constipation, etc.

3. Causes of peripheral neuropathy

The causes of peripheral neuropathy can be many. There are several hundred of them, the most frequent of which are :

Hereditary causes: indeed, a family history of neuropathy is a frequent cause in France. They are essentially a manifestation of the genetic disease of Charcot-Marie-Tooth.
Neurotoxic causes: certain drugs (particularly those used in chemotherapy for the treatment of cancers, such as vincristine or cisplatin), but also exposure to neurotoxic elements in the diet and in the environment (lead, mercury, industrial chemicals, etc.) can cause peripheral neuropathy. Excessive and regular consumption of alcohol can also be a cause.
Metabolic causes: kidney or liver dysfunction (chronic renal failure, hepatitis), hypothyroidism, poorly controlled diabetes, cancer, AIDS, autoimmune diseases such as rheumatoid arthritis or lupus can lead to the development of peripheral neuropathy.

4. Peripheral neuropathy: when to consult?

In the event of persistent pain that is not relieved by traditional analgesics, or lasting sensory, motor or neurovegetative symptoms, it is important to consult your doctor, who will refer you to a specialist (neurologist, rheumatologist, etc.) if necessary. Indeed, if peripheral neuropathy is not treated, complications may arise. This can be observed in the following cases:

Falls: in the event of muscular weakness or orthostatic discomfort, the person may fall and injure themselves (fracture, head trauma, etc.).
Infections: if the person has hypoesthesia, they may not perceive their wounds, especially on the foot, and allow them to become infected. This can lead to a major gangrene-like infection. This is why, especially for people with diabetes, it is recommended to regularly inspect the feet and areas of the body at risk and to scrupulously disinfect the smallest wounds.
Burns: in the case of paresthesia or hypoesthesia, the patient may not be aware of the excessive heat of the water or the affected surface and may get burned.

5. Investigations and diagnoses of peripheral neuropathy

According to the Canadian Cancer Society, to establish the diagnosis of peripheral neuropathy, the physician, neurologist or rheumatologist relies on several elements:

A discussion with the patient: this involves determining the chronology and evolution of the symptoms, the context of their appearance, the location of the symptoms and the factors that aggravate or alleviate them. But it is also a question of finding out about the existence of similar cases in the family, possible exposure to neurotoxic agents, etc.
A clinical and neurological examination: this aims to analyse muscle strength, reflexes, the functioning of the cranial nerves, sensations, posture and coordination.
An electromyogram (an examination that measures the electrical activity of the muscles) and a nerve conduction examination may be useful. These can determine whether the problem is located in the nerves, the nerve-muscle junction or the muscle.
A biological check-up: analysis of fasting blood sugar to detect possible diabetes, search for hypothyroidism, blood count...
A genetic test: if there is a suspicion of a hereditary disease such as Charcot-Marie-Tooth disease.
A nerve or skin biopsy: a small part of a nerve or skin is removed to detect any abnormality.
A medical imaging test such as an MRI or CT scan, to detect tumours, hernias or other problems.

6. Treatments for peripheral neuropathy

Treatments for peripheral neuropathy have two aims: firstly, to treat the condition that caused the neuropathy and, secondly, to relieve the symptoms. To do this, the doctor has various means at his disposal:

Medicinal treatments: the specialist may prescribe analgesics (such as gabapentin or pregabalin for example), and non-steroidal anti-inflammatory drugs. Anti-epileptic drugs can also help relieve nerve pain, as can certain tricyclic antidepressants (venlafaxine, amitriptyline, etc.). Finally, topical treatments, such as capsaicin cream or lidocaine patches, can help reduce pain.
Non-medicinal treatments: various options are available, depending on the nature of the neuropathy. If there is pressure on one or more nerves, surgery may help to release the compressed nerve(s). Another possibility is transcutaneous electrical nerve stimulation (TENS). This is carried out in a daily session of 30 minutes over a period of one month and consists of diffusing a gentle electric current at variable frequencies on the skin.
A healthy lifestyle: eating a balanced diet rich in fibre, vitamins, antioxidants and lean protein helps to maintain the nervous system. A healthy lifestyle also includes regular physical activity compatible with the state of health: it is recommended to exercise for 30 minutes every day.
Psychological support: as peripheral neuropathy sometimes greatly affects the quality of life of patients, psychological support may be necessary to live as well as possible with this pathology.

Alternative medicine can be a complement in the case of peripheral neuropathy.

7. How to prevent peripheral neuropathy

The best way to prevent peripheral neuropathic disease is to try to limit the risks upstream, i.e. to properly manage the conditions that play a role in its development. This can be achieved through various measures, such as:

Limiting alcohol and tobacco consumption. If necessary, seek the help of an alcohol or drug specialist.
Monitoring blood sugar levels to detect possible diabetes and, if this is the case, having it monitored in order to balance it.
Adopting a healthy diet: eating 5 fresh fruits and vegetables a day, limiting the intake of animal proteins and saturated fats, and getting enough vitamin B12 to keep the nervous system in good condition.
Regular physical exercise, of the order of 30 minutes a day, 5 days a week.
Use good posture to limit pressure on the nerves.
Avoiding exposure to nerve agents in your professional or personal environment.