Sensory neuropathy: symptoms, can it be cured?

What is sensory neuropathy?

Sensory neuropathy is a particular and rare form of neuropathy : “In the nervous system, we distinguish the central nervous system comprising the spinal cord and the brain, from the peripheral nervous system, which includes the peripheral nerves. Sensory neuropathy is therefore a disease of the peripheral system, which exclusively affects its sensory part and not the driving part“explains Dr. Frédéric Taithe, neurologist. “THE peripheral sensory neuron concerned by this pathology is composed of a cell body located in the posterior rachidian ganglion, connected to an axon, which corresponds in a way to an electrical cable itself surrounded by a sheath of myelin, serving, among other things, to quickly conduct electricity. These different parts of the peripheral nerve can present a malfunction and be the cause of a particular form of sensory neuropathy”.

What is the evolution of a sensory neuropathy?

Sensory neuropathy is classified according to its evolution over time and its location. This classification makes it possible to guide the etiological assessment, i.e. the search for the diseases or disorders at the origin of the symptoms. The mode of evolution of the symptoms is divided into 3 types:

• acute when the onset of symptoms is sudden and progressive over a few days;
• Sub-acute : the signs appear in a few weeks or even a few months;
• Chronic : Symptoms develop over months to years.

It is necessary to distinguish 3 major types of anatomical damage.

► The sensory polyneuropathy “translates symmetrically, first affecting the extremity of the lower limbs before having an upward evolution, to subsequently affect the upper limbs (length-dependent impairment). Two main types of polyneuropathy exist:

• There polyneuropathy with involvement of large nerve fibers : impairment of fine tactile sensitivity and proprioception (perception of orientation in the space of one’s own body)
• There polyneuropathy with involvement of small intraepidermal fibers : Impairment of gross and thermo-algic sensitivity (increased sensitivity to heat).

► The multiple mononeuropathies are asymmetric and asynchronous (evolution delayed in time). “For example, the median nerve of the left arm is affected, then the ulnar nerve of the right arm, then the nerve of the leg, etc.“, illustrates Doctor Taithe.

► The sensory neuronopathies. It is an attack on the cell body of sensory neurons: “exceptionally, the cell body of the neuron is destroyed and generates a degeneration of the whole sensory neuron. This impairment induces a particular sensory expression asymmetric diffuse, not length-dependent, painful and ataxia (neuromuscular contraction“. Symptoms usually start in the hands, then the legs, or sometimes both at the same time.”Sensory neuronopathies often hide serious illnesses that need to be diagnosed quicklyyou“, adds the neurologist.

What are the symptoms of sensory neuropathy?

“The clinical expression of the disease is variable and depends on the location of the attack and its severity. A patient with this pathology may describe a loss of feeling (hypoesthesia), pain – for example tingling (paraesthesia), burning or a feeling of tightness like a vice- and sometimess balance disorders. The medical examination may show a loss of sensitivity on one or more modes (thermal -hot cold-, pain, fine or coarse tact, proprioception), a proprioceptive ataxia (balance disorder) or even a abolition of osteotendinous reflexes.

What causes sensory neuropathy?

In the case of polyneuropathy with damage to the large nerve fibers, the causes sought are:

• THE inflammatory (or dysimmune) diseases;
• THE vasculitis ;
• THE blood diseases ;
• The causes metabolic (including vitamin B12 and vitamin E deficiency, vitamin B6 overdose))
• THE infectious causes (leprosy and HIV);
• THE toxic causes drugs (chemotherapy);
• hereditysuch as some form of Charcot-Marie Tooth disease.

The causes of small intraepidermal fiber polyneuropathy are:

• metabolic : diabetes (leading cause in industrialized countries);
• toxic : alcohol, drugs;
• infectious (HIV);
• Inflammatory and gammopathy;
• Hereditary : Fabry or Tangier disease;

Sometimes, no cause of these sensory polyneuropathies is identified, we then speak of sensory neuropathy idiopathic“which concerns 1 out of 2 cases, despite a complete assessment.” The main causes of sensory mono-neuropathy are vasculitis, infectious causes (including leprosy) and idiopathic causes. Sensory neuronopathy can be of dysimmune, metabolic, toxic (chemotherapy) or genetic origin.like the CANVAS which is a genetic pathology very recently discovered and which was able to explain a large number of cases whose etiological assessment had remained negative until then“, says Dr. Taithe.

Can sensory neuropathy be cured?

“It all depends on the cause of the sensory neuropathy. In many cases we mainly try toto stop the progression of neuropathy by treating the cause if it has been found and is curable: for example, if the etiology is toxic, the responsible product must be eliminated. If diabetes is the cause of peripheral nerve disease, diabetes must be balanced. If the cause is infectious, it must be treated with antibiotics or antivirals…”explains the neurologist.

“The most important thing is to deal with the cause in the hope of eventually improving the complaints of the patient, but the management of the immediate consequences of this neuropathy should not be neglected. Neurogenic pain is treated with painkillers. If the sensory neuropathy is causing a disturbance in balance, the proprioceptive physiotherapy will be recommended”.

Thanks to Dr Frédéric Taithe, neurologist in the Neurology Department of Clermont-Ferrand University Hospital, head of its reference center for rare neuromuscular diseases.