Paresthesia: causes, treatment and associated phenomena.

A neurological symptom that should receive professional attention if it persists over time.

When a nerve is subjected to physical pressure (as happens when we fall asleep with our head on an arm, for example), abnormal sensations such as tingling or numbness are common. This phenomenon is known as paresthesia, and sometimes has a chronic and pathological character..

In this article we will describe the causes and treatment of chronic paresthesia. We will also describe synthetically other similar sensory disturbances, many of them characterized by the appearance of pain, unlike paresthesia.

What is paresthesia?

Paresthesia is a phenomenon that consists of the appearance of prickling, tingling, itching, numbness or burning sensations in different parts of the body.. It most commonly occurs in the arms, hands, legs and feet, although it does not always occur in these areas. It is usually not associated with pain symptoms.

The term "paresthesia" comes from the Greek words "aisthesia", which means "sensation", and "para", which can be translated as "abnormal". The word came into common usage in the 19th century, although some earlier occasional reference can be found in classical Greek literature.

Experiences of paresthesia are relatively common in the general population, so they do not always merit consideration as pathology or disturbance. For example, it is common for sensations of this type to occur when a limb is numbed by sustained pressure from a nerve.as can happen when crossing the legs.

Cases of chronic paresthesia, on the other hand, are considered medical problems. This type of paresthesia occurs as a consequence of disorders affecting the central nervous system, as well as severe lesions of the peripheral nerves; when this happens it is common for paresthesia to have a painful component.

Causes

Transient, non-pathological paresthesia occurs when a nerve is pressurized and disappears shortly after the pressure is interrupted. In contrast, chronic paresthesia is a sign of lesions in the central or peripheral nervous system.

Transient paresthesia is also related to hyperventilationincluding that occurring in the context of anxiety crises, and with herpes virus infection. However, in most cases these experiences are due to unnatural postures for the body.

Among the disorders that affect the central nervous system and are associated with the occurrence of chronic paresthesia are multiple sclerosis, encephalitis, transverse myelitis and ischemic stroke. Tumors that press on certain regions of the brain or spinal cord can also cause this type of paresthesia.

Peripheral nerve compression syndromes are also common causes of chronic paresthesia accompanied by painful sensations. This group of disorders includes carpal tunnel syndrome, in which the median nerve is compressed inside the carpal tunnel, a group of bones in the wrist.

Other common causes of paresthesia include diabetes, rheumatoid arthritis, circulatory problems, and other conditions. (for example in cases of atherosclerosis), malnutrition, metabolic disorders such as diabetes and hypothyroidism, systemic lupus erythematosus, alcohol abuse and benzodiazepine withdrawal syndrome.

Treatment of this disorder

The treatment of chronic paresthesia is mainly aimed at correcting the underlying causes of the disorder.It is usually accompanied by other physical and cognitive symptoms of greater significance when it affects the central nervous system. Cases of transient paresthesia do not require any type of intervention since they are normal phenomena.

Depending on the underlying alteration, one or another drug will be used. Some of the most commonly used drugs include Antiviral drugs, anticonvulsants, the corticosteroid prednisone or intravenous injection of gamma globulin.

On the other hand, topically applied medications, such as lidocaine, are sometimes prescribed to reduce paresthesia sensations when they are bothersome or painful in themselves. Of course, this type of treatment only relieves symptoms temporarily, but may be necessary in cases where the cause cannot be eliminated.

Associated sensory phenomena

There are various sensory phenomena similar to paresthesia.. Dysesthesia, hyperesthesia, hyperalgesia and allodynia, among others, are abnormal sensations that occur as a result of certain types of stimulation.

Dysesthesia

The term "dysesthesia" is used to refer to the occurrence of abnormal sensations that are unpleasant; in other words, it is a painful or uncomfortable variant of paresthesia.

2. Hyperesthesia

We call hyperesthesia an increase in pain sensitivity, i.e., a reduction of the pain threshold. This phenomenon includes allodynia and hyperalgesia.

3. Hyperalgesia

Hyperalgesia is the increased perception of pain in the presence of painful stimuli. The source of the sensation and the sensation occur in the same sensory modality (e.g., a pinprick causes mechanical pain).

4. Allodynia

Allodynia consists of the occurrence of pain sensations in response to objectively non-painful stimuli. The sensory modality of the stimulus and the sensation need not be equivalent.