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 one arm, for example) it is common to produce abnormal sensations such as tingling or numbness. This phenomenon is known as paresthesia, and it is sometimes chronic and pathological.
In this article we will describe the causes and treatment of chronic paresthesia. We will also synthetically describe 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 stinging, tingling, itching, numbness or burning sensations in different parts of the body. It is more common to occur in the arms, hands, legs and feet, although it does not always occur in these areas. It is generally 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 began to be used on a regular basis in the 19th century, although some specific previous reference can be found in classical Greek literature.
Paresthesia experiences are relatively common in the general population, so they do not always merit the consideration of pathology or alteration. For example, it is common for sensations of this type to appear when a limb becomes numb due to sustained pressure of 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 that affect the central nervous system, as well as severe peripheral nerve injuries; when this happens it is common for paresthesia to have a painful component.
Transient, non-pathological paresthesia occurs when a nerve is under pressure and disappears shortly after it is interrupted. In contrast, chronic paresthesia is a sign of lesions in the central or peripheral nervous system.
Transient paresthesia is also associated with hyperventilation, including that which occurs in the context of panic attacks, and with herpes virus infection. However, in most cases these experiences are due to postures that are not natural for the body.
Among the alterations that affect the central nervous system and are associated with the appearance of chronic paresthesia are multiple sclerosis, encephalitis, transverse myelitis and ischemic cerebrovascular accidents. 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. Among this group of alterations, it is worth highlighting the carpal tunnel syndrome, in which the median nerve is compressed within the carpal tunnel, a group of bones in the wrist.
Other common causes of paresthesia include diabetes, rheumatoid arthritis, circulatory problems (for example in cases of atherosclerosis), malnutrition, metabolic disturbances such as diabetes and hypothyroidism, systemic lupus erythematosus, alcohol abuse, and benzodiazepine withdrawal syndrome.
Treatment of this alteration
The treatment of chronic paresthesia is fundamentally aimed at correcting the ultimate causes of the disorder, which is also 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 the other drug will be used. Some of the most commonly used include antiviral medications, anticonvulsants, the corticosteroid prednisone, or intravenous injection of gamma globulin.
On the other hand, topical medications such as lidocaine are sometimes prescribed to reduce the sensations of paresthesia when they are bothersome or painful in themselves. Of course, this type of treatment only relieves symptoms temporarily, but it may be necessary in cases where the cause cannot be eliminated.
Associated sensory phenomena
There are different 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.
The term “dysesthesia” is used to refer to the appearance of abnormal sensations that are unpleasant; In other words, it is a painful or annoying variant of paresthesia.
We call hyperesthesia the increase in sensitivity to pain, that is, a reduction in the pain threshold. This phenomenon includes allodynia and hyperalgesia.
Hyperalgesia is the increased perception of pain in the presence of painful stimuli. The source of sensation and sensation occur in the same sensory modality (eg, a pin prick causes mechanical pain).
Allodynia consists of the appearance of pain sensations in response to objectively non-painful stimuli. The sensory modality of stimulus and sensation do not have to be equivalent.