Paresthesia

Paresthesia is an abnormal skin sensation that occurs without any prior stimulus. It is usually perceived as tingling, numbness, itching, or mild prickling sensations. Although it can occur anywhere in the body, paresthesia is more common in the arms, hands, legs, and feet.

There are two types of paresthesia depending on how it manifests:

• Transient paresthesia: temporary in nature, as it disappears within a few minutes, or even seconds, after changing position or relieving pressure. It is commonly described as having a "fallen asleep" limb.
• Chronic paresthesia: skin sensitivity is persistently altered and does not disappear with movement. In some cases, it may last for years. It is a manifestation of an underlying condition usually associated with nerve damage.

Limb sensation may be affected in different ways:

• Reduced sensation:
  • Hypoesthesia: decreased sensitivity.
  • Anesthesia: complete loss of sensation.
  • Hypalgesia: reduced ability to perceive pain.
• Increased sensation:
  • Hyperesthesia: stimuli are perceived as intensified.
  • Dysesthesia: unpleasant sensations are perceived despite the absence of prior stimuli.

It may be a symptom of many different diseases, making a thorough evaluation necessary to determine its origin. Most patients experience transient paresthesia, so the prognosis is very good and does not leave sequelae. However, chronic paresthesia requires specific treatment for the underlying cause, which may be serious.

Symptoms

Paresthesia is characterized by the following symptoms:

• • Numbness.
• Tingling.
• Loss of sensation.
• Itching.
• Burning sensation.
• Sensation of coldness.
• Difficulty contracting the muscles in the affected area.

If any of the following warning signs appear, immediate medical attention should be sought:

• Changes in vision.
• Difficulty speaking.
• Altered level of consciousness.
• Previous trauma to the head, neck, or back.

Causes

Temporary paresthesia is usually the result of temporary nerve compression, for example, when maintaining the same position for a prolonged period of time. The causes of chronic paresthesia, however, are usually more serious conditions:

• Multiple sclerosis: chronic autoimmune disease in which the body attacks myelin, the layer that protects nerve fibers.
• Fibromyalgia: chronic disease that causes widespread pain, severe fatigue, and sleep problems.
• Peripheral neuropathy: damage to the peripheral nerves that are neither in the brain nor the spinal cord.
• Diabetic neuropathy: nerve damage caused by high blood sugar levels.
• Stroke: interruption of blood flow to the brain as a result of rupture (hemorrhage) or blockage (ischemia) of a blood vessel.
• Cerebral aneurysm: weakening of one of the brain arteries that presents as a bulge. There is a high risk of rupture and hemorrhage.
• Encephalitis: inflammation of the brain caused by an autoimmune disease or an infection.
• Herniated disc: part of the central nucleus of an intervertebral disc protrudes through a tear in the outer ring, compressing the nerves.
• Transverse myelitis: rare disease in which both sides of a segment of the spinal cord become inflamed.
• Herpes zoster infection: very painful infection caused by reactivation of the varicella-zoster virus.
• Spinal stenosis: narrowing of the spinal canal leading to compression of the nerve roots.
• Carpal tunnel syndrome: compression of the median nerve as it passes through the wrist.
• Reduced blood flow.
• Anxiety: hyperventilation caused by anxiety may alter oxygen and carbon dioxide levels in the blood, causing paresthesia.
• Stress: the release of hormones such as cortisol or adrenaline results in changes in blood flow and hyperventilation.
• Migraines.
• HIV infection.
• Syphilis: when left untreated and progressing to advanced stages, affecting the nervous system (neurosyphilis).
• Nutritional deficiencies: deficiency of vitamins B12 and E, which are essential for nerve function, may cause nerve damage.
• Heavy metal poisoning, such as lead or mercury poisoning.
• Certain antibiotics.
• Chemotherapy.
• Radiation therapy.
• Injuries to the head, neck, or back.
• Animal bites.
• Insect stings.

Risk factors

Factors that increase the risk of developing paresthesia include:

• Age: more common between 30 and 60 years of age.
• Hyperglycemia: higher-than-normal blood glucose levels may damage the blood vessels that nourish peripheral nerves.
• Diabetes: associated hyperglycemia may cause neuropathy.
• Hypothyroidism: hormonal deficiency may lead to fluid retention and, consequently, nerve compression.
• Exposure to blows and trauma.
• Excessive alcohol and tobacco consumption.
• Dental procedures: in some cases, they may damage facial nerves.

Complications

The most common complications of paresthesia are:

• Loss of sensation, increasing the risk of trips and falls.
• Secondary injuries caused by lack of sensation in an area of the body, such as cuts, burns, or wounds.
• Difficulty performing daily activities.
• Problems speaking or chewing.
• Muscle atrophy when paresthesia persists for a long time.
• Sleep disturbances due to persistent burning or prickling sensations.
• Chronic pain.
• Dependence.
• Anxiety.
• Depression.

Which doctor treats paresthesia?

Paresthesia is usually treated within the specialties of Neurology or Neurosurgery. Depending on the underlying disease causing the symptom, specialists in Dentistry, Oral and maxillofacial surgery, Physical Therapy, Endocrinology and Nutrition, or Pain management unit may also be involved.