Paresthesia

Paresthesia (from Greek para — alongside, deviation and aisthesis — sensation) is a qualitatively altered, spontaneously occurring unpleasant sensation on the skin, which appears without any visible external physical stimuli.

Patients most commonly describe this phenomenon as the sensation of “crawling ants,” tingling, burning, or the passage of a mild electrical current.

Etiology and pathophysiology

The pathophysiological basis of this symptom is the local irritation (stimulation) of the sensory fibers of a peripheral nerve, nerve root, or sensory conducting pathways in the spinal cord. Mechanical impact leads to alterations in the permeability of axonal ion channels and the generation of ectopic (abnormal, chaotic) nerve impulses.

In traumatology, the most common cause of paresthesia is acute mechanical compression of the nerve by a displaced bone fragment, growing hematoma, or tissue swelling. This symptom can also be caused by transient ischemia of the nerve trunk, for example, due to prolonged and improper application of a tourniquet to a limb.

Clinical significance

Paresthesia is an exceptionally important early clinical marker of compressive-ischemic nerve injury. Its precise localization on the body allows the physician to accurately determine (topically diagnose) the level of the affected nerve or root even before instrumental examinations are conducted.

It is important to clearly distinguish paresthesia from hyperesthesia (painfully increased sensitivity to ordinary touch) and anesthesia (complete loss of sensation). Persistent post-traumatic paresthesia is a warning signal requiring immediate surgical release of the nerve to prevent irreversible damage.