Paresthesia (or paraesthesia) is an abnormal dermal sensation (e.g., a tingling, pricking, chilling, burning, or numb sensation on the skin) with no apparent physical cause. The manifestation of a paresthesia may be transient or chronic, and may have any of dozens of possible underlying causes. Paresthesias are usually painless and can occur anywhere on the body, but commonly occur in the extremities (e.g., hands, feet, arms, or legs).
The most familiar kind of paresthesia is the sensation known as "pins and needles" or of a limb "falling asleep". A less well-known and uncommon but important paresthesia is formication, the sensation of bugs crawling underneath the skin.