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One of the most important functions of peripheral nerve cells is to alert a person to tissue injury and noxious stimuli or events in their environment. Normally, pain is a signal of imminent or actual harm to the body that initiates protective reflexes to prevent or minimize that danger. When tissue damage occurs, the resulting pain prompts special attention to the affected area and the person responds either by removing the source of danger (e.g. pulling a hand away from a hot object) or by initiating treatment quickly. The pain which is felt in response to a harmful stimulus is known as nociceptive pain. It is caused by stimulation of certain pain receptors and is generally described as sharp, aching, or throbbing. It is also the type of pain felt in some chronic, painful conditions (e.g., arthritis).

However, when pain occurs in the absence of dangerous stimuli, does not prompt protective reflexes, nor subsides when the danger is past or when the injury has healed, it is said to be maladaptive or dysfunctional and is called neuropathic pain. The nervous system malfunctions and becomes the cause of the pain. This type of pain serves no protective or biological function. It may or may not be triggered by an injury and can persist for years or decades. It is often described as burning, electric, tingling and/or shooting pain and can be continuous or intermittent. Symptoms of neuropathic pain tend to predominate in the peripheral limbs (in the feet more than in the hands) but can also appear in different locations (e.g., in the cranial nerve as trigeminal neuralgia).