Pain

In some debates regarding physician-assisted suicide or euthanasia, pain has been used as an argument to permit people who are terminally ill to end their lives.

Euthanasia (from εὐθανασία; "good death": εὖ, eu; "well" or "good" – θάνατος, thanatos; "death") is the practice of intentionally ending a life to relieve pain and suffering.

Pain is usually transitory, lasting only until the noxious stimulus is removed or the underlying damage or pathology has healed, but some painful conditions, such as rheumatoid arthritis, peripheral neuropathy, cancer and idiopathic pain, may persist for years.

It typically results in warm, swollen, and painful joints.

Pain is usually transitory, lasting only until the noxious stimulus is removed or the underlying damage or pathology has healed, but some painful conditions, such as rheumatoid arthritis, peripheral neuropathy, cancer and idiopathic pain, may persist for years.

Pain is classed as acute (short term) or chronic (long term).

Visceral pain is diffuse, difficult to locate and often referred to as distant, usually superficial, structure.

Referred pain, also called reflective pain, is pain perceived at a location other than the site of the painful stimulus.

Most pain resolves once the noxious stimulus is removed and the body has healed, but it may persist despite removal of the stimulus and apparent healing of the body.

It is a prerequisite for nociception, which itself is a prerequisite for nociceptive pain.

Nociceptive pain is caused by stimulation of sensory nerve fibers that respond to stimuli approaching or exceeding harmful intensity (nociceptors), and may be classified according to the mode of noxious stimulation.

Some intense stimuli trigger reflex withdrawal, certain autonomic responses, and pain.

Examples include sprains and broken bones.

Pain

Allodynia is pain experienced in response to a normally painless stimulus.

Allodynia (Ancient Greek άλλος állos "other" and οδύνη odúnē "pain") refers to central pain sensitization (increased response of neurons) following normally non-painful, often repetitive, stimulation.

Local anesthetic injections into the nerves or sensitive areas of the stump may relieve pain for days, weeks, or sometimes permanently, despite the drug wearing off in a matter of hours; and small injections of hypertonic saline into the soft tissue between vertebrae produces local pain that radiates into the phantom limb for ten minutes or so and may be followed by hours, weeks or even longer of partial or total relief from phantom pain.

A local anesthetic (LA) is a medication that causes absence of pain sensation.

Visceral structures are highly sensitive to stretch, ischemia and inflammation, but relatively insensitive to other stimuli that normally evoke pain in other structures, such as burning and cutting.

Clinical manifestations of acute limb ischemia (which can be summarized as the "six P's") include pain, pallor, pulseless, paresthesia, paralysis, and poikilothermia.

Visceral structures are highly sensitive to stretch, ischemia and inflammation, but relatively insensitive to other stimuli that normally evoke pain in other structures, such as burning and cutting. The most common categories are "thermal" (e.g. heat or cold), "mechanical" (e.g. crushing, tearing, shearing, etc.) and "chemical" (e.g. iodine in a cut or chemicals released during inflammation).

Dolor (pain)

Neuropathic pain may be divided into peripheral, central, or mixed (peripheral and central) neuropathic pain.

Central pain syndrome is a neurological condition caused by damage or malfunction in the Central Nervous System (CNS) which causes a sensitization of the pain system.

Phantom pain is pain felt in a part of the body that has been amputated, or from which the brain no longer receives signals.

Phantom limb pain is the feeling of pain in an absent limb or a portion of a limb.

The International Association for the Study of Pain's widely used definition defines pain as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage"; however, due to it being a complex, subjective phenomenon, defining pain has been a challenge. Although unpleasantness is an essential part of the IASP definition of pain, it is possible to induce a state described as intense pain devoid of unpleasantness in some patients, with morphine injection or psychosurgery.

The International Association for the Study of Pain (IASP) is an international learned society promoting research, education, and policies for the understanding, prevention, and treatment of pain.

Examples of injuries that produce superficial somatic pain include minor wounds and minor (first degree) burns.

Although unpleasantness is an essential part of the IASP definition of pain, it is possible to induce a state described as intense pain devoid of unpleasantness in some patients, with morphine injection or psychosurgery.

It can be taken for both acute pain and chronic pain.

Management of breakthrough pain can entail intensive use of opioids, including fentanyl.

Opioids are effective for the treatment of acute pain (such as pain following surgery).

A much smaller number of people are insensitive to pain due to an inborn abnormality of the nervous system, known as "congenital insensitivity to pain".

Congenital insensitivity to pain (CIP), also known as congenital analgesia, is one or more rare conditions in which a person cannot feel (and has never felt) physical pain.

This is usually the result of acquired damage to the nerves, such as spinal cord injury, diabetes mellitus (diabetic neuropathy), or leprosy in countries where that disease is prevalent.

Relatively common conditions which may be associated with diabetic neuropathy include third, fourth, or sixth cranial nerve palsy ; mononeuropathy; mononeuropathy multiplex; diabetic amyotrophy; a painful polyneuropathy; autonomic neuropathy; and thoracoabdominal neuropathy.

Mirror box therapy produces the illusion of movement and touch in a phantom limb which in turn may cause a reduction in pain.

A mirror box is a box with two mirrors in the center (one facing each way), invented by Vilayanur S. Ramachandran to help alleviate phantom limb pain, in which patients feel they still have a limb after having it amputated.

Most people with congenital insensitivity to pain have one of five hereditary sensory and autonomic neuropathies (which includes familial dysautonomia and congenital insensitivity to pain with anhidrosis).

Congenital insensitivity to pain with anhidrosis (CIPA), also called hereditary sensory and autonomic neuropathy type IV, is an extremely rare inherited disorder of the nervous system which prevents the sensation of pain, heat, cold, or any real nerve-related sensations (including feeling the need to urinate); however, patients can still feel pressure.

Most people with congenital insensitivity to pain have one of five hereditary sensory and autonomic neuropathies (which includes familial dysautonomia and congenital insensitivity to pain with anhidrosis).

Familial dysautonomia (FD), sometimes called Riley–Day syndrome and hereditary sensory and autonomic neuropathy type III (HSAN-III), is a disorder of the autonomic nervous system which affects the development and survival of sensory, sympathetic and some parasympathetic neurons in the autonomic and sensory nervous system resulting in variable symptoms, including insensitivity to pain, inability to produce tears, poor growth and labile blood pressure (episodic hypertension and postural hypotension).

Another 20th-century theory was gate control theory, introduced by Ronald Melzack and Patrick Wall in the 1965 Science article "Pain Mechanisms: A New Theory".

The gate control theory of pain asserts that non-painful input closes the nerve "gates" to painful input, which prevents pain sensation from traveling to the central nervous system.

Another 20th-century theory was gate control theory, introduced by Ronald Melzack and Patrick Wall in the 1965 Science article "Pain Mechanisms: A New Theory".

Patrick David "Pat" Wall (25 April 1925 – 8 August 2001) was a leading British neuroscientist described as 'the world's leading expert on pain' and best known for the gate control theory of pain.

Nociceptive pain is caused by stimulation of sensory nerve fibers that respond to stimuli approaching or exceeding harmful intensity (nociceptors), and may be classified according to the mode of noxious stimulation.

This process, called nociception, usually causes the perception of pain.