What is Pain?

Pain is an unpleasant sensation that can range from a mild, localized discomfort to agonizing pain that is localized or spread out. Pain has both a physical and an emotional component. The physical part of pain results from stimulation of the nervous system. Pain may be contained to a discrete area, as in a specific injury such as a back sprain or it may be a diffuse pain as in fibromyalgia. Pain is mediated by specific nerve fibers that carry the pain impulses to the brain where their conscious appreciation may be modified by a multitude of factors.

Acute pain is pain that comes on quickly, can be severe, but lasts a relatively short period of time. Pain that lasts longer than 90 days would be considered chronic pain.

Chronic pain is defined as pain that lasts longer than 3 months. However, some experts define it as lasting longer than 6 months. Chronic pain is different than acute pain in that it is often difficult to find the cause. The medical diagnosis may reveal no injury in the body at all, and yet the patient can be experiencing very debilitating pain.

One way that chronic pain begins is from an injury. Scientists have found that repeated pain from an acute injury changes the way the brain perceives that you know you have pain. Even after the acute injury has healed, pain messages can often replay over and over again in the brain.

Common Medical Terms
Used In Pain Management

Allodynia: Pain due to a stimulus which does not normally provoke pain.

Analgesia: Absence of pain in response to stimulation which would normally be painful.

Complex Regional Pain Syndrome I: CRPS I formerly known as reflex sympathetic dystrophy, consists of continuous pain (allodynia or hyperalgesia) in part of an extremity after trauma including fractures. However, the pain does not correspond to the distribution of a single peripheral nerve. The pain is worse with movement and associated with sympathetic hyperactivity. The patient often complains of cool, clammy skin which later becomes pale, cold, stiff and atrophied. This process often occurs within weeks of trauma, which may be mild.

Complex Regional Pain Syndrome II: CRPS 2 formerly known as causalgia, consists of burning pain in the distribution of a partially damaged peripheral nerve (most commonly median, ulnar or sciatic). Pain may occur within a month of injury and may radiate beyond the nerve’s distribution. The condition results from abnormal sweat and vasomotor sympathetic efferent pathways, possibly due to abnormal connections between efferent sympathetic fibers and somatic sensory fibers at the injury site. The skin is classically cold, moist and swollen, becoming atrophic later.

Central pain: Pain initiated or caused by a primary lesion or dysfunction in the central nervous system.

Dysaesthesias: An unpleasant abnormal sensation, whether spontaneous or evoked.

Hyperalgesia: An increased response to a stimulus which is normally painful.

Hyperesthesia: Increased sensitivity to stimulation, excluding the special senses.

Hyperpathia: A painful syndrome characterized by an abnormally painful reaction to a stimulus, especially a repetitive stimulus, as well as an increased threshold.

Hypoalgesia: Diminished pain in response to a normally painful stimulus.

Hypoesthesia: Decreased sensitivity to stimulation, excluding the special senses.

Neuralgia: Pain in the distribution of a nerve or nerves.

Neuritis: Inflammation of a nerve or nerves.

Neuropathic pain: Pain initiated or caused by a primary lesion or dysfunction in the nervous system.

Neuropathy: A disturbance of function or pathological change in a nerve: in one nerve, mononeuropathy; in several nerves, mononeuropathy multiplex; if diffuse and bilateral, polyneuropathy.

Nociceptor: A receptor preferentially sensitive to a noxious stimulus or to a stimulus which would become noxious if prolonged.

Noxious stimulus: A noxious stimulus is one which is damaging to normal tissues.

Pain threshold: The least experience of pain which a subject can recognize.

Pain tolerance level: The greatest level of pain which a subject is prepared to tolerate.

Parasthesias: An abnormal sensation, whether spontaneous or evoked.

Peripheral neuropathic pain: Pain initiated or caused by a primary lesion or dysfunction in the peripheral nervous system.