The American Academy of Pain Medicine (AAPM) defines pain as – “An unpleasant sensation and emotional response to that sensation”.
The Web version of the Encyclopedia Britannica defines pain as – “A complex experience consisting of a physiological (bodily) response to a noxious stimulus followed by an affective (emotional) response to that event. Pain is a warning mechanism that helps to protect an organism by influencing it to withdraw from harmful stimuli. It is primarily associated with injury or the threat of injury, to bodily tissues.”
Pain is an individual sensation that can be described or defined by the person having it. It may cause distress and discomfort, it is usually described as: aching, pinching, throbbing or stabbing. We may distinguish between two basic types of pain – acute and chronic.
Acute pain lasts a relatively short time. It is a signal that body tissue is being injured. The pain generally disappears when the injury heals. Acute pain results from disease, inflammation or tissue injury. It may appear suddenly, such as after surgery trauma and may be accompanied by emotional or anxiety distress. The cause of acute pain can usually be diagnosed and treated accordingly. In certain cases it may become chronic.
Chronic pain may range from mild to severe and lasts usually for long periods of time, more than three months. It is associated with the disease itself. Chronic pain may get worse by psychological or environmental factors.
The cause of chronic pain is not always evident. In certain cases, it may be associated with chronic conditions such as: arthritis, fibromyalgia or lupus with symptoms such as: swollen joints, unexplained fever, extreme fatigue, sleep problems or red skin rash. Chronic pain syndromes, in particular, are complex and their effective treatment often involves coordinated, multidisciplinary consultation.
In contrast to acute pain, chronic pain can be mysterious, intractable and is often very expensive to treat. The complexity of chronic pain stems from the fact that it is a bio-psycho-social condition, which occurs in various forms.
Since pain is a bio-psycho-social condition, all aspects of the condition must be treated. Assuming that a condition is “all in the patient’s head” makes the mistake of overlooking possible real pain.
On the other hand, failure to assess the psycho-social factor can also lead to longer recovery. The complex nature of chronic pain disorders makes it impossible for a single professional to treat it successfully.
We may distinguish between peripheral and central pain.
Peripheral pain originates in the peripheral nerves or in muscles, usually via trauma.
Central pain arises from Central Nervous System (CNS) pathology or dysfunction. This is primarily due to structural changes in the CNS, such as: spinal cord injury, multiple sclerosis, stroke and epilepsy.
Inhibition of pain is important and needed especially when our safety is more important, like when we are running away from dangerous situation. The purpose of pain is to tell us via our brain when something needs to be done about a damaged area. The brain will assist us whether to pay attention to the painful area or ignore it.
This information is transmitted by the brain and travels to the spinal cord or brain stem via electrical impulses in fibers of spinal or certain cranial nerves. Those signals pass electrically to higher CNS levels.
Therefore, monitoring those signals in real time may be used as essential parameters in our effort for detecting and verifying pain.
Pain and Gender. Recent studies using Positron Emission Tomography (PET) brain scans of patients during pain stimuli showed different brain responses between men and women.
Several areas of male and female brains responded differently to the same pain stimuli. Female’s brain showed more activity in emotion related centers where males responded in the cognitive or analytical regions. Those differences may relate to our evolution process and the different social tasks of males and females.
Women often have high pain experience levels but lower pain tolerance. Their sensitivity to pain is affected by many factors such as biological, inherited conditions and hormone levels.
Pain and Animals. The presence of pain is by the observation of change from normal behavior.
Pain may be evident as a limp or a change in gait, withdrawal or protection of an injured part, abnormal postures, licking, rubbing or scratching at an area. Signs of pain and distress particular to rodents include eating too much, chewing toes and feet.
Signs of pain may be subtle such as a change in respiration, reluctance to move, apprehension, sudden aggression, inability to rest or sleep normally, or a worried or anxious expression.