Pain is divided into two types:
- Acute pain
- Chronic pain
Acute pain is pain of sudden onset, lasting for hours to days and disappears once the underlying cause is treated. Acute pain has a clear cause. It could result from any illness, trauma, surgery or any painful medical procedures. Hence it is beneficial to the patient because but for the pain, the individual will ignore his illness resulting in complications and even death.
Acute pain signals that there is something wrong and motivates the person to get help. For example- just because the nociception is caused by appendicitis, the person consults a doctor and undergoes surgery to get relieved. If pain is not there he will not seek medical advice and his appendix may burst and form a mass which is more difficult to treat. Thus acute pain can be beneficial.
Examples of acute pain include:
- the pain of heart attack
- acute appendicitis
- bone fracture
- muscle sprain
- prolapsed intervertebral disc of the spine
Chronic pain is the pain that starts as an acute pain and continues beyond the normal time expected for resolution of the problem or persists or recurs for various other reasons It is not therapeutically beneficial to the patient.
In acute pain, attention is focused to treat the cause of pain whereas in chronic pain, the emphasis is laid upon reducing the pain to give relief, limit disability and improve function.
About 9% of the US population and 18% of the European population suffer from chronic pain. It is rarely accompanied by signs of sympathetic nervous system arousal. The severity and extent of chronic pain may be out of proportion to the original injury and may continue long past the period in which the damage tissue has healed. Chronic pain is pain that has outlived its usefulness and is no longer beneficial.
Acute & Chronic Pain Treatment Goals
Acute and chronic pains have different treatment goals. The primary goal of acute pain treatment is to diagnose the source and remove it.
With chronic pain, the main goals are to minimize the pain and maximize the person’s functioning. Complete relief of pain is rare in chronic pain. The more realistic goal is to decrease the level of pain to a tolerable level that allows the person focus on everyday activities.
The treatment of chronic pain is multidisciplinary that blends physical, emotional, intellectual and social skills. Returning to work is clearly a desirable goal, but in fact, only 50% percent of patients who undergo comprehensive multidisciplinary pain rehabilitation are able to return to work.
Chronic pain is further divided into:
- Nociceptive pain
- Neuropathic pain
Nociceptive pain is pain arising from damage to tissues other than nerve fibers. It is also called tissue pain. The undamaged nerve cells called nociceptors carry the sensation to spinal cord from where it is relayed to the brain. It is called somatic pain if it results from injury to muscles, tendons and ligaments. Somatic pain is usually well localized.
It is called visceral pain if it results from injury to the internal organs like stomach, gall bladder and urinary bladder. Visceral pain is usually diffuse and non-localizing.
Somatic pain in turn is classified in to cutaneous somatic pain if the pain arises from the skin and deep somatic pain if it is from deeper musculoskeletal tissues. The various causes of joint pain are grouped under musculoskeletal pain.
Neuropathic pain is the pain caused by the lesion in the nervous system when they are structurally or functionally damaged. It is called central pain if the lesion is the central nervous system. It is called peripheral neuropathic pain if the lesion is in the peripheral nervous system. The neuropathic pain is described as severe, sharp, lancinating, lightning-like, stabbing, burning, cold, numbness, tingling or weakness. It may be felt traveling along the nerve path from the spine down to the arms/hands or legs/feet. It does not respond to the routine analgesics.
Keep in mind that nociceptive and neuropathic pain can co-exist in the same patient in certain conditions like Sciatica.
Many other types of pain are also described.
- Malignant pain
- Breakthrough pain
- Complex Regional Pain Syndrome I
- Complex Regional Pain Syndrome II
- Phantom limb pain
- Psychogenic pain
- Anesthesia dolorosa
- Anginal pain
- Idiopathic pain
Malignant pain is the pain suffered by the patients with cancer. The pain can be either due to the disease itself or due to the treatment given for cancer like surgery, radiotherapy and chemotherapy.
When pre-existing chronic pain is aggravated, it results in breakthrough pain needing adjustments in treatment to obtain relief. In other words, breakthrough pain is the pain that results from the worsening of the previously present chronic pain for which the person is on regular treatment. It usually comes on quickly and may last from a few minutes to an hour. The reason for this worsening of pain cannot be understood or anticipated by the person. The routine doses of analgesic never help and a readjustment of the analgesic doses is necessary along with the modification of the physical activities.
Allodynia is a pain that results from the stimulus which does not normally evoke any pain sensation. Many people aquire allodynia after they’ve been in pain for quite some time and they become hypersensitive to touch.
Hyperalgesia is an increased response to a stimulus which is normally painful.
Paresthesia is abnormal sensation which is described as “pins and needles”. It can occur either spontaneously or evoked by certain stimuli.
Hyperpathia is a painful syndrome resulting from an abnormally painful reaction to a stimulus. The stimulus in most of the cases is repetitive with an increased pain threshold. Pain threshold can be defined as the least experience of pain which a subject can recognize.
Complex Regional Pain Syndrome I:
Complex Regional Pain syndrome I also called as Reflex Sympathetic Dystrophy is a continuous pain in the form of either allodynia or hyperalgesia in the extremities resulting from trauma which is associated with sympathetic hyperactivity. The pain does not correspond to the distribution of a single nerve and it is worsened by movement. The person affected usually complains of cool, clammy skin which later becomes pale, cold, stiff and atrophied.
Complex Regional Pain Syndrome II:
Complex Regional Pain Syndrome II also called as Causalgia is a burning type of pain along the distribution a partially damaged peripheral nerve. The pain extends beyond the distribution of the nerve. This results from abnormal connections between various nerves. The skin of the person affected is classically cold, moist and swollen, becoming atrophic later.
Phantom limb pain:
Phantom limb pain is the pain that is felt in the amputated part of the body. The brain misinterprets the nerve signals as coming from the amputated limb. The phantom limb pain is described as squeezing, burning, or crushing sensations, but it often differs from any sensation previously experienced.
Psychogenic pain is seen in persons with psychological disorders. They have persistent pain without any evidence of physical cause of pain. Though it is termed psychogenic the person suffers from real pain. This pain is also called chronic pain syndrome. Sometimes psychogenic factors may worsen a pre-existing physical pain.
Anesthesia dolorosa is the pain that is felt in the part of the body that is numb to any other sensation.
Anginal pain is the pain of cardiac origin. It is described as a feeling of oppression or tightness. It occurs due to disruption of the blood supply to the heart muscle.
When a reasonable cause for the pain cannot be made out, it is called idiopathic pain.