Understanding of etiology, pathophysiology and symptomatology of acute or chronic pain for a non-clinical person is difficult. Aim of this article is to provide information of acute or chronic pain without going into too much details of cause, pathophysiology or symptomatology. Author hope patient or relatives may be able to guide the health provider to narrow the spectrum of investigation and symptomatology. Cost of investigation, hospitalization for investigation and some complication after certain invasive testing is astronomical in almost all the countries. Pain is divided into acute and chronic pain.


Pain is classified as acute or chronic depending on the period of suffering with severe intractable pain. If pain is less than 6 month in duration, it is considered as acute pain. If it is more than 6 month it defined as a chronic pain. Pain is abnormal and unpleasant sensation caused by injuries to soft tissue such as skin, subcutaneous tissue, muscles and internal organs. Acute pain also caused by inflammation of bruises, contusion and abscess) and trauma to skeletal system (fracture, tendon rupture, muscle tear and joint injuries). Pain leads to emotional experiences such as anxiety and depression. Acute pain is also described as nociceptive pain.

Pain is protective physiological response to harmful stimulation to external and internal organs of the human body. We all have natural tendency to withdraw from harmful stimulation when we feel pain at the contact. Response to withdraw is protective and helps to minimized further injuries to body. If tissue damage is minimum pain may not last beyond few minutes to hours. If tissue damage is substantial such laceration of skin, loss of tissue mass, fracture of bones and internal organ injuries, pain could last for several days or months.

Pain may occur without any contact by injuries of tendon, muscles or bones while walking, running or playing sports. Twist or turn of limbs or joints can cause severe musculoskeletal injuries causing acute pain. Whiplash injury to neck, lower back or limbs are common in automobile accident. The blunt trauma secondary to whiplash injury could be temporary and last for short period of time.

Acute pain is sharp and sudden in occurrence. It is a protective and preventive physiological response after tissue damage. It warns of threat to body tissue. Example of Acute Pain- Skin laceration and bruises, fracture and joint sprain, Tear of muscles and tendons, Post surgery incisional pain Toothache Deep and superficial Burns Labor and childbirth

Acute pain might be mild and last just a moment, or it might be severe and last for weeks or months. In most cases, acute pain does not last longer than six months, and it disappears when the underlying cause of pain has been treated or has healed. Unrelieved acute pain, however, might lead to chronic pain. The phase of acute pain should not last more than 3 to 6 months. Rehab, medications, physical therapy, interventional pain therapy and surgery are choice of treatment. Individual may not recovered 100%. Occupational therapy and work hardening should be considered to improve the functional capacity so that patient in acute pain can improve indoors and outdoors activities. If functional impairment is less than 30 to 40% individual patient can go back to work with work restrictions. Returning to work and performing restricted work adds to rehab and work hardening. The familiar surrounding of work helps to reduced psychological trauma and builds confidence to enhance performance.

If acute pain continues and response to treatment is sluggish, recovery can be prolonging. Continuous pain over 6 months becomes chronic. Chronic pain is associated with change in behavior of pain transmitting nerves and receptors. Changes also seen with neuron transmitters. These changes are temporary or permanent. Percent changes in neurophysiology of pain could be reversible or irreversible. Static behavior, psychological changes in mood such as depression or anxiety will lead to changes in neurotransmitter. Further necessity of additional treatment such as multiple medications, aggressive physical therapy, interventional treatment or surgery may assist to improve the symptomatology and functional capacity.

Pain tolerance could be lower or higher with each individual. Pain tolerance can be analyzed through specialist and close family members. If pain behavior changed to increase pain tolerance recovery can be faster. Change of pain behavior to increase pain tolerance can assist in work hardening and occupational therapy. If pain behavior cannot be changed because of continuous severe intensity of pain and secondary gain, goal to achieve pain relief become extremely difficult. Secondary gain could be family sympathy and extra attention by close family members; alternatively secondary gain could be paid disability for not going to work. In these situation acute pain will become chronic intense pain in due course of time. Physiological changes in neuroreceptors and neuropsychology will lead to chronic irreversible pain. Close family members will need to encourage patient to avoid any secondary gain and rehab to get better to resume normal activates. It is beneficial in long term to return to normal activities sooner than suffer through the chronic pain not responding to any treatment. Find a best pain specialist earlier rather than later.

Goal is to recover as soon as possible and get back to near normal activities. If acute pain continues after 3 to 4 months recovery could be slow, further treatment will be necessary. Any treatment either repeated or added can lead to certain percentage of side effects and complications. There is not any scientific evidence available to pin point the complication rate or failure rate of any treatment. There are several scientific papers published to indicate treatment do have side effects and complications.

Acute Pain is usually following surgery is temporary and last until wound is healed. Requirement of pain meds are higher during first few days and later phase after 3 to 4 days requirement of analgesics are less. Acute pain after laceration, muscle trauma also last for few days depending on extend of injuries and area of injury. Pain last until the noxious stimulus is removed or the underlying damage or pathology has healed. Primary and Secondary Gain- Primary gain produces positive internal motivations. Most of the patient with acute pain wants to feel better and get back to normal activities. Primary gain is to feel better soon. Patient with dominant feeling of getting better to resume normal activities exhibit primary gain. Gain is observed by close family member and if secondary is eliminated or avoided patient will recover faster if the tissue damage is not interfering with recovery. Secondary gain is a major factor in recovery from suffering of acute pain. Secondary gain is external behavior, which is promoted by added benefits from employer or family members. Secondary gain changes external behavior, symptoms of pain and injuries are substantially exaggerated. Examples of secondary gain are- Patient will miss work and get paid; expression of symptoms gains sympathy from family members particularly spouses, and parents. Patients may not recognize these symptoms, these are not deliberate act. These are unconscious psychological part of the symptoms and not malingering. Secondary gain is a personality change influenced by psychological behavior. Presence of secondary gain if recognized earlier and eliminated sooner response to treatment is better and recovery is faster.

Types of Acute pain- a) Somatic pain- localized in skin, subcutaneous tissue and muscles. Cause of pain could be skin abscess, laceration, injuries, hair follicle infection, muscle tear, muscle injuries and severe spasm. b) Visceral pain- originates from any and all internal organs. Visceral pain in chest caused by heart, lungs and blood vessels. Abdominal pain can be stomach ulcers, severe constipation, severe distension of intestine, gall bladder infection, and stones impacting bile duct. c) Osseous pain- localized in ligaments, joints and bones. Treatment: A) Medications- i) Initial: Acetaminophen
, Non Steroidal anti-inflammatory drugs (NSAIDs), Topical (local anesthetics spray or ointment), corticosteroids in smaller dosage. Most common medications used are Motrin ( Advil), Naproxen ( Aleve) ii) Later: a) opioids- tramadol, vicodine, oxycodone, morphine, b) Antidepressants- Tricyclic antidepressants, Cymbalta, c) Anticonvulsants- Neurontin, Lyrica B) Alternative treatment- i) Tactile stimulation- TENS unit ii) Cold packs
 iii) Acupuncture iv) Physical Therapy v) Interventional Therapy such as Peripheral Nerve block vi) Interventional Therapy such as Epidural or spinal medication vii) Surgery viii) Psychotherapy ix) Relaxation techniques such as deep breathing x) Biofeedback

Specialist to consult- Somatic pain- Dermatologist- for pain originating from skin, Physical Medicine Rehab physician- for pain originating from muscles Osseous Pain- Orthopedic surgeon Nerve and pain from spine- Neurologist, Neurosurgeon or orthopedic surgeon Visceral pain- a) Gastroenterologist- Pain originating from stomach, intestine, pancreas and gall bladder, b) Gynecologist -Pain from Uterus, Vagina, Ovaries and female organs- c) Vascular Surgeons- Pain from vascular structures such as aorta or major blood vessels secondary to trauma or aneurysm

Diagnostic and Treatment Algorithm Patient with sudden occurrence of acute pain would be rushed to Emergency room of hospital or primary care physician. After initial examination in E.R. further investigation will be advised if necessary. Investigation could be blood examination, X-Ray, CAT scan or MRI. In some cases ultra sound scanning may be performed to evaluate cause of pain if internal organ is involved. Superficial pain from skin, muscles and ligament may not need further investigation. Initial examination may be followed by medication and local treatment of the injured area of the body. Joint pain or pain from skeletal system such leg or arm bones will be followed by X-ray to rule out fracture or injuries to bones and joints. If diagnosis is not conclusive then CAT scan or MRI will be performed. Severe headache and internal organ pain in chest or abdomen will be evaluated with detail clinical examination and followed by either CAT scan or MRI. In some cases if diagnosis may be difficult or non-conclusive then advanced investigations such as PET scan, bone scan, body scan, blood examination to rule different types of cancer will be performed.



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