Chronic pain

Chronic pain

ICD-10	R52.1-R52.2
ICD-9	338.2

Chronic pain has several different meanings in medicine. Traditionally, the distinction between acute and chronic pain has relied upon an arbitrary interval of time from onset; the two most commonly used markers being 3 months and 6 months since the initiation of pain,^[1] though some theorists and researchers have placed the transition from acute to chronic pain at 12 months.^[2] Others apply acute to pain that lasts less than 30 days, chronic to pain of more than six months duration, and subacute to pain that lasts from one to six months.^[3] A popular alternative definition of chronic pain, involving no arbitrarily fixed durations is "pain that extends beyond the expected period of healing."^[1]

Contents 1 Classification 2 Pathophysiology 3 Management 3.1 Behavioral model 4 Prognosis 5 Psychology 5.1 Personality 6 See also 7 References 8 External links

Classification

Chronic pain may be divided into "nociceptive" (caused by activation of nociceptors), and "neuropathic" (caused by damage to or malfunction of the nervous system).^[4]

Nociceptive pain may be divided into "superficial somatic" and "deep", and deep pain into "deep somatic" and "visceral". Superficial somatic pain is initiated by activation of nociceptors in the skin or superficial tissues. Deep somatic pain is initiated by stimulation of nociceptors in ligaments, tendons, bones, blood vessels, fasciae and muscles, and is dull, aching, poorly-localized pain. Visceral pain originates in the viscera (organs). Visceral pain may be well-localized, but often it is extremely difficult to locate, and several visceral regions produce "referred" pain when injured, where the sensation is located in an area distant from the site of pathology or injury.^[5]

Neuropathic pain is divided into "peripheral" (originating in the peripheral nervous system) and "central" (originiting in the brain or spinal cord).^[6] Peripheral neuropathic pain is often described as “burning,” “tingling,” “electrical,” “stabbing,” or “pins and needles.” ^[7] Bumping the "funny bone" elicits peripheral neuropathic pain.

Pathophysiology

Under persistent activation nociceptive transmission to the dorsal horn may induce a wind up phenomenon. This induces pathological changes that lower the threshold for pain signals to be transmitted. In addition it may generate nonnociceptive nerve fibers to respond to pain signals. Nonnociceptive nerve fibers may also be able to generate and transmit pain signals. In chronic pain this process is difficult to reverse or eradicate once established.^[8]

Chronic pain of different etiologies has been characterized as a disease affecting brain structure and function. Magnetic Resonance Imaging studies have shown abnormal anatomical^[9] and functional connectivity ^[10] involving areas related to the processing of pain. Also, persistent pain has been shown to cause grey matter loss, reversible once the pain has resolved. ^[11]

Management

Complete and sustained remission of many neuropathies and most idiopathic chronic pain (pain that extends beyond the expected period of healing, or chronic pain that has no known underlying pathology) is rarely achieved, but much can be done to reduce suffering and improve quality of life.

Pain management (also called pain medicine) is that branch of medicine employing an interdisciplinary approach to the relief of pain and improvement in the quality of life of those living with pain.^[12] The typical pain management team includes medical practitioners, clinical psychologists, physiotherapists, occupational therapists, and nurse practitioners.^[13] Acute pain usually resolves with the efforts of one practitioner; however, the management of chronic pain frequently requires the coordinated efforts of the treatment team.^[14][15][16]

Behavioral model

The behavioral model of chronic pain comes from the applied behavior analysis literature. The model focuses on decreasing pain behaviors ^[17]. This model has shown effectiveness in reducing pain responses though operant based interventions.^[18]. More recently a [behavioral activation] model has been generated for pain ^[19]. This model has research support and has been replicated^[20]

Prognosis

Chronic pain may cause other symptoms or conditions, including depression and anxiety. It may also contribute to decreased physical activity given the apprehension of exacerbating pain.^[21] Very little work has been done on the cognitive effects of chronic pain, with most of the publications focussing on the effects of cognition on pain but only 5% examining the effects of pain on cognition.^[22]

People with high-intensity chronic pain have significantly reduced ability to perform attention-demanding tasks.^[23] Pain appears to strongly capture the attention of people with chronic pain; tests assessing the ability to attend show poorer performance than pain-free people on all tests demanding attention.^[24] The exception is found with tasks that are highly demanding of attention, where performance between the two groups is equivalent.^[24] In experimental testing, two-thirds of individuals with chronic pain demonstrate clinically significant impairment of attention, independent of age, education, medication and sleep disruption. Individuals with the highest levels of pain showed greatest disruption of memory traces, suggesting that pain diminishes working memory.^[25]

Psychology

Personality

Two of the most frequent personality profiles found in chronic pain patients by the Minnesota Multiphasic Personality Inventory (MMPI) are the conversion V and the neurotic triad. The conversion V personality, so called because the higher scores on MMPI scales 1 and 3, relative to scale 2, form a "V" shape on the graph, expresses exaggerated concern over body feelings, develops bodily symptoms in response to stress, and often fails to recognize their own emotional state, including depression. The neurotic triad personality, scoring high on scales 1, 2 and 3, also expresses exaggerated concern over body feelings and develops bodily symptoms in response to stress, but is demanding and complaining.^[26]

See also

• Suffering

Conditions related to pain

• Arthritis
• Back pain
• Cancer
• Chronic Fatigue Syndrome
• Complex Regional Pain Syndrome
• Restless Leg Syndrome
• Clinical depression
• Fibromyalgia
• Headache
• Sciatica
• Spinal stenosis

Drugs

• Analgesia
• Antiepileptics
  • Gabapentin
  • Pregabalin
  • Levetiracetam
  • Topiramate
  • Lamotrigine
  • Zonisamide
• Antidepressants
• Local anesthetics
  • Ketamine
• Acetaminophen (Paracetamol)
• NSAIDs
• Opioids
• Medical cannabis
• Other agents:
  • Clonidine
  • Ziconotide

Other approaches in Physical medicine and rehabilitation (Physiatry) Cryotherapy Exercise Hot pack Occupational therapy Physical therapy TENS Alternative therapies Acupuncture Chiropractic Massage therapy Hypnosis Behavioral therapy Prolotherapy Structural Integration Surgery Spinal cord stimulation

References

External links

• Pain Journal of the International Association for the Study of Pain
• American Chronic Pain Association
• American Pain Foundation
• Family Health & Wellness from the Institute for Good Medicine
• International Association for the Study of Pain- IASP
• Patient consumer web page sponsored by the APS
• A directory of physicians that specialize in the field of chronic pain
• Media related to pain at Wikimedia Commons

v • d • e Pain and nociception Head and neck Headache · Neck · Odynophagia (swallowing) · Otalgia (ear) · Toothache Torso Abdomen · Back (Upper, Lower) · Chest · Mastodynia (Breast) · Pelvic pain Musculoskeletal Arthralgia (joint) · Bone pain · Myalgia (muscle) Other conditions Delayed onset muscle soreness · Congenital insensitivity to pain · HSAN (Type I, II congenital sensory neuropathy, III familial dysautonomia, IV congenital insensitivity to pain with anhidrosis, V congenital insensitivity to pain with partial anhidrosis) · Neuralgia · Pain asymbolia · Pain disorder · Paroxysmal extreme pain disorder · Allodynia · Breakthrough pain · Chronic pain · Hyperalgesia · Hypoalgesia · Hyperpathia · Phantom pain · Referred pain Tests Cold pressor test · Dolorimeter Related concepts Anterolateral system · Pain management (Anesthesia, Cordotomy) · Pain scale · Pain threshold · Pain tolerance · Posteromarginal nucleus · Substance P · Suffering · OPQRST  · Philosophy of pain M: CNS anat(s,m,p,4,e,b,d,c,a,f,l,g)/phys/devp/cell noco(m,d,e,h,v,s)/cong/tumr,sysi/epon,injr proc,drug(N1A/2AB/C/3/4/7A/B/C/D) M: PNS anat(h, r, t, c, b, l, s)/phys/devp noco/auto/cong/tumr, sysi/epon, injr proc, drug(N1B)

v • d • e Symptoms and signs: general / constitutional (R50-R61, 780.6-780.9) Temperature heat: Fever (Fever of unknown origin, Drug-induced fever, Postoperative fever) • Hyperhidrosis (e.g., Sleep Hyperhidrosis; "Sweating") • Hyperpyrexia • Hyperthermia cold: Chills Aches/Pains Headache • Chronic pain Malaise and fatigue Atrophy (e.g., Muscle Atrophy) • Debility (or Asthenia) • Lassitude • Lethargy • Muscle tremors • Tenderness Miscellaneous Flu-Like Symptoms