A pain that lasts for more than 3 to 6 months is termed as chronic pain. Pain in the affected region can continue for duration longer than this. The pain that is experienced is defined as sharp or dull, with burning or aching sensation, which may either be constant, or occur in between intervals.

In addition to the persistent pain that is experienced, affected individuals also suffer from undue fatigue, decreased appetite and sleep disturbances. Individuals also undergo significant mood changes, which are strong enough to cause suicidal ideation. Chronic pain is also known to significantly disrupt daily activities, and also negatively impacts the quality of life. Patients also report that, chronic pain takes a toll on their relationships and is a major cause of anxiety and depression.

Proper diagnostic procedures need to be employed for determining any underlying disease condition that is causing the pain. In many instances, diagnosis of chronic pain is made based on the symptoms that are reported by the patient. Imaging studies such as MRI of the brain is indicated to study structural changes that take place during chronic pain [9]. Several laboratory studies may also be required to determine the underlying etiology.

Chronic pain can be effectively managed with combination of medications and other therapies. Anti-inflammatory non-steroidal drugs are used for relieving pain. Topical application of these compounds should be considered and is particularly meant for those individuals who are unable to tolerate oral drugs. Individuals suffering from low back pain are given strong opoids. In addition to pain relieving medications, antidepressants should also be given to patients to cope with strong mood fluctuations [10]. Physical therapy in form of exercises forms an integral part of treatment regime and should be religiously followed by all individuals suffering from chronic pain.

Individuals affected by chronic pain experience depression and anxiety. In addition, sleep disturbance and onset of insomnia, is a common occurrence, which are induced by the medications prescribed for relieving the pain. Affected individuals also decrease physical activity, due to inability to work with pain or the fear that pain would increase upon physical exertion. Research has shown that, chronic pain is significantly associated with 10 year mortality [8].

The following factors can give rise to chronic pain:

• Chemical: If the chemicals in the brain fail to suppress pain, it can cause development of persistent pain. 
• Neurogenic: In this factor, the pain primarily results from the nerves due to damage to the central nervous system.
• Psychogenic: In such cases, the pain stems from psychological stress or emotional issues, which trigger the perception of chronic pain.
• Psychological: Chronic pain occurs due to certain underlying psychological illnesses that presents as physical ailments.

In addition to the above mentioned conditions, several risk factors can also increase the risk of developing chronic pain. These include [2]:

• Underlying disease conditions such as arthritis, diabetes, depression, fibromyalgia and anxiety disorders
• Conditions such as limb amputation, joint injuries and surgeries
• Smoking 
• Weakened immunity
• Poor dietary habits and sedentary lifestyle
• Emotional stress

Statistics have revealed that, about 116 million Americans suffer from some or other type of chronic pain. Of these, about 63% seek medical advice for chronic pain. The prevalence of chronic pain in the US is estimated to be 30%. Research has pointed towards the fact that, chronic pain utilizes a major share of health care resources. Women are known to be more affected by the condition than men. In an internet based research study, it was revealed that 34.3% women and 26.7% men in the US suffered from chronic pain [3]. A survey carried out in the year 2010, stated that 19% of adult population in US reported to suffer from chronic pain for at least 3 months or more [4].

Chronic pain is classified as nociceptive and neuropathic. The former type occurs due to activation of nociceptors and the latter occurs due to malfunctioning of the nervous system [5].

When the nociceptive receptors are constantly activated, there is transmission to the dorsal horn, which may in turn induce “pain wind-up phenomenon”. Such a type of phenomenon creates pathological changes that lower the threshold of pain, along with activation of the nociceptive receptors to respond to the sensation of pain [6]. The nerve fibers that are involved in these series of events are C-fibers, which have a low conductivity, giving rise to sensation of pain that continues over a long period.
It is believed that, several structural changes occur in the brain in response to chronic pain. In addition, grey matter loss also takes place, which is, however, reversible when the pain subsides [7].

Leading an active lifestyle and adhering to a healthy diet can help in preventing onset of chronic pain. However, if the pain occurs as a result of injury or some diseases, then carefully following a treatment plan along with regular exercises can help in effective management of pain.

Based on all the theories stating different duration of chronic pain, another popular definition has defined chronic pain, as the one that is experienced and extends beyond the anticipated period of healing. Such type of pain cannot be cured; but can be managed with a proper treatment regime [1].

• Definition: Chronic pain is defined as the pain that continues for more than 3 to 6 months. Persistent pain significantly interferes with quality of life, and is an important factor for development of psychological stress and anxiety.
• Cause: Injury or underlying disease condition can be a significant cause for development of chronic pain. Damage to the nerves can also be yet another factor for chronic pain.
• Symptoms: Patients describe the pain as dull or sharp, with constant or intermittent aching sensation in the affected area of the body. Certain individuals would also experience burning sensation in the area of pain. Along with physical symptoms, individuals also suffer from depression and anxiety as well.
• Diagnosis: Diagnosis is made based on the physical examination and past medical history of the patient. Laboratory studies and blood work can give insights on underlying disease condition that is causing the pain. Imaging studies such as MRI and CT scan can also be carried out.
• Treatment: Non-steroidal anti-inflammatory drugs (NSAIDs) form the primary basis of treatment regime. Individuals are also given ointments for topical application on the affected area. In addition to these, exercise is also required to further improve the condition.

1. Alford DP, Liebschutz J, Chen IA, et al. Update in pain medicine. J Gen Intern Med 2008; 23:841.
2. Thomas EN, Blotman F. Aerobic exercise in fibromyalgia: a practical review. Rheumatol Int. Mar 26 2010;
3. Hardt J, Jacobsen C, Goldberg J, et al. Prevalence of chronic pain in a representative sample in the United States. Pain Med 2008; 9:803.
4. Henschke N, Kamper SJ, Maher CG. The Epidemiology and Economic Consequences of Pain. Mayo Clin Proc 2015; 90:139.
5. Merskey H, Bogduk N. Classification of Chronic Pain, 2nd ed, IASP Press, Seattle 1994.
6. McCleskey EW, Gold MS. Ion channels of nociception. Annu Rev Physiol 1999; 61:835.
7. Smith HS. Pain Taxonomy. In: The Neurologic Basis for Pain, Pappagalo M (Ed), McGraw-Hill, New York 2005. p.289.
8. van Tilburg MA, Spence NJ, Whitehead WE, Bangdiwala S, Goldston DB. Chronic pain in adolescents is associated with suicidal thoughts and behaviors. J Pain. Oct 2011;12(10):1032-9
9. Cleeland CS, Ryan KM. Pain assessment: global use of the Brief Pain Inventory. Ann Acad Med Singapore 1994; 23:129.
10. Dworkin RH, O'Connor AB, Backonja M, et al. Pharmacologic management of neuropathic pain: evidence-based recommendations. Pain 2007; 132:237.