of the pain will help the examining physician to accurately diagnose the problem. For example, chest pain described as extreme heaviness may indicate myocardial infarction, while chest pain described as tearing may indicate aortic dissection. Physiological measurement
Functional magnetic resonance imaging brain scanning has been used to measure pain, and correlates well with self-reported pain. Mechanisms
Nociceptive
Nociceptive pain is caused by stimulation of sensory nerve fibers that respond to stimuli approaching or exceeding harmful intensity (nociceptors), and may be classified according to the mode of noxious stimulation. The most common categories are "thermal" (e.g. heat or cold), "mechanical" (e.g. crushing, tearing, shearing, etc.) and "chemical" (e.g. iodine in a cut or chemicals released during inflammation). Some nociceptors respond to more than one of these modalities and are consequently designated polymodal. Nociceptive pain may also be classed according to the site of origin and divided into "visceral", "deep somatic" and "superficial somatic" pain. Visceral structures (e.g., the heart, liver and intestines) are highly sensitive to stretch, ischemia and inflammation, but relatively insensitive to other stimuli that normally evoke pain in other structures, such as burning and cutting. Visceral pain is diffuse, difficult to locate and often referred to a distant, usually superficial, structure. It may be accompanied by nausea and vomiting and may be described as sickening, deep, squeezing, and dull. 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. Examples include sprains and broken bones.
Surgery
As of 2015 there is not good evidence comparing surgery to lifestyle change for obesity in children, though there are a number of high quality ongoing studies looking at this issue. Bariatric surgical procedures are increasingly used amongst adolescents with severe adolescent obesity to promote weight loss. Epidemiology
From 1980 to 2013, the prevalence of overweight and obesity in children increased by nearly 50%. Currently 10% of children worldwide are either overweight or obese. In 2014, the World Health Organization established a high-level commission to end childhood obesity.With more than 42 million overweight children around the world, childhood obesity is increasing worldwide. Since 1980, the number of obese children has doubled in all three North American countries, Mexico, the United States, and Canada. Although the rate of childhood obesity in the United States has stopped increasing, the current rate remains high. In 2010, 32.6 percent of 6- to 11-year-olds were overweight, and 18 percent of 6- to 9-year-olds were obese. Canada
The rate of overweight and obesity among Canadian children has increased dramatically in recent years. In boys, the rate increased from 11% in the 1980s to 30% in the 1990s. Brazil
The rate of overweight and obesity in Brazilian children increased from 4% in the 1980s to 14% in the 1990s. In 2007 the prevalence of children overweight and childhood obesity was 11.1% and 2.7% in girls, 8.2% and 1.5% in boys, respectively. United States
The rate of obesity among children and adolescents in the United States has nearly tripled between the early 1980s and 2000.