Abigail Loraine "Abby" Hensel and Brittany Lee Hensel (born March 7, 1990) are American dicephalic parapagus twins; in other words, they are conjoined twins, each of whom has a separate head, but whose bodies are joined.

They are highly symmetric for conjoined twins, giving the appearance of having a single body without marked variation from normal proportions. In fact, several vital organs are doubled; each twin has a separate heart, stomach, spine, pair of lungs, and spinal cord.

Each twin controls her half of their body, operating one arm and one leg. As infants, the initial learning of physical processes that required bodily coordination, such as clapping, crawling, and walking, required the cooperation of both twins.

While they can eat and write separately and simultaneously, activities such as running and swimming require them to coordinate and alternate their actions symmetrically. Other activities as diverse as brushing hair and driving a car require each twin to perform separate actions that coordinate with the other's.

Due to the curiosity that their condition generated, the twins' progress as they were growing up was covered in a number of popular media, including "Life" magazine and "The Oprah Winfrey Show". At the age of 16, they gave an interview on The Learning Channel on December 17, 2006, in which they discussed aspects of their daily lives and plans for the future. They starred in their own reality series, "Abby & Brittany", on TLC in 2012.

The twins were born in Carver County, Minnesota, to Patty, a registered nurse, and Mike Hensel, a carpenter and landscaper. They have a younger brother and sister. They were raised in New Germany, Minnesota, attended Mayer Lutheran High School in Mayer, and graduated from Bethel University in St. Paul in 2012.

Polycephaly is the condition of having more than one head. The term is derived from the Egyptian stems "poly" (Greek: "πολύ") meaning "many" and "kephalē" (Greek: "κεφάλη") meaning "head". A polycephalic organism may be thought of as one being with a supernumerary body part, or as two or more beings with a shared body.

Two-headed animals (called bicephalic or dicephalic) and three-headed (tricephalic) animals are the only type of multi-headed creatures seen in the real world, and form by the same process as conjoined twins from monozygotic twin embryos.

In humans, there are two forms of twinning that can lead to two heads being supported by a single torso. In dicephalus parapagus dipus, the two heads are side by side. In craniopagus parasiticus, the two heads are joined directly to each other, but only one head has a functional torso. Survival to adulthood is rare, but does occur in some forms of dicephalus parapagus dipus.

There are many occurrences of multi-headed animals in mythology. In heraldry and vexillology, the double-headed eagle is a common symbol, though no such animal is known to have ever existed.

Two-headed people and animals, though rare, have long been known to exist and documented.

"'Conjoined twins" are identical twins joined in utero. An extremely rare phenomenon, the occurrence is estimated to range from 1 in 49,000 births to 1 in 189,000 births, with a somewhat higher incidence in Southeast Asia and Africa. Approximately half are stillborn, and an additional one-third die within 24 hours. Most live births are female, with a ratio of 3:1.

Two contradicting theories exist to explain the origins of conjoined twins. The more generally accepted theory is "fission", in which the fertilized egg splits partially. The other theory, no longer believed to be the basis of conjoined twinning, is fusion, in which a fertilized egg completely separates, but stem cells (which search for similar cells) find like-stem cells on the other twin and fuse the twins together. Conjoined twins share a single common chorion, placenta, and amniotic sac, although these characteristics are not exclusive to conjoined twins as there are some monozygotic but non-conjoined twins who also share these structures in utero.

The most famous pair of conjoined twins was Chang and Eng Bunker (Thai: อิน-จัน, In-Chan) (1811–1874), Thai brothers born in Siam, now Thailand. They traveled with P.T. Barnum's circus for many years and were labeled as the Siamese twins. Chang and Eng were joined at the torso by a band of flesh, cartilage, and their fused livers. In modern times, they could have been easily separated. Due to the brothers' fame and the rarity of the condition, the term "Siamese twins" came to be used as a synonym for conjoined twins.

As the symptoms become prominent, the child will visit their pediatrician or family doctor to confirm whether or not the child has Panner Disease. When the child visits the doctor, the doctor will seek information about the child’s age, sports participation, activity level, and what the child’s dominant arm is. The affected elbow will be compared to the healthy elbow and any differences between the two will be noted. The location of where the pain is in the elbow, and the child’s range of motion and extension will also be determined to make an accurate diagnosis. To check the child’s range of motion and extension limitation the child will be asked to move the arm of the affected elbow in various directions. The movement of the arm in various directions will allow the doctor to conclude how good the child is able to move the arm and the doctor will be able to determine if there is pain caused by the various directions of movement.

To confirm the diagnosis, an x-ray or MRI scan will be done. The radiograph will enable the doctor to visualize irregularities and see the shape of the capitellum and also visualize the growth plate. In Panner Disease, the capitellum may appear flat and the bone growth plate will look irregular and fragmented. The areas where bone breakdown has occurred can also be visualized on the radiograph. When the patient undergoes a MRI scan any irregularities of the capitellum will able to be visualized, and the bone will be able to be visualized in more detail to determine the extent of swelling, if any. In the MRI results for Panner disease, there will be a decreased signal intensity of the capitellum on a T1 series and increased signal intensity on a T2 series.

Being an extremely rare disease, it is unknown as to what exactly causes Panner Disease. It is believed that the disease may be brought on by continuous overuse of the elbow and that puts pressure on the elbow and also strains the elbow in children during the period of rapid bone growth. The overuse of the elbow can be due to the involvement in sports such as baseball, handball, and gymnastics where these sports involve throwing or putting a lot of pressure on the joints. These repeated activities cause microtraumas and results in the affected elbow being swollen, irritated, and in pain. Panner Disease results when the blood supply to the capitellum is disrupted and therefore the cells within the growth plate of the capitellum die and it becomes flat due to the softening and collapsing of the surrounding bone. To prevent future instances of Panner Disease the child is instructed to cease all physical and sports activities that involve the use of the affected elbow until the symptoms are relieved.

Conjoined twins are typically classified by the point at which their bodies are joined. The most common types of conjoined twins are:

- Thoraco-omphalopagus (28% of cases): Two bodies fused from the upper chest to the lower chest. These twins usually share a heart, and may also share the liver or part of the digestive system.

- Thoracopagus (18.5%): Two bodies fused from the upper thorax to lower belly. The heart is always involved in these cases. As of 2015, separation of a genuinely shared heart has not offered survival to two twins; a designated twin may survive if allotted the heart, sacrificing the other twin.

- Omphalopagus (10%): Two bodies fused at the lower abdomen. Unlike thoracopagus, the heart is never involved in these cases; however, the twins often share a liver, digestive system, diaphragm and other organs.

- Parasitic twins (10%): Twins that are asymmetrically conjoined, resulting in one twin that is small, less formed, and dependent on the larger twin for survival.

- Craniopagus (6%): Fused skulls, but separate bodies. These twins can be conjoined at the back of the head, the front of the head, or the side of the head, but not on the face or the base of the skull.

Other less-common types of conjoined twins include:

- Syncephalus: One head with a single face but four ears, and two bodies.

- Cephalothoracopagus: Bodies fused in the head and thorax. In this type of twins, there are two faces facing in opposite directions, or sometimes a single face and an enlarged skull.

- Xiphopagus: Two bodies fused in the xiphoid cartilage, which is approximately from the navel to the lower breastbone. These twins almost never share any vital organs, with the exception of the liver. A famous example is Chang and Eng Bunker.

- Ischiopagus: Fused lower half of the two bodies, with spines conjoined end-to-end at a 180° angle. These twins have four arms; one, two, three or four legs; and typically one external set of genitalia and anus.

- Omphalo-Ischiopagus: Fused in a similar fashion as ischiopagus twins, but facing each other with a joined abdomen akin to omphalopagus. These twins have four arms, and two, three, or four legs.

- Parapagus: Fused side-by-side with a shared pelvis. Twins that are dithoracic parapagus are fused at the abdomen and pelvis, but not the thorax. Twins that are diprosopic parapagus have one trunk and two faces. Twins that are dicephalic parapagus have one trunk and two heads, and have two (dibrachius), three (tribrachius), or four (tetrabrachius) arms.

- Craniopagus parasiticus: Like craniopagus, but with a second bodiless head attached to the dominant head.

- Pygopagus (Iliopagus): Two bodies joined at the pelvis.

- Rachipagus: Twins joined along the dorsal aspect (back) of their bodies, with fusion of the vertebral arches and the soft tissue from the head to the buttocks

In Chinese alchemy, elixir poisoning refers to the toxic effects from elixirs of immortality that contained metals and minerals such as mercury and arsenic. The official "Twenty-Four Histories" record numerous Chinese emperors, nobles, and officials who ironically died from taking elixirs in order to prolong their lifespans. The first emperor to die from elixir poisoning was likely Qin Shi Huang (d. 210 BCE) and the last was Yongzheng (d. 1735). Despite common knowledge that immortality potions could be deadly, fangshi and Daoist alchemists continued the elixir-making practice for two millennia.

International Organization for Standardization helps set standards for monitoring environments, analyzing data, and interpreting results.

The diagnostic criteria for Dorian Gray syndrome are:

- Signs of dysmorphophobia

- Arrested development (inability to mature)

- Using at least two different medical-lifestyle products and services:

- Hair-growth restoration (e.g. finasteride)

- Antiadiposita to lose weight (e.g. orlistat)

- Anti-impotence drugs (e.g. sildenafil)

- Anti-depressant drugs (e.g. fluoxetine)

- Cosmetic dermatology (e.g. laser resurfacing)

- Cosmetic surgery (e.g. a face-lift, liposuction)

The association with Anne of Denmark is based on portraiture, although history does not suggest that she suffered an underactive thyroid. The eponym is disputed by some, though it has been suggested that Anne of France, Anne of Brittany, Anne of Austria, Anne Boleyn and Anne of Cleves may all be eliminated as candidates.

Heat alert programs should be developed for implementation when hotter than normal temperatures, or a heat wave occurs.

In developing countries, women who are affected by obstetric fistulae do not necessarily have full agency over their bodies or their households. Rather, their husbands and other family members have control in determining the healthcare that the women receive. For example, a woman's family may refuse medical examinations for the patient by male doctors, but female doctors may be unavailable, thus barring women from prenatal care. Furthermore, many societies believe that women are supposed to suffer in childbirth, thus are less inclined to support maternal health efforts.

Growth stunting is identified by comparing measurements of children's heights to the World Health Organization 2006 growth reference population: children who fall below the fifth percentile of the reference population in height for age are defined as stunted, regardless of the reason. The lower than fifth percentile corresponds to less than two standard deviations of the WHO Child Growth Standards median.

As an indicator of nutritional status, comparisons of children's measurements with growth reference curves may be used differently for populations of children than for individual children. The fact that an individual child falls below the fifth percentile for height for age on a growth reference curve may reflect normal variation in growth within a population: the individual child may be short simply because both parents carried genes for shortness and not because of inadequate nutrition. However, if substantially more than 5% of an identified child population have height for age that is less than the fifth percentile on the reference curve, then the population is said to have a higher-than-expected prevalence of stunting, and malnutrition is generally the first cause considered.

Prevention is the key to ending fistulae. UNFPA states that, “Ensuring skilled birth attendance at all births and providing emergency obstetric care for all women who develop complications during delivery would make fistula as rare in developing countries as it is in the industrialized world.” In addition, access to health services and education – including family planning, gender equality, higher living standards, child marriage, and human rights must be addressed to reduce the marginalization of women and girls. Reducing marginalization in these areas could reduce maternal disability and death by at least 20%.

Prevention comes in the form of access to obstetrical care, support from trained health care professionals throughout pregnancy, providing access to family planning, promoting the practice of spacing between births, supporting women in education, and postponing early marriage. Fistula prevention also involves many strategies to educate local communities about the cultural, social, and physiological factors of that condition and contribute to the risk for fistulae. One of these strategies involves organizing community-level awareness campaigns to educate women about prevention methods such as proper hygiene and care during pregnancy and labor. Prevention of prolonged obstructed labor and fistulae should preferably begin as early as possible in each woman's life. For example, improved nutrition and outreach programs to raise awareness about the nutritional needs of children to prevent malnutrition, as well as improve the physical maturity of young mothers, are important fistula prevention strategies. It is also important to ensure access to timely and safe delivery during childbirth: measures include availability and provision of emergency obstetric care, as well as quick and safe cesarean sections for women in obstructed labor. Some organizations train local nurses and midwives to perform emergency cesarean sections to avoid vaginal delivery for young mothers who have underdeveloped pelvises. Midwives located in the local communities where obstetric fistulae are prevalent can contribute to promoting health practices that help prevent future development of obstetric fistulae. NGOs also work with local governments, like the government of Niger, to offer free cesarean sections, further preventing the onset of obstetric fistulae.

Promoting education for girls is also a key factor to preventing fistulae in the long term. Former fistula patients often act as "community fistula advocates" or "ambassadors of hope," a UNFPA-sponsored initiative, to educate the community. These survivors help current patients, educate pregnant mothers, and dispel cultural myths that obstetric fistulae are caused by adultery or evil spirits. Successful ambassador programs are in place in Kenya, Bangladesh, Nigeria, Ghana, Côte d'Ivoire, and Liberia.

Several organizations have developed effective fistula prevention strategies. One, the Tanzanian Midwives Association, works to prevent fistulae by improving clinical healthcare for women, encouraging the delay of early marriages and childbearing years, and helping the local communities to advocate for women's rights.

The Sign of Hertoghe or Queen Anne's sign is a thinning or loss of the outer third of the eyebrows, and is a classical sign of hypothyroidism or dermatitis atopica, but it can also be detected in lepromatous leprosy. The sign is named after Eugene Hertoghe of Antwerp, a pioneer in thyroid function research.

In summary, key policy interventions for the prevention of stunting are:

- Improvement in nutrition surveillance activities to identify rates and trends of stunting and other forms of malnutrition within countries. This should be done with an equity perspective, as it is likely that stunting rates will vary greatly between different population groups. The most vulnerable should be prioritized. The same should be done for risk factors such as anemia, maternal under-nutrition, food insecurity, low birth-weight, breastfeeding practices etc. By collecting more detailed information, it is easier to ensure that policy interventions really address the root causes of stunting.

- Political will to develop and implement national targets and strategies in line with evidence-based international guidelines as well as contextual factors.

- Designing and implementing policies promoting nutritional and health well-being of mothers and women of reproductive age. The main focus should be on the 1000 days of pregnancy and first two years of life, but the pre-conception period should not be neglected as it can play a significant role in ensuring the fetus and baby's nutrition.

- Designing and implementing policies promoting proper breastfeeding and complementary feeding practice (focusing on diet diversity for both macro and micronutrients). This can ensure optimal infant nutrition as well as protection from infections that can weaken the child's body. Labor policy ensuring mothers have the chance to breastfeed should be considered where necessary.

- Introducing interventions addressing social and other health determinants of stunting, such as poor sanitation and access to drinking water, early marriages, intestinal parasite infections, malaria and other childhood preventable disease (referred to as “nutrition-sensitive interventions”), as well as the country's food security landscape. Interventions to keep adolescent girls in school can be effective at delaying marriage with subsequent nutritional benefits for both women and babies. Regulating milk substitutes is also very important to ensure that as many mothers as possible breastfeed their babies, unless a clear contraindication is present.

- Broadly speaking, effective policies to reduce stunting require multisectoral approaches, strong political commitment, community involvement and integrated service delivery.

Obesity in North Africa and the Middle East is a notable health issue. In 2005, the World Health Organization measured that 1.6 billion people were overweight and 400 million were obese. It estimates that by the year 2015, 2.3 billion people will be overweight and 700 million will be obese. The Middle East, including the Arabian Peninsula, Eastern Mediterranean, Turkey and Iran, and North Africa, are no exception to the worldwide increase in obesity. Subsequently, some call this trend the New World Syndrome. The lifestyle changes associated with the discovery of oil and the subsequent increase in wealth is one contributing factor.

Urbanization has occurred rapidly and has been accompanied by new technologies that promote sedentary lifestyles. Due to accessibility of private cars, television, and household appliances, the population as a whole is engaging in less physical activity. The rise in caloric and fat intake in a region where exercise is not a defining part of the culture has added to the overall increased percentages of overweight and obese populations. In addition, women are more likely to be overweight or obese due to cultural norms and perceptions of appropriate female behavior and occupations inside and outside of the home.

The medical condition of being overweight or obesity is defined as "abnormal or excessive fat accumulation that may impair health". It is measured through the Body Mass Index (BMI), defined as a person's weight, in kilograms, divided by the square of the person's height, in meters. If an individual has a BMI of 25–29, he or she is overweight. Having a BMI of 30 or more means an individual is obese. The greater the BMI, the greater the risk of chronic diseases as a result of obesity. These diseases include cardiovascular diseases, diabetes, musculoskeletal disorders, cancer, and premature death.

Making a correct diagnosis for a genetic and rare disease is often times very challenging. So the doctors and other healthcare professions rely on the person’s medical history, the severity of the symptoms, physical examination and lab tests to make and confirm a diagnosis.

There is a possibility of interpreting the symptoms of PWS with other conditions such as AVMs and or AVFs. This is because AVMs and AVFs also involve the characteristic overgrowth in soft tissue, bone and brain. Also PWS can be misdiagnosed with Klippel–Trenaunay syndrome (KTS). However, KTS consists of the following: triad capillary malformation, venous malformation, and lymphatic malformation.

Usually a specific set of symptoms such as capillary and arteriovenous malformations occur together and this is used to distinguish PWS from similar conditions. Arteriovenous malformations (AVMs) and arteriovenous fistulas (AVFs) are caused by RASA1 mutations as well. Therefore, if all the other tests (discussed below) fail to determine PWS, which is highly unlikely, genetic testing such as sequence analysis and gene-targeted deletion/duplication analysis can be performed to identify possible RASA1 gene mutations.

But PWS can be distinguished from other conditions because of its defining port-wine stains that are large, flat and pink. The port-wine stains and physical examination are enough to diagnose PWS. But additional testing is necessary to determine the extent of the PWS syndrome. The following tests may be ordered by physicians to help determine the appropriate next steps: MRI, ultrasound, CT/CAT scan, angiogram, and echocardiogram.

MRI: This is a high-resolution scan that is used to identify the extent of the hypertrophy or overgrowth of the tissues. This can also be used to identify other complications that may arise a result of hypertrophy.

Ultrasound: this can be necessary to examine the vascular system and determine how much blood is actually flowing through the AVMs.

CT/CAT scan: this scan is especially useful for examining the areas affected by PWS and is helpful for evaluating the bones in the overgrown limb.

Angiogram: an angiogram can also be ordered to get a detailed look at the blood vessels in the affected or overgrown limb. In this test an interventional radiologist injects a dye into the blood vessels that will help see how the blood vessels are malformed.

Echocardiogram: depending on the intensity of the PWS syndrome, an echo could also be ordered to check the condition of the heart.

And PWS often requires a multidisciplinary care. Depending on the symptoms, patients are dependent on: dermatologists, plastic surgeons, general surgeons, interventional radiologists, orthopedists, hematologists, neurosurgeons, vascular surgeons and cardiologists. Since the arteriovenous and capillary malformations cannot be completely reconstructed and depending on the extent and severity of the malformations, these patients may be in the care of physicians for their entire lives.

Body Mass Index (BMI) is a common and useful measurement of body fat that helps individuals understand the difference between being overweight and obese. The system can be used to calculate a persons Body Mass Index (BMI) by dividing their weight (in kilograms) by the square of their height (in meters). According to the World Health Organisation (2015) a BMI greater than or equal to 25 kg/m2 in adults is overweight and greater than or equal to 30 kg/m2 regards individuals as obese. Using the BMI method, however, to measure a child's excess weight can encounter regular issues. The Body Mass Index is used to decipher an individuals excess body weight but not their excess body fat. In this way the measurements taken from a child who is at different stages of their sexual maturation compared to another may alter the reliability of the data. Other issues that may affect the results surrounding this method for children and adolescents includes their age, sex, ethnicity muscle and bone mass, their height as well as their sexual maturation levels. Using the percentile ranking to determine whether or not a child or adolescent between 2–20 years old is overweight or obese inherits the same techniques as a BMI except the interpretation of the data collected is varied. Information gathered using the percentile ranking takes into consideration the childs age and sex, recognising that the amount of body fat regularly changes with age and sex. The BMI-for-age highlights the values among children of the same sex and age and categorises overweight adolescents as being between the 80th percentile and less than the 95th percentile. Obese children are classified as being equal to or greater than the 95th percentile.

Although calculating an individuals BMI is the most recommended indicator it doesn't distinguish the risk of disease. Regular monitoring of fat distribution, genetics and fitness levels should be maintained to assess the likelihood of disease. Alternative ways in which an individual can have their weight assessed, other than a BMI test, includes measuring the circumference of their waist or using the skin fold test.

Treatment for fiddler’s neck is unnecessary if it is painless and shows minimal swelling, particularly since minor cases are taken as a mark of pride. But fiddler’s neck may lead to worse disorders. The primary methods of treatment involve adjustments to playing of the instrument:

- good hygiene for the affected area and for the instrument

- use of a clean cotton cloth that is changed frequently

- use of a shoulder rest to reduce pressure below the jaw

- a suitable chin rest, especially one carved or molded for the individual

- Covering or changing potentially allergenic materials on the instrument.

- shifting the chin rest to the center of the body over the tailpiece

- smoothing coarse surfaces to reduce abrasion

- for males, growing a beard to avoid folliculitis

Surgery is necessary for sialolithiasis, parotid tumors, and cysts. Cervical lymph nodes that are larger than 1 cm must be biopsied. Connective tissue can be removed by excision when a non-inflamed mass is large, and there is generally little recurrence. Infections should be treated conservatively, and causative species should be identified through smear and culture for appropriate antibiotic selection. Reduction of playing time may be helpful for cases without inflammation, but in 30% of cases this did not improve the symptoms.

The causes of childhood obesity can be based on both a combination of individual choices and socio-environmental adaptions with genetic factors playing an important role also.

Because it is rare and has a wide spectrum of clinical, histological, and imaging features, diagnosing lymphangiomatosis can be challenging. Plain x-rays reveal the presence of lytic lesions in bones, pathological fractures, interstitial infiltrates in the lungs, and chylous effusions that may be present even when there are no outward symptoms.

The most common locations of lymphangiomatosis are the lungs and bones and one important diagnostic clue is the coexistence of lytic bone lesions and chylous effusion. An isolated presentation usually carries a better prognosis than does multi-organ involvement; the combination of pleural and peritoneal involvement with chylous effusions and lytic bone lesions carries the least favorable prognosis.

When lung involvement is suspected, high resolution computed tomography (HRCT) scans may reveal a diffuse liquid-like infiltration in the mediastinal and hilar soft tissue, resulting from diffuse proliferation of lymphatic channels and accumulation of lymphatic fluid; diffuse peribronchovascular and interlobular septal thickening; ground-glass opacities; and pleural effusion. Pulmonary function testing reveals either restrictive pattern or a mixed obstructive/restrictive pattern. While x-rays, HRCT scan, MRI, ultrasound, lymphangiography, bone scan, and bronchoscopy all can have a role in identifying lymphangiomatosis, biopsy remains the definitive diagnostic tool.

Microscopic examination of biopsy specimens reveals an increase in both the size and number of thin walled lymphatic channels along with lymphatic spaces that are interconnecting and dilated, lined by a single attenuated layer of endothelial cells involving the dermis, subcutis, and possibly underlying fascia and skeletal muscle. Additionally, Tazelaar, et al., described a pattern of histological features of lung specimens from nine patients in whom no extrathoracic lesions were identified, which they termed "diffuse pulmonary lymphangiomatosis" (DPL).

Recognition of the disease requires a high index of suspicion and an extensive workup. Because of its serious morbidity, lymphangiomatosis must always be considered in the differential diagnosis of lytic bone lesions accompanied by chylous effusions, in cases of primary chylopericardium, and as part of the differential diagnosis in pediatric patients presenting with signs of interstitial lung disease.