Zebra is the American medical slang for a surprising, often exotic, medical diagnosis, especially when a more commonplace explanation is more likely. [1] It is shorthand for the aphorism coined in the late 1940s by Theodore Woodward, professor at the University of Maryland School of Medicine, who instructed his medical interns: "When you hear hoofbeats behind you, don't expect to see a zebra." [2] (Since zebras are much rarer than horses in the United States, the sound of hoofbeats would almost certainly be from a horse.) By 1960, the aphorism was widely known in medical circles. [3] [4] The saying is a warning against the statistical base rate fallacy where the likelihood of something like a disease among the population is not taken into consideration for an individual.
Medical novices are predisposed to make rare diagnoses because of (a) the availability heuristic ("events more easily remembered are judged more probable") and (b) the phenomenon first enunciated in Rhetorica ad Herennium (c. 85 BC), "the striking and the novel stay longer in the mind." Thus, the aphorism is an important caution against these biases when teaching medical students to weigh medical evidence. [5]
Diagnosticians have noted, however, that "zebra"-type diagnoses must nonetheless be held in mind until the evidence conclusively rules them out:
In making the diagnosis of the cause of illness in an individual case, calculations of probability have no meaning. The pertinent question is whether the disease is present or not. Whether it is rare or common does not change the odds in a single patient. [...] If the diagnosis can be made on the basis of specific criteria, then these criteria are either fulfilled or not fulfilled.
— A. McGehee Harvey, James Bordley II, Jeremiah Barondess [6]
Comparable slang for an obscure and rare diagnosis in medicine is fascinoma .
Necrotic skin lesions in the United States are often diagnosed as loxoscelism (recluse spider bites), even in areas where Loxosceles species are rare or not present. This is a matter of concern because such misdiagnoses can delay correct diagnosis and treatment. [7]
Ehlers–Danlos syndrome is considered a rare condition and those with it are known as medical zebras. The zebra was adopted across the world as the EDS mascot to bring the patient community together and raise awareness. [8]
Iridology is an alternative medicine technique whose proponents claim that patterns, colors, and other characteristics of the iris can be examined to determine information about a patient's systemic health. Practitioners match their observations to iris charts, which divide the iris into zones that correspond to specific parts of the human body. Iridologists see the eyes as "windows" into the body's state of health.
Myalgia or muscle pain is a painful sensation evolving from muscle tissue. It is a symptom of many diseases. The most common cause of acute myalgia is the overuse of a muscle or group of muscles; another likely cause is viral infection, especially when there has been no injury.
Ehlers–Danlos syndromes (EDS) are a group of 13 genetic connective-tissue disorders. Symptoms often include loose joints, joint pain, stretchy velvety skin, and abnormal scar formation. These may be noticed at birth or in early childhood. Complications may include aortic dissection, joint dislocations, scoliosis, chronic pain, or early osteoarthritis. The current classification was last updated in 2017, when a number of rarer forms of EDS were added.
Rheumatology is a branch of medicine devoted to the diagnosis and management of disorders whose common feature is inflammation in the bones, muscles, joints, and internal organs. Rheumatology covers more than 100 different complex diseases, collectively known as rheumatic diseases, which includes many forms of arthritis as well as lupus and Sjögren's syndrome. Doctors who have undergone formal training in rheumatology are called rheumatologists.
Dysautonomia, autonomic failure, or autonomic dysfunction is a condition in which the autonomic nervous system (ANS) does not work properly. This may affect the functioning of the heart, bladder, intestines, sweat glands, pupils, and blood vessels. Dysautonomia has many causes, not all of which may be classified as neuropathic. A number of conditions can feature dysautonomia, such as Parkinson's disease, multiple system atrophy, dementia with Lewy bodies, Ehlers–Danlos syndromes, autoimmune autonomic ganglionopathy and autonomic neuropathy, HIV/AIDS, mitochondrial cytopathy, pure autonomic failure, autism, and postural orthostatic tachycardia syndrome.
Raynaud syndrome, also known as Raynaud's phenomenon, is a medical condition in which the spasm of small arteries causes episodes of reduced blood flow to end arterioles. Typically the fingers, and, less commonly, the toes, are involved. Rarely, the nose, ears, nipples, or lips are affected. The episodes classically result in the affected part turning white and then blue. Often, numbness or pain occurs. As blood flow returns, the area turns red and burns. The episodes typically last minutes but can last several hours. The condition is named after the physician Auguste Gabriel Maurice Raynaud, who first described it in his doctoral thesis in 1862.
Sutton's law states that when diagnosing, one should first consider the obvious. It suggests that one should first conduct those tests which could confirm the most likely diagnosis. It is taught in medical schools to suggest to medical students that they might best order tests in that sequence which is most likely to result in a quick diagnosis, hence treatment, while minimizing unnecessary costs. It is also applied in pharmacology, when choosing a drug to treat a specific disease you want the drug to reach the disease. It is applicable to any process of diagnosis, e.g. debugging computer programs. Computer-aided diagnosis provides a statistical and quantitative approach.
Hypermobility, also known as double-jointedness, describes joints that stretch farther than normal. For example, some hypermobile people can bend their thumbs backwards to their wrists and bend their knee joints backwards, put their leg behind the head or perform other contortionist "tricks". It can affect one or more joints throughout the body.
Theodore Englar Woodward was an American medical researcher at the University of Maryland, Baltimore. In 1948, he received a Nobel Prize nomination for his role in finding cures for typhus and typhoid fever.
Hypermobility spectrum disorder (HSD), related to earlier diagnoses such as hypermobility syndrome (HMS), and joint hypermobility syndrome (JHS) is a heritable connective tissue disorder that affects joints and ligaments. Different forms and sub-types have been distinguished, but it does not include asymptomatic joint hypermobility, sometimes known as double-jointedness.
Type III Collagen is a homotrimer, or a protein composed of three identical peptide chains (monomers), each called an alpha 1 chain of type III collagen. Formally, the monomers are called collagen type III, alpha-1 chain and in humans are encoded by the COL3A1 gene. Type III collagen is one of the fibrillar collagens whose proteins have a long, inflexible, triple-helical domain.
Medical diagnosis is the process of determining which disease or condition explains a person's symptoms and signs. It is most often referred to as a diagnosis with the medical context being implicit. The information required for a diagnosis is typically collected from a history and physical examination of the person seeking medical care. Often, one or more diagnostic procedures, such as medical tests, are also done during the process. Sometimes the posthumous diagnosis is considered a kind of medical diagnosis.
Orthostatic headache is a medical condition in which a person develops a headache while vertical and the headache is relieved when horizontal. Previously it was often misdiagnosed as different primary headache disorders such as migraine or tension headaches. Increasing awareness of the symptom and its causes has prevented delayed or missed diagnosis.
Genu recurvatum is a deformity in the knee joint, so that the knee bends backwards. In this deformity, excessive extension occurs in the tibiofemoral joint. Genu recurvatum is also called knee hyperextension and back knee. This deformity is more common in women and people with familial ligamentous laxity. Hyperextension of the knee may be mild, moderate or severe.
Nevo syndrome is a rare autosomal recessive disorder that usually begins during the later stages of pregnancy. Nevo syndrome is caused by a NSD1 deletion, which encodes for methyltransferase involved with chromatin regulation. The exact mechanism as to how the chromatin is changed is unknown and still being studied. Nevo syndrome is an example of one of about twelve overgrowth syndromes known today. Overgrowth syndromes are characterized with children experiencing a significant overgrowth during pregnancy and also excessive postnatal growth. Studies concerning Nevo syndrome have shown a similar relation to Ehlers–Danlos syndrome, a connective tissue disorder. Nevo syndrome is associated with kyphosis, an abnormal increased forward rounding of the spine, joint laxity, postpartum overgrowth, a highly arched palate, undescended testes in males, low-set ears, increased head circumference, among other symptoms.
The Ehlers–Danlos Society is an international nonprofit organization dedicated to patient support, scientific research, advocacy, and increasing awareness for the Ehlers–Danlos syndromes (EDS) and hypermobility spectrum disorder (HSD). The society has organized multiple events around the world in an attempt to raise awareness for EDS and HSD. These events include a rally in Baltimore's Inner Harbor, and a conference in India. The society also organizes symposiums dedicated to research on EDS and HSD. The 2016 symposium resulted in the reclassification of Ehlers–Danlos subtypes. Ehlers-Danlos Society has collaborated with XRP Healthcare to offer a Prescription Savings Card, providing up to 80% off medications for EDS and HSD, including pain relievers and muscle relaxants. Accepted at over 68,000 U.S. pharmacies, including Walmart, CVS, and Walgreens, this partnership offers significant savings.
Stephen Porter is Director of UCL Eastman Dental Institute where he has been Professor of Oral Medicine since 1997. He is a consultant in Oral Medicine at University College Hospital, London and a member of the Faculty of Dental Surgery of the Royal College of Surgeons. Porter has published more than 450 scholarly works, including the scientific journals The BMJ, The British Dental Journal and The Journal of the American Dental Association.
Craniocervical instability (CCI) is a medical condition characterized by excessive movement of the vertebra at the atlanto-occipital joint and the atlanto-axial joint located between the skull and the top two vertebra, known as C1 and C2. The condition can cause neural injury and compression of nearby structures, including the brain stem, spinal cord, vagus nerve, and vertebral artery, resulting in a constellation of symptoms.
The zebra print ribbon is the awareness ribbon for uncommon or rare diseases and cancers including but not limited to neuroendocrine tumors, carcinoid cancer, Ehlers-Danlos Syndromes, Whipple's disease and awareness of other rare diseases, cancers and disorders.
In keeping with Intersectionality theory, the perception of disabled people, diagnoses they receive, and treatment available to them is linked to the way they present their gender, both from a historical and a modern perspective.