An insulinoma is a tumour of the pancreas derived from the beta cells which while retaining the ability to synthesize and secrete insulin is autonomous of the normal feedback mechanisms. Patients present with symptomatic hypoglycemia which is ameliorated by feeding. The diagnosis of an insulinoma is usually made biochemically with low blood sugar, elevated insulin, pro-insulin and C-peptide levels and confirmed by medical imaging or angiography. The definitive treatment is surgery.

Insulinomas are rare neuroendocrine tumours with an incidence estimated at 1 to 4 new cases per million persons per year. Insulinoma is one of the most common types of tumour arising from the islets of Langerhans cells (pancreatic endocrine tumours). Estimates of malignancy (metastases) range from 5% to 30%. Over 99% of insulinomas originate in the pancreas, with rare cases from ectopic pancreatic tissue. About 5% of cases are associated with tumours of the parathyroid glands and the pituitary (Multiple endocrine neoplasia type 1) and are more likely to be multiple and malignant. Most insulinomas are small, less than 2 cm.

Patients with insulinomas usually develop neuroglycopenic symptoms. These include recurrent headache, lethargy, diplopia, and blurred vision, particularly with exercise or fasting. Severe hypoglycemia may result in seizures, coma, and permanent neurological damage. Symptoms resulting from the catecholaminergic response to hypoglycemia (i.e. tremulousness, palpitations, tachycardia, sweating, hunger, anxiety, nausea) are not as common. Sudden weight gain (the patient can become massively obese) is sometimes seen.

The diagnosis of insulinoma is suspected in a patient with symptomatic fasting hypoglycemia. The conditions of Whipple’s triad need to be met for the diagnosis of “true hypoglycemia” to be made:

The following blood tests are needed to diagnose insulinoma:

If available, a proinsulin level might be useful as well. Other blood tests may help rule out other conditions which can cause hypoglycemia.

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Inguinal hernias (IPA: /’??gw?n?l ‘h?ni?z/) are protrusions of abdominal cavity contents through the inguinal canal. They are very common (it is estimated that 7% of the population will develop an abdominal wall hernia)[citation needed] and their repair is one of the most frequently performed surgical operations.

There are two types of inguinal hernia, direct and indirect. Direct inguinal hernias occur when abdominal contents herniate through a weak point in the fascia of the abdominal wall and into the inguinal canal. Indirect inguinal hernias occur when abdominal contents protrude through the deep inguinal ring; this is ultimately caused by failure of embryonic closure of the processus vaginalis.

In men, indirect hernias follow the same route as the descending testes, which migrates from the abdomen into the scrotum during the development of the urinary and reproductive organs. The larger size of their inguinal canal, which transmitted the testicle and accommodates the structures of the spermatic cord, might be one reason why men are 25 times more likely to have an inguinal hernia than women. Although several mechanisms such as strength of the posterior wall of the inguinal canal and shutter mechanisms compensating for raised intra-abdominal pressure prevent hernia formation in normal individuals, the exact importance of each factor is still under debate.[1]

Hernias present as bulges in the groin area that can become more prominent when coughing, straining, or standing up. They are often painful, and the bulge commonly disappears on lying down. The inability to “reduce”, or place the bulge back into the abdomen usually means the hernia is “incarcerated,” often necessitating emergency surgery.

As the hernia progresses, contents of the abdominal cavity, such as the intestines, can descend into the hernia and run the risk of being pinched within the hernia, causing an intestinal obstruction. If the blood supply of the portion of the intestine caught in the hernia is compromised, the hernia is deemed “strangulated,” and gut ischemia and gangrene can result, with potentially fatal consequences. The timing of complications is not predictable; some hernias remain static for years, others progress rapidly from the time of onset. Provided there are no serious co-existing medical problems, patients are advised to get the hernia repaired surgically at the earliest convenience after a diagnosis is made. Emergency surgery for complications such as incarceration and strangulation carry much higher risk than planned, “elective” procedures.

The diagnosis of inguinal hernia rests on the history given by the patient and the physician’s examination of the groin. Further tests are rarely needed to confirm the diagnosis. However, in unclear cases an ultrasound scan or a CT scan might be of help, especially to rule out a hydrocele.

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Influenza, commonly known as the flu, is an infectious disease that affects birds and mammals caused by RNA viruses of the family Orthomyxoviridae (the influenza viruses). The name influenza comes from the Italian: influenza, meaning “influence”, (Latin: influentia). In humans, common symptoms of the disease are chills and fever, pharyngitis, muscle pains, severe headache, coughing, weakness and general discomfort.[1] In more serious cases, influenza causes pneumonia, which can be fatal, particularly in young children and the elderly. Although it is often confused with the common cold, influenza is a much more severe disease and is caused by a different type of virus.[2] Influenza can produce nausea and vomiting, especially in children,[1] but these symptoms are more characteristic of the unrelated gastroenteritis, which is sometimes called “stomach flu” or “24-hour flu”.[3]

Typically, influenza is transmitted from infected mammals through the air by coughs or sneezes, creating aerosols containing the virus, and from infected birds through their droppings. Influenza can also be transmitted by saliva, nasal secretions, feces and blood. Infections also occur through contact with these body fluids or with contaminated surfaces. Flu viruses can remain infectious for about one week at human body temperature, over 30 days at 0 °C (32 °F), and for much longer periods at very low temperatures.[4][5] Most influenza strains can be inactivated easily by disinfectants and detergents.[6][7][8]

Flu spreads around the world in seasonal epidemics, resulting in the deaths of hundreds of thousands annually — millions in pandemic years. Three influenza pandemics occurred in the 20th century and killed tens of millions of people, with each of these pandemics being caused by the appearance of a new strain of the virus in humans. Often, these new strains result from the spread of an existing flu virus to humans from other animal species. A deadly avian strain named H5N1 has posed the greatest risk for a new influenza pandemic since it first killed humans in Asia in the 1990s. Fortunately, this virus has not mutated to a form that spreads easily between people.[9]

Vaccinations against influenza are usually given to people in developed countries with a minor risk of contracting the disease[10] and to farmed poultry.[11] The most common human vaccine is the trivalent influenza vaccine that contains purified and inactivated material from three viral strains. Typically, this vaccine includes material from two influenza A virus subtypes and one influenza B virus strain.[12] A vaccine formulated for one year may be ineffective in the following year, since the influenza virus changes rapidly over time, and different strains become dominant. Antiviral drugs can be used to treat influenza, with neuraminidase inhibitors being particularly effective.

The word influenza comes from the Italian language and refers to the cause of a disease; initially, this ascribed illness to unfavorable astrological influences.[13] Changes in medical thought led to its modification to influenza del freddo, meaning “influence of the cold”. The word influenza was first used in English in 1743 when it was adopted, with an anglicized pronunciation, during an outbreak of the disease in Europe.[14] Archaic terms for influenza include epidemic catarrh, grippe (from the French), sweating sickness, and Spanish fever (particularly for the 1918 pandemic strain).[15]

The symptoms of human influenza were clearly described by Hippocrates roughly 2,400 years ago.[17][18] Since then, the virus has caused numerous pandemics. Historical data on influenza are difficult to interpret, because the symptoms can be similar to those of other diseases, such as diphtheria, pneumonic plague, typhoid fever, dengue, or typhus. The first convincing record of an influenza pandemic was of an outbreak in 1580, which began in Asia and spread to Europe via Africa. In Rome, over 8,000 people were killed, and several Spanish cities were almost wiped out. Pandemics continued sporadically throughout the 17th and 18th centuries, with the pandemic of 1830–1833 being particularly widespread; it infected approximately a quarter of the people exposed.[19]

The most famous and lethal outbreak was the so-called Spanish flu pandemic (type A influenza, H1N1 subtype), which lasted from 1918 to 1919. Older estimates say it killed 40–50 million people,[20] while current estimates say 50 million to 100 million people worldwide were killed.[21] This pandemic has been described as “the greatest medical holocaust in history” and may have killed as many people as the Black Death.[19] This huge death toll was caused by an extremely high infection rate of up to 50% and the extreme severity of the symptoms, suspected to be caused by cytokine storms.[20] Indeed, symptoms in 1918 were so unusual that initially influenza was misdiagnosed as dengue, cholera, or typhoid. One observer wrote, “One of the most striking of the complications was hemorrhage from mucous membranes, especially from the nose, stomach, and intestine. Bleeding from the ears and petechial hemorrhages in the skin also occurred.”[21] The majority of deaths were from bacterial pneumonia, a secondary infection caused by influenza, but the virus also killed people directly, causing massive hemorrhages and edema in the lung.[16]

The Spanish flu pandemic was truly global, spreading even to the Arctic and remote Pacific islands. The unusually severe disease killed between 2 and 20% of those infected, as opposed to the more usual flu epidemic mortality rate of 0.1%.[16][21] Another unusual feature of this pandemic was that it mostly killed young adults, with 99% of pandemic influenza deaths occurring in people under 65, and more than half in young adults 20 to 40 years old.[22] This is unusual since influenza is normally most deadly to the very young (under age 2) and the very old (over age 70). The total mortality of the 1918–1919 pandemic is not known, but it is estimated that 2.5% to 5% of the world’s population was killed. As many as 25 million may have been killed in the first 25 weeks; in contrast, HIV/AIDS has killed 25 million in its first 25 years.[21]

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Infective endocarditis is a form of endocarditis caused by infectious agents. The agents are usually bacterial, but other organisms can also be responsible.

The valves of the heart do not receive any dedicated blood supply, defensive immune mechanisms (such as white blood cells) cannot directly reach the valves via the bloodstream. If an organism (such as bacteria) attaches to a valve surface and forms a vegetation, the host immune response is blunted. The lack of blood supply to the valves also has implications on treatment, since drugs also have difficulty reaching the infected valve.

Normally, blood flows smoothly through these valves. If they have been damaged – from rheumatic fever, for example – the risk of bacteria attachment is increased.[1]

Historically, infective endocarditis has been clinically divided into acute and subacute[1] presentations (because untreated patients tended to live longer with the subacute as opposed to the acute form). This classifies both the rate of progression and severity of disease.

This terminology is now discouraged, because the ascribed associations (in terms of organism and prognosis) were not strong enough to be relied upon clinically. The terms short incubation (meaning less than about six weeks), and long incubation (greater than about six weeks) are preferred.[2]

Infective endocarditis may also be classified as culture-positive or culture-negative. Culture-negative endocarditis can be due to micro-organisms that require a longer period of time to be identified in the laboratory, such organisms are said to be fastidious because they have demanding growth requirements, or due to absence of an organism as in marantic endocarditis. Some pathogens responsible for culture-negative endocarditis include Aspergillus species, Brucella species, Coxiella burnetii, Chlamydia species, and HACEK bacteria. Another possible reason for culture negativity, even with the more typical pathogens, is prior antibiotic treatment.

Endocarditis can also be classified by the side of the heart affected:

Another form of endocarditis is nosocomial endocarditis which is when the patient is diagnosed with endocarditis and has had hospital care one month prior to the incident and is usually secondary to IV catheters, Total parenteral nutrition lines, pacemakers, etc.[3]

Finally, the distinction between native-valve endocarditis and prosthetic-valve endocarditis is clinically important. Prosthetic valve endocarditis can be early (< 2 months of valvular surgery) or late (> 2 months of valvular surgery).

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Infant respiratory distress syndrome (IRDS), also called neonatal respiratory distress syndrome[1] or respiratory distress syndrome of newborn, previously called hyaline membrane disease, is a syndrome caused in premature infants by developmental insufficiency of surfactant production and structural immaturity in the lungs. It can also result from a genetic problem with the production of surfactant associated proteins. RDS affects about 1% of newborn infants and is the leading cause of death in preterm infants.[2] The incidence decreases with advancing gestational age, from about 50% in babies born at 26-28 weeks, to about 25% at 30-31 weeks. The syndrome is more frequent in infants of diabetic mothers and in the second born of premature twins.

Respiratory distress syndrome begins shortly after birth and is manifest by tachypnea, tachycardia, chest wall retractions (recession), expiratory grunting, flaring of the nostrils and cyanosis during breathing efforts.

As the disease progresses, the baby may develop ventilatory failure (rising carbon dioxide concentrations in the blood), and prolonged cessations of breathing (“apnea”). Whether treated or not, the clinical course for the acute disease lasts about 2 to 3 days. During the first, the patient worsens and requires more support. During the second the baby may be remarkably stable on adequate support and resolution is noted during the third day, heralded by a prompt diuresis. Despite huge advances in care, RDS remains the most common single cause of death in the first month of life. Complications include metabolic disorders (acidosis, low blood sugar), patent ductus arteriosus, low blood pressure, chronic lung changes, and intracranial hemorrhage. The disease is frequently complicated by prematurity and its additional defects in other organ function.

The characteristic pathology seen in babies who die from RDS was the source of the name “hyaline membrane disease”. These waxy-appearing layers line the collapsed tiny air sacs (“alveoli”) of the lung. In addition, the lungs show bleeding, over-distention of airways and damage to the lining cells.

The lungs of infants with respiratory distress syndrome are developmentally deficient in a material called surfactant, which helps prevent collapse of the terminal air-spaces (the future site of alveolar development) throughout the normal cycle of inhalation and exhalation. Surfactant is a complex system of lipids, proteins and glycoproteins which are produced in specialized lung cells called Type II cells or Type II pneumocytes. The surfactant is packaged by the cell in structures called lamellar bodies, and extruded into the air-spaces. The lamellar bodies then unfold into a complex lining of the air-space. This layer reduces the surface tension of the fluid that lines the air-space. Surface tension is responsible for approximately 2/3 of the elastic recoil forces. In the same way that a bubble will contract to give the smallest surface area for a given volume, so the air/water interface means that the liquid surface will tend towards being as small as possible, thereby causing the air-space to contract. By reducing surface tension, surfactant prevents the air-spaces from completely collapsing on exhalation. In addition, the decreased surface tension allows re-opening of the air-space with a lower amount of force. Therefore, without adequate amounts of surfactant, the air-spaces collapse and are very difficult to expand. Microscopically, a surfactant deficient lung is characterized by collapsed air-spaces alternating with hyper-expanded areas, vascular congestion and, in time, hyaline membranes. Hyaline membranes are composed of fibrin, cellular debris, red blood cells, rare neutrophils and macrophages. They appear as an eosinophilic, amorphous material, lining or filling the air spaces and blocking gas exchange.[3] As a result, blood passing through the lungs is unable to pick up oxygen and unload carbon dioxide. Blood oxygen levels fall and carbon dioxide rises, resulting in rising blood acid levels and hypoxia. Structural immaturity, as manifest by decreased number of gas-exchange units and thicker walls, also contributes to the disease process. Therapeutic oxygen and positive-pressure ventilation, while potentially life-saving, can also damage the lung. The diagnosis is made by the clinical picture and the chest xray, which demonstrates decreased lung volumes (bell-shaped chest), absence of the thymus (after about 6 hours), a small (0.5-1 mm), discrete, uniform infiltrate (sometimes described as a “ground glass” appearance) that involves all lobes of the lung, and air-bronchograms (ie the infiltrate will outline the larger airways passages which remain air-filled). In severe cases, this becomes exaggerated until the cardiac borders become inapparent (a ‘white-out’ appearance).

Most cases of hyaline membrane disease can be ameliorated or prevented if mothers who are about to deliver prematurely can be given one of a group of hormones glucocorticoids. This speeds the production of surfactant. For very premature deliveries, a glucocorticoid is given without testing the fetal lung maturity. In pregnancies of greater than 30 weeks, the fetal lung maturity may be tested by sampling the amount of surfactant in the amniotic fluid, obtained by inserting a needle through the mother’s abdomen and uterus. Several tests are available that correlate with the production of surfactant. These include the lecithin-sphingomyelin ratio (“L/S ratio”), the presence of phosphatidol glycerol (PG), and more recently, the surfactant/albumin (S/A) ratio. For the L/S ratio, if the result is less than 2:1, the fetal lungs may be surfactant deficient. The presence of PG usually indicates fetal lung maturity. For the S/A ratio, the result is given as mg of surfactant per gm of protein. An S/A ratio <35 indicates immature lungs, between 35-55 is indeterminate, and >55 indicates mature surfactant production(correlates with an L/S ratio of 2.2 or greater).

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Iminoglycinuria, sometimes called familial iminoglycinuria,[1][2][3] is an autosomal recessive[4] disorder of renal tubular transport affecting reabsorption of the amino acid glycine, and the imino acids proline and hydroxyproline.[4][5] This results in excess urinary excretion of all three acids (-uria denotes “in the urine”).[6]

Iminoglycinuria is a rare and complex disorder, associated with a number of genetic mutations which cause defects in both renal and intestinal transport systems of glycine and imino acids.[4][7][8][9]

Imino acids typically contain an imine functional group, instead of the amino group found in amino acids. Proline is considered and usually referred to as an amino acid,[10][11] but unlike others, it has a secondary amine. This feature, unique to proline, identifies proline also as an imino acid.[12] [13] Hydroxyproline is another imino acid, made from the naturally-occurring hydroxylation of proline.[12]

The primary characteristic of iminoglycinuria is the presence of glycine and imino acids in the urine. Otherwise, it is thought to be a relatively benign disorder,[14][6] although symptoms associated with disruptions of proline and glycine metabolism caused by malabsorption may be present with iminoglycinuria.[4][15] These include encephalopathy, mental retardation,[2] deafness,[3] blindness,[16] kidney stones,[17] hypertension[18] and gyrate atrophy.[19]

Gyrate atrophy is an inherited degenerative disorder of the retina and choroid,[20] sometimes accompanying the metabolic condition hyperornithinemia.[19][21] The presence of gyrate atrophy with iminoglycinuria stems from a deficiency of proline in chorioretinal tissues, while processes behind hyperornithinemia disrupt the metabolic pathway from ornithine to proline, which alters the catabolism of ornithine, and also results in reduced levels of proline. Thus, gyrate atrophy can be found with either disorder, with proline deficiency as an underlying feature.[22][19]

Hyperglycinuria is another disorder affecting reabsorption of glycine and imino acids, similar to iminoglycinuria and considered to be a heterozygous form.[3][4] When accompanied by a specific type of kidney stone (nephrolithiasis), it is sometimes referred to as “iminoglycinuria, type II”.[15][23][24]

Glycine, proline and hydroxyproline share common renal tubular mechanisms of reabsorption,[7] a function specific to the proximal tubule.[4][5] Both reabsorption or absorption of glycine and imino acids takes place respectively at the proximal tubule or intestinal brush border epithelium. The more selective transport of proline and other imino acids is driven at the molecular level by a mammalian cellular transport mechanism aptly known as system IMINO.[5][25][26]

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IgA nephropathy (also known as IgA nephritis, IgAN, Berger’s disease and synpharyngitic glomerulonephritis) is a form of glomerulonephritis (inflammation of the glomeruli of the kidney). This should not be confused with Buerger’s disease, an unrelated condition.

IgA nephropathy is the most common glomerulonephritis throughout the world. Primary IgA nephropathy is characterized by deposition of the IgA antibody in the glomerulus. There are other diseases associated with glomerular IgA deposits, the most common being Henoch-Schönlein purpura, which is considered by many to be a systemic form of IgA nephropathy. Henoch-Schönlein purpura presents with a characteristic skin rash, occurs more commonly in young adults (16-35 yrs old) and is associated with a more benign prognosis than IgA nephropathy, which typically presents with hematuria in adults and may lead to chronic renal failure.

The classic presentation (in 40-50% of the cases) is episodic frank hematuria which usually starts within a day of an upper respiratory tract infection (hence synpharyngitic, as opposed to post-streptococcal glomerulonephritis which occurs some time after an initial infection). Flank pain can also occur. The frank hematuria resolves after a few days, though the microscopic hematuria persists. These episodes occur on an irregular basis, and in most patients, this eventually stops (although it can take many years). Renal function usually remains normal, though rarely, acute renal failure may occur (see below). This presentation is more common in younger adults.

A smaller proportion (20-30%), usually the older population, have microscopic hematuria and proteinuria (less than 2 grams of protein per 24 hours). These patients may not have any symptoms and are only picked up if a doctor decides to take a urine sample. Hence, the disease is picked up more commonly in situations where screening of urine is compulsory, e.g. schoolchildren in Japan.

Very rarely (5% each), the presenting history is:

A variety of systemic diseases are associated with IgA nephropathy such as liver failure, celiac disease, rheumatoid arthritis, Reiter’s disease, ankylosing spondylitis and HIV. Diagnosis of IgA Nephropathy and a search for any associated disease occasionally reveals such an underlying serious systemic disease. Occasionally, there are simultaneous symptoms of Henoch-Schönlein purpura; see below for more details on the association.

For an adult patient with isolated hematuria, tests such as ultrasound of the kidney and cystoscopy are usually done first to pinpoint the source of the bleeding. These tests would rule out kidney stones and bladder cancer, two other common urological causes of hematuria. In children and younger adults, the history and association with respiratory infection can raise the suspicion of IgA nephropathy directly. A urinalysis will show red blood cells, usually as red cell urinary casts. Proteinuria, usually less than 2 grams per day, also may be present. Other renal causes of isolated hematuria include thin basement membrane disease and Alport syndrome, the latter being a hereditary disease associated with hearing impairment. A kidney biopsy is necessary to confirm the diagnosis. The biopsy specimen shows proliferation of the mesangium, with IgA deposits on immunofluorescence and electron microscopy. However, all patients with isolated microscopic hematuria (i.e. without associated proteinuria and with normal kidney function) are not usually biopsied since this is associated with an excellent prognosis.

Other blood tests done to aid in the diagnosis include CRP or ESR, complement levels, ANA, ANCA and LDH. Protein electrophoresis and immunoglobulin levels can show increased IgA1 in 30% to 50% of all patients. may be normal or reduced. Tests such as electrolytes, renal function (creatinine, urea), total protein, serum albumin help in establishing the prognosis. Other tests such as bleeding time, full blood count, PT and PTT are done before performing a biopsy.

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Idiopathic intracranial hypertension (IIH), sometimes called by the older names benign intracranial hypertension (BIH) or pseudotumor cerebri (PTC), is a neurological disorder that is characterized by an increased intracranial pressure (pressure around the brain) in the absence of a tumor or other diseases. The main symptoms are headache, nausea and vomiting as well as pulsatile tinnitus (buzzing in the ears), double vision and visual symptoms. If untreated, it may lead to vision loss due to associated swelling of the optic disc in the eye.[1]

IIH is diagnosed with a brain scan (to rule out other causes) and a lumbar puncture; lumbar puncture may also provide temporary and sometimes permanent relief from the symptoms. Some respond to medication (with the drug acetazolamide), but others require surgery to relieve the pressure. The condition may occur in all age groups, but is most common in young women, especially those suffering from obesity.[1]

The most common symptom of IIH is headache, which occurs in almost all (92–94%) cases. It is characteristically worse in the morning, generalized in character and throbbing in nature. It may be associated with nausea and vomiting. The headache can be made worse by any activity that further increases the intracranial pressure, such as coughing and sneezing. The pain may also be experienced in the neck and shoulders. Many have pulsatile tinnitus, a whooshing sensation in one or both ears (64–87%). Various other symptoms, such as numbness of the extremities, generalized weakness, loss of smell, and incoordination, are reported more rarely; none are specific for IIH.[1] In children, numerous nonspecific signs and symptoms may be present.[2]

The increased pressure leads to compression and traction of the cranial nerves, a group of nerves that arise from the brain stem and supply the face and neck. Most commonly, the abducens nerve (sixth nerve) is involved. This nerve supplies the muscles that pull the eye outward. Those with sixth nerve palsy therefore experience horizontal double vision which is worse when looking towards the affected side. More rarely, the oculomotor nerve and trochlear nerve (third and fourth nerve palsy, respectively) are affected; both play a role in eye movements.[2][3] The facial nerve (seventh cranial nerve) is affected rarely–the result is weakness of all face muscles on one side of the face.[1]

The increased pressure leads to papilledema, which is swelling of the optic disc, the spot where the optic nerve enters the eyeball. This occurs in practically all cases of IIH, but not everyone experiences symptoms from this. Those who do experience symptoms typically report “transient visual obscurations”, episodes of difficulty seeing that occur in both eyes but not necessarily at the same time. Long-term untreated papilledema leads to visual loss, initially in the periphery but progressively towards the center of vision.[1][4]

Physical examination of the nervous system is typically normal apart from the presence of papilledema, which is seen on examination of the eye with a small camera called an ophthalmoscope or in more detail with a fundus camera. If there are cranial nerve abnormalities, these may be noticed on eye examination in the form of a squint (third, fourth and sixth) or as facial nerve palsy. If the papilledema has been longstanding, visual fields may be constricted and visual acuity may be decreased. Visual field testing by automated (Humphrey) perimetry is recommended as other methods of testing may be less accurate. Longstanding papilledema leads to optic atrophy, in which the disc looks pale and visual loss tends to be advanced.[1][4]

“Idiopathic” means “without an underlying cause”. Therefore, IIH can only be diagnosed if there is no alternative explanation for the symptoms. Intracranial pressure may be increased due to various other causes. This may be medication, such as high-dose vitamin A derivatives (e.g. for acne), long-term tetracycline antibiotics (for a variety of skin conditions) and the oral contraceptive. There are numerous other diseases, mostly rare conditions, that may lead to intracranial hypertension. If there is an underlying cause, the condition is termed “secondary intracranial hypertension”.[1]

Common secondary causes of intracranial hypertension include obstructive sleep apnea (a sleep-related breathing disorder), systemic lupus erythematosis (SLE), chronic kidney disease and Behçet’s disease.[4]

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Ichthyosis bullosa of Siemens is a rare skin disorder which is a type of familial, autosomal dominant ichthyosis.[1]:491 It is also known as bullous congenital ichthyosiform erythroderma of Siemens or ichthyosis exfoliativa. It is a genetic disorder with no known cure which is estimated to affect about 1 in 500,000 people.[2]

Ichthyosis bullosa of Siemens (IBS) was first described by the German dermatologist Hermann Werner Siemens in 1937 from his study of an affected family. [3]

In 1994 the gene causing IBS was discovered and it was also proved in the same year that ichthyosis exfoliativa is the same disease as IBS. [4]

IBS has symptoms very similar to epidermolytic hyperkeratosis (EHK) but is generally milder than EHK. IBS affects only the upper layers of the epidermis whilst EHK affects the suprabasal layer which is deeper in the skin. [5]

At birth the baby’s skin has a red appearance like a sun burn (erythema). Blistering is usually present at birth and may be extensive or localized depending on the severity of the disease.[4]

Over the first few weeks the red appearance disappears and is replaced by dry, flaking skin on the arms, legs and around the belly button.[6] Other areas of skin appear normal. The skin is fragile and is prone to blistering (caused by mild trauma or sweating).[6] After a few months hyperkeratosis develops with a dark grey or brown, ridged appearance on the ankles, knees and elbows.[4] Palms and soles are generally unaffected.[5] A slightly unpleasant, sweet odour may be present.[2]

A distinctive characteristic of IBS which is not present in other forms of ichthyosis is called the “Mauserung phenomenon” (Mauserung is german for “moulting” and was first described by H.W.Siemens). These are small patches of bare, apparently normal skin in the middle of areas of hyperkeratosis.[7][5]

As the sufferer ages the flaking and blistering should improve. The hyperkeratosis may grow more severe but more localized and is generally only present on flexural folds of the major joints.[4]

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IBIDS syndrome (also known as “Trichothiodystrophy,” and “Tay’s syndrome”[1]:485 ) was first described by Tay in 1971, an autosomal recessive disorder characterized by a congential ichthyosiform erythroderma, growth and mental retardation, progeria-like facies, and brittle hair.[1]:501 The association of ichthyosis, brittle hair, intellectual impairment, decreased fertility, and short stature has been given the acronym IBIDS syndrome.[1]:501 In some cases, it can be diagnosed prenatally.[2]

It is named after Dr. Tay Chong Hai, a Singaporean doctor who discovered and subsequently published a paper on it in 1971.[3] Dr. Tay is the first doctor in South East Asia to be honoured by having a disease named after him. The Tay syndrome should not be confused with the Tay-Sachs disease.[citation needed]

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