Property:Explanation
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This is a property of type Text.
W
The patient in this vignette has the early (primary) stage of Lyme disease, caused by the spirochete ''Borrelia burgdorferi''. ''Borrelia burgdorferi'' is a zoonotic bacteria that is carried by the Ixodes (deer) tick. In its early stages, Lyme disease causes flu-like symptoms and a characteristic “bullseye” rash called erythema chronicum migrans present in 80% of patients. The incubation period of Lyme disease can vary greatly, but is typically 1 to 2 weeks.
If untreated, Lyme disease can cause facial palsy and AV nodal block (secondary Lyme disease) progressing to chronic monoarthritis or migratory polyarthritis (tertiary Lyme disease). It is endemic to Northeastern USA. Treatment is generally by doxycyline.<br/>
'''Educational Objective:''' Primary (early) Lyme disease is characterized by the presence of a rash with a bullseye appearance. It is caused by the organism ''Borrelia burgdorferi'' that is transmitted by Ixodes (deer) tick. It is endemic in Northeastern USA.<br/>
'''References:''' First Aid 2014 page 141 +
The patient in this vignette is presenting with a history consistent with ectopic pregnancy. Ectopic pregnancy occurs when an egg is fertilized but implants outside of the uterus, most commonly in the fallopian tube. These pregnancies are not viable, but represent a significant health risk to patients. Early on, ectopic pregnancies can present with pain in the lower abdomen or upon micturition with or without low grade fever. Sometimes mild vaginal bleeding episodes can occur due to poor progesterone production by the corpus luteum and therefore withdrawal of the uterine lining. However, late ectopic pregnancies almost always present with significant pain with either vaginal or internal bleeding. They may also be complicated by peritonitis, marked by high-grade fever, excruciating abdominal pain, with rebound tenderness and guarding on abdominal physical exam.
One of the main risk factors for ectopic pregnancy is pelvic inflammatory disease (PID). PID causes salpingitis, defined as inflammation of the fallopian tubes, which can lead to scarring if untreated. The scarring of the fallopian tube serves as a nidus for inappropriate implantation of the embryo. The most common cause of PID is untreated infection with either ''Neisseria gonorrhea'', (65% of cases) or ''Chlamydia trachomatis'' (10% of cases). Patients may be remain asymptomatic despite presence of either/both organisms. ''Neisseria gonorrhea'' is a gram-negative maltose-nonfermenting rod which can be treated with ceftriaxone. Due to high prevalence of ''N. gonorrhea'' and ''C. trachomatis'' co-infection, patients with ''N. gonorrhea'' are often also treated with presumable C. trachomatis co-infection with doxycycline.<br/>
'''Educational Objective:''' Ectopic pregnancy may be a complication of pelvic inflammatory disease (PID) due to tubal scarring. ''N. gonorrhea'', a gram-negative maltose-nonfermenting rod, is a very common cause of PID<br/>
'''References:''' First Aid 2014 page 177 +
Rotavirus, an non-enveloped segmented dsRNA reovirus with an icosahedral capsid, is the most common cause of watery diarrhea in children. It is particularly prevalent in settings where many children come in contact with each other, such as daycare centers. Rotavirus causes watery diarrhea because the virus causes sloughing off of intestinal mucosa that leads to poor absorption of water and Na+. The infection typically lasts a few days before spontaneous recovery. However, some cases require hospitalization for rehydration following dehydration associated with severe diarrhea. Residual lactose intolerance as a result of epithelial degeneration may require prolonged periods of time before recovery.<br/>
'''Educational Objective:''' Rotavirus is the most common cause of watery diarrhea in children. It is is a dsRNA virus.<br/>
'''References:''' First Aid 2014 page 162 +
The correct answer is D.
This patient has ARDS secondary to multiple crush injuries and her vital signs and chest X-ray are consistent with this diagnosis. In ARDS, patients have decreased lung compliance and increased airway resistance leading to increased requirement of positive pressure ventilation called PEEP. They will have impaired oxygenation (E), not ventilation (B), hyperventilation leading to low CO2 levels (A), and usually they are very hypotensive with poor peripheral perfusion(C).<br/>
'''Educational Objective:''' <br/>
'''References:''' +
The correct answer is B.
This patient has Hashimoto’s thyroiditis. Hashimoto's thyroiditis (chronic autoimmune thyroiditis) is the most common cause of hypothyroidism in iodine-sufficient areas of the world. It is characterized clinically by gradual thyroid failure, goiter formation, or both, due to autoimmune-mediated destruction of the thyroid gland involving apoptosis of thyroid epithelial cells. Nearly all patients have high serum concentrations of antibodies against one or more thyroid antigens, diffuse lymphocytic infiltration of the thyroid, which includes predominantly thyroid-specific B and T cells, and follicular destruction.<br/>
'''Educational Objective:''' <br/>
'''References:''' +
Cystic fibrosis is caused by a mutation that encodes the cystic fibrosis transmembrane conductance regulator (CFTR) protein. The protein is primarily expressed in epithelial and blood cells. It is part of the ATP-binding cassette (ABC), or traffic APTase, gene family. Thus, it characteristically contains 2 ATP hydrolysis domains and 12 membrane-spanning alpha helixes. Its main function is a chloride channel; however it also functions to inhibit sodium transporter through the epithelial sodium channel. The "low-volume" hypothesis states that CFTR impairment in the airways leads to loss of inhibition of epithelial sodium channels, causing excessive sodium and water reabsorption and dehydration in the airways. In contrast, a "high-salt" hypothesis suggests that excess sodium and chloride are retained in the airway surface liquid due to CFTR absence.
Normally in sweat glands, sodium is reabsorbed from the ductular lumen via apical sodium channels and CFTR. This process is followed by a chloride counter-ion. In patients with CF, there is impaired reabsorption of chloride leading to restricted sodium reabsorption. Accordingly, sweat in patients with CF contains high levels of sodium. This is opposite to the "low-volume" model, but consistent with the "high-salt" model.
Diagnosis of CF is suspected when newborns fail to pass meconium in the first 24-48 hours and thus suffer from meconium ileus. Nonetheless, some patients may remain undiagnosed until adulthood. Diagnosis is made when chloride sweat levels are elevated > 60 mmol/L (requiring pilocarpine iontophoresis and quantitative determination of chloride levels) for most patients and 2 disease-causing CFTR mutations are identified. Some patients, such as infants, may require less chloride concentrations to make the diagnosis. Although manifestations greatly vary, classically the liver, the pancreas (both exocrine and endocrine), the liver, and the genitals are involved. Although more than 1000 CFTR mutations have already been described, phenylalanine absence at position 508 accounts for the majority of mutations in Northern Europe and North America.<br/>
'''Educational Objective:''' Normally in sweat glands, sodium is reabsorbed from the ductular lumen via apical sodium channels and CFTR. This process is followed by a chloride counter-ion. In patients with CF, there is impaired reabsorption of chloride leading to restricted sodium reabsorption. Accordingly, sweat in patients with CF contains high levels of sodium.<br/>
'''References:''' Antunovic SS, Lukac M, Vujovic D. Longitudinal cystic fibrosis care. ''Clin Pharmacol Ther''. 2013;93(1):86-97
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Rigot JM, Lafitte JJ, Dumur V, et al. Cystic fibrosis and congenital absence of the vas deferens. ''N Engl J Med''. 1991;325(1):64-5.
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O'Sullivan BP, Freedman SD. Cystic fibrosis. ''Lancet''.373(9678):1891-1904.
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Rowe SM, Miller S, Sorscher EJ. Cystic fibrosis. ''N Engl J Med''. 2005;352:1992-2001.
The patient is most likely diagnosed with Hirschsprung's disease. It is a congenital aganglionosis of the submucosal (Meissner's) and the myenteric (Auerbach's) neural plexuses that affect the rectosigmoid or rectal portions of the GI tract. The pathophysiology of the disease is thus linked to the absence of autonomic neural crest-derived ganglion cells in the terminal hindgut.
Failure to pass the first stool postnatally after the first 24-48 hours is consistent with the diagnosis of Hirschsprung's disease. Failure to pass stools is characterized by intestinal obstruction, abdominal distension, and bilious vomiting that occur soon after birth. In patients with Hirschsprung's disease, patients eventually pass a meconium plug followed by sparse bowel movements. Barium enema often shows small-to-normal aganglionic bowel of normal diameter with proximal dilated bowels, termed megacolon.
Failure of passage of meconium may be also be associated with cystic fibrosis. Abdominal radiographs in these patients reveals distended bowels with few air-fluid levels, and presence of "ground-glass" appearing meconium mixed with air. In contrast, a microcolon is observed on barium enema. On barium enema.
The normal function of ''RET'' (REarranged during Transfection) proto-oncogene is the encoding of a receptor tyrosine kinase that plays a role in activation of signalling pathways via phosphorylation of tyrosine residues. ''RET'' proto-oncogene mutation is associated with MEN 2A and 2B, Hirschsprung's disease, and Neuroblastoma. While loss of function mutations of ''RET'' are observed in Hirschsprung's disease, gain of function is associated with MEN 2A, 2B, and medullary thyroid carcinoma.
MEN 2A syndrome:
*Parathyroid tumor
*Medullary thyroid cancer
*Pheochromocytoma
MEN 2B syndrome:
*Oral/intestinal ganglioneuromas
*Medullary thyroid cancer
*Pheochromocytoma<br/>
'''Educational Objective:''' ''RET'' is a proto-oncogene whose mutation can give rise to Hirschsprung's disease or multiple endocrine neoplasia (MEN). Medullary thyroid carcinoma may be associated with multiple endocrine neoplasias type 2A and 2B.<br/>
'''References:''' Chernyavsky VS, Farghani S, Davidov T, et al. Calcitonin-negative neuroendocrine tumor of the thyroid: a distinct clinical entity. ''Thyroid''. 2011;21(2):193-6.
Chen F, Winston JH, Jain SK et al. Hirschsprung's disease in a young adult: report of a case and review of the literature. ''Ann Diagn Pathol''. 2006;10(6):347-51.
Edery P, Lyonnet S, Mulligan LM, et al. Mutations of the ''RET'' proto-oncogene in Hirschsprung's disease. ''Nature''. 1994;367:378-380.
Loening-Baucke V, Kimura K. Failure to pass meconium: diagnosing neonatal intestinal obstruction. ''Am Fam Physician''. 1999;60(7):2043-2050
Martucciello G, Lerone M, Bricco L, et al. Multiple endocrine neoplasia type 2B and RET proto-oncogene. ''Ital J Pediatr.'' 2012. 38:9
First Aid 2014 page 329
The patient is most likely diagnosed with recurrent corneal erosions. It is a disorder of the eyes characterized by the failure of the cornea's outermost layer of epithelial cells to attach to the underlying basement membrane (Bowman's layer). The condition is frequently painful because the loss of these cells results in the exposure of sensitive corneal nerves. Patients presents with recurring attacks of acute eye pain, foreign-body sensation, photophobia (i.e. sensitivity to bright lights), and tearing often at the time of awakening or during sleep when the eyelids are rubbed or opened.<br/>
'''Educational Objective:''' <br/>
'''References:''' +
Amiodarone-induced hypothyroidism (AIH) is believed to result from the inability of the thyroid to escape from the '''Wolff-Chaikoff''' effect. Amiodarone is a benzofuranic-derivative iodine-rich drug, the large amount of iodide released during the metabolism of amiodarone leads to an adaptive blockage of further thyroidal iodide uptake and thyroid hormone biosynthesis, the so-called '''Wolff-Chaikoff''' effect.
The reported incidence of AIH varies widely, ranging from 6% in countries with low iodine intake to 13% in countries with a high dietary iodine intake.
The risk of developing hypothyroidism is independent of the daily or cumulative dose of amiodarone. However, the risk is greater in the elderly and in female patients, probably as a result of a higher prevalence of underlying thyroid abnormality. The relative risk of developing AIH was found to be 13-fold higher in female patients with positive thyroid microsomal or thyroglobulin antibodies, as compared with men without thyroid antibodies.
'''Reference''':
*"Effects of amiodarone on thyroid function.", journal = Ann Intern Med, volume = 126, issue = 1, month = Jan, year = 1997, PMID = 8992925.
*"Amiodarone and the thyroid: a practical guide to the management of thyroid dysfunction induced by amiodarone therapy.", journal = Heart, volume = 79, issue = 2, month = Feb, year = 1998, PMID = 9538302.
*"Incidence, predictability, and pathogenesis of amiodarone-induced thyrotoxicosis and hypothyroidism." journal = Am J Med, volume = 91, issue = 5, month = Nov, year = 1991, PMID = 1951413.<br/>
'''Educational Objective:''' <br/>
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Congenital rubella syndrome results from the infection of fetus by the transmission of the virus from the mother during the viremic stage of the infection. The rubella virus travels through the blood stream of the fetus and damages the blood vessels. This results in ischemic injury to the cells in the germ layers. The risk of congenital infection and defects is highest during the first 12 weeks of gestation, and decreases after the 12th week of gestation with defects rare after the 20th week of gestation. If infection occurs within 0–28 days before conception, there is a 43% chance the infant will be affected. If the infection occurs within 0–12 weeks after conception, there is a 51% chance the infant will be affected. If the infection occurs within 13–26 weeks after conception there is a 23% chance the infant will be affected by the disease. Infants are not generally affected if rubella is contracted during the third trimester, or 26–40 weeks after conception.<br/>
'''Educational Objective:''' <br/>
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The treatment of choice for onchocerciasis is ivermectin which is given in the dose of 150 mcg/kg orally in one dose every 6 months, for both adults and children. Ivermectin kills by interfering with nervous system and muscle function of the microfilariae. Ivermectin has been shown to reduce the occurrence of blindness, and to reduce the occurrence and severity of skin symptoms.
An evolving treatment for oncocerciasis is doxycycline, which has been shown in studies to kill Wolbachia, an endosymbiotic rickettsia-like bacteria that appears to be required for the survival of the O.volvulus macrofilariae and for embryogenesis. Doxycycline does not kill the microfilariae, so treatment with ivermectin would be needed to result in a more rapid decrease of symptoms.<br/>
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Explanation: All infants born to mothers who have reactive non-treponemal and treponemal test results should be evaluated with a quantitative non-treponemal serologic test (RPR or VDRL) performed on infant serum, because umbilical cord blood can become contaminated with maternal blood and yield a false-positive result. Conducting a treponemal test (i.e., TP-PA, FTA-ABS, EIA, or chemiluminescence assay) on a newborn’s serum is not necessary.<br/>
'''Educational Objective:''' <br/>
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Asthma is a chronic lung disease characterized by inflammation of the airways, causing recurrent symptoms. The characteristic symptoms are wheezing, chest tightness, shortness of breath, or cough. Symptoms often worsen in the face of certain triggers, which include allergens, cold air, exercise, or other irritants. Physical examination may reveal hyperexpansion of the thorax, expiratory wheezing with a prolonged expiratory phase of respiration, and signs of allergies or atopic dermatitis.
Educational objective: Asthma can be diagnosed by a history of episodic symptoms of airway obstruction (wheeze, dyspnea, cough, chest tightness), establishing the presence of airflow obstruction that is at least partially reversible and ruling out other causes of these symptoms/signs.<br/>
'''Educational Objective:''' <br/>
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Hypertrophic Obstructive Cardiomyopathy (HOCM) is an autosomal dominant genetic disorder. It is caused by a missense mutation in 1 of at least 14 genes that encode cardiac sarcomeres. Most common mutations encode beta-myosin heavy chain (MYH7) and cardiac myosin binding protein C (MYBPC3). HOCM is characterized by a hypertrophic cardiomyopathy that involves the ventricular septum, resulting in dynamic left ventricular outflow tract obstruction, mitral regurgitation, and diastolic dysfunction. The majority of patients lead a normal life. Some experience symptoms of myocardial ischemia such as angina and dyspnea; and a minority of patients suffer ventricular arrhythmias and die at young age.
HOCM may be diagnosed incidentally during routine physical examination or work-up. The most important finding suggestive of HOCM on physical examination is a systolic ejection murmur best heard at the left sternal bordern (LSB) that increases in intensity during maneuvers the decrease preload, such as standing from a squatting position. ECG findings include evidence of left ventricular hypertrophy. The definitive diagnosis of HOCM is made by 2-D echocardiography, which demonstrates asymmetric hypertrophy of the myocardium with a septal thickness greater than the thickness of the free well, and continuous-wave Doppler echocardiography, which reveals resting obstruction. Myocardial biopsy is not required, but it demonstrates myofibrillar disarray, myocyte hypertrophy, and fibrosis.
Management of patients with HOCM includes symptomatic relief using beta-blockers of verapamil. Other prophylactic measures include infective endocarditis prophylaxis, avoidance of high intensity exercise or dehydration, genetic counseling, and period screening for other immediate family members. Surgical intervention by septal myomectomy is rarely required.<br/>
'''Educational Objective:''' Hypertrophic Obstructive Cardiomyopathy (HOCM) is an autosomal dominant genetic disorder. It is caused by a missense mutation in 1 of at least 14 genes that encode cardiac sarcomeres. Most common mutations encode beta-myosin heavy chain (MYH7) and cardiac myosin binding protein C (MYBPC3).<br/>
'''References:''' McCarthy TV, Quane KA, Lynch PJ. Ryanodine receptor mutations in malignant hyperthermia and central core disease. Hum Mutat. 2000;15(5):410-7
Mosher DS, Quignon P, Bustamante CD, et al. A mutation in the myostatin gene increases muscle mass and enhances racing performance in heterozygous dogs. PLoS Genet. 2007;3(5):e79
Nader A, Massumi A, Cheng J, et al. Inherited arrhythmic disorders: long QT and Brugada syndromes. Tex Heart Inst J. 2007;34(1):67-75
Nishimura RA, Holmes DR. Hypertrophic obstructive cardiomyopathy. N Engl J Med. 2004;350:1320-7
Roncarati R, Latronico MV, Musumeci B, et al. Unexpectedly low mutation rates in beta-myosin heavy chain and cardiac myosin binding protein genes in Italian patients with hypertrophic cardiomyopathy. J Cell Physiol. 2011;226(11):2894-900.
First Aid 2014 page 290
The most common complication of a supracondylar fracture is neurovascular injuries (8-21% of cases) as reported in some studies. Palsy to the anterior interosseus nerve at time of injury is most common, followed by brachial artery injuries. Injury to the ulnar nerve is reported as well, but it is less common. Brachial artery injury is also a common complication of this fracture, but neuopraxias are more common. It presents as cold, pale, and pulseless hand. long term complication can lead to Volkmann's contracture, also known as Volkmann's ischaemic contracture, which is a permanent flexion contracture of the hand at the wrist, resulting in a claw-like deformity of the hand and fingers. Radial nerve palsy is the second most common neuropraxia (close second).<br/>
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TSH, BUN, creatinine, Pregnancy test are necessary tests to perform prior to starting patients on lithium due to associated teratogenicity, renal injury and thyroid disorders with lithium therapy. Liver or adrenal injury is not known to occur with lithium as indicated in the distractors.<br/>
'''Educational Objective:''' <br/>
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EDUCATIONAL OBJECTIVE: In benign positional vertigo (BPV), Patients presents with brief episodes of vertigo with positional changes, typically when turning over in bed. They often have positive response to the Dix-Hallpike maneuver, which confirms the diagnosis.<br/>
'''Educational Objective:''' <br/>
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The patient has chronic hepatitis B. The presence of antibody to hepatitis B core with a positive hepatitis B surface antigen is indicative of chronic infection. Any patient who is hepatitis B surface antigen positive is at risk for delta hepatitis. This patient would be at risk for delta hepatitis by virtue of having a positive hepatitis B surface antigen. There is no level of transaminases, even normal transaminases, which would preclude antiviral therapy. The level of viral production indicated by the hepatitis B quantitative viral load, along with an assessment of the underlying liver pathology, is the best indication of need for treatment. As mentioned earlier, the antibody to hepatitis B would show the patient is less infectious and likely have a lower viral load. +
EDUCATIONAL OBJECTIVE: In benign positional vertigo (BPV), Patients presents with brief episodes of vertigo with positional changes, typically when turning over in bed. They often have positive response to the Dix-Hallpike maneuver, which confirms the diagnosis.<br/>
'''Educational Objective:''' <br/>
'''References:''' +
Beta thalassemia is a hereditary hemoglobinopathy that is commonly caused by splice site mutations that result in deficiency in beta-globin hemoglobin chains. It is prevalent among Mediterranean populations. Beta-thalassemia is a severe microcytic, hypochromic anemia. Clinical manifestations of beta-thalassemia include anemia with ineffective erythropoiesis, hepatosplenomegaly, and severe bone deformities. Patients with thalassemia major are considered transfusion-dependent because they require chronic blood transfusions to survive. Nonetheless, chronic transfusions are accompanied by severe life-threatening complications, such as transfusion-transmitted infections such as viral hepatitis B and C, and iron overload, which is believed to be caused by 2 factors: First, hemosiderosis associated with the transfusions; and second, the paradoxically excessive GI iron absorption due to the presence of a humoral factor that down-regulates hepcidin which normally inhibits iron absorption. Iron overload may result in iron deposition in organs, such as the heart, the liver, and endocrine gland that lead to organ failure. To prevent complications such as cardiotoxicity, iron chelat2qion by deferoxamine, deferiprone, or deferasirox. Although chronic transfusions are needed for survival of patients with beta-thalassemia major, the only cure for these patients is bone marrow transplantation. Transfusion associated hemochromatosis is a serious complication of beta-thalassemia, but can be managed with iron chelators such as deferoxamine. Mutations of the ''HFE'' gene cause a hereditary form of hemochromatosis. Cure of beta-thalassemia is possible only by bone marrow transplantation.<br/>
'''Educational Objective:''' Transfusion-associated secondary hemochromatosis is a serious complication of beta-thalassemia and other diseases that require chronic transfusions. Iron overload can be managed by iron chelators such as deferoxamine. Mutations in the ''HFE'' gene cause a hereditary form of hemochromatosis.<br/>
'''References:''' Rund D, Rachmilewitz E. B-thalassemia. N Engl J Med. 2005;353:1135-46.<br>First Aid 2014 page 383