A 6-year-old boy is brought to his family physician because he was observed to fall frequently and has difficulty getting up from the floor. Physical exam shows no abnormalities other than positive Gower sign and a heart rate of 115 bpm. With appropriate work-up, neuropathies and inflammatory and metabolic myopathies are excluded. The family physician suspects Duchenne or Becker muscular dystrophy.
Which of the following pieces of history or lab results would support the diagnosis of Becker muscular dystrophy (BMD) rather than Duchenne muscular dystrophy (DMD)?
Correct Answer D:
Becker muscular dystrophy (BMD), is a mild form of X-linked muscle dystrophy with late onset. Patients with this disease usually remain ambulatory beyond the age of 15 to 20 years. Like BMD, Duchenne muscular dystrophy (DMD) is also X-linked but has an early onset and patients with this disease are usually confined to wheel chair by the age of 7 years. A maternal uncle who has muscle dystrophy but is ambulatory at the age of 17 (choice D) would favor the diagnosis of BMD rather than DMD. A maternal uncle with dystrophy suggests the X-linked transmission of dystrophy and the fact that the maternal uncle is ambulatory at the age of 17 years suggest the milder form or BMD. Thus, if there is a family history of maternal uncle with dystrophy and who is ambulatory beyond the age of 15 years, BMD rather than DMD is the likely diagnosis.
→ A male sibling without any obvious health problems who has normal serum creatine kinase at the age of 17 years (choice A) can be a sibling to a patient with Duchenne muscular dystrophy (DMD) or Becker muscular dystrophy (BMD). Both diseases are transmitted as x-linked recessive and only 50% of male off-spring of female carriers develop the diseases. The other 50% might inherit the normal X chromosome from the female carrier and might thus, be normal. So, a normal male sibling cannot differentiate between DMD and BMD.
→ A female sibling without any obvious health problems who has normal serum creatine kinase at the age of 8 years (choice B) can be a sibling to a patient with DMD or BMD. Both diseases are transmitted as x-linked recessive and only 50% of female off-springs of female carriers would be carriers and have high serum creatine kinase. The other 50% might inherit the normal X chromosome from the female carrier and are thus, not carriers and have normal serum creatine kinase. So, a normal female sibling cannot differentiate between DMD and BMD.
→ A father without any obvious health problems at the age of 35 years (choice C) could a father to a patient with DMD or BMD. Fathers give their Y chromosomes to their sons and cannot transmit X-linked recessive diseases like DMD or BMD.
→ A paternal uncle without any obvious health problems at the age of 17 years (choice E) could be an uncle to a patient with DMD or BMD. Both disease are transmitted as x-linked recessive and are not transmitted from the paternal side.
Key point:
A patient with muscular dystrophy who has a maternal uncle with dystrophy who is ambulatory beyond the age of 15 years, most likely has Becker muscular dystrophy rather than Duchenne muscular dystrophy.
A mother brings her 4-month-old baby because she thinks he looks a little “blue” and seems to be a bit short of breath when feeding him. He has no significant perinatal or other history, and neither does his mother or father.
On examination, you confirm that the baby is cyanotic and seems to have severe respiratory distress, especially when attempting to bottle-feed him. There is a hyperactive right ventricle impulse, quadruple rhythm, fixed and widely split S2, a systolic ejection murmur and a mid-diastolic rumble on the left lower sternal border. The blood pressure appears normal and equal in all extremities.
His ECG reveals a right ventricle hypertrophy and right axis deviation. The X-ray shows an enlarged right heart and an increased pulmonary vascular markings and the radiologist reports a “classic pattern of a snowman in a storm.”
Which of the following is your presumptive diagnosis before obtaining an echocardiogram?
Correct Answer C:
Total anomalous pulmonary venous return is a congenital heart disease in which, instead of draining into the left auricle, the pulmonary vein drains into any of the following locations: Supracardiac (most common, Superior Vena Cava), Cardiac (coronary sinus or Right Auricle), Subdiaphragmatic (Inferior Vena Cava, Portal Vein, Ductus Venosus, or hepatic vein), or mixed site.
The examination findings are a hyperactive RV impulse, quadruple rhythm, S2 fixed and widely split, 2-3/6 systolic ejection murmur at the left upper sternal border and mid-diastolic rumble at the left lower sternal border. The ECG reports right axis deviation and right ventricle hypertrophy, and may come with right atrial enlargement. The X-ray shows cardiomegaly at expense of the right heart and the classic finding of “snowman in a storm,” which is due to enlargement of the heart and the presence of a dilated right superior vena cava, innominate vein, and left vertical vein.
→ Tetralogy of Fallot (choice A) will have a loud systolic ejection murmur at the left midsternal border and left upper sternal border, and a loud, single S2. The ECG will show right axis deviation and right ventricle hypertrophy. A boot-shaped heart with normal heart size and decreased pulmonary venous markings will appear on the chest x-ray.
→ Tricuspid Atresia (choice B) will show a single S2 with a 2-3/6 systolic regurgitation murmur at the left lower sternal border if a ventricular septal defect is present. The ECG will show a superior axis deviation and a right auricle enlargement or common atrial enlargement and left ventricle hypertrophy. The heart will appear of normal or slightly enlarged size in the chest x-ray and have a boot shape.
→ Coarctation of the aorta (choice D) usually presents with a 2-3/6 systolic ejection murmur at the left upper sternal border radiating to the interescapular area. Classically, the lower extremities will have a lower BP than the upper extremities, and this may be accompanied by a discrepancy of > 5% discrepancy between upper and lower extremities pulse oximetry.
→ Patent Ductus Arteriosus (choice E) usually exhibits a 1-4/6 continuous machinery murmur that is loudest at the left upper sternal border and a wide pulse pressure.
Careful clinical examination and x-ray of the newborn and infant with suspected congenital heart disease can point towards the diagnosis before obtaining an Echocardiogram.
A 3-year-old boy presents to your walk-in clinic with a 4-day history of fever, decreased appetite and irritability. His mother adds that he has been pulling his right ear for the last four days. He has normal urine output and energy. He is otherwise healthy.
Vital signs: temperature:
On examination you see an energetic boy. Otoscopic examination reveals a red, bulging tympanic membrane on the right side. The opposite ear is normal. Examination of the oropharynx is normal. There is no head or neck lymphadenopathy.
What is your next step in the immediate management of this patient?
The high spontaneous recovery rate (80-90%) of acute otitis media may warrant watchful waiting for 48-72 hours before starting antibiotic therapy. However, in cases where there is prolonged fever such as in this boy, treatment with antibiotics is clinically warranted. The treatment of choice for acute otitis media is currently amoxicillin at a dose 80-90 mg/kg/d divided into two doses for 7 days (choice D). Amoxicillin is favoured for its low cost, narrow coverage spectrum, and side effect profile. Further cases where treatment with antibiotics is suggested include:
Generally speaking, treatment with antibiotics occurs in the above conditions as well as in clinical settings where follow-up may be uncertain. Treatment of otitis media with antibiotics does have the following benefits over conservative treatment:
→ While reassurance and follow-up (choice A) are reasonable options, closer follow-up period of 48-72 hours would be advisable for this patient with fever.
→ Amoxicillin-clavulanate (choice B) is often reserved as second-line treatment or in cases where there has been recent antibiotic use in the last three months.
→ Amoxicillin 40 mg/kg/d for 7 days (choice C) has fallen out of favour due to increasing resistance by Streptococcus pneumoniae.
→Typically, spontaneous recovery (choice E) is seen in 50% of patients by 3 days and 90% of patients by 7 days.
Acute otitis media has a high spontaneous recovery rate, however in select cases including age less than two, and cases where follow-up is uncertain, first line treatment for otitis media is amoxicillin 80-90 mg/kg daily divided into two doses for 7 days.
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