USMLE Step 3 (Fach) / Pediatrics (Lektion)

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• Tetralogy of Fallot 1. Right ventricular outflow obstruction (RVOT) due to pulmonary valve stenosis  2. Right ventricular hypertrophy3. Ventricular septal defect (VSD)4. Overriding aorta (above the VSD) Epidemiology: Most common cause of cyanotic CHD Etiology:- Typically sporadic; sometimes associated with genetic defects (e.g., Down syndrome, DiGeorge syndrome)- Associated with other cardiac anomalies in ∼ 40% of patients Clinical findings:- Mild cyanosis- Tet spells  → Intermittent hypercyanotic, hypoxic episodes with a peak incidence 2-4 months after birth→ Associated with psychological and physical stress (e.g., crying, feeding, defecation)- Untreated young children tend to squat.  - Auscultatory finding: harsh systolic murmur that is best heard over Erb's point and left upper sternal border   Diagnostics:- Pulse oximetry: ↓ SpO2- Hyperoxia test: to distinguish cardiac from pulmonary causes of cyanosis  - ECG: right axis with right heart hypertrophy; P pulmonale with increasing age- Echocardiography: detection of the main features of TOF, quantification of right ventricular outflow tract pressure gradient (supplementary cardiac catheterization may be performed)- Chest x-ray: absent pulmonary artery segment, decreased pulmonary vasculature, small “boot-shaped” heartTreatment:- Severe RVOT: IV prostaglandin (PGE1) until surgery- Acute hypoxia (tet spells):→ Administer oxygen→ Knee to chest position, squatting→ IV morphine for sedation and fluids→ If above measures fail: IV beta blockers  - Long-term management→ Surgery: performed within the first year of life, if possible VSD repair: patch closure of the ventricular septal defect; ensuring correct aortal positioning above the left ventricle→ Enlargement of the RVOT: resection of the obstructive infundibular musculature→ Follow-up care: to prevent long-term complications such as heart failure, arrhythmias, and neurodevelopmental impairment
• Transposition of the great vessels (TGV) Anatomical reversal of the aorta and the pulmonary artery   Epidemiology: Accounts for ∼ 20 % of all cyanotic CHD   Etiology:- Infants born to diabetic mothers- Maternal alcohol consumption/poor nutrition- Maternal age > 40 years- Rubella infection or other viral illness- Rarely associated with genetic syndromes or extracardiac malformations→ DiGeorge syndrome  → Down syndrome, Edward syndrome, Patau syndrome Clinical findings:- Postnatal cyanosis (not affected by exertion or supplemental oxygen)  - Tachypnea- Auscultation: Single loud S2- If concurrent VSD is present: systolic murmur at the left sternal border Diagnostics:- Echocardiography: (confirmatory test) demonstrates transposition of the great arteries and shunts- Pulse oximetry: ↓ SpO2- X-ray: Heart with an “egg on a string” appearance, ↑ Pulmonary vascular markings Treatment:- Initially: infusion of prostaglandin (PGE1) to prevent closure of the PDA- Definite repair: surgical correction within the first two weeks of life with arterial switch procedure  - Balloon atrial septostomy→ Indications: if surgery cannot be performed or if hypoxia is severe despite IV PGE1 administration prior to surgery
• Coarctation of the aorta Definition:- Narrowing of the aorta at the aortic isthmus   Epidemiology:- Sex: ♂ > ♀- Usually associated with bicuspid aortic valve, VSD, and/or PDA Etiology:- Associated with Turner syndrome   Clinical findings:Newborns:- Asymptomatic if PDA is present or aortic narrowing is only mild- Cyanosis in lower extremities (differential cyanosis)- Weak femoral pulses (brachial-femoral delay)  - In severe stenosis: shock and multi-organ failure, when ductus arteriosus closes   Childhood:- Chest pain, cold feet, and lower-extremity claudication on physical exertion- ↑ BP in upper extremities and ↓ BP in lower extremities  - Auscultation: systolic ejection murmur over left paravertebral region and/or continuous murmur below left clavicula and between the shoulder blades  - Palpation of strong displaced apical impulse to the left Adults:- Hypertension- Variability in blood pressure in the upper and lower extremities  - Headache, epistaxis, tinnitus  - Claudication of the lower extremities with exertion Diagnostics:- Best initial test: upper and lower extremity blood pressure measurement and search for brachial-femoral delay- Pulse oximetry: ↓ SpO2- Echocardiography with doppler (confirmatory test): location and extent of stenosis; concurrent anomalies- X-ray:→ Cardiomegaly and ↑ pulmonary vascular markings→ “Figure of 3” sign  → Rib notching (on inferior border of the ribs)  - Genetic testing for Turner syndrome Treatment:- Initial management: infusion of PGE1 (alprostadil)  - Surgery: Should be performed as soon as possible in critical cases.→ Techniques: surgical correction or balloon angioplasty  - Follow-up and monitor for restenosis, aortic aneurysm and aortic dissection Complications:- Secondary hypertension and/or cerebral aneurysms in adulthood→ Intracranial hemorrhage  - Heart failure, aortic dissection, coronary artery disease, endocarditis, ischemic stroke, myocardial infarction
• Hypertrophic pyloric stenosis Epidemiology:- Sex: ♂ > ♀ (∼ 5:1)- More common in firstborn children Etiology:- Exposure to nicotine during pregnancy- Bottle feeding  - Genetic factors: patients with affected relatives have a higher risk of hypertrophic pyloric stenosis- Macrolide antibiotics Clinical features:- Symptoms usually develop between the 2nd and 7th week of age (rarely after the 12th week). - Frequent regurgitation progressing to projectile, nonbilious vomiting immediately after feeding- An enlarged, thickened, "olive-shaped”, non-tender pylorus (diameter of 1-2 cm) should be palpable in the epigastrium- A peristaltic wave, moving from left to right, may be evident in the epigastrium- "Hungry vomiter": demands re-feeding after vomiting, demonstrates a strong rooting and sucking reflex, irritable- If left untreated: dehydration, weight loss, failure to thrive   Diagnostics:- Initial imaging: abdominal ultrasound → shows an elongated and thickened pylorus  - Barium studies: If ultrasound is inconclusive→ Narrow pyloric orifice→ String sign: elongated, thickened pylorus→ Beak sign: The pylorus is only partially open to the stomach because of hypertrophy, resulting in two muscular layers adjacent to one another with an "open beak."  - Endoscopy- Laboratory tests: Hypochloremic, hypokalemic metabolic alkalosis Treatment- Conservative measures: before surgery→ Correct electrolyte imbalance (e.g., replace K+)→ IV rehydration→ Frequent administration of small meals (12-24 per day)→ Elevate head- Treatment of choice: Ramstedt pyloromyotomy (a longitudinal muscle-splitting incision of the hypertrophic sphincter)
• Intussusception Epidemiology:- Sex: ♂ > ♀ (3:2)- Peak incidence: 3-12 months; otherwise commonly occurs in children 5 months to 6 years of age   Etiology:- Mostly idiopathic (usually in children 3 months to 5 years of age)→ 75% of cases have no identifiable lead point  → Disorganized peristalsis with enlarged Peyer's patches may underlie idiopathic cases.  - Pathological lead points: more likely the underlying cause in patients with recurrent episodes of intussusception; more common in children < 3 months or > 5 years of age→ Meckel's diverticulum (most common)→ Intestinal polyps or other tumors (2nd most common)→ Bowel wall thickening in Henoch-Schönlein purpura→ Recent rotavirus immunization→ Cystic fibrosis Clinical features:- Child typically looks healthy- Acute cyclical colicky abdominal pain (sudden screaming or crying spells), often with legs drawn up, with asymptomatic intervals - Acute attacks occur approx. every 15-30 min. - Vomiting (initially nonbilious)  - Lethargy, pallor, and other symptoms of shock or altered mental status may be present.- Abdominal tenderness, palpable sausage-shaped mass in the RUQ, and an “emptiness” or retraction in the right lower quadrant (Dance sign) during palpation - High-pitched bowel sounds on auscultation  - “Currant jelly stool” (usually a late sign) may be noticed in passed stool or during digital rectal examination Approach:- If clinical suspicion is high: perform enema.- If the diagnosis is unclear at presentation or pathological lead points are suspected: perform radiographic imaging (ultrasoundor abdominal x-ray) to confirm the diagnosis. Treatment:- Initial steps: nasogastric decompression and fluid resuscitation- Nonsurgical management (performed under continuous ultrasound or fluoroscopic guidance)→ Air (pneumatic) enema: treatment of choice→ Hydrostatic reduction: normal saline (or water-soluble contrast enema)→ Observe for 24 hours post-reduction, as there is a small risk of perforation and recurrence is common during this period- Surgical reduction:→ When a pathological lead point is suspected→ Failed conservative management→ Suspected gangrenous or perforated bowel→ Critically ill patient (e.g., shock)→ Open or laparoscopic method
• Intestinal malrotation and volvulus Intestinal malrotation: arrest in the normal rotation of the gut in utero, resulting in an abnormal orientation of the bowel and mesentery within the abdominal cavity Midgut volvulus: torsion of a malrotated midgut causing mechanical bowel obstruction, mostly in neonates and infants Epidemiology:- Sigmoid volvulus (most common, 80%): ∼ 70 years; ♂ > ♀- Cecal volvulus (15%): 40-60 years; ♀ >♂  - Intestinal malrotation and midgut volvulus: neonates and infants   Clinical presentation:- Malrotation: mostly asymptomatic  - Midgut volvulus:→ Bilious vomiting with abdominal distension in a neonate/infant  → Signs of bowel ischemia: hematochezia, hematemesis, hypotension, and tachycardia  → Features of duodenal obstruction: bilious vomiting without abdominal distension  → Variable presentation in older children/adults: recurrent episodes of abdominal pain and vomiting; failure to gain weight; malabsorption  → Abdominal examination is unreliable  - Features of associated congenital anomalies: Commonly associated anomalies: congenital diaphragmatic hernia (∼ 100%); congenital heart defects (up to 90%); omphalocele (up to 45%) Diagnotics:- Laboratory studies: complete blood count; electrolyte levels; arterial blood gas analysis  - Upper GI series (gold standard in hemodynamically stable patients)  - Barium enema (lower GI series) Treatment:- Midgut volvulus with/without peritonitis→ Initial resuscitation: nil per oral; nasogastric tube insertion; IV fluids; correction of electrolyte imbalance; broad-spectrum IV antibiotics→ Emergency surgery (Ladd procedure)  - Incidentally detected/asymptomatic intestinal malrotation: elective surgery (Ladd procedure)
• Meckel diverticulum Epidemiology:- Prevalence: most common congenital gastrointestinal tract anomaly (∼ 2% of the population)- Sex: ♂ > ♀ (2:1)- Age: < 2 years of age   Anatomy:- Meckel diverticulum is a true diverticulum.  - Located ∼ 2 feet proximal to the ileocecal valve  - Usually ≤ 2 inches in size- There may be 2 types of mucosal lining: Native ileal mucosa + Heterotopic mucosa  - Blood supply: vitelline artery   Clinical features:- Asymptomatic (∼ 96%)  - Symptomatic (2-4%)→ Painless lower gastrointestinal bleeding (most common presentation)  → Hematochezia  → Tarry stools  → Currant jelly stools   Diagnostics:- Meckel scintigraphy scan (Meckel scan): a noninvasive nuclear medicine imaging technique using radiolabelled technetium (99mTc), which is preferentially absorbed by the gastric mucosa and can identify ectopic gastric mucosa  - CT angiography: may demonstrate the vitelline artery or even contrast extravasation from a bleeding Meckel diverticulum- Enteroscopy Treatment:- Asymptomatic: no treatment necessary- Symptomatic or complicated Meckel diverticulum→ Initial stabilization of the patient  → Surgical resection of all symptomatic/complicated Meckel diverticuli
• Necrotizing enterocolitis Epidemiology:- More common in premature infants→ NEC is the most common cause of acute abdomen in premature infants- Peak incidence: 2nd-4th week after birth (not during the first week!) Diagnostics:- Neutrophil counts < 1500/μL are associated with a poor prognosis.- The degree of thrombocytopenia correlates with the severity of NEC.- ↑ Inflammatory markers- Check for signs of DIC → see disseminated intravascular coagulation- Arterial blood gas analysis: Metabolic acidosis is associated with advanced NEC.- Blood cultureAbdominal radiography→ Pneumatosis intestinalis: bubbles of gas within the wall of the intestine  → Portal venous gas (pneumatosis hepatis)→ Increased intestinal wall thickness→ Dilated intestinal loops  → Air‑fluid levels→ Pneumoperitoneum as a result of intestinal perforation  - Abdominal ultrasound: when abdominal radiography is inconclusive Treatment:- Stop enteral feeding → parenteral feeding and substitution of fluids- Gut decompression via nasogastric tube- IV broad-spectrum antibiotics  - Radiographic monitoring: plain supine abdominal radiographs every 6-12 hours in the initial phase of the disease- Surgery: primary peritoneal drainage and/or laparotomy with necrotic bowel excision→ Indications: perforation, peritonitis and/or clinical worsening despite medical therapy
• Croup (acute laryngotracheobronchitis) Epidemiology:- Peak incidence: 6 months to 3 years- Most common in fall and winter   Etiology:- Most common pathogen: parainfluenza viruses (75% of cases)- Second most common pathogen: respiratory syncytial virus (RSV) Clinical features:- Prodromal phase→ Rhinitis with nasal discharge and congestion→ Low-grade fever→ Possible erythematous pharynx- Laryngotracheal inflammation phase→ Symptoms of croup primarily occur during the late evening/night.→ Mild: seal-like barking cough, hoarseness, and mild inspiratory stridor due to subglottic narrowing→ Moderate: dyspnea at rest, pronounced thoracic retractions, pallor, tachycardia > 160/min→ Severe: Upper airway obstruction can cause pulsus parodoxus. Severe tachydyspnea at rest with increasing respiratory failure, cyanosis, hypoxemia, bradycardia, and altered mental status. Diagnostics: Clinical Treatment:- Mild:→ Decrease infant's anxiety→ Cool mist inhalation→ Placing infant to sleep in an upright position→ Breathing cool air at night (especially in the winter) helps to soothe symptoms→ Dexamethasone- Moderate to severe:→ Patients with severe croup should always be hospitalized→ Inhaled racemic epinephrine→ Dexamethasone→ Humidified air or oxygen if necessary→ IV fluids to prevent dehydration→ Intubation is indicated when airway compromise is imminent (required in < 1% of infants with severe croup)
• Epiglottitis Epidemiology: Peak incidence: 6-12 years (but can occur in any age, including adults, especially when unimmunized) Etiology:- Traditionally: Haemophilus influenzae type b (Hib)- Most cases now involve: Streptococcus pyogenes, Streptococcus pneumoniae, Staphylococcus aureus, Non-typable H. influenzae Clinical features:- Acute onset of high fever (39-40 °C or 102-104 °F)- Toxic appearance- “Tripod” position  - Sore throat- Dysphagia- Drooling- Muffled voice (i.e., resembling a “hot-potato” voice) with painful speech- Respiratory distress (inspiratory retractions, cyanosis) and inspiratory stridor  - Restlessness and/or anxiety Diagnostics: Clinical Treatment:1. Keep child comfortable and as calm as possible2. If signs of respiratory distress → emergency airway management- Extubation should be performed 2–3 days (at the earliest) after starting antibiotic treatment.3. IV Antibiotics→ Empiric therapy: third-generation cephalosporin (e.g., ceftriaxone) + antistaphylococcal antibiotic against MRSA (e.g. clindamycin), if MRSA is suspected
• Pertussis Catarrhal stage (∼ 1-2 weeks):- Nonspecific symptoms similar to an upper respiratory infection (mild cough, watery nasal discharge, rarely low-grade fever)- Possibly conjunctivitis Paroxysmal stage (∼ 2-6 weeks)- Intense paroxysmal coughing (often occurring at night)- Followed by a deep and loud inhalation or high-pitched “whooping” sound- Accompanied by tongue protrusion, gagging, and struggling for breath- Possibly accompanied by cyanosis- Increases in frequency and severity throughout the stage- Followed by the expulsion of phlegm or posttussive vomiting (risk of dehydration)- In infants (< 6 months): risk of apnea; infants may not develop the typical cough and only manifest with apnea → close monitoring necessary! Diagnostics: Clinical diagnosis possible in patients with a cough lasting ≥ 2 weeks and at least one of the following symptoms:- Coughing paroxysms- Whoop on inspiration- Vomiting following coughing attack- Apnea (in infants) Laboratory tests:- Blood count: lymphocyte-predominant leukocytosis (50,000–60,000/μL) that corresponds with disease severity  - Culture (gold standard) or PCR: samples from deep nasopharyngeal aspiration or posterior nasopharyngeal swab  As B. pertussis only grows on respiratory epithelium, blood cultures are always negative! Treatment:- Hospitalization and monitoring: infants < 4 months; severe cases (e.g., respiratory distress, cyanosis, apnea, inability to feed)- Oxygen administration with humidification- Increased fluid intake and nutritional support  - If necessary, sedation- Macrolides (e.g., azithromycin, clarithromycin, erythromycin)→ In children > 1 month and adults: any macrolide  → Alternative if macrolides are not tolerated: trimethroprim-sulfamethoxazole→ Infants < 1 month: azithromycin  
• Bronchiolitis Epidemiology:- Primarily affects children < 2 years- Peak incidence: 2–6 months of age- Common during winter months Etiology: Respiratory syncytial virus (RSV) Clinical features:- Initially presents with upper respiratory tract symptoms (e.g., rhinorrhea), fever, and cough- Respiratory distress (usually occurs in infants)  - Tachypnea, prolonged expiration- Nasal flaring, intercostal retractions- Cyanosis- Poor feeding in breastfed infants- Auscultatory findings: wheezing, crackles Diagnostics: Clinical Treatment:- Supportive treatment (adequate hydration, relief of nasal congestion/obstruction, monitoring)- Indications for hospitalization→ Toxic appearance, poor feeding, dehydration, lethargy→ Marked respiratory distress, oxygen saturation < 92%→ Age < 12 weeks and/or history of prematurity (< 34 weeks)→ Pre-existing heart, lung, or neurological conditions→ Immunodeficiency Prognosis: Bronchiolitis in infancy is associated with an increased risk of developing asthma.
• Cystic fibrosis Gastrointestinal- Meconium ileus in newborns- Failure to thrive due to malabsorption- Exocrine pancreatic insufficiency: Foul-smelling steatorrhea (fatty stools), malabsorption, abdominal distention, diarrhea, deficiency of fat-soluble vitamins (e.g., night blindness due to vitamin A deficiency, rickets due to vitamin D deficiency)- CF-related diabetes mellitus (CFRD)  - Cholecystolithiasis, cholestasis- Fatty metamorphosis of the liver, eventually progressing to liver cirrhosis  - Biliary cirrhosis with portal hypertension- Intestinal obstruction: abdominal distention, pain, and a palpable mass Respiratory- Obstructive lung disease with bronchiectasis- Chronic sinusitis; nasal polyps may eventually develop  - S. aureus is the most common cause of recurrent pulmonary infection in infancy and childhood.- P. aeruginosa is the most common cause of recurrent pulmonary infections in adulthood. - Expiratory wheezing (obstruction), barrel chest, moist rales (indicate pneumonia), hyperresonance to percussion- Signs of chronic respiratory insufficiency: digital clubbing associated with chronic hypoxia- Airway hyperreactivity (e.g., wheezing)   Sweat glands- Especially salty-tasting sweat → electrolyte wasting Musculoskeletal- Frequent fractures because of osteopenia- Kyphoscoliosis Urinary- Nephrolithiasis, nephrocalcinosis- Frequent urinary tract infections Men:- Obstructive azoospermia is common.  - The vas deferens may also be absent.  - Undescended testicle Women:- Viscous cervical mucus can obstruct fertilization.- Menstrual abnormalities (e.g., amenorrhea)   Diagnostics:- Neonatal screening: ↑ Immunoreactive trypsinogen (IRT)- Quantitative pilocarpine iontophoresis (sweat test) is the best initial test.→ Chloride levels > 60 mmol/L on two or more occasions are consistent with CF.- Nasal potential difference test- Contraction alkalosis and hypokalemia may occur (due to excessive loss of H2O and NaCl via the sweat glands and renal H+/K+ wasting)  - Stool: ↓ chymotrypsin and pancreatic elastase   Treatment:Respiratory:- Hypertonic saline nebulization or aerosolized dornase alpha (recombinant DNAse that is a specific mucolytic agent that breaks down extracellular DNA in sputum)  - Bronchodilator therapy (e.g., albuterol)- Chest physiotherapy-  In chronic rhinosinusitis: intranasal glucocorticoids (see sinusitis)- Mucolytics (e.g., N-acetylcysteine)- High-dose ibuprofen has been shown to reduce respiratory disease progression.  - In chronic respiratory insufficiency: Long-term oxygen inhalation therapy- Treatment of last resort: lung transplantation Diet:- Additional sodium chloride intake  - High-energy diet to compensate for increased demand  - Pancreatic enzyme supplements- Oral supplementation of lipophilic vitamins A, D, K, and E CFTR modulators - Indication: patients with CF who are homozygous for the delta F508 mutation in the CFTR gene- Ivacaftor: improves Cl- transport by increasing the likelihood that the Cl- channel is open at the cell surface.- Lumacaftor: improves the conformational stability of the defective CFTR protein, which leads to increased intracellular processing and trafficking of functional CFTR protein to the cell surface Preventive measures:- Annual influenza vaccine for all CF patients > 6 months with inactivated influenza vaccine (IIV)- Pneumococcal vaccine - Palivizumab: antibody against respiratory syncytial virus (RSV) for infants < 24 months- Long-term treatment with azithromycin may be used to prevent recurrent pulmonary infections.
• Febrile seizures Febrile seizures are seizures that are associated with fever (mainly temperatures exceeding 38°C (100.4°F)) in the absence of CNS infection, metabolic abnormalities, or a history of afebrile seizures. Epidemiology:- Peak incidence: 2nd year of life; most commonly occurs between 6 months and 5 years of age- Prevalence: Febrile seizures occur in ∼ 4% of all children. Simple febrile seizure (∼75%):- Generalized, usually tonic-clonic seizures (clonic seizures are also possible)- Symmetrical- No other apparent neurologic disorders- < 15 min- Maximum of one seizure within 24 h- 6 months to 5 years Complex febrile seizure (∼25%):- Focal onset- Pronounced on one side of the body- Transient hemiparesis and speech impairment- > 15 min- > 1 seizure within 24 h- More commonly outside the typical range of 6 months to 5 years Diagnostics:- Simple febrile seizures do not require specific diagnostic workup- Complex febrile seizures always require specific investigative tests (e.g., EEG and imaging). Determine the cause of fever:- Urinalysis and urine cultures- Consider blood tests (CBC with differential blood, CRP, electrolytes, blood glucose)- Consider imaging to locate the source of infection (ultrasound, X-ray)- In suspected cases of intoxication: toxicology screen Treatment: - Uncomplicated seizures usually resolve after a few minutes spontaneously. However, abortive therapy should be administered if seizures ≥ 5 min or complex.- Abortive therapy: Treatment of choice: IV lorazepam  - After a febrile seizure, initiate antipyretic therapy (NSAIDs and acetaminophen) at an early stage (temperatures from 38°C) as they restore the central thermoregulatory setpoint back to normal by reducing the synthesis of prostaglandin E2.
• Wilms tumor (nephroblastoma) Epidemiology:- Peak incidence: 2-5 years  - Most common malignant neoplasm of the kidney in children Associated syndromes:- Approx. 10% of Wilms tumors occur in children with syndromes.- Denys-Drash syndrome: → Wilms tumor→ Pseudohermaphroditism, undescended testes in males→ Early-onset nephrotic syndrome- WAGR syndrome:→ Wilms tumor→ Aniridia→ Genitourinary anomalies: Pseudohermaphroditism, undescended testes in males, early-onset nephrotic syndrome→ Intellectual disability (mental Retardation)- Beckwith-Wiedemann syndrome  Clinical features:- Abdominal mass (often found incidentally!)→ Non-tender→ Unilateral, not crossing midline (however, up to 10% of cases are bilateral and/or multifocal)→ Smooth and firm- Abdominal pain (∼ 40% of cases)- Hematuria (∼ 25% of cases)- Hypertension (∼ 25% of cases)- In cases of subcapsular hemorrhage: anemia, and possibly fever Diagnostics:- Urinalysis: hematuria may be present- Imaging: → Best initial test: ultrasound→ Abdominal CT/MRI: assess extent of involvement and help with surgical planning→ CT thorax/CXR: determine metastases and staging Treatment: - Nephrectomy- Patients with unfavorable (anaplastic) histology and/or high-risk molecular markers are treated with additional chemotherapy (i.e. cyclophosphamide and etoposide) and radiation in any stage. Prognosis: Good
• Neuroblastoma Epidemiology:- Most common malignancy in infants and third most common childhood cancer overall, following leukemia and brain tumors- Mean age at diagnosis: 1-2 years- The majority of children have progressed to advanced-stage disease by the time of diagnosis. Risk factors:- Maternal: gestational diabetes, opiates, folate deficiency- Congenital syndromes: Turner syndrome, neurofibromatosis, Hirschsprung's disease, Beckwith-Wiedemann syndrome- Familial Clinical featurs:- Failure to thrive or weight loss- Fever- Nausea, vomiting, loss of appetite- Hypertension   Paraneoplastic syndromes- Chronic diarrhea → electrolyte imbalances  - Opsoclonus-myoclonus-ataxia: a paraneoplastic syndrome of unclear etiology involving rapid and multi-directional eyemovements, rhythmic jerks of the limbs, and ataxia  - Hypertension, tachycardia, palpitations, sweating, flushing Diagnostics:- Urine: ↑ Catecholamine metabolites homovanillic acid (HVA) and vanillylmandelic acid (VMA) in 24-hour urine- Blood: ↑ Catecholamine metabolites (HVA/VMA) - Abdominal ultrasound- CT or MRI: to identify the primary site- MIBG scan: Uptake scan of metaiodobenzylguanidine (MIBG) combined with a radioactive iodine tracer.- Biopsy: Image-guided needle aspiration of the tumor or biopsy at the time of surgical tumor resection→ Evaluation for MYCN gene amplification→ Evaluation for DNA ploidy  Treatment:- Low risk: generally children with early-stage disease (Stages 1-2) and no MYCN amplification- Intermediate risk: generally children with intermediate and late-stage disease (Stages 3-4) and no MYCN amplification- High risk: generally children with late-stage disease and/or MYCN amplification
• Retinoblastoma Epidemiology:- Most common primary intraocular malignancy among children  - Age of onset: < 3 years- ∼ 30% of children develop retinoblastomas in both eyes. Clinical features:- Leukocoria (“cat's eye pupil”)  - Strabismus  - A painful, red eye  - Loss of vision  - Retinal detachment (later stages) - Rarely: orbital cellulitis, nystagmus, proptosis Diagnostics:- Fundus examination: grayish white, vascularized retinal tumor- Ocular ultrasound- Contrast-enhanced MRI of the cranium
• Childhood absence epilepsy (pyknolepsy) Epidemiology:- 6-7 years- Sex: ♂ < ♀ Clinical findings:- Absence seizures  → Lasting 5-10 seconds up to 100x/day→ Brief unresponsiveness without convulsions→ Amnestic during seizures; children appear to be staring or daydreaming→ Lip smacking, eye fluttering or head nodding are common- No postictal phase- Atypical absence seizure: more gradual onset and ending, duration of > 30 seconds.  - Triggers: hyperventilation, lights Ictal EEG: 3 Hz spikes and waves in all regions of the brain   Treatment:- 1st line: ethosuximide- 2nd line: sodium valproate  - 3rd line: lamotrigine Prognosis:- 80% of children are seizure-free with treatment- Usually subsides before adulthood
• Juvenile absence epilepsy Epidemiology:- 9-13 years- Sex: ♂ = ♀ Clinical features:- Absence seizures  - Tonic-clonic seizures (on awakening) are common- Photosensitivity less common Ictal EEG: Regular 3-4 Hz spikes and waves in all regions of the brain Treatment:- 1st-line: valproic acid- Avoid triggers: sleep deprivation, alcohol, drugs, flickering lights Prognosis:- 60% are seizure-free under treatment- Transition to juvenile myoclonic epilepsypossible
• Juvenile myoclonic epilepsy (Janz syndrome) Epidemiology: 12-20 years Clinical features:- Triad of seizures: Bilateral symmetrical myoclonic jerks, primarily after awakening, without impaired consciousness- Generalized tonic-clonic seizures- Absence seizures with impaired consciousness  - Triggers: sleep deprivation, alcohol consumption, flickering lights Ictal EEG: Irregular 3-5 Hz polyspikes and waves with frontocentral predominance Treatment:- 1st-line: valproic acid- Avoid triggers: sleep deprivation, alcohol, drugs, flickering lights Prognosis:- Responds well to antiseizure drug therapy; seizures become less frequent in adulthood- Life-long treatment usually required (high risk of recurrence)- Increased risk of psychiatric comorbidities
• Infantile spasms (West syndrome) Epidemiology:- 3-7 months - Sex: ♂ > ♀ Etiology:- Perinatal infections- Hypoxic-ischemic injury- PKU- Tuberous sclerosis complex- Idiopathic   Clinical features:- Sudden symmetric, synchronous spasms, usually in clusters of 5-10  - Jerking flexion (jackknife movement) or extension of the neck, torso, and extremities  - Followed by a tonic phase EEG:- Hypsarrhythmia: characteristic finding in interictal EEG; high-voltage delta waves with irregular multifocal spikes and slow waves- Ictal EEG: very heterogeneous   Treatment:- First-line treatment: ACTH, prednisone, or vigabatrin   Prognosis:- Poor; increased mortality- Neurodevelopmental delay, regression of psychomotor abilities in > 85% of cases- In ∼ 50% of cases spasms cease before age 5 years- Most cases develop other forms of epilepsy
• Lennox-Gastaut syndrome Epidemiology:- 3–5 years- Sex: ♂ > ♀ Etiology:- Majority of cases due to structural brain abnormalities  - 40% of cases are cryptogenic   Clinical features:- Multiple types of seizures: myoclonic, tonic, atonic, absences- Developmental delays- Frequently periods of status epilepticus EEG: Multifocal sharp and slow wavesAbnormal interictal EEG: slow spike-wave pattern Treatment:- Attempt anticonvulsive treatment, e.g., valproic acid, clobazam, lamotrigine, felbamate- Ketogenic diet, vagus nerve stimulation, surgery  Prognosis:- Poor; only 10% are seizure-free under treatment- Developmental delay, cognitive impairment, and psychotic symptoms- Mortality rate of 3-7%
• Trisomy 13 (Patau syndrome) Frequency: ∼ 1:10,000 children Clinical features:- Microcephaly, holoprosencephaly  - Cleft lip and palate, Cutis aplasia (“punched-out” scalp lesions), low-set malformed ears, bulbous nose, small chin- Microphthalmia (small orbits, which may be unilateral or bilateral), possibly coloboma, ocular hypotelorism- Polydactyly, primarily hexadactyly, flexed fingers- Congenital heart defects (particularly ventricular septal defect, patent ductus arteriosis)- Rocker-bottom feet- Visceral and genital anomalies, especially of the kidneys and ureter  - Severe intellectual disability- Aplasia cutis congenita: congenital absence of skin in an area that may extend to the bone or the dura- Capillary hemangioma   Diagnostics: Usually detected during first trimester screening with combined ultrasound and maternal serum testing (↓↓ PAPP-A, ↑ nuchal translucency) Prognosis: Only 5% of infants survive past 6 months of age.
• Trisomy 18 (Edwards syndrome) Epidemiology:- Frequency: ∼ 1:6,000 children- After trisomy 21, trisomy 18 (Edwards syndrome) is the most common autosomal trisomy in which fetuses can survive to birth- Gender: ♀ > ♂ Clinical features:- Prominent occiput, microcephaly- Low-set ears (malformed auricle), micrognathia (congenital mandibular hypoplasia), cleft lip and palate, high palate, broad nose- Clenched fists, with flexion contracture of the fingers  - Rocker-bottom feet: convex deformity of the plantar side of the foot, with a vertical talus, and prominent calcaneus  - Congenital heart defects (particularly VSD, ASD, tetralogy of Fallot)- Malformations of internal organs: diaphragmatic hernia, ureter, and kidneys (horseshoe kidneys)- Severe intellectual disability Diagnosis: Commonly detected in the second trimester screening: quadruple test shows ↓ free estriol, ↓ AFP, ↓ Inhibin A, and ↓ β-HCG Prognosis: Only 5-10% of patients survive past 12 months of age.
• Down syndrome Epidemiology:- Most common autosomal chromosome aberration (∼ 1:700 live births).- The risk of a Down syndrome pregnancy rises with maternal age20 years: ∼ 1:1500 30 years: ∼ 1:90040 years: ∼ 1:10045 years: ∼ 1:3050 years: ∼ 1:6Down syndrome is the most common genetic cause of intellectual disability. Fragile X syndrome is the most common heritable cause of intellectual disability. Clinical features:- Eyes→ Upward slanting of the eyelids, epicanthal folds, hypertelorism→ Brushfield spots (aggregation of connective tissue in periphery of iris, visible as white or grayish-brown spots)→ Refractive errors (e.g., short-sightedness, astigmatism), strabismus→ Cataracts (congenital, infantile, or juvenile)- Mouth→ Small oral cavity, large tongue→ High arched palate→ Abnormal teeth  - Brachycephaly  - Hypoplastic nasal bones, broad and flat nasal bridge- Ear anomalies (small, round low-set ears, adherent earlobes)- Single transverse palmar crease: crease across the palm, which runs along the metacarpophalangeal joints perpendicular to the fingers- Sandal gap: large space between the first and second toe  - Clinodactyly, camptodactyly, brachydactyly- Soft tissue: connective tissue deficiency → ↑ increased risk of umbilical and inguinal hernias; marked hyperextension of joints may occur- Atlantoaxial instability- Heart: congenital heart defects in ∼ 50% of cases – atrioventricular septal defect (∼ 40%), ventricular septal defect (∼ 30%), atrial septal defects (∼ 15%), tetralogy of Fallot (∼ 5%)- Gastrointestinal tract: duodenal atresia/stenosis, annular pancreas, imperforate anus, enlargement of the colon, rectal prolapse, Hirschsprung disease- Urogenital system: hypogonadism, cryptorchidism, decreased fertility in men- Further features: hypothyroidism, celiac disease, sleep apnea, hearing loss due to recurrent otitis media, ↑ risk of leukemia (acute lymphoblastic leukemia, acute myeloid leukemia), ↑ risk of early-onset of Alzheimer disease (75% of individuals affected by age of 40 years), ↑ risk of developing epilepsy Screening procedures:- First trimester combined test (11-13 weeks):→ Ultrasound: Nuchal translucency measurement (thickened nuchal fold), absent or hypoplastic nasal bone, shortened middle phalanges of the fifth digits with clinodactyly, shortened long bones (humerus, femur)→ Maternal serum: ↓ pregnancy-associated plasma protein-A (PAPP-A); ↑ β-hCG- Second trimester quadruple test (15-18 weeks):→ Screens for trisomy 18 and 21, not trisomy 13→ Trisomy 21: ↓ free estriol, ↓ alpha-fetoprotein (AFP), ↑ inhibin A and ↑ human chorionic gonadotropin (β-hCG)- Full integrated test  - Sequential integrated test: Combination of the first trimester combined test plus chorionic villus sampling.- Cell-free fetal DNA (cfDNA)  - Diagnostic fetal karyotyping→ Indications: positive screening test, previous trisomy 21 pregnancy, parent with known chromosomal translocation or aberration→ Procedures: chorionic villus sampling (1st trimester), amniocentesis (3rd trimester)→ Risks: bleeding, infection, fetal injury or loss
• Idiopathic scoliosis Deformity of the spine occurring during growth, characterized by a lateral curvature (Cobb angle > 10°) and simultaneous rotation of the vertebrae. Epidemiology:- Sex: ♀ > ♂ (∼ 5:1)  - Peak incidence: 10-12 years  - The spinal curvature deformity can progress in ∼ ⅔ of skeletally immature patients as they grow. Clinical features:- Evaluation of the spinal shape from the back of the head to the intergluteal cleft  - Adam's forward bend test (most important clinical test) may show:→ Thoracic rotation ("rib hump")→ Lumbar rotation ("lumbar hump")→ Asymmetry of the waistline, leg length discrepancy→ Asymmetry of the shoulder girdles, protrusion of the scapulae→ Assessment of severity based on scoliometer measurements  - Respiratory and cardiopulmonary impairment in cases of severe thoracic deformity→ Dyspnea, difficulty breathing (thoracic restriction)→ Cor pulmonale with right heart failure as a late sequela  - Pain occurs secondary to degeneration, compression, or irritation of spinal discs and nerves. Diagnostics:- Conventional x-ray- Indicated to evaluate necessity for treatment; performed in cases of deviations > 7° on scoliometer measurements  → Evaluation of the lateral curvature (in anterior-posterior projection, full-length views)→ Cobb angle: refers to the angle between the following lines1. Perpendicular to a line drawn across the superior endplate of the highest affected vertebra2. Perpendicular to a line drawn across the inferior endplate of the lowest affected vertebra   Treatment based on the Cobb angle:- Cobb angle < 10°: per definition not scoliosis, and therefore not monitored- Cobb angle 10-19°: continual monitoring for progression- Cobb angle 20-29°: monitoring or bracing- Cobb angle 30-39°: bracing- Cobb angle > 40° or rapidly progressing scoliosis: surgery Bracing:- 18 hours/day, if possible- Bracing is usually able to halt progression, but cannot cure the underlying condition.   Surgery:- Goal: correct spinal arching and rotation- Various surgical techniques and approaches exist (ventral, lateral, dorsal, or combined approach).- Spondylodesis: fusion of the vertebrae by bridge plating or by internal fixation- Risks: paraplegia (< 1% of cases), development of pseudarthroses, infection of surgical material
• Antibiotics in pediatric sepsis Age < 28 days:- E. coli, Group B Strep- Ampicillin + Cefotaxime or Gentamicin Age > 28 days:- S. pneumoniae, N. meningitidis- Ceftriaxone or Cefotaxime ± Vancomycin (when meningeal involvement is suspected)
• Measles-mumps-rubella (MMR) vaccination Administration:- Ages 1 & 4  Side effects:- Fever- Rash- Transient lymphadenopathy Contraindications:- Anaphylaxis to prior MMR vaccination, neomycin, or gelatin- Immunodeficiency (eg, HIV with CD4 < 200/mm3, leukemia)- Pregnancy
• Pediatric traumatic brain injury (PECARN rule) High-risk features age < 2- Altered mental status (fussy behavior)- Loss of consciousness- Severe mechanism of injury (fall > 0.9 m [3 ft], high impact, MVC)- Nonfrontal scalp hematoma- Palpable skull fracture High-risk features age ≥ 2-18- Altered mental status (eg, somnolence, agitation)- Loss of consciousness- Severe mechanism of injury (fall > 1.5 m [5 ft], high impact, MVC)- Vomiting, severe headache- Basilar skull fracture signs (eg, CSF rhinorrhea) Management- Head CT scan without contrast
• Acute otitis media Epidemiology:- Highest incidence between 6-24 months of age∼ 70% of children < 2 years old experience AOM at least once- Slightly higher incidence in boys- Immunization of infants against pneumococci has decreased the incidence of AOM Etiology:- Bacterial superinfection following a viral URT infection (95% of cases)  → S. pneumoniae (most common: 35% of cases)→ Haemophilus influenzae (25% of cases)→ Moraxella catarrhalis (15% of cases)→ Group A ß-hemolytic streptococci (in older children) Risk Factors for AOM:- Bottle feeding/formula feeding, inadequate breastfeeding  - Pacifier use  - Passive cigarette smoke  - Children who attend day care centers  - Poor socioeconomic status Clinical features:In infants:- Irritability- Incessant crying- Refusal to feed (anorexia)- Repeatedly touching the affected ear- Fever and febrile seizures- Tender mastoid in late stagesIn older children:- Otalgia/earache, commonly with throbbing- Hearing loss in the affected ear- Fever- Tender mastoid in late stages Diagnostics:- Otoscopy: tympanic membrane (TM) evaluation: Retracted and hypomobile, Loss of light reflex- Tuning fork test: conductive hearing loss Treatment:- Symptomatic pain management (paracetamol, ibuprofen)- Antibiotics: not always indicated→ Bilateral otitis media→ Symptoms do not improve after 48 hours→ Severe illness in children (very high fever, vomiting, malaise, and immunosuppression)- First line: oral amoxicillin→ Add clavulanic acid if no improvement after 48 hours- Alternative for patients with penicillin allergy→ If past immediate reaction → macrolides (e.g., azithromycin, clarithromycin, erythromycin)→ If past delayed reaction → cephalosporins (e.g., cefuroxime/ceftriaxone)
• Cryptorchidism Risk factors:- Prematurity- Small for gestational age- Low birth weight (<2.5 kg [5.5 lb])- Genetic disorders Clinical features:- Empty, hypoplastic, poorly rugated scrotum or hemiscrotum± Inguinal fullness Treatment:- Orchiopexy before age 1 year Complications:- Inguinal hernia- Testicular torsion- Subfertility- Testicular cancer

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