Questions, Board Review

Board Review Questions: August 2020

PEER (Physician’s Evaluation and Educational Review in Emergency Medicine) is ACEP’s gold standard in self-assessment and educational review. These questions are from PEER, updated continually on its digital platform. Order PEER to prepare!

1. A 54-year-old man with a history of diabetes, hypertension, and smoking presents complaining of dizziness since he woke up this morning. He says he feels like the room is spinning. He is also nauseated and cannot stand or walk without falling to the right. He denies numbness or weakness and is unable to complete finger-to-nose testing. Which vessel is most likely occluded?
A. Anterior cerebral artery
B. Cerebral venous sinus
C. Middle cerebral artery
D. Posterior inferior cerebellar artery


2. What is definitively seen in cardiac tamponade?
A. Electrical alternans
B. Inferior vena cava collapsibility
C. Pulsus paradoxus
D. Right ventricular diastolic collapse


3. Which pathogen most commonly causes pneumonia in young children with cystic fibrosis?
A. Burkholderia cepacia
B. Pseudomonas aeruginosa
C. Staphylococcus aureus
D. Streptococcus pneumoniae


4. Systemic toxicity is most likely to occur after topical dermal exposure to which acid?
A. Acetic acid
B. Hydrochloric acid
C. Hydrofluoric acid
D. Sulfuric acid


5. Which physical examination finding indicates a cribriform plate fracture as a serious complication of trauma to the face and nose?
A. Clear nasal discharge
B. Epistaxis
C. Hemotympanum
D. Septal hematoma

ANSWERS 

1. The correct answer is D, Posterior inferior cerebellar artery.

Why is this the correct answer?
This patient has suffered a stroke due to occlusion of the blood supply to the cerebellum. The vessel most commonly associated with a cerebellar infarct is the posterior inferior cerebellar artery, a branch of the vertebral artery that feeds the brain from the posterior side. Cerebellar infarcts present with ataxia, vertigo, nystagmus, and difficulty with coordination. The nystagmus in cerebellar infarcts is often “direction-changing” and has a fast beat component in the same direction as the patient’s gaze. Patients may also have difficulty with finger-to-nose or heel-to-shin tests. One of the most significant clinical findings in patients with cerebellar infarcts is severe ataxia; patients are unable to balance and walk normally. This is a useful clue to distinguish a patient with benign positional vertigo from one who has had a cerebellar stroke. Other clues to a stroke in this case include the patient’s age and comorbidities, all of which are strongly associated with stroke risk.

Why are the other choices wrong?

  • A stroke from occlusion of the anterior cerebral artery results in gait impairment due to weakness and sensory loss in the contralateral foot. It can also result in mental slowing for frontal cortex release signs. This patient has normal mentation and no weakness or sensory loss.
  • A thrombosis of the cerebral venous sinus results in headache, motor weakness, difficulty speaking, and seizures, but the neurologic deficits do not clearly follow the path of arterial blood supply. This patient’s predominant symptoms are vertigo and ataxia.
  • A stroke from occlusion of the middle cerebral artery results in contralateral paralysis of the arms and legs and, if it occurs on the left side of the head, aphasia. This patient denies motor complaints and is speaking normally.

REFERENCES
Ledyard HK. Transient ischemic attack and acute ischemic stroke. In: Adams JG, Barton ED, Collings JC, DeBlieux PMC, Gisondi MA, Nadel ES, eds. Emergency Medicine Clinical Essentials. 2nd ed. Elsevier Saunders; 2013:870-880.

Crocco TJ, Meurer WJ. Stroke. In: Walls RM, Hockberger RS, Gausche-Hill M, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. Vol 2. 9th ed. Elsevier; 2018:1241-1255.

2. The correct answer is D, Right ventricular diastolic collapse.

Why is this the correct answer?
Tamponade develops when intrapericardial fluid produces pressure sufficient to compress the cardiac chambers, which subsequently impairs ventricular diastolic filling and stroke volume. The pericardium is capable of stretching and can accommodate several liters of fluid when the fluid accumulates slowly. However, if the fluid accumulates rapidly, as in trauma, the intrapericardial pressure is changed all at once, and pericardial tamponade can ensue. Compensatory mechanisms such as tachycardia can temporarily sustain blood pressure, but as the pericardial fluid continues to increase, the compensatory mechanisms begin to fail, which results in diminished cardiac output, hypotension, and full cardiovascular collapse.

Why are the other choices wrong?

  • Although beat-to-beat swinging of the heart indicates a large effusion, causing electrical alternans, this alone does not suggest impending cardiovascular collapse, especially if the fluid has accumulated gradually.
  • With pericardial tamponade, pericardial effusion is present on echocardiography with a dilated inferior vena cava without inspiratory collapse. Other findings on echocardiography that are diagnostic of pericardial tamponade include early diastolic right ventricular collapse, late diastolic right atrial collapse, and hemodynamic derangements.
  • Pulsus paradoxus (drop in systolic blood pressure >10 mm Hg during normal inspiration) can be seen in tamponade; however, its presence has limited specificity. Several other conditions that are associated with hypotension or dyspnea can also produce pulsus paradoxus, including massive PE, hemorrhagic shock, and obstructive lung disease.

REFERENCES
Mattu A, Martinez JP. Pericarditis, pericardial tamponade, and myocarditis. In: Adams JG, Barton ED, Collings JC, DeBlieux PMC, Gisondi MA, Nadel ES, eds. Emergency Medicine Clinical Essentials. 2nd ed. Elsevier Saunders; 2013:514-523.

Jouriles NJ. Pericardial and myocardial disease. In: Walls RM, Hockberger RS, Gausche-Hill M, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. Vol 1. 9th ed. Elsevier; 2018:987-999.

3. The correct answer is C, Staphylococcus aureus.

Why is this the correct answer?

  1. S. aureus and Haemophilus influenzae are the most common pathogens of childhood pneumonia in patients with cystic fibrosis. Cystic fibrosis is caused by defects in chloride transport in the cellular membranes, which results in reduced ciliary clearance of mucus, thicker mucus, and ultimately, enhanced bacterial adherence to the airway. Patients with cystic fibrosis frequently have pneumonia. An important component of the treatment of pneumonia includes aggressive pulmonary toilet, aerosolized treatments, and mucolytics.

Why are the other choices wrong?

  • B. cepacia is a common pathogen that causes pneumonia in cystic fibrosis patients. Although not the most common cause of pneumonia, infection with this organism is related to increased morbidity and mortality rates.
  • By age 18 years, 80% of patients with cystic fibrosis have been colonized with P. aeruginosa. Empiric antibiotics generally include a penicillin and aminoglycoside. Typically, an emergency physician should consider expert consultation before treating cystic fibrosis. Investigation of the patient’s history and evaluation of prior sputum cultures are warranted.
  • S. pneumoniae is the most common cause of pneumonia overall in both immunocompetent and immunocompromised patients.

REFERENCES
Roosevelt GE. Pediatric respiratory emergencies: diseases of the lungs. In: Walls RM, Hockberger RS, Gausche-Hill M, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. Vol 2. 9th ed. Elsevier; 2018:2090-2098.

Overmann KM, Florin TA. Pneumonia in infants and children. In: Tintinalli JE, Ma OJ, Yealy DM, et al, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 9th ed. McGraw-Hill; 2020:811-819.

4. The correct answer is C, Hydrofluoric acid.

Why is this the correct answer?
Most acids cause a coagulative necrosis when they contact skin that limits further penetration. Hydrofluoric acid, however, is a major exception: Deep tissue penetration can occur due to the strong electronegativity of the fluoride ion and corresponding high affinity to its hydrogen ion. Systemic toxicity results from fluoride binding to calcium and magnesium, which can cause life-threatening hypocalcemia and hypomagnesemia. Delayed-onset hyperkalemia from its effect on sodium-potassium ATPase is also possible. Aggressive decontamination of the skin followed by topical application of calcium or magnesium preparations can limit absorption. Initial treatment of systemic toxicity is focused on preventing and treating the hypocalcemia and hypomagnesemia.

Why are the other choices wrong?

  • Acetic acid, which is found in some hair-wave neutralizers, is not expected to cause systemic toxicity with topical dermal exposures. Like most acids, acetic acid can cause coagulative necrosis on skin contact, which limits further acid penetration.
  • Hydrochloric acid, like most acids, can cause severe dermal burns; however, most preparations in household products are so diluted that severe burns are unusual. Hydrochloric acid is not expected to cause systemic toxicity with topical dermal exposures.
  • Sulfuric acid is often found in car batteries and drain cleaners. It is not expected to cause systemic toxicity with dermal exposures.

REFERENCES
Su MK. Hydrofluoric acid and fluorides. In: Nelson LS, Howland MA, Lewin NA, Smith SW, Goldfrank LR, Hoffman RS, eds. Goldfrank’s Toxicologic Emergencies. 11th ed. McGraw-Hill Education; 2019:1397-1403.

Pizon AF, Lynch M. Chemical burns. In: Tintinalli JE, Ma OJ, Yealy DM, et al, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 9th ed. McGraw-Hill; 2020:1391-1396.

5. The correct answer is A, Clear nasal discharge.

Why is this the correct answer?
Clear nasal discharge after blunt facial trauma is a concerning finding. When the mechanism of injury is a forceful blow to the bridge of the nose, the nasoethmoidal complex (or cribriform plate) can be injured, which can result in a CSF leak indicated by clear rhinorrhea. If the diagnosis is in question, the fluid can be sent to the laboratory for a beta-2 transferrin test for confirmation. Patients with this injury should receive a maxillofacial CT scan to evaluate for other concomitant facial fractures; there may also be concern for intracranial injuries, pneumocephalus, or infection.

Why are the other choices wrong?

  • Epistaxis is common after blunt nasal trauma and can occur with or without fracture, but it is not indicative of cribriform plate injury. Traumatic epistaxis is managed similarly to other etiologies of epistaxis.
  • Hemotympanum is seen in severe epistaxis when blood travels through the eustachian tube to the middle ear. It can also be seen with temporal bone fractures but is not associated with cribriform plate fractures.
  • Septal hematoma is an important complication of nasal bone fracture that appears as a grapelike mass in the naris after nasal trauma. Septal hematomas are managed with incision and drainage followed by nasal packing. Failure to recognize and manage this complication can lead to nasal septal necrosis.

REFERENCES
Mayersak RJ. Facial trauma. In: Walls RM, Hockberger RS, Gausche-Hill M, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. Vol 1. 9th ed. Elsevier; 2018:330-344.

Sprinkel K, Colucciello S. Maxillofacial injuries. In: Wolfson AB, Cloutier RL, Hendey GW, Ling LJ, Rosen CL, Schaider JJ, eds. Harwood-Nuss’ Clinical Practice of Emergency Medicine. 6th ed. Wolters Kluwer; 2015:158-166.

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