Exam 2: Section 4

Abstract

This practical question and answer book contains two full-length practice exams that mimic the tone and scope of the American Board of Psychiatry and Neurology’s certifying exam in neurocritical care. It covers aspects of neurology, neurosurgery, general critical care, and emergency medicine, with rationale and discussion provided in the answers section at the end of each exam. This useful study guide will help prepare critical care fellows and residents from a variety of backgrounds for the ABPN exam, and help test their critical care competencies in general.

Section 4: Answers

• 1. The correct answer is A. Short term reductions in oxygen consumption with the use of neuromuscular blocking agents has been suggested as a potential benefit in septic shock, not ARDS. In ARDS, the proposed benefits of neuromuscular blocking agents are (1) improvement in patient-ventilator synchrony, (2) matching of target and delivered tidal volumes, (3) decrease in delivered alveolar pressure, and 4) reduced breath stacking [1].

• 2. The correct answer is D. The STASH trial was a randomized, double-blind, placebo-controlled, multicenter study evaluating the use of simvastatin to improve functional outcomes after aSAH. A favorable outcome was defined by a modified Rankin score of 0-2 at six months. There were no significant differences between the control and placebo groups in this study [2].

• 3. The correct answer is D. The architecture of brain arteriovenous malformations consists of direct arterial-to-venous connections without an intervening capillary network. Supratentorial lesions account for 90% of AVMs, and the remainder are in the posterior fossa. They usually occur as single lesions, but as many as 9% are multiple. The high-flow arteriovenous communication potentiates a variety of flow-related phenomena, such as the development of aneurysms and arterialization of the venous limb. Patients with cortically-located, large, and superficial-draining arteriovenous malformations are more likely to present with seizures. Cavernous malformations are often described as having a “mulberry” appearance.

• 4. The correct answer is E. Case reports have demonstrated the feasibility of APRV in patients with increased ICP. Recruitment maneuvers improve alveolar ventilation, improve compliance and may lessen ICP when effective. Veno-venous ECMO can be performed without the use of anticoagulation, and is therefore considered a possibility as a rescue technique in severe TBI. Nitric oxide does not increase ICP, and may improve ventilation/perfusion matching in severe lung injury. Prone positioning may lead to a significant increase in ICP and a critical decrease in CPP, making it the least safe option in a patient with elevated ICP [3].

• 5. The correct answer is D. The patient has multiple reasons for his abnormal sleeping pattern. His gender, obesity, and neck circumference (>17 inches) places him at a higher risk for obstructive sleep apnea [OSA]. In fact, roughly two-thirds of people with a BMI >30 kg/m² have OSA. He also has an acute ischemic infarct, which can lead to central sleep apneas, such as Cheyne-Stokes, cluster breathing, and central neurogenic hyperventilation. Polysomnography is the gold standard diagnostic test for these sleep-related breathing disorders. Apnea, by convention, is reduction of airflow to less than 90% for more than 10 seconds. For central apneas, there is no respiratory effort. With obstructive apneas, a central drive is still present, with some resultant respiratory effort. Overnight oximetry may show episodic desaturations in oxygen, depending on the sleep disorder, but it would not differentiate central from obstructive apneas. Arterial blood gasses also may show hypocapnia if there is hyperventilation or hypoxemia, but it would not be as useful as a sleep study [4].

• 6. The correct answer is B. This patient is having significant hemoptysis, most likely a result of his pulmonary malignancy. There is no universal consensus on the definition massive hemoptysis. Some define it as more than 500 mL in a 24-h period, or more than 100 mL/h. Others define it as any amount that leads to abnormal gas exchange. Semantics aside, massive hemoptysis can be fatal, more the result of asphyxiation rather than blood loss. The initial steps in management include correctly positioning the patient, establishing a secure airway, ensuring adequate gas exchange and cardiovascular function, and controlling bleeding. In this case, bronchoscopy identified bleeding from the right lower lobe. Therefore, the patient should be placed on his right side, with the presumed bleeding source in the dependent position, since spillage may impair gas exchange in the healthy lung.

• 7. The correct answer is E. It has long been recognized that brain metastases from certain malignancies are at a higher risk of bleeding episodes. These include melanoma, renal cell carcinoma, choriocarcinoma, and thyroid carcinoma. Breast metastases are not considered high-risk lesions [5].

• 8. The correct answer is D. This patient has a complicated parapneumonic pleural effusion seen as multiple fibrinous septations within the anechoic pleural effusion, and requires placement of a chest tube for drainage. Point-of-care ultrasound (POCUS) allows the distinction between effusion and lung consolidation, and is more accurate at detecting pleural effusion in comparison with bedside chest x-rays. Sensitivity of chest x-ray decreases in more supine positioning, while POCUS can detect effusions as small as 20 mL. Although definitive distinction between transudative and exudative pleural effusion requires thoracentesis, POCUS can suggest the nature of pleural effusion. According to the characteristics of the pleural effusion on US, it can appear as anechoic (black), complex non-septated (black with white strands), complex septated (black with white septae), or homogeneously echogenic (white). In general, the presence of a complex pleural effusion suggests exudative effusion, whereas an anechoic effusion is likely transudative; however, clinical correlation is warranted since exudative effusions may be anechoic, while longstanding transudative effusion may appear as complex non-septated. Continuing only medical therapy with antibiotics or diuresis would not be appropriate, since this complex pleural effusion requires drainage [6].

• 9. The correct answer is B. This patient has an upper gastrointestinal (GI) bleed from a duodenal ulcer. The Forrest classification is most widely used to classify the endoscopic appearance of bleeding peptic ulcers, which are divided into class I a/b (active bleeding), class II a/b/c (recent bleeding), and class III (no evidence of recent bleeding). Acute management of upper GI bleeding typically involves resuscitation and supportive therapy while investigating the underlying cause and attempting to correct it. Initial management includes nothing by mouth, adequate IV access, IV fluid resuscitation (with normal saline or lactated Ringer solution), blood grouping and cross match, blood transfusion typically starting if hemoglobin is <7, proton pump inhibitors, and stopping any antiplatelet/anticoagulants with consideration of reversal [7].

• 10. The correct answer is C. Approximately one third of brain abscesses arise via hematogenous spread from remote sites. The most common cause, however, is via contiguous spread of infected structures., accounting for one half of all cases [8].

• 11. The correct answer is A. This patient has newly discovered diffuse subarachnoid hemorrhage, and requires DVT prophylaxis that will not increase her risk of bleeding complications. Intermittent pneumatic compression alone is appropriate until the source of her bleeding is controlled. If a source is not identified after a thorough work-up (i.e., conventional angiography and MR imaging of the neuroaxis), chemoprophylaxis can be initiated after her hemorrhage is stable on repeat imaging [9].

• 12. The correct answer is E. Thyroid storm management typically consists of a beta-blocker to treat adrenergic tone, a thionamide to block new hormone synthesis, and an iodine solution to block the release of thyroid hormone. Cooling blankets may also be used to correct pyrexia.

• 13. The correct answer is C. Myoclonic status is associated with a broad range of brain injuries, including anoxic brain injury, toxic-metabolic encephalopathies, and exacerbations of certain epilepsy syndromes. The clinical presentation and significance of frequent myoclonic jerks differs greatly by etiology. Controversies persist about prognostic significance and management of myoclonic status epilepticus following anoxic brain injury, but recent data suggest that in the era of therapeutic hypothermia, post-anoxic myoclonic status epilepticus may not be as ominous a sign as previously thought. Valproate and benzodiazepines are the most successful agents for myoclonic status. In the context of anoxia, when myoclonus represents the erratic last sparks of disseminated neuronal populations, benzodiazepines will mask the behavioral correlate with no impact on recovery; this may serve an appropriately palliative purpose (primarily for the benefit of the family) [10].

• 14. The correct answer is A. Although the FAST exam is useful in the initial evaluation of a patient with blunt abdominal trauma, hemodynamic instability and suspected hollow viscous injury mandate immediate surgical exploration without delay. Contrast-enhanced CT may take too long in this setting, and peritoneal lavage is rarely performed since the widespread use of bedside sonography.

• 15. The correct answer is B. The American Heart Association’s 2013 policy statement recommends that policies be developed to allow ambulances to bypass non-stroke centers when patients have stroke symptoms that started within 6–8 h, and when that diversion will take no more than 15–20 min [11].

• 16. The correct answer is D. The time of death is the time that a physician or licensed provider examines the patient and declares them to have expired. This may occur long after asystole and physical death have occurred, particularly if the provider is delayed in performing their exam.

• 17. The correct answer is C. Clifton et al published two of the largest series on hypothermia for patients with severe TBI; both studies showed that therapeutic hypothermia had no impact on neurologic outcomes. The POLAR trial in 2018 was performed to evaluate the effect of early prophylactic hypothermia, sustained up to 7 days in the setting of high ICP, on neurological outcomes at 6 months, but did not find benefit. TBI guidelines currently recommend against the use of prophylactic hypothermia. The rest of the choices are true. Regarding choice D, the HYPERION trial showed increase in 90-day favorable functional outcome in the hypothermia group while TTM1 and TTM2 trials showed no difference in outcomes between the hypothermia and normothermia groups [12, 13].

• 18. The correct answer is C. Currently guidelines from the ASA and AHA recommend surgical clot removal in this circumstance. While EVD placement may not put patients at a high risk of upwards herniation as previously feared, it is still not recommended as the preferred option. Lumbar puncture, mannitol, or hypertonic saline will not be curative in this case [14].

• 19. The correct answer is C. According to the landmark NASCET trial data, carotid endarterectomy is clearly beneficial in symptomatic patients when the amount of stenosis exceeds 70%. Patients with 50–69% stenosis may be considered for treatment as well, although the risk/benefit analysis is more equivocal [15].

• 20. The correct answer is D. Nearly two thirds of the cases of volvulus and subsequent large bowel obstruction occur at the sigmoid colon, with the cecum being the second most common location. Volvulus of the descending colon, transverse colon, or splenic flexure have been documented, but are rare [16].

• 21. The correct answer is D. Medications used often in the ICU setting can affect the metabolism of cyclosporine. Phenobarbital, phenytoin, carbamazepine, and modafinil increase the metabolism of cyclosporine and lead to a decrease in serum concentration. Levetiracetam does not affect serum cyclosporine levels.

• 22. The correct answer is B. Chlorpropamide is a sulfonylurea that may also be used in cases of central diabetes insipidus. However, it results in predictable and often severe hypoglycemia that has caused it to fall out of favor in the treatment of central DI, particularly compared to desmopressin.

• 23. The correct answer is B. In this patient with recent cardiac arrest, known renal insufficiency, and an EKG with sine wave morphology suggesting hyperkalemia, administration of calcium gluconate in order to promote cardiac stabilization is the next most important step. The role of sodium bicarbonate in severe hyperkalemia is controversial, and although it is not unreasonable to administer it in this setting, it is certainly not as crucial as giving this patient calcium. Initiation of therapeutic hypothermia, non-contrast head CT, and cardiology consultation are reasonable considerations, but not before addressing the patient’s underlying hemodynamic instability [17].

• 24. The correct answer is B. In adults, oliguric renal failure is defined as urine output less than 400 ml in a 24-h period. The 0.5 mL/kg/h formula is used for children, while the 1 mL/kg/h formula is used for infants. Less than 50 ml in 24 h generally defined anuria.

• 25. The correct answer is E. Normal pressure hydrocephalus is a clinical syndrome of gait abnormalities, cognitive dysfunction, and urinary incontinence. It may be idiopathic, or the result of prior CNS insult. There are numerous clinical entities which may result in secondary hydrocephalus. These include trauma, hemorrhage, neoplasm, and CNS infection.

• 26. The correct answer is E. In general, mannitol may be administered if the serum osmolarity is 320 mOsm/kg or less. For levels greater than 320, the osmolar gap should be calculated. This is measured as follows: serum osmolarity – [(Na x 2) + (BUN/3) + (Glucose/18)]. A gap > 20 indicates the presence of circulating mannitol, and a new dose should be held until the circulating mannitol is cleared. In this case, the gap is 338 – (318 + 7 + 10), or 3; the next dose of mannitol may be administered [18].

• 27. The correct answer is A. Central cord syndrome is the most common incomplete spinal cord injury, and is usually the result of hyperextension of the cervical spine. The result is weakness more pronounced in the upper extremities as compared to the lower extremities [19].

• 28. The correct answer is D. Acute pancreatitis is diagnosed when two of the following three criteria are met: abdominal pain characteristic of pancreatitis (upper quadrant, radiating to back), serum amylase and/or lipase greater than the three times upper limit of normal, or abnormal imaging characteristic of pancreatitis. This patient meets the diagnostic criteria and therefore, management should be directed accordingly. The cornerstones in the management include aggressive early intravenous hydration, appropriate nutrition, necessary interventions, and pain management. Early fluid resuscitation has been shown to reduce mortality. Recent guidelines from the AGA suggest that normal saline and Ringer’s lactate are equally efficacious. The AGA also recommends early oral feeding (within 24 h) of mild pancreatitis, and in patients who are unable to tolerate oral feeding, early enteral (vs total parental nutrition) feeding. Pain management remains essential, as uncontrolled pain can lead to hemodynamic instability and poorer outcomes [20].

• 29. The correct answer is E. The CRASH-2 trial was a randomized, placebo-controlled multicenter trial evaluating the safety and efficacy of tranexamic acid (load of 1 g over 10 min, followed by 1g over 8-h infusion) in adult trauma patients at risk of severe hemorrhage (or in hemorrhagic shock) if administered within 8 h of presentation. Overall mortality was decreased in the TXA group, particularly in regards to bleeding as a cause of death. There was no statistically significant difference in thrombotic adverse events between the two groups, nor was there a difference in need for surgical intervention or blood product administration. The number needed to treat (NNT) was 67 (1.5% absolute risk reduction) [21].

• 30. The correct answer is A. A hyperdynamic precordium causes movement of the chest wall that may be mistaken for respiration, and this is a common cause of false negative apnea testing. Electromagnetic interference may prevent a determination of brain death in regards to EEG testing. Ictal activity requires functioning neurons, and by definition, precludes brain death. Physician inattentiveness may result in a false positive apnea test, as patient respirations may go unnoticed. Severe hypocarbia should be addressed and corrected before performing apnea testing in the first place, as it may also result in false positive testing.

• 31. The correct answer is E. The evaluation of serum ammonia in patients with hepatic encephalopathy remains somewhat controversial. Although patients usually present with elevated serum ammonia levels, there has been no cutoff that is consistently associated with symptomatic patients, nor is there a clear association between an increased serum ammonia level and a more severe degree of encephalopathy [22].

• 32. The correct answer is B. WHO grade I astrocytomas include pilocytic astrocytoma, pleomorphic xanthoastrocytoma, subependymal giant cell astrocytoma, and subependymoma. WHO grade II astrocytomas include fibrillary astrocytoma and mixed oligoastrocytoma. WHO grade III and IV respectively include anaplastic astrocytoma and glioblastoma multiforme (GBM).

• 33. The correct answer is E. Although osmotic demyelination syndromes, such as pontine and extrapontine myelinolysis, are often thought to carry universally poor prognoses, but this has not borne out in the research. In one study of chronic alcoholics suffering from osmotic demyelination, nearly went on to make a complete recovery from their illness [23].

• 34. The correct answer is A. Paroxysmal pulmonary edema is a long-recognized complication of naloxone-mediated μ-opioid antagonism. Massive catecholamine surges are thought to result in increased pulmonary hydrostatic pressures and abnormal capillary permeability. Direct cardiac dysfunction may also be a contributing factor in certain cases, but is less likely in this otherwise healthy 19-year-old with no hemodynamic compromise [24].

• 35. The correct answer is E. One of the main goals of mechanical ventilation in status asthmaticus is to prevent worsening of dynamic hyperinflation and its consequences (such as barotrauma and hypotension). Minute ventilation is the most important determinant of dynamic hyperinflation in status asthmaticus; hence increasing tidal volume or respiratory rate would increase minute ventilation, and may worsen dynamic hyperinflation. In addition, increasing respiratory rate may shorten expiratory time and lead to worsening auto-PEEP. A certain degree of hypercarbia is tolerated unless patients have any compelling contraindications, such as raised intracranial pressure or hyperkalemia. In most cases, with continued bronchodilator therapy, airway resistance improves and dynamic hyperinflation is reversed. Addition of a bicarbonate drip at pH of 7.24 is unwarranted, and may lead to post-hypercapnic metabolic alkalosis. Switching to a pressure limited mode of ventilation may correct high peak airway pressure; however high airway pressures with normal plateau pressures in status asthmaticus are due to airway narrowing, and do not lead to alveolar over distension and barotrauma. In addition, use of pressure control ventilation in status asthmaticus may lead to dangerously low tidal volume delivery that may reduce alveolar ventilation.

• 36. The correct answer is A. Amyl nitrate is not the antidote for methemoglobinemia, and in fact, is used to induce methemoglobinemia in the setting of cyanide toxicity. All of the other toxin/antidote pairings are correct.

• 37. The correct answer is B. Nimodipine, while used frequently in neurocritical care settings for the prevention of delayed cerebral ischemia following subarachnoid hemorrhage, is not available as a continuous infusion. Clevidipine and nicardipine infusions are used primarily as antihypertensives, while diltiazem is used primarily for rate control in the setting of paroxysmal atrial fibrillation.

• 38. The correct answer is C. Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a rare mitochondrial disorder characterized by headaches, muscle weakness, seizures, vomiting, and altered mental status. The majority of cases are caused by mutations in the MT-TL1 gene, and there is usually a family history of similar symptoms (though rare spontaneous cases are reported in the literature). Like other mitochondrial cytopathies, the inheritance pattern is maternal. Unfortunately, there is no cure, and the disease is both progressive and fatal. Because MELAS is so rare, and the clinical presentation is so varied, it is often misdiagnosed.

• 39. The correct answer is C. The absence of fevers, purulence, wheezing, and a normal I:E ratio make a COPD exacerbation very unlikely. Salivation and increased bronchial secretions are a well-described muscarinic receptor mediated side effect of acetylcholinesterase inhibitors, and can be managed with glycopyrrolate, which affects primarily the muscarinic receptors while still preserving the desired nicotinic effects of acetylcholinesterase inhibitors.

• 40. The correct answer is E. There are numerous mechanisms for refractory seizure activity when status epilepticus is prolonged. These include an upregulation of transport molecules which clear medications like phenytoin and phenobarbital, an upregulation of excitotoxic NMDA receptors, a downregulation of suppressive GABA receptors, and in influx of numerous proinflammatory molecules which may alter blood-brain barrier permeability.

• 41. The correct answer is A. Guillain-Barre often follows an antecedent respiratory or gastrointestinal illness by several days to weeks. Distal muscle groups are primarily affected, with gradual progression to more proximal groups. As it is a peripheral nerve disorder, areflexia or at least hyporeflexia are common. Approximately 50% of patients develop weakness of the facial or oropharyngeal muscles.

• 42. The correct answer is D. Left ventricular ballooning with preserved basal function is the most common echocardiographic pattern of stress-induced left ventricular dysfunction from neurologic injury (also known as Takotsubo cardiomyopathy). Preserved right ventricular apical function with basal dilation is often referred to as McConnell’s sign, and is a marker of acute right ventricular failure in the setting of an acute increase in right-sided afterload. The other choices represent valve-related pathology that would be less likely in a patient with no past medical history.

• 43. The correct answer is A. Atherosclerotic disease accounts for a plurality of spinal cord ischemia. Aortic pathology and degenerative disease also account for a significant number of cases. Spinal cord ischemia and infarction secondary to systemic hypotension or a cardioembolic source is relatively less common [25].

• 44. The correct answer is D. Chemical (sterile) meningitis is a postoperative complication that may be difficult to distinguish from bacterial meningitis. Operative and postoperative factors linked to bacterial meningitis include sinus or spine manipulation, CSF rhinorrhea or otorrhea, or the presence of new seizures or focal neurologic deficits. Chemical meningitis is more likely to be present in the immediate postoperative period [26].

• 45. The correct answer is B. The etiology of primary angiitis is unknown, and it is an uncommon disease overall, with an annual incidence of 2.4 cases per 1,000,000 person-years. A 2:1 male predominance is seen. Headache is the most common presenting symptom, seen in about 60% of cases [27].

• 46. The correct answer is E. Surgical management of refractory status epilepticus in the absence of a definable brain lesion is a last-ditch effort, and usually with more of a palliative purpose. In this case, there are numerous other medical therapies that can be attempted before resorting to surgical options, including midazolam, pentobarbital, ketamine, and therapeutic hypothermia.

• 47. The correct answer is B. Low molecular weight heparin should be initiated within 72 h post-injury, and a dose should be held prior to surgical intervention and resumed within 24 h post-surgery. Unfractionated heparin is not the preferred method of prophylactic anticoagulation in acute spinal cord injury [28].

• 48. The correct answer is E. The overall annual hemorrhage rate of arteriovenous malformation based on a meta-analysis of about 4000 patients is 3%. Risk factors that impact hemorrhage rates include the following: hemorrhage at the time of clinical presentation (which was the strongest predictor of subsequent hemorrhage in patients with untreated arteriovenous malformations), the presence of associated aneurysms, exclusive deep venous drainage and deep brain location. Earlier retrospective studies noted that a small AVM size is a potential risk factor for hemorrhage, presumably from a greater feeding artery pressures in these lesions, but a recent large meta-analysis has shown that size of the AVM does not appear to impact hemorrhage risk [29].

• 49. The correct answer is D. The WFNS grading scale for subarachnoid hemorrhage is as follows: Grade 1, GCS 15, no motor deficit; Grade 2, GCS 13–14, no motor deficit; Grade 3, GCS 13–14, with motor deficit; Grade 4, GCS 7–12, with or without motor deficit; Grade 5, GCS 3–6, with or without motor deficit.

• 50. The correct answer is A. This presentation is consistent with Ogilvie’s syndrome, also known as colonic pseudo-obstruction. If untreated, severe dilatation can lead to perforation. In this case, pro-motility agents (erythromycin) and cessation of all opiates have already proven ineffective. Surgical treatments have a high rate of complication for this entity, and should only be attempted after all medical therapies have been exhausted. Percutaneous cecostomy has been described, but it is also somewhat invasive, and without a proven record of success. Neostigmine is a cholinesterase inhibitor, increasing post synaptic concentrations of acetylcholine and boosting colonic motor function. Small controlled trials have shown success using neostigmine for colonic pseudo-obstruction, but it must be administered carefully. Side effects can include severe bradycardia with cardiovascular collapse, as well as severe bronchospasm. Neostigmine is also contraindicated if there is evidence of mechanical obstruction [30].

• 51. The correct answer is D. The PROSEVA trial demonstrated that patients with ARDS and severe hypoxemia (PaO₂:FiO₂ ratio of < 150 mm Hg, with an FiO₂ > 0.6 and PEEP > 5 cm water) may benefit from prone positioning, with an unadjusted 28-day mortality of 16% vs. 32.8% in the standard care group. None of the other intervention listed has been shown to confer a mortality benefit in this setting [31].

• 52. The correct answer is A. In order to prevent rapid shifts in fluid and solute concentrations during intermittent hemodialysis, the dialysis prescription should include a dialyzer membrane with a small surface area, a low blood flow rate and dialysate flow rate, a high dialysate sodium concentrate, a low bicarbonate concentrate, a cooler dialysate temperature, a low rate of urea removal and a low rate of ultrafiltration.

• 53. The correct answer is A. Echinocandins, including anidulafungin, are the treatment of choice for empiric coverage of presumed candida infections, except for the central nervous system, eye, and urinary tract. Echinocandins do not penetrate the CSF. Amphotericin B formulations are currently considered treatment of choice for empiric coverage in this scenario; fluconazole is reserved for step-down therapy once the diagnosis has been confirmed and the patient is improving. Flucytosine may be added to amphotericin B therapy at clinician discretion [32].

• 54. The correct answer is C. Although the majority of fevers in the ICU are infectious in origin, a significant minority may be non-infectious, particularly among patients with subarachnoid hemorrhage. The onset tends to be earlier versus infectious fever, usually within the first 72 h. Central fever may be difficult to confirm in many cases, as it is usually a diagnosis of exclusion [33].