e96 SECTION XV Pediatric Critical Care Board Review Questions the head to the left) As a result, the patient’s eye movement is directed away from the cold water Warm water produces the op posite effec[.]
e96 S E C T I O N XV Pediatric Critical Care: Board Review Questions the head to the left) As a result, the patient’s eye movement is directed away from the cold water Warm water produces the opposite effect; the endolymph warms and rises within the semicircular canal producing the same fluid movement as moving the head toward the ear being irrigated The patient’s eye movement is directed toward the warm water The normal response to cold water instilled in one ear gives rise to the acronym COWS (cold-opposite, warm-same) But alas, there are no COWS in the ICU; the usual response will not be seen The irrigation of cold water into the ear of a comatose patient with an intact brainstem will produce a slow conjugate deviation toward the ear being irrigated An absent or asymmetric response suggests brainstem dysfunction An intact conjugate response with nystagmus toward the midline is unusual in a comatose patient A patient presented with a head injury as a result of an automobile crash that occurred 24 hours ago During the initial evaluation, the patient was difficult to arouse and responsive only to painful stimulation Further physical examination noted a swelling of the right upper and lower eyelids; the lids could only be retracted with difficulty The initial radiologic evaluation demonstrated multiple right orbital fractures, an intraorbital hematoma, a small subarachnoid bleed in the left parietal area, and a displaced right humeral fracture On physical examination this morning, the patient is able to be aroused and follow commands, but he is not moving his right arm Which statement best describes the extent of the patient’s injury? A Brainstem injury is likely because the patient is awake and has a focal neurologic finding B Central herniation is less likely because the patient was not able to be aroused on presentation and had an eye injury C Diencephalic and brainstem injury are less likely because the patient has awakened and is following commands D Medullary and corticospinal tract injury are likely because the patient does not move his right arm Preferred response: C Rationale An altered level of arousal is seen in patients who sustain direct brainstem-diencephalic injury to the reticular formation and ascending reticular activating system (ARAS) nuclei or in patients who have bilateral cerebral dysfunction as a result of a diffuse cerebral injury, metabolic injury, or the effects of drugs Because conscious behavior (i.e., the ability to follow commands) depends on the interplay between the cerebral cortex and ARAS, it is unlikely that the patient sustained injury to the diencephalon and brainstem A patient with significant brainstem injury is unlikely to awaken quickly given the fact that many ARAS structures important to arousal are located in the brainstem Central herniation causes both diencephalic and brainstem dysfunction, which would be noted by altered mental status, alteration in pupillary function, alteration in the respiratory pattern, and posturing Uncal herniation classically presents with a unilateral dilated pupil and contralateral hemiparesis Often mentation is normal in the early stages of uncal herniation Medullary tract lesions are associated with problems in bulbar muscles such as speech and swallowing Injury to the corticospinal tract causes hypertonia, but corticospinal tract injury also can cause extensor posturing 8 The right eye of the patient from the previous scenario appears less swollen on follow-up examination this morning and the lids retract, but the pupillary examination is abnormal Detailed examination shows anisocoria—that is, the right pupil is larger than the left The right pupil is nonreactive to direct light, indirect light, and near stimulus Extraocular movements are not intact, and ptosis is present Which of the following can best describe the abnormality? A Afferent disorder B Horner syndrome C Sympathetic abnormality D Third nerve palsy Preferred response: D Rationale The patient’s examination is consistent with a third nerve palsy due to traumatic injury Third nerve palsy is the result of lesions anywhere between the oculomotor nucleus and the extraocular muscles as the nerve follows a long course from the brainstem into the orbit Given this association, third nerve palsy is often seen in patients with trauma to the orbits The third nerve innervates the levator muscle of the eyelid, four of the six ipsilateral extraocular muscles (the medial rectus, the superior rectus, the inferior rectus, and the inferior oblique), and the sphincter pupillae (parasympathetic fibers) Patients with third nerve palsy present with ptosis, gaze abnormalities, and varying degrees of pupillary dysfunction (papillary dilation and decreased ability to respond to light) Complete third nerve palsy classically results in an eye that is turned down and out Unilateral sympathetic dysfunction and unilateral parasympathetic dysfunction present with anisocoria If sympathetic dysfunction is present, the small pupil is abnormal The discrepancy in pupillary size is greater in darkness than in light Poor pupillary dilation is noted on the abnormal side If parasympathetic dysfunction is present, the larger pupil is abnormal The pupillary size discrepancy is greater in light than in darkness Poor pupillary constriction is noted on the abnormal side Anisocoria is indicative of a lesion in the efferent fibers supplying the pupillary sphincter muscles (dilator pupillae and the sphincter pupillae) Normally pupils are the same size because the efferent limb of the pupillary reflex is bilateral, so that both pupils receive the same command Lesions in the afferent limb of the pupillary reflex not produce anisocoria if the consensual pupillary response to light is intact Afferent pupillary defects are noted when the direct and consensual responses to light are different Afferent papillary defects are sensitive markers for abnormalities of the afferent limb of the visual pathways Horner syndrome occurs as a result of injury to the sympathetic pathway and presents with miosis, ptosis, and anhidrosis In Horner syndrome, anisocoria occurs and the small pupil is abnormal A lag in dilation or asymmetry in the speed of dilation is noted in the affected pupil In children, the most common causes of Horner syndrome are birth trauma, closed head injury, neck trauma, neuroblastoma, and trauma due to surgery CHAPTER 136 Board Review Questions A 5-year-old victim of child abuse presents with bilateral pinpoint pupils reactive to light, apneustic breathing, and decerebrate posturing in response to noxious stimulus Which of the following is the most likely site of central nervous system injury? A Cortex B Medulla C Midbrain D Pons Preferred response: D e97 Rationale In Ondine curse, involuntary respiration fails while voluntary respiration is retained The injury is in the medulla 1 Which of the following is a manifestation of midbrain lesion? A Cheyne-Stokes respiration B Fixed, pinpoint pupils C Inferior and lateral gaze deviation D Ipsilateral hemiplegia Preferred response: C Rationale Rationale The supratentorial compartment mainly contains the cortex, thalamus, and other structures above the midbrain Asymmetric findings on physical examination are indicative of cortical lesions Given a “focal” or asymmetric examination, hemiparesis suggests a lesion in a contralateral upper motor neuron pathway Hypotonia, a diminished level of consciousness, and equally reactive pupils are likely to be localized to a cortical lesion on the contralateral side Acute unilateral cortical lesions often dampen alertness but not lead to stupor or coma Expansion of cortical lesions result in raised intracranial pressure, which may reduce blood flow to other areas of the brain and cause the level of consciousness to diminish Cortical lesions associated with contralateral thalamic lesions present with contralateral hemiparesis, decorticate (flexor) posturing, a “down and in” gaze deviation (inferiorly and medially), and small reactive pupils Decorticate posturing (tonic flexion of the upper extremities and tonic extension, adduction, and internal rotation of lower extremities) reflects a lesion above the midbrain Although not always reliable for localization, posturing suggests that cortical control centers are not functioning Midbrain lesions frequently present with hemiplegia contralateral to the lesion and an ipsilateral midposition, nonreactive pupil due to third cranial nerve (CN) palsy Third CN palsy generally causes both eyes to deviate laterally or inferiorly and laterally When gaze is deviated down and out, the patient is said to have setting sun sign Decerebrate or extensor posturing is elicited in response to noxious stimuli in patients with sixth midbrain lesions This complex yet abnormal response consists of tonic extension of the upper extremities and extension, adduction, and internal rotation of lower extremities Contralateral hemiplegia and medial deviation of the ipsilateral eye (CN VI) are hallmarks of medial lesions in the caudal portion of the pons The ipsilateral pupil remains small and reactive to light Midline pontine hemorrhages, however, may cause bilateral pinpoint pupils Patients with hemiplegia, swallowing difficulties, problems with phonation, nonreactive normal-sized pupils, and normal extraocular eye movements are likely to have an injury to the medulla CNs VIII to XII exit the brainstem in the area of the medulla Consequently, medullary lesions are associated with dysfunctional bulbar muscles, such as speech and swallowing If respiratory centers are affected, apnea may ensue Midbrain lesions frequently present with hemiplegia contralateral to the lesion and an ipsilateral midposition, nonreactive pupil due to third cranial nerve (CN) palsy Third CN palsy generally causes both eyes to deviate laterally or inferiorly and laterally When gaze is deviated down and out, the patient is said to have setting sun sign Decerebrate or extensor posturing is elicited in response to noxious stimuli in patients with sixth midbrain lesions This complex yet abnormal response consists of tonic extension of the upper extremities and extension, adduction, and internal rotation of lower extremities Fixed, pinpoint pupils indicate injury to the pons CheyneStokes respiration occurs with bilateral hemispheric dysfunction Swallowing dysfunction indicates injury to the medulla 10 Injury to which of the following central nervous system sites is responsible for the respiratory pattern seen in a child with Ondine curse? A Cortex B Medulla C Midbrain D Pons Preferred response: B Chapter 63: Intracranial Hypertension and Monitoring When intracranial hypertension is more marked in the supratentorial compartment as a result of a unilateral intracerebral hematoma, which of the following observations is true? A The herniation may be more marked anteriorly in the hippocampus B The temporal lobe on the contralateral side may be displaced into the tentorial notch C Unilateral transtentorial herniation results from displacement of the affected temporal lobe D Unilateral transtentorial herniation is evident when there is contralateral third nerve palsy and ipsilateral hemiparesis Preferred response: C Rationale When intracranial hypertension is more marked in the supratentorial compartment with an intracerebral hematoma, the temporal lobe on the ipsilateral side, not contralateral side, may be displaced into the tentorial notch The herniation may be more marked posteriorly, not anteriorly, in the hippocampus Herniation is commonly accompanied by displacement of the ipsilateral cingulate gyrus under the falx Unilateral transtentorial herniation is evident when there is ipsilateral, not contralateral, third nerve palsy and contralateral, not ipsilateral, hemiparesis e98 S E C T I O N XV Pediatric Critical Care: Board Review Questions Intracranial pressure (ICP) is being monitored in a child following a closed head injury Which of the following observations related to ICP values and traces is true? A ICP waves directly related to changes in arterial blood pressure and hyperemic events indicate refractory intracranial hypertension B In the 30-degree elevated position, a normal ICP value in a healthy, nonmechanically ventilated child is negative with a range of around –5 mm Hg but not exceeding –10 mm Hg C In the standing upright position, a normal ICP value in healthy children is positive with a range from to 10 mm Hg D In the horizontal position, a normal ICP value in healthy children is 15 to 20 mm Hg Preferred response: A Rationale In the 30-degree elevated position, a normal ICP value in a healthy, nonmechanically ventilated child is positive in relation to atmospheric pressure In the standing upright position, a normal ICP value in healthy children is negative in relation to atmospheric pressure In the horizontal position, a normal ICP value in healthy children is in the range of to 10 mm Hg In normal children, vasogenic B waves and plateau waves in the ICP trace represent abnormal findings When ICP waves directly relate to changes in arterial blood pressure and hyperemic events, refractory intracranial hypertension is typically present Chapter 64: Status Epilepticus An 18-month-old male with a history of seizures is transported to the emergency department because he was having generalized tonic-clonic seizures The parents cannot recall the name of the antiepileptic medication the child is taking The child took the morning dose and was noted to be febrile to 102°F prior to his nap, for which he received ibuprofen On arrival the patient is actively seizing What should be administered next? A Atracurium B Lorazepam C Phenytoin D Phenobarbital Preferred response: B Rationale The child is presenting in status epilepticus despite being on an antiepileptic drug according to the parents It is not unreasonable to assume the drug level may not be in the therapeutic range The recommended first-line treatment for status epilepticus (now defined operationally as seizures lasting more than minutes) is to administer a benzodiazepine All three benzodiazepines (diazepam, lorazepam, and midazolam) have an onset of action that is less than minutes and enhance inhibitory neurotransmission by binding to a specific benzodiazepine site on the GABAA receptor However, diazepam’s duration of antiepileptic action appears to be less than hour, making it less attractive than lorazepam Atracurium in a neuromuscular blocker (NMB) and any NMB that is used to facilitate management of the airway should be short acting NMBs will mask the motor component of the seizure The remaining choices are second- (phenytoin) and third-line (levetiracetam and phenobarbital) antiepileptic agents to be considered after one or two doses of benzodiazepines have failed to terminate the seizure 2 A 12-year-old female is brought into the emergency department for altered behavior according to her parents She is an honor student at school and her grades have been falling over the past several weeks While you are examining her, her eyes deviate to the left, her right arm begins to shake, and she develops a full-blown tonic-clonic seizure Intravenous access is rapidly attained, and after minutes she is given an appropriate dosage of lorazepam She continues to seize and receives a second dose of lorazepam 10 minutes later followed by an intravenous load of fosphenytoin over 20 minutes You are arranging to transport her to the PICU when suddenly she begins to have another generalized tonic-clonic seizure and she is given a loading dose of levetiracetam over 20 minutes Which of the following statements is true? A Effective treatment regimens have been established for this patient B The risk of complications with refractory status epilepticus (RSE) is the same as that of status epilepticus (SE) C This patient is at risk to have underlying encephalitis D To meet criteria for RSE, this patient needs to seize continuously for over hours Preferred response: C Rationale SE that persists beyond hour despite antiepileptic drug (AED) therapy is considered refractory (RSE) About 30% of SE cases may prove resistant to standard treatment with one of the benzodiazepines and phenytoin This subgroup of patients has a higher risk of complications, longer hospital stays, and worsened mortality Most of them have some structural cerebral damage, metabolic disorders, or cerebral hypoxia Other risk factors include delay in receiving treatment, metabolic encephalopathy, hypoxia, and encephalitis Conventional AEDs have low efficacy in RSE, and although conventional AEDs (e.g., topiramate, levetiracetam, and carbamazepine) should be continued during this treatment phase, higher dose or higher potency agents are required to abort RSE Therapeutic options include high-dose benzodiazepines, barbiturates, propofol, valproic acid, ketamine, lidocaine, and inhalational anesthetic agents Currently, insufficient evidence exists to conclude which of these high-dose suppressive medications, either alone or in combination, has superior efficacy in the treatment of RSE A 3-year-old previously well boy is admitted to your intensive care unit following a first episode of febrile status epilepticus His seizures continue despite appropriate therapy with lorazepam, phenobarbital, phenytoin, and a midazolam infusion What is the most important reason for requesting continuous electroencephalographic (EEG) monitoring at this time? A To assist in prognostication for the family B To facilitate the detection and treatment of nonconvulsive seizures C To predict the risk for future seizure recurrence D To assist in the evaluation for possible brain death Preferred response: B Rationale Nonconvulsive seizures commonly occur after convulsive seizures Antiepileptic drug therapy should be directed at controlling both convulsive and nonconvulsive seizures Nonconvulsive seizures cannot be detected without an EEG, justifying the request for continuous EEG monitoring in this scenario EEG also may be CHAPTER 136 Board Review Questions used for prognostication and to evaluate the risk for seizure recurrence, but this can be accomplished with a routine 30-minute EEG rather than continuous EEG monitoring EEG is not useful in monitoring for anticonvulsant adverse effects EEG is no longer recommended in the evaluation of suspected brain death A child continues to have generalized tonic-clonic status epilepticus despite receiving two doses of lorazepam delivered by bolus and loading with fosphenytoin Such prolonged seizures have been associated with impaired neuronal inhibition involving which of the following neurotransmitters? A Acetylcholine B g-Amino-butyric acid (GABA) C Glutamate D N-methyl-D-aspartate Preferred response: B Rationale Prolonged seizures have been associated with deficits in GABAmediated neuronal inhibition due to altered GABAA receptor structure and function and the rapid internalization of synaptic GABAA receptors Excitotoxicity resulting from glutamate represents another major mechanism for neuronal injury in persons with status epilepticus (SE) Glutamate is the major excitatory neurotransmitter in the central nervous system (CNS) In addition, both N-methyl-D-aspartate (NMDA) and a-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid glutamate receptors have been implicated in the excitotoxicity pathophysiology of persons with SE Which of the following is the most common cause of status epilepticus in the pediatric population? A CNS infection B Hypoxia C Low levels of acute antiepileptic drugs D Non-CNS infection Preferred response: D Rationale One of the largest series of SE in children was published in 1970 This review of 239 cases of SE in children identified 47% of cases as symptomatic (26% acute symptomatic and 21% remote symptomatic) and the remaining 53% of cases as idiopathic, including febrile SE The cause of SE is age dependent; infection plays a larger role in the cause of SE in children In a 1996 study in Richmond, Virginia, the three major causes of SE in children were infection with fever, remote symptomatic cause, and low anticonvulsant drug levels The three major causes in adults were low antiepileptic drug levels, remote symptomatic cause, and stroke The cause also differs among younger and older children Febrile SE and acute symptomatic SE are more common in children younger than years, whereas idiopathic and remote symptomatic causes are most common in older children During status epilepticus, which of the following ions is responsible for sustaining depolarization of the N-methyl-D-aspartate (NMDA) receptors, leading to prolonged excitation? A Calcium B Magnesium C Potassium D Sodium Preferred response: A e99 Rationale Prolonged seizures have been associated with deficits in GABAmediated neuronal inhibition due to altered GABAA receptor structure and function and the rapid internalization of synaptic GABAA receptors SE causes neuronal injury by both hypoxic-ischemic and excitotoxic mechanisms The hypoxic-ischemic mechanism involves an increase in neuronal metabolic demand early in SE with a compensatory increase in cerebral blood flow (CBF) and brain oxygenation Later in SE, these homeostatic mechanisms are unable to keep up with the sustained increase in cerebral metabolic demand Autoregulation of CBF fails, and consequently a higher mean arterial pressure is required to maintain adequate brain perfusion As systemic blood pressure falls, a subsequent reduction in brain parenchymal oxygenation occurs In the face of increased neuronal metabolic demand, uncontrolled muscular contractions, hyperthermia, and impaired airway control, both impaired oxygenation and ventilation contribute to the mismatch between metabolic supply and demand However, neuropathologic injury occurs even when these systemic factors are controlled and before CBF is reduced, presumably because of unmet neuronal metabolic demands alone Excitotoxicity is the second major mechanism for neuronal injury in SE Glutamate is the major excitatory neurotransmitter in the CNS, and glutamate agonists are used to induce seizures in experimental animal models of SE Studies have implicated both the NMDA and a-amino-3-hydroxy-5-methyl-4isoxazole-propionic acid glutamate receptors in the pathophysiology of SE The NMDA receptor may have a dual function in the pathophysiology of SE Magnesium blocks the NMDA channel when it is in its normal state With depolarization, magnesium no longer blocks the channel, and calcium, which is allowed to flow into the cell, produces further depolarization Thus the NMDA receptor is activated when the cell is depolarized and responds by further depolarizing the cell, sustaining the excitation This process has also been implicated in SE-induced neuronal injury, as the accumulation of intracellular calcium activates pathologic processes, resulting in both necrotic and apoptotic cell death Refractory status epilepticus (RSE) is characterized by seizures that have not responded to first- and second-line therapy and have lasted longer than which of the following? A 15 minutes B 30 minutes C 60 minutes D 120 minutes Preferred response: C Rationale RSE is characterized by seizures that persist beyond 60 minutes and fail to respond to first- and second-line therapy Which of the following antiepileptic drugs is associated with the purple glove syndrome? A Lorazepam B Phenytoin C Phenobarbital D Propofol Preferred response: B e100 S E C T I O N XV Pediatric Critical Care: Board Review Questions Rationale Phenytoin blocks the fast repetitive firing of neurons through the use-dependent inhibition of voltage-gated sodium channels Advantages of phenytoin include minimal sedation and respiratory depression at therapeutic levels The main disadvantage of phenytoin is that it must be infused relatively slowly to minimize the risk of cardiac arrhythmia, infusion site pain, and thrombophlebitis The maximum recommended infusion rate is mg/kg per minute (maximum, 50 mg/min); therefore an infusion of 20 mg/kg requires 20 minutes Extravasation of phenytoin at the infusion site has been associated with a so-called purple glove syndrome, which consists of localized extremity edema and discoloration that occasionally requires fasciotomy or amputation Purple glove syndrome, as well as the more common adverse effects of hypotension and cardiac arrhythmia, is attributed to the fact that phenytoin is dissolved in a solution of propylene glycol and ethanol with a pH of 12 Phenytoin must be infused slowly to avoid which of the following adverse effects? A Cardiac arrhythmias B Laryngospasm C Malignant hyperthermia D Respiratory depression Preferred response: A Rationale The main disadvantage of phenytoin is that it must be infused relatively slowly to minimize the risk of cardiac arrhythmia, infusion site pain, and thrombophlebitis Chapter 65: Anoxic Ischemic Encephalopathy In a recent meeting of the quality assurance committee, it is noted that the resuscitation rates at Children’s Hospital are 10% below the national average As director of the resuscitation committee, you perform a review of mock code performance measures and note only 15% adherence to international pediatric resuscitation guidelines Which of the following you recommend as the best evidence-based method to improve the poor guideline adherence to improve outcomes? A Administer quarterly online certifications where guidelines are reviewed, and users are tested in computer simulation scenarios B Perform brief resuscitation training exercises with didactic and hands-on simulation repeated every 3–6 months with staff likely to encounter a cardiac arrest C Require all members of the code team to undergo PALS certification every year D Require all members of the code team to undergo PALS certification every years with online refreshers every months E Require all members of code team personnel to undergo Pediatric Advanced Life Support (PALS) certification every years Preferred response: B Rationale Cardiopulmonary resuscitation (CPR) providers require regular skills training and education to maintain high-quality performance that can improve patient outcomes following cardiac arrest “Rolling refreshers” provide opportunities for providers to maintain skills 2 You are caring for a 2-year-old girl who suffered a pediatric cardiac arrest days prior as the result of drowning The child remains in a coma despite being off sedation days, with no voluntary movements, a limited gag and cough, brisk pupillary reflexes, and extensor posturing with noxious stimuli in all four extremities The exam has been unchanged the last days Brain computerized tomography (CT) on the day of drowning and days later was unremarkable Electroencephalogram (EEG) showed burst suppression for the first days and now shows persistent slowing (delta) with variability but no reactivity Somatosensory evoked potentials (SSEP) performed yesterday showed absent N20 (negative peak at 20 ms) in all four extremities What is your advice to family at this point regarding their child’s prognosis? A A brain MRI is accurate enough alone to determine prognosis following pediatric cardiac arrest B It is very difficult to determine the outcome at this stage since pediatric brain injury after cardiac arrest can improve dramatically over the course of months after the injury C The child is very likely to have a poor outcome (vegetative or minimally conscious) D The child is likely to have a good outcome based on the lack of edema on head CT, the presence of brainstem reflexes, and the presence of a variable delta background on EEG E The child is likely to have a poor outcome (vegetative or minimally conscious) based on the limited gag and lack of corneal reflexes on physical exam Preferred response: C Rationale Predicting long-term child outcomes after cardiac arrest requires multiple assessment modalities because no one test is accurate alone Some modalities include neurological examination often over several days, brain testing (i.e., electroencephalography) and imaging (e.g., magnetic resonance imaging) Interpretation of tests may be confounded by pharmacologic therapy, young age, and occurrence of secondary conditions (e.g., seizures) Which of the following is true regarding the pathophysiology of pediatric cardiac arrest? A Apoptosis occurs over days to weeks following brain reperfusion in selectively vulnerable neurons B Brain injury patterns following ventricular fibrillation and asphyxia are similar C Infants have higher survival rates than older children following cardiac arrest secondary to their potential for neuroplasticity D Neurons require at least one hour of hypoxia-ischemia and reperfusion duration before undergoing necrotic cell death Preferred response: A Rationale Neuronal cell death after hypoxia-ischemia-reperfusion can occur by many distinct and overlapping pathways including apoptosis Apoptosis is an organized pathway involving programmed cell death that has been shown to occur over days to weeks after the initial insult This may represent an opportunity for supportive and therapeutic interventions ... contralateral to the lesion and an ipsilateral midposition, nonreactive pupil due to third cranial nerve (CN) palsy Third CN palsy generally causes both eyes to deviate laterally or inferiorly and... contralateral to the lesion and an ipsilateral midposition, nonreactive pupil due to third cranial nerve (CN) palsy Third CN palsy generally causes both eyes to deviate laterally or inferiorly and... regimens have been established for this patient B The risk of complications with refractory status epilepticus (RSE) is the same as that of status epilepticus (SE) C This patient is at risk to have