Neurologic/NM

Question 1

Which of the following conditions would MOST likely results in an upregulation of acetylcholine receptors?

Answer 1

During times of decreased stimulation at the neuromuscular junction such as in severe burns, infection, sepsis, immobilization, cerebrovascular accidents, and extended use of neuromuscular blocking agents, there is an upregulation of immature (fetal) nAChRs. This upregulation results in an increased sensitivity to acetylcholine and succinylcholine but a decreased sensitivity to nondepolarizing neuromuscular blocking agents.

Question 2

In a patient in the lateral decubitus position for thoracic surgery. Which of the following is the correct location of a roll in order to prevent perioperative positional injury to the brachial plexus?

Answer 2

The axillary roll should be located caudal to the axilla to prevent direct pressure on the brachial plexus and should be large enough to relieve any pressure from the mattress on the lower shoulder.

Question 3

Which of the following MOST accounts for heat loss during general anesthesia?

Answer 3

Heat loss from radiation is the major cause of heat loss during general anesthesia.

Question 4

Which cranial nerve is responsible for the afferent arc of the gag reflex?

Answer 4

The glossopharyngeal nerve is responsible for the afferent arc of the gag reflex while the vagus nerve is responsible for the efferent arc.

Question 5

Which of the following intravenous fluids is MOST APPROPRIATE for resuscitation in patients with traumatic head injuries?

Answer 5

Normal saline is appropriate for intravenous fluid resuscitation in patients with a traumatic head injury. Hypotonic, low sodium, and dextrose-containing fluids should be avoided or used with caution in head injury.

Question 6

The patient was dialyzed yesterday, and potassium is 5.4 mEq/L this morning on an electrolyte panel. Of the following, which is the MOST APPROPRIATE way to plan for neuromuscular blocking medications for a one-hour diagnostic laparoscopy for endometriosis in an appropriately fasted patient with end-stage renal disease on dialysis?

Answer 6

Neuromuscular blocking drug dosages should be carefully considered and planned in patients with ESRD due to the alterations in drug metabolism and excretion. Patients with ESRD can safely be given succinylcholine but one must pay careful attention to the potassium and remember that it can increase 0.5 to 1.0 mEq/L. Use of nondepolarizing agents is also safe but there may be some prolongation with pancuronium in particular. Cisatracurium and atracurium metabolism does not depend on renal clearance and thus dose alterations are not needed. This highlights the absolute importance of proper monitoring of neuromuscular blocking medications with twitch monitoring. It is recommended to always check twitches before administering any additional medications, even with succinylcholine as a patient could have pseudocholinesterase deficiency.

Question 7

A 78-year-old female with severe COPD on home oxygen therapy is undergoing a left carotid endarterectomy. Her history includes a right carotid endarterectomy 6 months prior. Arterial blood gas on room air reveals pH 7.41, PaCO2 55 mm Hg, and PaO2 62 mm Hg. General anesthesia with 1% isoflurane, vecuronium, and fentanyl (2 mcg/kg) is administered.

Following skin closure, the neurologic examination is grossly intact with full strength in all four extremities. Adequate tidal volume and vital capacity are obtained ONLY when prompted. End-tidal CO2 is 68 mm Hg. Which of the following is the MOST likely explanation for the lack of spontaneous ventilation?

Answer 7

Bilateral carotid endarterectomy carries a high complication rate for bilateral carotid body denervation. The carotid bodies are the main peripheral chemoreceptors involved in the chemical control of ventilation. They are very sensitive to changes in PaO2 mainly between 50-65 mm Hg. Patients dependent on hypoxic ventilatory drives have resting PaO2 values ranging between 50-65 mm Hg for this reason. Hypoxemia is worsened during carotid body denervation due to the impaired ventilatory response of hypercapnia. Central chemoreceptors are located within the medulla. They are mainly sensitive to changes in PaCO2, pH, and acid-base disturbances that alter CSF chemistry.

Question 8

A teenager collides with another player during a hockey game and has a brief loss of consciousness. Based on Glasgow Coma Scale, their score determines they have a mild traumatic brain injury. What is the MOST LIKELY finding on a computed tomography scan?

Answer 8

A concussion is an alteration of brain function without a physical effect on brain tissue. Hence, a computed tomography (CT) scan would not identify any structural lesions or changes.

Question 9

Which of the following is TRUE regarding the nicotinic acetylcholine receptor?

Answer 9

Fetal nicotinic acetylcholine receptors consist of five subunits: two α, one β, one γ, and one δ subunit arranged as a rosette around a central channel. The mature receptors differ from the fetal receptors by replacing the γ subunit with the ε subunit.

Question 10

What is the expected patient anesthetic state if the electroencephalogram (EEG) shows alpha wave oscillations and the bispectral index (BIS) monitor reading is 78?

Answer 10

In a sedated patient, the EEG will show alpha wave oscillations and a bispectral index score of 65-85. Alpha waves have a frequency of 8 to 13 Hz and are found in a resting adult with eyes closed.

Question 11

Which of the following medications should be AVOIDED for electroconvulsive therapy?

Answer 11

ECT requires minimum seizure duration of 25-30 seconds to ensure adequate antidepressant efficacy. Methohexital or etomidate are the best options depending on patient circumstances. Avoidance of etomidate in patients with baseline hypertension or CAD is advisable as it does not blunt the sympathetic surge associated with ECT.

TrueLearn Insight : If patients are experiencing excessively long seizures (>100 seconds), propofol may be a useful alternative to methohexital

Question 12

Which of the following is MOST commonly found in patients with myelomeningocele?

Answer 12

Hydrocephalus is commonly found in patients with myelomeningocele, occurring in 60-90% of patients depending on the location of their lesion. Ventriculoperitoneal shunting is often indicated and the hydrocephalus may also be associated with Arnold-Chiari malformations.

Question 13

Within the neuromuscular junction, there is acetylcholine vesicle fusion to the presynaptic membrane. Which of the following enzymatic actions on synapsin proteins results in acetylcholine vesicle fusion?

Answer 13

The opening of voltage-dependent Ca2+ channels leads to induction of a cascade resulting in phosphorylation of synapsins and subsequent fusion of presynaptic acetylcholine vesicles to the presynaptic membrane. This causes a release of acetylcholine through exocytosis at the synaptic cleft.

Question 14

Paraplegia, as opposed to quadriplegia, occurs with spinal cord injury below what level?

Answer 14

Quadriplegia occurs with injury above the first thoracic vertebra and paraplegia occurs with injury below the first thoracic spinal level.

Question 15

Which of the following describes the CORRECT path of stimulus to terminal recording of a somatosensory evoked potential?

Answer 15

Somatosensory evoked potentials are generated from electrical stimulation in peripheral nerves and are recorded anywhere along the ascending sensory pathway including the peripheral nerve, spinal cord, or cerebral cortex. The basic pathway of an SSEP, from stimulus to terminal recording is: peripheral nerve, dorsal root ganglia, posterior spinal cord, brainstem, thalamus, cortex.

Question 16

Which of the following is associated with autoimmune destruction, or inactivation, of postsynaptic acetylcholine receptors at the neuromuscular junction?

Answer 16

Myasthenia gravis is a result of autoimmune destruction or inactivation of postsynaptic acetylcholine receptors at the neuromuscular junction.

Question 17

Where are MOST of the voltage-gated calcium channels located on a motor neuron?

Answer 17

The axon terminal is where most voltage-gated calcium channels reside. After an action potential is initiated and it propagates down the axon, the voltage-gated calcium channels are activated at the axon terminal.

Question 18

Which of the following is associated with the highest relative risk of venous air embolism?

Answer 18

The risk of venous air embolism is significantly high when the pressure within an open vein is subatmospheric. This particular situation is possible when the surgical field is above the level of the heart. Of the choices listed above, total hip arthroplasty has the highest relative risk of air embolism.

Question 19

A 78-year-old female with severe COPD on home oxygen therapy is undergoing a left carotid endarterectomy. Her history includes a right carotid endarterectomy 6 months prior. Arterial blood gas on room air reveals pH 7.41, PaCO2 55 mm Hg, and PaO2 62 mm Hg. General anesthesia with 1% isoflurane, vecuronium, and fentanyl (2 mcg/kg) is administered.

Which of the following is NOT an appropriate explanation for why general anesthesia was chosen over a regional technique in this patient?

Answer 19

Superior neurologic outcomes have not been well established with either GA or RA in the setting of a carotid endarterectomy.

TrueLearn Insight : Transcranial Doppler (TCD) ultrasonography is an important neuromonitoring tool utilized during GA. It allows for the detection of cerebral ischemia during cross-clamping of the carotid artery, assessment of embolic phenomena perioperatively, and checking blood flow velocities during reperfusion.

Question 20

Which of the following is the correct laterality and levels of origin of the great anterior radiculomedullary artery within the spinal cord?

Answer 20

The left side of the aorta is the most common location where the artery of Adamkiewicz can be found. This artery spans across several vertebral levels and most commonly between T9 and L2.

Question 21

A patient with urosepsis is found to be in a coma. Which of the following findings would MOST likely be consistent with sepsis-associated encephalopathy?

Answer 21

Sepsis can cause sepsis-associated encephalopathy (SAE) with symptoms ranging from delirium coma, even in the absence of CNS infection. Disruption of the blood-brain barrier and inflammation in the brain can lead to SAE. Abnormalities in MRI and EEG can be seen, but SAE is a diagnosis of exclusion and CNS infectious must be ruled out. vasogenic odema on MRI, microglial activation

Question 22

A 68-year-old male with a history of hypertension presents for complex, multilevel spine surgery. Which of the below strategies is most likely to REDUCE the risk of postoperative vision loss in prone spine cases?

Answer 22

POVL is a rare but serious postoperative complication. Risk factors such as extreme case length, high blood loss, prolonged hypotension, high crystalloid administration, and anemia have been associated with POVL, and interventions to minimize these risk factors such as staging complex repairs may reduce the risk of POVL in high-risk populations.

Question 23

A patient with myotonic dystrophy presents for placement of a percutaneous gastrostomy feeding tube. Which of the following statements about myotonic dystrophy is TRUE?

Answer 23

Myotonic disorders include dystrophic and non-dystrophic diseases. Myotonias are temporary, involuntary contractions of muscle fibers that occur due to abnormal ion channels causing prolonged depolarization following action potentials. Neuromuscular blocking drugs do not effectively treat myotonic reactions. Cold, stress, pain, succinylcholine, and anticholinergic reversal agents can precipitate myotonias.

Question 24

An otherwise healthy patient is undergoing a prolonged procedure in the lithotomy position. Which of the following nerves is at the highest risk of perioperative neuropathy?

Answer 24

The common peroneal nerve is at increased risk for injury when procedures are performed in the lithotomy position. Extreme degrees of positioning, as well as prolonged procedures, increases this risk.

Question 25

Which of the following is TRUE regarding cerebral protection during neurosurgical procedures?

Answer 25

There are multiple ways to protect the brain after an insult. This includes temperature management, euglycemia, decreasing the duration of the insult, certain medications, anesthetic agents, and prevention of reperfusion injury.

Question 26

A patient is found to have antibodies directed against presynaptic voltage-gated calcium channels at the neuromuscular junction. The resulting disease process would be MOST LIKELY to manifest with which of the following presentations?

Answer 26

It is important to be familiar with the effects of succinylcholine and nondepolarizing neuromuscular blocking agents in patients with the above syndromes. Patients with MG tend to exhibit decreased sensitivity to blockade with succinylcholine and increased sensitivity to blockade with nondepolarizing agents (e.g. rocuronium). By contrast, patients with LEMS often demonstrate increased sensitivity to both succinylcholine and nondepolarizing agents. Dose adjustments should be made accordingly.

Question 27

A 45-year-old man presents for transthoracic thymectomy for management of myasthenia gravis (class III), first diagnosed eight years ago. He has a past medical history significant for rheumatoid arthritis. He currently takes 60 mg of pyridostigmine four times daily for his myasthenia gravis. Pulmonary function testing was done three months ago and showed a vital capacity of 3.0 L and a diffusing capacity of the lungs for carbon monoxide (DLCO) of 70% predicted. Which of the following is MOST likely to increase the patient’s risk for needing postoperative ventilatory support?

Answer 27

Risk factors that predicted the need for mechanical ventilation included the following:
Disease duration > 6 years
Chronic respiratory illness
Pyridostigmine dosage > 750 mg/day (newer data suggest > 250 mg/day)
Vital capacity < 2.9 L
Risk factors related to the newer minimally invasive approach include the following:
Advanced stage of myasthenia gravis (bulbar involvement)
Body mass index > 28 kg/m2
History of prior myasthenic crisis
Associated with pulmonary resection

Question 28

An otherwise healthy patient with no preoperative neurologic derangements is one hour into a posterior fossa surgery for tumor resection in the prone position. There is acute hypertension and bradycardia while the surgeon is performing retraction. Which of the following mechanisms is behind this finding?

Answer 28

Brainstem manipulation or pressure on the brainstem can cause significant hemodynamic derangements. The Cushing triad of hypertension, bradycardia, and breathing alterations are due to brainstem compression (from either cerebral edema pushing down on the brainstem or from surgical manipulation intraoperatively).

Question 29

Which of the following is MOST TRUE regarding post-resuscitation interventions following a non-traumatic cardiac arrest?

Answer 29

Global hypoxic brain injury can onset just minutes after a significant decrease in cerebral blood flow such as during cardiac arrest. This injury causes an inflammatory cascade of cell death that is sped by the neurotoxic release of excitatory neurotransmitters within the brain parenchyma. Targeted hypothermia is used as a therapy following the return of spontaneous circulation to decrease this cerebral inflammation as well as to decrease the cerebral metabolic rate of oxygen and is associated with improved neurologic outcomes.

Question 30

Which of the following cranial nerves would be affected in a patient who suffered a medial pontine infarction?

Answer 30

The olfactory nerve, cranial nerve I, is not affected in a pontine infarct. The olfactory nerve is responsible for processing the sensation of smell.

Question 31

During awake craniotomy for seizure focus localization, which of the following is the BEST first step for a seizure triggered by cortical stimulation?

Answer 31

In awake craniotomy, if a seizure is caused by cortical stimulation, administration of propofol or the application of iced saline should be the first-line action.

Question 32

Which of the following nerve fibers transmit pain impulses?

Answer 32

Aδ fibers transmit pain impulses, temperature, and sensation of touch.

Question 33

A 40-year-old male is scheduled for an elective cholecystectomy. He reports a five-year history of generalized weakness and involuntary skeletal muscle contractions that cause stiffness. He reports occasionally visualizing muscle twitches with a rippling appearance under his skin that feels like a “bag of worms”. He has difficulty with ambulation, stiffness, lack of balance, and constant cramping, which may also continue during sleep. Administration of phenytoin helps alleviate his symptoms. What is the most likely mechanism of this patient’s neuromuscular disorder?

Answer 33

Acquired neuromyotonia is an autoimmune condition that manifests with impaired muscle relaxation, myokimia, stiffness, muscle cramping, excessive sweating, and muscle hypertrophy, with most individuals having antibodies against voltage-gated potassium channels.

Question 34

A 25-year-old obese (BMI 35) man presents for a laparoscopic appendectomy. He has never had surgery before, however, prior to surgery, he informs the anesthesiologist that his father has hypokalemic periodic paralysis. The patient has not eaten in 2 days, and his blood glucose on preoperative laboratory evaluation is 69 mg/dL. He is otherwise asymptomatic except for his ongoing abdominal pain. Which of the following BEST describes the appropriate course of action at this time?

Answer 34

Perioperative considerations in the management of a patient with known or suspected hypokalemic period paralysis include minimization of surgical stimulus to prevent a hyperglycemic stress response, avoidance of insulin boluses, and avoidance of hypothermia. Given the association between hypokalemic period paralysis and malignant hyperthermia, a non-trigger anesthetic should be considered for any patient with hypokalemic period paralysis who is undergoing surgery if it is at all feasible.

Question 35

Which of the following changes will cause the GREATEST decrease in cerebral blood flow during otherwise normal physiologic conditions?

Answer 35

Cerebral blood flow is directly related to body temperature, PaCO2 (within normal physiologic ranges), and extremes of MAPs (< 50 or >150 mm Hg). Cerebral blood flow is inversely related to PaO2 when less than 50 mm Hg. Cerebral blood flow remains unchanged within the autoregulatory range of MAPs (50-150 mm Hg) and with PaO2 >50 mm Hg.

Question 36

A patient is undergoing resection of a unilateral arteriovenous malformation of the parietal lobe. The neurosurgeon informs you that she plans to perform a vessel occlusion test. Which of the following would be the most appropriate to monitor during this test?

Answer 36

AVM resections use neuromonitoring depending on where the AVM is located. One that is located in the parietal lobe, ischemic changes would result in motor and sensory changes. Neuromonitoring should then include sensory evoked potentials (SEP) and motor evoked potentials (MEP).

Question 37

Which of the following conditions is associated with increased activity of GABA nuclei in the basal ganglia and inhibition of thalamic nuclei?

Answer 37

Parkinson disease is characterized by a progressive loss of dopamine in the nigrostriatal pathway, there is also an increase in the GABA nuclei in the basal ganglia leading to inhibition of thalamic and brainstem nuclei. Thalamic inhibition suppresses the motor system in the cortex.

Question 38

Which of the following disorders is characterized by dilated cardiomyopathy?

Answer 38

Duchenne muscular dystrophy is characterized by dilated cardiomyopathy, but not hypertrophic cardiomyopathy. Cardiovascular complications are responsible for a large portion of the morbidity and mortality associated with Duchenne’s muscular dystrophy.
Friedrich ataxia, myotonic muscular dystrophy, and Noonan syndrome are associated with hypertrophic cardiomyopathy.

Question 39

Which of the following is TRUE regarding congenital myasthenic syndromes (CMS)?

Answer 39

Congenital myasthenic syndrome (CMS) is a set of rare genetically inherited disorders. Perioperative management needs to be developed on a case-by-case basis since they are not all the same. It is imperative to know the type and what protein or signaling pathway is defective to tailor treatment. CMS are not similar to other myasthenic like syndromes and thus treatment is different.

Question 40

A 25-year-old man suffers a traumatic brain injury and is intubated and sedated in the intensive care unit. A decision is made to insert a jugular venous oximetry (SjvO2) catheter. The correct location of the catheter tip in the internal jugular vein at the C1-C2 level below the jugular foramen is confirmed with a lateral radiograph. The catheter is inadvertently advanced 5 cm during a dressing change two days later. The catheter tip is MOST likely located in which of the following structures?

Answer 40

Cerebral venous blood flows from the deep and superficial veins into the cerebral sinuses (straight sinus, occipital sinus, and superior sagittal sinus) which all join at the confluence of sinuses and travel through the bilateral transverse sinuses which turn into the sigmoid sinuses that eventually exit the skulls through the jugular foramina where they then become the internal jugular veins.

TrueLearn Insight : A jugular venous oximetry (SjvO2) catheter is usually utilized in the setting of neurological injury in the intensive care unit and is inserted in a retrograde fashion into the internal jugular vein. The proper location is at the level of the C1-C2 vertebrae in the internal jugular vein just below the jugular foramen. Measurements are used to estimate cerebral tissue oxygen extraction and delivery. A value less than normal (55%-75%) is indicative of poor outcomes.

Question 41

A 38-year-old man with a history of spinal cord transection at the T2 level 3 years ago is scheduled for suprapubic catheter placement. During surgery, he is noted to have an acute rise in blood pressure, to 204/115 mm Hg. Which of the following signs or symptoms is LEAST likely to coincide with this rise in blood pressure?

Answer 41

During an autonomic hyperreflexia episode, the intense sympathetic response below the level of a spinal cord injury (SCI) can cause acute hypertension (≥ 20-40 mm Hg above baseline), reflex bradycardia, cardiac arrhythmias, and myocardial infarction. Hypertension can further lead to headaches, blurred vision, retinal or intracranial hemorrhage, stroke, seizure, and/or cerebral edema. Additionally, the intense vasoconstriction leads to cool, dry, pale skin of the lower extremities. The reflex cutaneous vasodilation above the level of the SCI leads to nasal congestion, diaphoresis, and warm, flushed skin on the upper extremities, shoulders, neck, and face.

TrueLearn Insight : Autonomic hyperreflexia is generally not observed until at least 2 weeks to 6 months after the spinal cord injury.

Question 42

A patient is undergoing shoulder surgery performed in the sitting position. The blood pressure cuff reading is at the level of the heart, which is 22 cm below the level of the patient’s external auditory meatus. The blood pressure measurement is currently 90/60 mm Hg. Which of the following represents the patient’s blood pressure at the circle of Willis?

Answer 42

The difference in blood pressure at 2 different sites equals the height difference in cm multiplied times the conversion factor 0.74.

TrueLearn Insight : A mnemonic to help remember which comes first (pressure or height) is “pH” or “pH 15 20”, where a pressure of 15 mmHg correlates to a height of 20 cm.

Question 43

Which of the following intravenous fluids would be MOST appropriate to administer in the resuscitation of a hypovolemic patient with a severe traumatic brain injury?

Answer 43

In the setting of coexisting traumatic brain injury and hypovolemia, targeted fluid resuscitation with isotonic to hypertonic crystalloid solutions like 0.9% saline is preferred. Resuscitation with colloids or hypotonic fluids may increase morbidity and mortality due to cerebral edema. Blood products should be given when appropriate indications are present.

Question 44

The influx of which of the following ions into the presynaptic terminal mediates the release of acetylcholine at the neuromuscular junction?

Answer 44

As the action potential travels down the axon and depolarizes the presynaptic terminal, the voltage-gated calcium channels are activated, leading to an influx of calcium into the presynaptic terminal. The increase in Ca2+ mediates the fusion of acetylcholine-containing vesicles with the presynaptic membrane, leading to the release of acetylcholine into the synaptic cleft at the neuromuscular junction.

TrueLearn Insight : Gabapentin and pregabalin function by blocking the voltage-gated calcium channels, thus inhibiting the release of acetylcholine and the transmission of the neuronal signal.

Question 45

Which of the following intravenous anesthetic agents increase cerebral oxygen consumption and cerebral blood flow?

Answer 45

Ketamine increases cerebral oxygen consumption, cerebral blood flow, and intracranial pressure.

Question 46

For each item in the following set, select the letter corresponding to the receptor of the autonomic nervous system listed below that best fits each description. Each letter may be used once, more than once, or not at all.
Stimulation of this receptor will result in increased lipolysis.

Answer 46

Beta-adrenergic receptor activation leads to lipolysis.

Question 47

Stimulation of this receptor will inhibit insulin release.

Answer 47

α2 (postsynaptic)	
Coronary constriction 
Inhibition of insulin release 
Decreased bowel motility 
Analgesia

Question 48

Stimulation of this receptor will cause relaxation of the gravid uterus.

Answer 48

β2 (postsynaptic)	
Inotropism and chronotropism 
Relaxation of vascular smooth muscle 
Relaxation of bronchial smooth muscle 
Relaxation of renal vessels

Question 49

Stimulation of this receptor will augment endogenous norepinephrine release.

Answer 49

β2 (presynaptic) Accelerate endogenous norepinephrine release

Question 50

Inhibition of norepinephrine release into the synaptic cleft.

Answer 50

α2 (presynaptic)
Inhibit norepinephrine release in vascular smooth muscle
Inhibition of CNS activity
Decrease MAC

Question 51

Which of the following would be MOST likely to result in an episode of autonomic dysreflexia?

Answer 51

Autonomic dysreflexia (AD), also known as autonomic hyperreflexia, is a complication of a spinal cord injury above the T6 level. AD is typically triggered by a noxious stimulus (such as bladder distension, visceral manipulation, or surgical stimulus) below the level of the spinal cord lesion. Bladder and bowel manipulation/pain are the most common causes of AD.

Question 52

A 31-year-old G3P2 with myasthenia gravis well-controlled on pyridostigmine just had a repeat cesarean delivery under spinal anesthesia. Which of these statements is TRUE regarding the care of the neonate?

Answer 52

Maternal antibodies to acetylcholine receptors freely cross the placenta and may cause transient neonatal myasthenia gravis (TNMG) with respiratory distress, poor feeding, and generalized hypotonia.

Question 53

A 29-year-old man is undergoing an endovascular embolization of a high-flow cerebral arteriovenous malformation (AVM). Which of the following perioperative complication is MOST commonly seen following embolization of this lesion?

Answer 53

Tight hemodynamic control is paramount in AVM embolization procedures. Cerebral dysautoregulation can result in rapid and profound cerebral edema in the downstream vascular distributions. This edema may require rapid action on the part of the anesthesiologist consisting of therapeutic hypotension, hypocapnia, hypothermia, or administration of sedative-hypnotic agents such as barbiturates or propofol.

Question 54

Which of the following statements about thiopental is TRUE?

Answer 54

The cerebral flow-metabolism relationship and cerebral autoregulation remain intact with the use of thiopental. Thiopental decreases both CBF and CMRO2 by 30% with induction doses and by 50% upon achievement of an isoelectric EEG.

TrueLearn Insight : Burst suppression on EEG is the goal target of reducing CMRO2 during an open cerebral aneurysm clipping. Burst suppression sufficiently indicates depressed CMRO2 while providing predictability of recovery and awakening once the IV anesthetic is turned off.

Question 55

A 51-year-old man presents following a subarachnoid hemorrhage for the clipping of a cerebral aneurysm. Which of the following will MOST LIKELY to cause rebleeding of his cerebral aneurysm?

Answer 55

The prevention of rebleeding is one of the primary anesthetic goals during the open clipping of a cerebral aneurysm. This is primarily done through the meticulous control of blood pressure during stimulating portions of the anesthesia and surgery, though factors that decrease a patient’s intracranial pressure such as profound hyperventilation or rapid cerebrospinal fluid drainage can also worsen the transmural pressure across the wall of a cerebral aneurysm and thereby increase the risk for rebleeding.

Question 56

A 34-year-old man is undergoing a craniotomy for an intracranial hemorrhage after a motor vehicle accident. The patient is awake, but slightly altered and known to have a high intracranial pressure. The patient also has a full stomach, is complaining of severe pain, and is hypertensive on arrival to the operating room. Which option describes the BEST strategy for induction of anesthesia in this patient with regards to controlling intracranial pressure and brain perfusion?

Answer 56

Etomidate is an appropriate induction agent for a patient with increased ICP. Other options include propofol, benzodiazepines, and barbiturates. Ketamine may lead to increased intracranial pressure and thus should be avoided.

Question 57

The spinal cord receives arterial supply via 2 posterior spinal arteries and 1 anterior spinal artery. What percentage of spinal cord blood supply comes from the anterior spinal artery?

Answer 57

The spinal cord receives its blood supply from 1 anterior spinal artery, which provides about 75% of the blood supply; this supplies the motor tracts. The 2 posterior spinal arteries supply the sensory tracts.

Question 58

A 47-year-old man with a T4 spinal cord injury is having a cystoscopy procedure under monitored anesthesia care with mild sedation. During the cystoscopy, he suddenly becomes diaphoretic in his upper extremities and flushed in his face, and his skin is pale in his lower extremities. His blood pressure is 200/110 mm Hg, and his pulse is 35 bpm. Which of the following treatment options is the MOST appropriate first step?

Answer 58

Autonomic dysreflexia (AD) is seen in patients with spinal cord injury at the T6 level or higher in response to a noxious stimulus (ie, distension of the bladder, visceral stimulation, surgical stimuli, or pain) below the level of the spinal cord injury. Treatment involves first removing the stimulus, followed by deepening the anesthetic and administering vasodilators (nitrates, hydralazine, and calcium-channel blockers).

Question 59

Which of the following modified Glasgow Coma Scale score ranges correlates with a conscious patient that has a traumatic brain injury with moderate disability?

Answer 59

The initial evaluation of a patient with a head injury includes use of the AVPU assessment and modified Glasgow Coma Scale to determine severity, prognosis, and state of consciousness. A GCS score of 3-8 correlates with deep coma, severe head trauma, and poor outcome. A GCS score of 9-12 correlates with a conscious patient with moderate head injury. A GCS score >12 correlates with a mild injury.

Question 60

With regard to myasthenia gravis and myasthenic syndrome, which of the following is correct?

Answer 60

Myasthenia gravis (MG) is an autoimmune disorder with antibodies against the motor end plate acetylcholine receptor (B). It tends to affect bulbar and ocular muscles first (C), the patient’s strength gets worse with repetition (A), and patients are generally less sensitive to succinylcholine (D).

Myasthenic syndrome is an autoimmune disorder with antibodies against the presynaptic calcium channel (B). It tends to affect large proximal muscles (C), patient’s weakness improves with repetition (A), and patients are generally more sensitive to succinylcholine (D).

Question 61

A 65-year-old male is to undergo a posterior fossa craniotomy for meningioma. While discussing the anesthetic with the surgeon you plan on using a noninvasive monitor to detect a venous air embolism. Which of the following would be the MOST APPROPRIATE choice if high sensitivity is needed?

Answer 61

There are many different monitors that can be used to help diagnosis VAE. The most specific of these monitors are TEE and precordial Doppler. While the TEE is more sensitive and specific, it is limited by being an invasive monitor. Of the noninvasive monitors the precordial Doppler is very sensitive and specific for VAE. It also provides the most accurate real-time data of all the noninvasive monitors for VAE.

Question 62

A 64-year-old man had a subarachnoid hemorrhage three days ago. Which of the following is NOT a treatment modality for cerebral vasospasm?

Answer 62

Cerebral vasospasm is a large cause of post-subarachnoid hemorrhage morbidity and mortality. Triple H therapy (hypertension, hemodilution, hypervolemia) has been the cornerstone of therapy to increase perfusion past the spasm. Chemical angioplasty is also being used by some centers to selectively treat the cerebral vasospasm. Specific calcium channel blockers (e.g. nimodipine) may help.

Question 63

In neurosurgical patients, which of the following is TRUE regarding fluid management?

Answer 63

Neurosurgical patients should be kept euvolemic or slightly hypervolemic in order to maintain CPP.

Question 64

Which of the following is the MOST accurate statement regarding myasthenia gravis or myasthenic syndrome?

Answer 64

Myasthenic syndrome is associated with small-cell carcinoma of the lung. Patients commonly have proximal limb weakness, improvement in strength with exercise, and sensitivity to succinylcholine. Myasthenia gravis patients display fatigue with exercise, are resistant to succinylcholine, and have extraocular, bulbar, and facial muscle weakness. Refer to the above table for additional key differences.

TrueLearn Insight : “Lambs are sensitive animals.” Lambert-Eaton is sensitive to both types of relaxants.

Question 65

A 56-year-old male with paraplegia is scheduled to undergo cystoscopy. At which level of spinal cord injury does the risk for autonomic dysreflexia begin to increase significantly?

Answer 65

Autonomic dysreflexia occurs most often in patients with spinal lesions above the T6 cord level.

Question 66

Which of the following is NOT a consideration when planning for airway manipulation in a patient with neurofibromatosis?

Answer 66

In patients with neurofibromatosis, careful airway planning may be required. Neurofibromas may be present in the airway and depending on their size may lead to complete airway collapse with induction. Neurofibromas are highly vascularized lesions that can bleed profusely if disrupted. Extreme care must be taken when present in the airway because damage may result in bleeding which is difficult to tamponade and may make visualization of the larynx impossible.

Question 67

A 57-year-old female presents for emergency burr holes for an altered level of consciousness. She fell out of bed at home suffering a left 2 cm subdural hematoma. No midline shift is seen on the computed tomography scan. The patient has a history of alcohol abuse, hypertension, and depression. The patient’s husband states she has been extremely fatigued and this progressed to lethargy over the past week but he attributed it to her drinking, although he admits he did not notice her alcohol intake. On physical examination, she has periorbital edema, bradycardia, and a GCS score of 8. Initial laboratory evaluation shows a thyroid-stimulating hormone of 75 mIU/L (normal range: 0.5 to 5.0 mIU/L) and a sodium level of 130 mEq/L. Which of the following is the MOST reasonable way to proceed?

Answer 67

Myxedema coma is a rare but potentially devastating complication of unrecognized hypothyroidism. All but emergent surgery should be postponed and treatment with intravenous thyroid replacement be administered. Consultation of endocrinology for recommendations is highly advised.

TrueLearn Insight : A much more common cause of altered mental status is hypoglycemia. Recognition of patients at risk is vital. Routine checking of glucose in patients with diabetes, especially in those on insulin therapy can help decrease the risk of severe consequences.

Symptoms of hypoglycemia fall into two groups: adrenergic excess (tachycardia, palpitations, tremulousness, or diaphoresis) or neuroglycopenia (headache, confusion, mental sluggishness, seizures, or coma). Giving a glucose-containing solution such as D50 is vital and rechecking glucose levels often.

Question 68

A 40-year-old female with advanced multiple sclerosis is undergoing an elective open hysterectomy. The surgeon feels the surgery will take approximately two hours. Which of the following would be the MOST appropriate anesthetic plan?

Answer 68

Succinylcholine should be avoided in patients with multiple sclerosis and they may be sensitive (or resistant) to non-depolarizing neuromuscular blockers.

TrueLearn Insight : Increased temperature blocks the conduction of demyelinated nerves, leads to the deterioration of nerve tissue at the sites of demyelination, and is more likely than the drugs used for anesthesia to result in postoperative exacerbation of symptoms of multiple sclerosis.

Question 69

A 27-year-old with a spinal cord injury at T4 is undergoing nephrolithotomy. The patient has no sensation below T8 and he is otherwise healthy. Preoperative vitals included a blood pressure of 100/65 mmHg, heart rate of 65 bpm, and oxygen saturation of 99% on room air. The patient is in the lithotomy position with a well seated laryngeal mask airway. Ten minutes following surgical instrumentation of the bladder the patient becomes hypertensive with a systolic blood pressure of 190 mmHg. Which of the following is MOST true regarding the diagnosis?

Answer 69

Autonomic hyperreflexia can occur in patients with spinal cord lesions above T10. It consists of severe hypertension from unopposed sympathetic stimulation below the level of the spinal cord lesion. Prompt recognition and treatment are vital to avoid significant complications. Signs below the level of spinal cord injury include pilomotor erection, blanching, and spasms. Signs above the spinal cord lesions include nausea, sweating, chills, headache, nasal congestion, flushing, dyspnea, blurred vision, chest pain, cardiac arrhythmias, seizures, and stroke.

Question 70

The following image is a cross-section view of the spinal cord at the cervical level, with dorsal and ventral horn laminae labeled I through X. Which of the following laminae identifies where fibers will decussate?

Answer 70

The central spinal cord is the location of lamina X and is the site of dorsal and ventral gray commissures where decussation takes place and fibers cross the midline of the spinal cord.