Anesthesia for Neurosurgery

Questions

DIRECTIONS (Questions 175-227): Each of the numbered items or incomplete statements in this section is followed by answers or by completions of the statement. Select the ONE lettered answer or completion that is BEST in each case.

175. As the temperature of the brain decreases

(A) MAC increases

(B) autoregulation of blood flow is lost

(D) cerebral Q₁₀ decreases

(E) brain oxygen extraction increases

176. Of the many factors affecting intracerebral blood flow, which one of the following is a correct description?

(A) Vasomotor paralysis: vasoconstriction of vessels in or near ischemic areas

(B) Autoregulation: ability of vessels to respond in a manner consistent with maintaining homeostasis

(D) Intracerebral steal: decrease of blood flow in normal areas with increased flow to ischemic areas

(E) Inverse steal: diversion of flow to normal areas from ischemic areas

177. Which one of these is the best agent to decrease cerebral oxygen requirement?

(A) A muscle relaxant

(B) A glucose solution

(D) A barbiturate

(E) Oxygen by mask

178. Use of succinylcholine to facilitate endotracheal intubation in patients with increased intracranial pressure is associated with

(A) increased intracranial pressure

(B) no change in intracranial pressure

(D) conditions more satisfactory than those with the use of pancuronium

(E) hyperkalemia

DIRECTIONS: Use the following scenario to answer Questions 179-180: A 45-year-old woman is undergoing a coil embolization procedure to obliterate a basilar tip aneurysm. She suffers from mild hypertension for which she takes hydrochlorothiazide. She is anesthetized with 2% sevoflurane in oxygen and vecuronium for muscle relaxation. The catheter approaches the aneurysm through the vertebral artery. On deploying the coil, there is a sudden increase in arterial blood pressure and global depression of ST segments detected by ECG.

179. The most likely diagnosis is

(A) hypertensive crisis

(B) dissection of the vertebral artery and brain stem ischemia

(D) pain from manipulation of the intra-arterial catheter

(E) rupture of the aneurysm with subarachnoid hemorrhage

180. Treatment should include all of the following EXCEPT

(A) hyperventilation

(B) emergent placement of an external ventricular drainage catheter

(D) immediate increase in sevoflurane concentration to reduce arterial blood pressure

(E) immediate angiography and continued placement of coils

181. In the artificially ventilated neurosurgical patient, PEEP

(A) should be used routinely

(B) should be used only on selected patients with the head of the patient never elevated

(D) should be withheld in all cases

(E) should be titrated against requirements for oxygenation and neurologic status

182. Treatment of the neurosurgical patient with mannitol may be followed by all of the following EXCEPT

(A) initial hypervolemia

(B) decreased urine volume

(D) decreased central venous pressure

(E) a decrease in arterial pressure

183. Nitrous oxide should be avoided in patients with

(A) brain tumor

(B) subarachnoid hemorrhage

(D) pneumocephalus

(E) subdural hematoma

184. To obtain maximum benefit from hyperventilation during a neurosurgical procedure, the PaCO₂ should be maintained at

(A) 15 to 20 mm Hg

(B) 20 to 25 mm Hg

(D) 35 to 40 mm Hg

(E) 40 to 45 mm Hg

185. Following closed head injury, systemic sequelae may include all of the following EXCEPT

(A) disseminated intravascular coagulation

(B) diabetes insipidus

(D) hyperglycemia

(E) hypocarbia

186. An intraoperative “wake up” test performed during surgery on the spine

(A) assesses integrity of the dorsal spinal cord

(B) is not necessary if somatosensory evoked potentials are monitored

(D) is intended to assess recall

(E) can be associated with venous air embolism

187. Electroconvulsive therapy (ECT)

(A) is relatively contraindicated in patients with known cerebral or aortic aneurysms

(B) never produces a seizure

(D) does not require hemodynamic monitoring

(E) cannot be performed with muscle relaxants

188. Attention must be given to the value of intracranial pressure on induction because increased intracranial pressure may lead to

(A) herniation of brain tissue

(B) increased cerebral blood flow

(D) brain retraction

(E) increased CSF volume

DIRECTIONS: Use the following scenario to answer Questions 189-192: A patient undergoing a craniotomy in the sitting position has both a radial artery and a right atrial pressure catheter in place. The external auditory canal is 26 cm above the level of the right atrium (5 cm below the manubrium). The cranium is open and the brain exposed.

189. With the arterial pressure transducers located at the level of the right atrium, the mean arterial blood pressure is 90 mm Hg and the central venous pressure is 5 mm Hg. What is the cerebral perfusion pressure?

(A) 95

(B) 85

(D) 59

(E) Cannot be determined directly

190. If the arterial catheter transducer were repositioned to the level of the external auditory canal, then

(A) the MAP would not require correction to measure perfusion pressure at the base of the brain

(B) the measured MAP would remain the same if the arm were not elevated

(D) CPP would equal measured MAP–CVP

(E) blood pressure determined with a cuff on the upper arm would be less than the measured pressure

191. When electronically “zeroing” the transducer system, the stopcock immediately above the transducer diaphragm is opened to air and

(A) the transducer should be positioned at the point where pressure is measured

(B) the position relative to the patient is irrelevant

(D) the arm must be positioned at the level of the right atrium

(E) the transducer should be re-zeroed whenever the position is changed

192. During the procedure the arterial catheter fails; cuff pressures are monitored. Cerebral perfusion pressure

(A) cannot be determined unless the head is lowered to the level of the heart

(B) can be determined only from a cuff pressure determined at the radial artery

(D) equals the systolic blood pressure determined at the brachial artery irrespective of location

(E) is determined from the mean blood pressure corrected for the difference in height where measured from the position of the external auditory canal

193. During a craniotomy, after the dura mater is opened, the intracranial pressure

(A) increases

(B) equals zero

(D) decreases only if the head is elevated

(E) is unchanged

194. Jugular venous oxygen saturation monitoring

(A) assesses global oxygen extraction from brain

(B) requires bilateral placement to fully assess the brain

(D) is highly sensitive to all cerebral ischemia

(E) is directly affected by cardiac output

DIRECTIONS: Use the following scenario to answer Questions 195-197: A 15-year-old girl had a spinal fusion with Harrington rod instrumentation. Motor and somatosensory evoked potentials were obtained throughout. On emergence, the patient was unable to move her left lower extremity.

195. The causes of this may include all of the following EXCEPT

(A) overcorrection of the scoliotic curve

(B) cord compression due to hematoma

(D) hypothermia

(E) traction of the anterior spinal artery

196. The best course of action on discovery of this loss of function is

(A) extubate the trachea, begin blood transfusion

(B) observe for 24 h

(D) immediate imaging of spine by CT or MRI

(E) initiate somatosensory evoked potentials

197. Motor evoked potentials for the left lower extremity were reduced during surgery but improved with induced hypertension. The appropriate initial maneuver on discovery of the deficit would be

(A) avoid pressors that could increase vascular constriction

(B) increase mean arterial blood pressure with pressors

(D) administer mannitol

(E) administer hypertonic saline infusion

198. All of the following are complications associated with the sitting position for cervical surgery EXCEPT

(A) sciatic and cranial nerve trauma

(B) pneumocephalus

(D) airway edema

(E) blindness

199. The advantage of the sitting position for craniotomy is

(A) reduced intraoperative blood loss

(B) easier positioning

(D) easy access to the airway

(E) hypertension

200. Hypertonic saline administered to a patient with elevated ICP

(A) may lead to hyperosmolar coma

(B) removes water from the normal brain tissue while increasing filling pressure

(D) is effective in doses of 0.25 g/kg

(E) is contraindicated in patients with renal failure

201. When administered to the neurosurgical patient, dexamethasone

(A) will reduce cerebral edema surrounding a brain tumor

(B) is effective because of its osmolar property

(D) is contraindicated in patients with Addison disease

(E) produces hypoglycemia

202. Administration of nitrous oxide 66% in oxygen

(A) reduces intracranial pressure

(B) depresses responsiveness of cerebral blood flow to carbon dioxide

(D) slows EEG

(E) increases metabolic suppression produced by propofol

203. Air embolism may be a fatal complication depending upon

(A) the site of entry

(B) the amount of air and rate of entry

(D) presence of a properly positioned pulmonary artery catheter

(E) patient position

204. Concerning magnetic resonance imaging

(A) motion artifacts are rare

(B) objects containing ferromagnetic material are propelled within the magnetic field

(D) large prosthetic metal implants are completely contraindicated

(E) automatic implanted cardiac defibrillators should be switched off before imaging

205. Sensitive methods to detect venous air embolism include all of the following EXCEPT

(A) precordial Doppler

(B) mass spectrometry

(D) electrocardiograph

(E) transesophageal echocardiography

206. Concerning induced hypothermia all of the following are true EXCEPT

(A) cerebral metabolism is decreased

(B) cerebral vascular resistance increases

(D) cerebral blood flow remains coupled to metabolism

(E) more glucose is required by the brain for metabolism

207. If surgery is to be performed on a patient in the sitting position

(A) the legs should be wrapped with elastic bandages

(B) the legs should be positioned below the level of the heart

(D) the neck should be hyperextended

(E) the patient should be positioned as quickly as possible to avoid loss of monitors

208. Morphine as a premedication is indicated to facilitate induction in

(A) infants

(B) patients with increased intracranial pressure

(D) very anxious patients

(E) pulmonary hypertension

209. During a cerebral aneurysm clip obliteration, sodium nitroprusside is infused. The expected results include

(A) short duration of action when infusion is terminated

(B) bradycardia

(D) elevated sodium thiosulfate levels

(E) methemoglobinemia

210. When a precordial Doppler ultrasonic transducer is used to detect air embolus, it

(A) can detect 0.5 mL of air

(B) functions at 15 Hz

(D) is positioned over the point of maximum intensity

(E) is less sensitive than capnography

DIRECTIONS: Use the following scenario to answer Questions 211-213: A patient with a convexity meningioma and several month history of severe headaches has a ventriculostomy for intracranial pressure monitoring in place preoperatively. Induction of general anesthesia with oxygen and nitrous oxide administered to the patient lead to an increased intracranial pressure.

211. The increase in intracranial pressure may be mitigated by administration of

(A) isoflurane

(B) vecuronium

(D) ketamine

(E) propofol

212. The effect of agents or drugs to modify a response of increased intracranial pressure

(A) remains independent of individual and brain state

(B) is consistent across situations

(D) can be determined with imaging

(E) is independent of ventilation state

213. Which one of the following will reduce the increase in intracranial pressure?

(A) Open the ventriculostomy to drain

(B) Positive pressure hypoventilation

(D) Facilitate venous drainage

(E) Lowering the transducer from the level of the external auditory canal to the mid axillary line

214. During surgery for excision of an intradural tumor in the lower thoracic level, integrity of the spinal cord may be confirmed by

(A) performing an intraoperative “wake-up” to test motor function in lower extremities

(B) monitoring brainstem-evoked potentials

(D) monitoring the train-of-four on all four limbs

(E) intraoperative MRI of the spine

215. Therapy for neurogenic pulmonary edema includes all of the following EXCEPT

(A) reduce intracranial hypertension

(B) α-adrenergic antagonists

(D) central nervous system depressants

(E) naloxone 4 mg IV

216. Cervical spine instability should be considered in any patients with

(A) ankylosing spondylitis

(B) Down syndrome

(D) spinal stenosis

(E) neurofibromatosis

DIRECTIONS: Use the following scenario to answer Questions 217-219: A previously healthy 42-year-old woman is admitted to the neurological intensive care unit after suddenly losing consciousness while sitting at her desk at work. A CT scan showed a subarachnoid hemorrhage, and a cerebral angiogram revealed that the hemorrhage was due to rupture of an aneurysm of the right middle cerebral artery. Her caregivers are concerned that she may develop vasospasm.

217. Detection of cerebral vasospasm includes all of the following EXCEPT

(A) transcranial Doppler

(B) assessment of mental status

(D) angiography

(E) assessment of motor function

218. Cerebral vasospasm is most likely to occur after subarachnoid hemorrhage on days

(A) 0-6

(B) 4-14

(D) 12-20

(E) up to one month

219. Endovascular treatment for cerebral vasospasm after subarachnoid hemorrhage includes all of the following EXCEPT

(A) intraarterial injection of mannitol

(B) angioplasty

(D) induced hypertension

(E) intracerebral stenting

220. A patient returns to surgery to treat a CSF leak after transsphenoidal resection of the pituitary. Induction of general anesthesia should include

(A) inhalational induction with nitrous oxide and sevoflurane

(B) head down positioning to prevent CSF drainage

(D) placement of a ventriculostomy to prevent CSF drainage

(E) placement of an nasogastric tube to empty the stomach of blood and CSF

221. During carotid endarterectomy with EEG monitoring, both hemispheres demonstrate profound slowing of frequency and burst suppression. The anesthetic technique consists of continuous infusions of propofol and remifentanil. The most likely diagnosis is

(A) propofol overdose

(B) hypothermia

(D) inadequate perfusion to both hemispheres

(E) elevated ICP

222. Signs of venous air embolism include all of the following EXCEPT

(A) arrhythmia

(B) hypertension

(D) bubbles at the operative site

(E) decreased end-expired carbon dioxide

DIRECTIONS (Questions 223-225): Each group of items below consists of lettered headings followed by a list of numbered phrases or statements. For each numbered phrase or statement, select the ONE lettered heading or component that is most closely associated with it. Each lettered heading or component may be selected once, more than once, or not at all.

(A) Amyotrophic lateral sclerosis

(B) Multiple sclerosis

(D) Guillain-Barre syndrome

(E) Myasthenia gravis

(F) Muscular dystrophy

(G) Familial periodic paralysis

(I) Myasthenic syndrome (Eaton-Lambert syndrome)

For each patient with muscle weakness, select the most likely disease process.

223. A 64-year-old woman has undergone thoracotomy for lobectomy to resect small cell carcinoma of the lung. On emergence she appears weak. She cannot maintain a sustained head lift and cannot generate sufficient tidal volumes to be extubated. Muscle relaxation had been maintained with vecuronium; there were three small twitches with fade elicited with a blockade monitor set to train-of-four before administration of neostigmine and glycopyrrolate. She reported a history of easy fatigue with exertion particularly when climbing stairs. There was no history of diplopia or dysphagia. There was no improvement with additional neostigmine.

224. A 47-year-old man has a six-month history of progressive dysarthria and dysphagia, and is presenting for a gastrostomy tube for weight loss from inadequate nutrition. He has difficulty managing oral secretions and has to sleep with the height of the bed at 45 degrees because of obstructive sleep apnea. He demonstrates no symptoms of weakness either with walking or movement of hands or arms.

225. A 27-year-old woman presents with sudden onset of loss of bowel and bladder function and weakness in both legs. She cannot stand or walk but can sit. She has an elevated white blood cell count with an abnormal smear; white blood cell differential is predominantly lymphocytes with the presence of multiple immature lymphocytes and blast cell. She is afebrile and free of pain.

DIRECTIONS (Questions 226-227): Each group of items below consists of lettered headings followed by a list of numbered phrases or statements. For each numbered phrase or statement, select the ONE lettered heading or component that is most closely associated with it. Each lettered heading or component may be selected once, more than once, or not at all.

(A) Atelectasis

(B) Pulmonary embolism

(D) Patent foramen ovale

(E) Aspiration

(F) Neurogenic pulmonary edema

(G) Spinal shock

For each patient with intraoperative coughing, select the appropriate diagnosis.

226. A 65-year-old man presents for spinal decompression and bilateral foraminotomies at multiple levels for spinal stenosis extending from T8 to L4. He has been incapacitated by pain and leg weakness, and has been largely bedridden for several weeks before surgery. He has undergone uneventful awake fiberoptic intubation after topical anesthesia of the airway with lidocaine while sitting upright. He has positioned himself prone on the operating room table and moved his legs on command before induction of general anesthesia. Anesthesia is maintained with remifentanil and nitrous oxide; no muscle relaxants have been administered. During laminectomy in the thoracic region he begins to cough. He becomes hypotensive and the SaO₂ falls from 98% to 89%. Positive pressure ventilation with 100% oxygen and high inflation pressure do not improve oxygen saturation.

227. A 16-year-old otherwise healthy male is undergoing Harrington rod placement to correct scoliosis. Anesthesia consists of continuous infusions of propofol and remifentanil; no muscle relaxants have been administered since induction. Standard monitoring with noninvasive blood pressure, ECG, SaO₂, and esophageal temperature probe are applied to the patient. He is prone and both somatosensory and motor evoked potentials have been unchanged since induction. Immediately after rod placement and distraction of the spine, a motor evoked potential is performed and the patient coughs several times. During closure the surgeon notices air bubbles in the arterial circulation in the epidural space.

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