Nervous System

Questions

DIRECTIONS (Questions 236-289): 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.

236. A 44-year-old woman is undergoing total pelvic exenteration for metastatic ovarian cancer. Several hours into the procedure her body temperature has dropped to 34.6°C despite measures to keep her warm. Core body temperature may decrease intraoperatively because of all the following factors EXCEPT

(A) exposure of body surfaces to room temperature air

(B) administration of room temperature intravenous fluids

(D) low humidity of inspired gases

(E) high inspired oxygen concentration

237. Of the cranial contents contributing to intracranial pressure (ICP), which one has the smallest volume?

(A) brain tissue

(B) tissue water

(D) arterial blood

(E) cerebrospinal fluid (CSF)

238. In the sympathetic nervous system

(A) preganglionic fibers synapse only in paravertebral sympathetic ganglia

(B) preganglionic cell bodies are located throughout the spinal cord

(D) target organ receptors are only adrenergic

(E) effects are mediated entirely through cyclic AMP

239. A 22-year-old man has an unidentified parietal mass and presents for open brain biopsy. He has some symptoms associated with a mild increase in intracranial pressure. Which one of the following induction agents may increase his intracranial pressure even further?

(A) thiopental

(B) methohexital

(D) propofol

(E) midazolam

DIRECTIONS: Use the following figure to answer Questions 240-243:

240. Between A and B on the curve

(A) there is a small ICP increase with increased intracranial volume

(B) a small ICP increase indicates poor compensatory effect

(D) intracranial contents do not effect ICP

(E) compensatory mechanisms are not functional

241. Intracranial pressure measurements similar to those shown in the graph are obtained from a

(A) needle in the caudal canal

(B) needle in the cervical epidural space

(D) catheter positioned in the carotid siphon

(E) catheter positioned in the jugular bulb

242. A patient at position B on the curve would be expected to

(A) have clinical manifestations of increased ICP

(B) move toward position C with hyperventilation

(D) move toward position A with administration of isoflurane

(E) may benefit from administration of intravenous hypertonic saline

243. At position C on the curve, a patient

(A) moves toward position D with hyperventilation

(B) moves toward position D with coughing

(D) will likely be hypotensive

(E) will likely be tachycardic

244. The ventilatory control centers

(A) contain no expiratory neurons

(B) receive no mechanical sensory input

(D) are located in the medulla and pons

(E) are activated by peripheral CO₂ tension

245. Absorption of cerebrospinal fluid (CSF) takes place through

(A) ependymal cells

(B) arachnoid villi

(D) the foramen of Monro

(E) the foramen of Magendie

246. The smallest nerve fiber, a postganglionic fiber associated with slow conduction, is the

(A) A-alpha fiber

(B) A-beta fiber

(D) B fiber

(E) C fiber

247. Integrity of all of the following structures can be monitored by sensory-evoked potentials EXCEPT the

(A) dorsal columns

(B) cerebellum

(D) vestibular-cochlear nerve

(E) inferior colliculus

248. A 61-year-old man has developed a resting tremor in his right hand. His neurologist believes it is consistent with early Parkinson disease. He is therefore likely to have dysfunction within the

(A) cerebellum

(B) lateral ventricle

(D) basal ganglia

(E) aqueduct of Sylvius

249. A nuclear group in the brain involved in transmission of sensory information to the cortex is the

(A) cerebellum

(B) caudate

(D) thalamus

(E) hippocampus

250. All of the following cranial nerves contain parasympathetic efferent fibers EXCEPT the

(A) oculomotor nerve (III)

(B) trigeminal nerve (V)

(D) glossopharyngeal nerve (IX)

(E) vagus nerve (X)

251. The electroencephalographic (EEG) waveform with a frequency range of 8 to 13 Hz is associated with

(A) alpha activity

(B) beta activity

(D) delta activity

(E) theta activity

252. In face of a declining supply of nutrients

(A) neuronal function deteriorates in an all-or-none fashion

(B) there is no reserve below the normal level of cerebral blood flow

(D) the actual CBF level at which neuronal function deteriorates varies with anesthetics

(E) an isoelectric EEG indicates irreversible neuronal damage

253. The substantia gelatinosa

(A) has the highest concentration of opioid receptors in the spinal cord

(B) is located in the lateral columns

(D) is in the motor area of the brain

(E) is in the ventral column

254. The oculocardiac reflex involves all of the following structures EXCEPT

(A) vagus nerve

(B) trigeminal ganglion

(D) oculomotor nerve

(E) brain stem

255. Hormonal products of the anterior pituitary include all of the following EXCEPT

(A) growth hormone

(B) luteinizing hormone

(D) follicle-stimulating hormone

(E) thyrotropin

256. After bringing a traumatized patient to the emergency department, the paramedic team reports that his Glasgow Coma Score is 11. This assessment is based on

(A) eye opening, verbal response, and motor response

(B) assessment of knee jerk and other motor reflexes

(D) assessment of respiration and autonomic brain stem functions

(E) assessment of EEG

257. An increase in PaCO₂ from 40 to 50 mm Hg will increase cerebral blood flow

(A) not at all

(B) 1 to 2 mL/100 g/min

(D) 10 to 20 mL/100 g/min

(E) 25 to 50 mL/100 g/min

258. The oxygen reserves of the brain are

(A) infinite

(B) capable of maintaining function for 25 min

(D) very low

(E) carried primarily in the cerebral hemispheres

259. Cerebral perfusion pressure may be estimated by

(A) MAP + ICP

(B) SBP – ICP

(D) MAP + CVP – ICP

(E) SBP – CVP

MAP: mean arterial blood pressure

ICP: intracranial pressure

SBP: systolic arterial blood pressure

CVP: mean central venous pressure

DIRECTIONS: Use the following case to answer Questions 260-262: A 47-year-old man is brought to the interventional radiology suite for insertion of a suprapubic catheter to provide long-term bladder drainage. He sustained a C6 fracture with transection of the cervical cord at age 23 in a motor vehicle accident. He takes no medications but has had several urinary tract infections treated with antibiotics. He has no motor function or sensation below the shoulders. He is sedated with 2 mg midazolam and 50 mcg fentanyl.

260. In the patient with an injury at the C 6-7 level, one would expect

(A) a major loss of diaphragmatic power

(B) no effective ventilation and ventilator dependency

(D) impaired alveolar ventilation

(E) profound bradycardia

261. On instillation of the bladder with saline, the blood pressure rises from 128/75 to 221/120 mm Hg and the heart rate falls from 87 to 45 bpm. What is the likely cause of these changes to blood pressure and heart rate?

(A) response to pain

(B) autonomic hyperreflexia

(D) response to cold solution in the bladder

(E) anxiety

262. This event could have been prevented by

(A) pretreatment with beta blockers

(B) lithotomy position

(D) light general anesthesia

(E) spinal anesthesia

263. A 38-year-old woman is in the neurological intensive care unit following rupture of an aneurysm of the right middle cerebral artery. A CT scan shows extensive subarachnoid hemorrhage. Which one of the following findings would be considered to be LEAST likely?

(A) hyponatremia

(B) dysrhythmias

(D) cerebral vasospasm

(E) ECG abnormalities consistent with ischemia

264. The basilar artery is formed by the merger of

(A) the vertebral arteries

(B) branches of the internal carotid artery

(D) the anterior and posterior communicating arteries

(E) the anterior and posterior spinal arteries

265. The celiac plexus

(A) contains visceral and somatic afferent and efferent fibers

(B) receives efferents from both sympathetic and parasympathetic ganglia

(D) is formed from nerve roots from T7 through T10

(E) may be blocked to relieve intractable angina pain

266. Cerebrospinal fluid (CSF)

(A) is formed in the choroid plexus by a passive process

(B) functions as a cushion for the brain

(D) production is affected to the least extent by enflurane of all of the volatile agents

(E) normally contains protein at about one-tenth the plasma concentration

267. Neurotransmitters in the central nervous system that exert an inhibitory action on postsynaptic neurons include

(A) dopamine, glycine, serotonin, γ-aminobutyric acid (GABA)

(B) acetylcholine, dopamine, histamine

(D) acetylcholine, γ-aminobutyric acid (GABA), glutamate

(E) dopamine, serotonin, epinephrine, histamine

268. Low cerebral blood flow (CBF) may disrupt adequate brain perfusion, and one of the main determinants of CBF is the cerebral metabolic rate for oxygen (CMRO₂). Which one of the following statements regarding CMRO₂ and CBF is TRUE?

(A) In adults, the normal rate of neuronal oxygen utilization is 30-40 mL/100 g/min.

(B) Blood flow in the brain is independent of CMRO₂.

(D) Oxygen utilization is higher in the white matter as compared to the gray matter.

(E) Blood flow in the brain is coupled to CMRO₂ in a ratio of 5:1.

269. A typical neuron has

(A) numerous branching dendrites

(B) three or four axons to conduct impulses

(D) a dendritic zone devoid of receptors

(E) a myelin sheath that covers the entire cell

270. Propofol

(A) has little effect on SSEP or MEP

(B) can decrease CMRO₂, CBF, and ICP

(D) increases the frequency of EEG

(E) has little effect on seizure activity

271. All of the following are true concerning hyperthermia EXCEPT that it

(A) increases ICP

(B) increases cerebral metabolic demand

(D) decreases cerebral blood flow

(E) increases cardiac output

272. A typical reflex arc includes all of the following EXCEPT a

(A) sense organ

(B) afferent neuron

(D) synapse on a peripheral effector

(E) ascending axon within the ventral column

273. The electroencephalogram (EEG)

(A) alone is sufficient for the diagnosis of brain death, because a flat line is synonymous with death

(B) shows decreased cortical activity with hypercapnia

(D) is unaffected by hypothermia

(E) is not useful in the diagnosis of a convulsive disorder

274. A 15-year-old girl is undergoing surgery to correct scoliosis. Intraoperative monitoring includes motor evoked potentials. These potentials

(A) test integrity of the descending corticospinal tracts

(B) are unaffected by muscle relaxants

(D) are increased during hypothermia

(E) are produced by electrical stimulation within the cerebellum

275. When the cranium is open, the ICP is

(A) increased by volatile anesthetic agents

(B) reduced by hyperventilation

(D) equal to ambient pressure

(E) cannot be measured by a ventricular catheter

276. The act of vomiting is an integrated activity that includes

(A) activation of the vomiting center in the cerebral cortex

(B) opening of the glottis

(D) activity mediated by cranial nerves VIII and XI

(E) activation of the chemoreceptor trigger zone in the area postrema

277. The compressed spectral array (CSA) recording of the electroencephalogram (EEG)

(A) is more accurate than a standard EEG tracing

(B) presents data in a format of amplitude, time, and frequency

(D) requires no training for interpretation

(E) should be in use for all neurosurgical procedures

278. Which one of the following is NOT involved in sensory transmission?

(A) dorsal root ganglion

(B) spinothalamic tract

(D) ventral posterior and ventral lateral nuclei of the thalamus

(E) precentral gyrus

279. In the adult, the spinal cord ends

(A) at the lower border of the second sacral vertebra

(B) at the lower border of the first lumbar vertebra

(D) midway between the 3rd and 4th lumbar vertebra

(E) at the lumbosacral junction

280. The normal brain

(A) has a constant metabolic rate

(B) maintains nearly constant blood flow between mean arterial blood pressures of 80 to 120 mm Hg

(D) couples regional blood flow to metabolic demand

(E) requires fructose for energy

281. The blood–brain barrier

(A) permits free passage of bicarbonate ion

(B) does not include the brainstem

(D) is permeable to mannitol

(E) is composed of tight junctions in the vascular endothelium

282. Hyperventilation may lead to

(A) cerebral vasodilatation

(B) reduced PaCO₂ in CSF

(D) increased cardiac output

(E) metabolic alkalosis

283. In administration of anesthesia to a patient with Arnold–Chiari malformation, all of the following considerations are important EXCEPT

(A) coughing on the endotracheal tube should be prevented

(B) a moderate increase in mean arterial pressure may lead to subarachnoid hemorrhage

(D) a coexistent syrix in the spinal cord is common

(E) extreme flexion-extension of the neck should be avoided

284. In the patient with amyotrophic lateral sclerosis, the anesthetic plan should include

(A) succinylcholine but not non-depolarizing muscle relaxants

(B) non-depolarizing muscle relaxants but not succinylcholine

(D) avoidance of respiratory depressants

(E) avoidance of isoflurane

285. Loss of cerebral autoregulation

(A) will cause the cerebral blood pressure to fall with systemic hypertension

(B) affects the entire brain at the same time

(D) only affects the lower end of the blood pressure range

(E) has no clinical significance

286. A 15-year-old girl with a history of myotonic dystrophy is scheduled for tonsillectomy and adenoidectomy under general anesthesia. Considerations regarding her anesthesia management include

(A) postoperative hyperthermia may precipitate a myotonic response

(B) myotonia can be relieved by nondepolarizing relaxants

(D) myotonia can be precipitated by succinylcholine

(E) neostigmine prevents myotonia

287. A 26-year-old man is scheduled to undergo elective resection of an arteriovenous malformation. In planning the anesthesia, the anesthesiologist should be prepared to manage

(A) blood pressure during induction within a very narrow range

(B) malignant brain swelling

(D) vasospasm during surgery treated with deliberate hypertension

(E) elevated ICP treated with the head-up position

288. Brain tumors affect intracranial pressure by all of the following processes EXCEPT

(A) increasing intracranial tissue content

(B) increasing cerebral metabolic rate

(D) obstructing CSF flow

(E) increasing interstitial fluid volume

289. Which is the most profound chemical stimulus for regulation of cerebral blood flow?

(A) metabolic alkalosis

(B) hypothermia