Hall Pain Questions Flashcards
1
Q
788. Tachyphylaxis to local anesthetics is most closely related to which of the following? A. Speed of injection B. Dosing interval C. Temperature of local anesthetic D. Volume of local anesthetic E. pH of solution
A
- (B) Tachyphylaxis is a well-known phenomenon associated with repeated injections of local anesthetics leading to
decreased effectiveness. Interestingly, the dosing interval seems most important in the development of tachyphylaxis.
If the dosing interval is short (and no pain between injections) tachyphylaxis does not develop. However,
with longer dosing intervals (and pain between injections) tachyphylaxis develops (Barash: Clinical Anesthesia,
ed 5, pp 458-459).
2
Q
789. Which of the following techniques is LEAST effective in a treatment of pruritus from administration of neuraxial opiates? A. Nalbuphine 5 mg IV B. Dexmedetomidine 30 μg IV C. Diphenhydramine 50 mg IV D. Hydroxyzine 20 mg IM E. Propofol 10 mg IV
A
- (B) The treatment of pruritus, the most common side effect of neuraxial opiates, is primarily with opioid antagonists,
mixed opioid agonist-antagonist, and antihistamine drugs (by their sedating effects). Nalbuphine is a
mixed opioid agonist-antagonist; diphenhydramine and hydroxyzine have antihistamine properties. Propofol at
very low doses (e.g., 10 mg) has been useful to treat pruritus not only induced by neuraxial opiates but also the
pruritus associated with cholestatic liver disease. Propofol does not affect analgesia, whereas opioid antagonists
and mixed agonist-antagonist may reverse some or all of the analgesia, depending upon dose. Dexmedetomidine
is a highly selective α2-receptor agonist that has a faster onset and shorter duration of action compared with
clonidine. Dexmedetomidine has analgesic properties, can potentiate neuraxial analgesia when injected spinally,
and can perhaps decrease the incidence of pruritus by reducing the narcotic dose is used. It does not treat pruritus
(Miller: Anesthesia, ed 6, p 2740; Stoelting: Pharmacology and Physiology in Anesthetic Practice, ed 4, pp 91,
158, 434).
3
Q
- The maximum dose of lidocaine containing 1:200,000 epinephrine that can be administered to a 70-kg patient for
regional anesthesia (other than spinal anesthesia) is
A. 50 mg
B. 100 mg
C. 200 mg
D. 500 mg
E. 1000 mg
A
- (D) The maximum dose of local anesthetics containing 1:200,000 epinephrine that can be used for major nerve
blocks is lidocaine, 500 mg; mepivacaine, 500 mg; prilocaine, 600 mg; bupivacaine, 225 mg; etidocaine,
400 mg; and tetracaine, 200 mg (Miller: Anesthesia, ed 6, pp 584-589).
4
Q
791. Which of the following concentrations of epinephrine corresponds to a 1:200,000 mixture? A. 0.5 μg/mL B. 5 μg/mL C. 50 μg/mL D. 0.5 mg/mL E. None of the above
A
- (B) 1:200,000 means 1 g = 1000 mg = 1,000,000 μg per 200,000 mL
1,000,000 μg/200,000 mL = 5 μg/mL
5
Q
- An anesthesia pain service consult is sought for a 78-year-old patient with a complaint of pain in the distribution of
the trigeminal nerve. The patient has no other medical problems except a history of congestive heart failure for which
he takes digoxin and thiazide. In addition to his chief complaint, the patient over the last 72 hours has complained of
dysesthesia in the feet, difficulty with vision, and emesis times three. The most appropriate step at this time would be
A. Trigeminal nerve block with bupivacaine
B. Obtain neurologic workup for multiple sclerosis
C. Administration of fentanyl and ondansetron
D. Initiate therapy with carbamazepine
E. Obtain a digoxin level
A
- (E) The early signs of digitalis toxicity include loss of appetite and nausea and vomiting. In some patients there may
be pain that is similar to trigeminal neuralgia. Pain or discomfort in the feet and pain and discomfort in the
extremities may be a feature of digitalis toxicity. Transient visual disturbances (e.g., amblyopia, scotomata) have
been reported in patients with digitalis toxicity. In this patient, it would be prudent to obtain a digoxin level as
an early part of the workup for these complaints. He may also have true trigeminal neuralgia, and workup for
this condition can be undertaken after digitalis toxicity has been ruled out (Stoelting: Pharmacology and Physiology
in Anesthetic Practice, ed 4, pp 314-315).
6
Q
793. Which of the following is the earliest sign of lidocaine toxicity? A. Shivering B. Nystagmus C. Lightheadedness and dizziness D. Tonic-clonic seizures E. Nausea and vomiting
A
- (C) Toxic reactions to local anesthetics are usually due to intravascular or intrathecal injection or to an excessive dosage.
The initial symptoms of local anesthetic toxicity are lightheadedness and dizziness. Patients also may note
perioral numbness and tinnitus. Progressive central nervous system (CNS) excitatory effects include visual and
auditory disturbances, shivering, muscular twitching, and ultimately, generalized tonic-clonic seizures. CNS
depression can ensue, leading to respiratory depression or arrest (Miller: Anesthesia, ed 6, pp 592-598).
7
Q
794. An analgesic effect similar to the epidural administration of 10 mg of morphine could be achieved by which dose of intrathecal morphine? A. 0.1 mg B. 1 mg C. 5 mg D. 10 mg E. There is no correlation
A
- (B) The site of action of spinally administered opiates is the substantia gelatinosa of the spinal cord. Epidural
administration is complicated by factors related to dural penetration, absorption in fat, and systemic uptake;
therefore, the quantity of intrathecally administered opioid required to achieve effective analgesia is typically
much smaller. The ratio of epidural to intrathecal dose of morphine is approximately 10:1. Morphine is typically
given in doses of 3 to 10 mg in the lumbar epidural space. Intrathecal morphine dosage is 0.2 to 1.0 mg.
Onset time for epidural administration is 30 to 60 minutes with a peak effect in 90 to 120 minutes. Onset time
for intrathecal administration is shorter than epidural administration. Duration of 12 to 24 hours of analgesic
effect can be expected by either route (Barash: Clinical Anesthesia, ed 5, pp 1422-1423).
8
Q
795. Which local anesthetic undergoes the LEAST hepatic clearance A. Chloroprocaine B. Bupivacaine C. Etidocaine D. Prilocaine E. Lidocaine
A
- (A) Commonly injected local anesthetics are divided chemically into two groups: the aminoesters (esters) and the
aminoamides (amides). The esters include procaine, chloroprocaine and tetracaine (all have one letter i in the
name). The amides are lidocaine, mepivacaine, prilocaine, bupivacaine, levobupivacaine, etidocaine and ropivacaine
(all have two i’s in the name). The esters undergo plasma clearance by cholinesterases and have relatively
short half-lives, whereas the amides undergo hepatic clearance and have longer half-lives (Barash: Clinical Anesthesia,
ed 5, p 462).
9
Q
- Which of the following is the most important disadvantage of interscalene brachial plexus block compared with other
approaches?
A. Not suitable for operations on the shoulder
B. Large volumes of local anesthetics required
C. Frequent sparing of the ulnar nerve
D. Frequent sparing of the musculocutaneous nerve
E. High incidence of pneumothorax
A
- (C) The major disadvantage of the interscalene block for hand and forearm surgery is that blockade of the inferior
trunk (C8-T1) is often incomplete. Supplementation of the ulnar nerve often is required. The risk of pneumothorax
is quite low, but blockade of the ipsilateral phrenic nerve occurs in up to 100% of blocks. This can cause
respiratory compromise in patients with significant lung disease (Miller: Anesthesia, ed 6, pp 1686-1689).
10
Q
- A 68-year-old woman is to undergo foot surgery under spinal anesthesia. Which of the following statements concerning
the immediate physiologic response to the surgical incision is true?
A. The cardiovascular response to stress will be blocked, but the adrenergic response will not
B. The adrenergic response to stress will be blocked, but the cardiovascular response will not
C. Both the adrenergic and cardiovascular responses will be blocked
D. Neither the adrenergic or cardiovascular response will be blocked
E. The cardiovascular response will be blocked but the adrenergic response will be augmented
A
- (C) Surgical trauma includes a wide variety of physiologic responses. General anesthesia has no or only a slight
inhibitory effect on endocrine and metabolic responses to surgery. Regional anesthesia inhibits the nociceptive
signal from reaching the CNS and, therefore, has a significant inhibitory effect on the stress response, including
adrenergic, cardiovascular, metabolic, immunologic, and pituitary. This effect is most pronounced with procedures
on the lower part of the body and less with major abdominal and thoracic procedures. The variable effect
is probably due to unblocked afferents, i.e., vagal, phrenic, or sympathetic (Barash: Clinical Anesthesia, ed 5,
p 1150).
11
Q
798. The “snap” felt just before entering the epidural space represents passage through which ligament? A. Anterior longitudinal ligaments B. Posterior longitudinal ligaments C. Ligamentum flavum D. Supraspinous ligament E. Interspinous ligament
A
- (C) The structures that are traversed by a needle placed in the midline prior to the epidural space are as follows: skin,
subcutaneous tissue, supraspinous ligament, interspinous ligament, and ligamentum flavum. The ligamentum
flavum is tough and dense and a change in the resistance to advancing the needle is often perceived and to many
feels like a “snap.” The anterior and posterior longitudinal ligaments bind the vertebral bodies together. See also
explanation and diagram in question 870 (Barash: Clinical Anesthesia, ed 5, pp 698-699).
12
Q
799. The common element thought to be present in every case of cauda equina syndrome after continuous spinal anesthesia is A. Use of microcatheter B. Maldistribution of local anesthetic C. Administration of lidocaine D. Addition of epinephrine E. Hyperbaricity
A
- (B) The symptoms of cauda equina syndrome include low back pain, bilateral lower extremity weakness, saddle
anesthesia and loss of bowel and bladder control. Pooling of local anesthetics in dependent areas of the spine
within the subarachnoid space has been identified as the causative factor in cases of cauda equina syndrome.
Microlumen catheters may enhance the nonuniform distribution of solutions within the intrathecal space, but
cauda equina syndrome has been associated with the use of larger catheters, 5% lidocaine with dextrose, and 2%
lidocaine, as well as 0.5% tetracaine (Barash: Clinical Anesthesia, ed 5, p 712; Stoelting: Basics of Anesthesia, ed 5,
pp 132, 631-632).
13
Q
- A sciatic nerve block is performed in a healthy 26-year-old male patient for bunion surgery. Fifteen mL of 1.5% mepivacaine
is slowly injected after the landmarks are identified and a paresthesia is elicited in the great toe. In what order
would the following nerve fibers be blocked?
A. Sympathetic, proprioception, pain, motor
B. Sympathetic, pain, proprioception, motor
C. Motor, pain, proprioception, sympathetic
D. Pain, proprioception, sympathetic, motor
E. Pain, proprioception, motor, sympathetic
A
- (B) Differential nerve blockade is a complex process where anatomic and chemical factors determine the susceptibility
of fibers to blockade by local anesthetics. Diameter, myelinization, and location within the nerve trunk affect
the onset and regression time. In general, the small unmyelinated sympathetic fibers are blocked first, followed
by unmyelinated C fibers (pain and temp), then small myelinated fibers (proprioception, touch, pressure), and
finally the large myelinated fibers (motor) (Barash: Clinical Anesthesia, ed 5, pp 456-457, 708; Cousins: Neural
Blockade in Clinical Anesthesia and Management of Pain, ed 3, pp 45-46).
14
Q
- A 95-year-old woman has persistent and prolonged thoracic pain after a herpes zoster infection. Which of the treatments
below would be the LEAST efficacious in the treatment of her pain?
A. Oral amitriptyline
B. Oral clonidine
C. Topical capsaicin ointment
D. Transcutaneous electrical nerve stimulation (TENS)
E. Topical lidocaine patch
A
- (B) Acute herpes zoster is due to the reactivation of the varicella-zoster virus. Acute treatment includes symptomatic
pain treatment and antiviral drugs (e.g., acyclovir). It is typically a benign and self-limiting disease in patients
younger than 50 years of age. As one gets older, the incidence of postherpetic neuralgia (PHN) defined as pain
persisting beyond the healing of the herpes zoster lesions increases. The incidence of PHN is about 50% in
patients older than 50 years. Treatment of established PHN has been shown to be resistant to interventions
and, thus, can be difficult. However, proven therapies include tricyclic antidepressants, anticonvulsants, topical
local anesthetics (e.g., 5% lidocaine patch), topical capsaicin and TENS. Sympathetic blocks can provide excellent
analgesia but are most useful during the more acute stages of the disease rather than during the late chronic
stages. Sympathetic blocks in the acute stages may decrease the incidence of PHN. Oral clonidine, which is used
to treat hypertension and opioid withdrawal, has not been shown to be an effective treatment for postherpetic
neuralgia (Morgan: Clinical Anesthesiology, ed 4, p 407; Raj: Practical Management of Pain, ed 3, pp 187-189).
15
Q
- The deep peroneal nerve innervates the
A. Lateral aspect of the dorsum of the foot
B. Entire dorsum of the foot
C. Web space between the great toe and the second toe
D. Web space between the third and fourth toes
E. Medial aspect of the dorsum of the foot
A
- (C) The deep peroneal nerve innervates the short extensors of the toes and the skin of the web space between the
great and second toe. The deep peroneal nerve is blocked at the ankle by infiltration between the tendons of the
anterior tibial and extensor hallucis longus muscle (Brown: Atlas of Regional Anesthesia, ed 3, pp 141-143; Miller:
Anesthesia, ed 6, pp 1703-1704).
16
Q
803. The correct arrangement of local anesthetics in order of their ability to produce cardiotoxicity from most to least is A. Bupivacaine, lidocaine, ropivacaine B. Bupivacaine, ropivacaine, lidocaine C. Lidocaine, bupivacaine, ropivacaine D. Ropivacaine, bupivacaine, lidocaine E. Lidocaine, ropivacaine, bupivacaine
A
- (B) Central nervous system (CNS) toxicity from local anesthetics generally parallels anesthetic potency (e.g.,
bupivacaine is four times as potent as lidocaine, ropivacaine is three times as potent as lidocaine). Cardiovascular
(CV) toxicity occurs at a higher blood level than CNS toxicity. For bupivacaine and ropivacaine,
CV toxicity occurs at two times the CNS dose, whereas for lidocaine the CV toxicity occurs at
seven times the CNS toxicity levels, making lidocaine the least cardiotoxic, and bupivacaine the most
cardiotoxic of the listed local anesthetics (Barash: Clinical Anesthesia, ed 5, pp 459-467; Stoelting: Basics
of Anesthesia, ed 5, pp 127-131).
17
Q
- Allodynia is defined as
A. Spontaneous pain in an area or region that is anesthetic
B. Pain initiated or caused by a primary lesion or dysfunction in the nervous system
C. An unpleasant abnormal sensation, whether spontaneous or evoked
D. An increased response to a stimulus that is normally painful
E. Pain caused by a stimulus that does not normally provoke pain
A
- (E) The International Association for the Study of Pain (IASP) has defined several pain terms. Anesthesia dolorosa
refers to spontaneous pain in an area or region that is anesthetic. Neuropathic pain is pain initiated or caused
by a primary lesion or dysfunction in the nervous system. Dysesthesia is an unpleasant abnormal sensation,
whether spontaneous or evoked. Hyperalgesia is an increased response to a stimulus that is normally painful.
Allodynia is pain caused by a stimulus that does not normally provoke pain (Morgan: Clinical Anesthesia ed 4,
p 361; Loeser: Bonica’s Management of Pain, ed 3, pp 17-20).
18
Q
805. The primary mechanism by which the action of tetracaine is terminated when used for spinal anesthesia is A. Systemic absorption B. Uptake into neurons C. Hydrolysis by pseudocholinesterase D. Hydrolysis by nonspecific esterases E. Spontaneous degradation at 37° C
A
- (A) Ester local anesthetics are hydrolyzed by cholinesterase enzymes that are present mainly in plasma and, in a
smaller amount, in the liver. Because there are no cholinesterase enzymes present in cerebrospinal fluid (CSF),
the anesthetic effect of tetracaine will persist until it is absorbed into systemic circulation. The rate of hydrolysis
varies, with chloroprocaine being fastest, procaine intermediate, and tetracaine the slowest. Toxicity is
inversely related to the rate of hydrolysis; tetracaine is, therefore, the most toxic (Miller: Anesthesia, ed 6, p 589;
Morgan: Clinical Anesthesiology, ed 4, p 309; Stoelting: Pharmacology and Physiology in Anesthetic Practice, ed 4,
pp 186-187).
19
Q
- Complex regional pain syndrome type I (reflex sympathetic dystrophy) is differentiated from complex regional pain
syndrome type II (causalgia) by knowledge of its
A. Etiology
B. Chronicity
C. Affected body region
D. Type of symptoms
E. Rapidity of onset
A
- (A) Complex regional pain syndrome type I or CRPS type I also called reflex sympathetic dystrophy (RSD) is a
clinical syndrome of continuous burning pain, usually occurring after minor trauma. Patients present with variable
sensory, motor, autonomic, and trophic changes. Complex regional pain syndrome type II or CRPS type II
(causalgia) exhibits the same features of reflex sympathetic dystrophy, but the etiology is usually major traumatic
damage to large nerves (e.g., median nerve of the upper extremity or tibial division of the sciatic nerve in the
lower extremity) (Barash: Clinical Anesthesia, ed 5, pp 1456-1458; Morgan: Clinical Anesthesia, ed 4, p 406; Raj:
Practical Management of Pain, ed 3, p 306).
20
Q
807. The primary determinant of local anesthetic potency is A. pKa B. Molecular weight C. Lipid solubility D. Concentration E. Protein binding
A
- (C) The potency of local anesthetics is directly related to their lipid solubility. In general, the speed or onset of
action of local anesthetics is related to the pKa of the drug. Drugs with lower pKa values have a higher amount
of non-ionized molecules at physiologic pH and penetrate the lipid portion of nerves faster (an exception is
chloroprocaine, which has a fast onset of action that may be related to the higher concentration of drug used).
The amount of protein binding seems related to the duration of action of local anesthetics (more protein binding
has longer duration of action) (Raj: Practical Management of Pain, ed 3, pp 560-561; Stoelting: Pharmacology
and Physiology in Anesthetic Practice, ed 4, pp 180-181).
21
Q
- Which of the following would have the greatest effect on the level of sensory blockade after a subarachnoid injection
of hyperbaric 0.75% bupivacaine?
A. Coughing during placement of the block
B. Addition of epinephrine to the local anesthetic solution
C. Barbotage
D. Patient weight
E. Patient position
A
- (E) Many factors have an effect on the sensory level after a subarachnoid injection. The baricity of the solution
and the patient position are the most important determinants of sensory level. The other listed options have
little to no effect on sensory level. Patient height also has little effect on sensory level (Miller: Anesthesia, ed 6,
p 1668).
22
Q
- Which of the following local anesthetics would produce the lowest concentration in the fetus relative to the maternal
serum concentration during a continuous lumbar epidural?
A. Etidocaine
B. Bupivacaine
C. Lidocaine
D. Chloroprocaine
E. Mepivacaine
A
- (D) Chloroprocaine is an ester local anesthetic that is rapidly metabolized by pseudocholinesterase. With the epidural
injection of chloroprocaine, very little drug is available to cross the placenta, because the half-life is about
45 seconds (and that which crosses is also rapidly metabolized making fetal effects essentially non-significant).
The amide local anesthetics undergo liver metabolism and have relatively long half-lives, but with prolonged
epidural administration may accumulate in the fetus (Barash: Clinical Anesthesia, ed 5, pp 1154-1155; Miller:
Anesthesia, ed 6, p 2323).
23
Q
- Severe hypotension associated with high spinal anesthesia is caused primarily by
A. Decreased cardiac output secondary to decreased preload
B. Decreased systemic vascular resistance
C. Decreased cardiac output secondary to bradycardia
D. Decreased cardiac output secondary to decreased myocardial contractility
E. Increased shunting through metarterioles
A
- (A) Hypotension with a high spinal anesthesia is related to sympathetic blockade; venodilation (decreases
preload), arterial dilation (decreases afterload) and a decrease in heart rate (cardioaccelerator fibers
T1-T4 blockade and a fall in right atrial filling that affects the intrinsic chronotropic stretch receptors).
With a high spinal, the decrease in venous dilation is the predominant cause of hypotension (Barash: Clinical
Anesthesia, ed 5, pp 708-709; Miller: Anesthesia, ed 6, pp 1658-1659; Stoelting: Basics of Anesthesia, ed 5,
pp 259-262).
24
Q
- Select the one true statement concerning phantom limb pain.
A. Most phantom limb pain becomes more severe with time
B. Most amputees do not experience phantom limb pain
C. Nerve blocks may be used to treat phantom limb pain
D. Trauma amputees have a higher incidence of phantom limb pain than nontrauma amputees
E. The incidence of phantom limb pain increases with more distal amputations
A
- (C) The incidence of phantom limb pain is estimated to be 60% to 85%. The incidence of phantom limb pain
does not differ between traumatic and nontraumatic amputees. The incidence of phantom pain increases with
more proximal amputation. Although very difficult to treat, nerve blocks are commonly used in an attempt to
treat phantom pain. These include trigger point injections, peripheral and central nerve blocks, and sympathetic
blocks (Raj: Practical Management of Pain, ed 3, pp 213-218).
25
Q
812. Which of the following local anesthetics used for intravenous regional anesthesia (Bier block) is most rapidly metabolized and thus, least toxic? A. Lidocaine B. Ropivacaine C. Mepivacaine D. Prilocaine E. Etidocaine
A
- (D) Prilocaine is the most rapidly metabolized of the amide local anesthetics and therefore least toxic. 2-Chloroprocaine
is hydrolyzed rapidly in the blood and, therefore, would appear to be ideal, but it has been associated with
a high incidence of thrombophlebitis and is therefore not recommended. To avoid toxicity, maximum doses
are as follows: prilocaine, 3 to 4 mg/kg; lidocaine, 1.5 to 3 mg/kg; ropivacaine, 1.2 to 1.8 mg/kg. Bupivacaine
is not recommended for Bier blocks because of reports of cardiovascular toxicity and death that have occurred
(Cousins: Neural Blockade in Clinical Anesthesia and Management of Pain, ed 3, p 400; Miller: Anesthesia, ed 6,
pp 586-588, 1695).
26
Q
- Select the FALSE statement regarding spinal anatomy and spinal anesthesia.
A. The addition of phenylephrine to lidocaine will prolong spinal anesthesia
B. A high thoracic sensory block will result in total sympathetic blockade
C. The largest vertebral interspace is L5-S1
D. The dural sac extends to the S4-S5 interspace
E. Tetracaine provides longer anesthesia than does procaine
A
- (D) Both phenylephrine and epinephrine will prolong a spinal anesthetic when administering lidocaine. The Taylor
approach for spinal anesthesia uses a paramedian approach to the L5-S1 interspace—the largest interspace of
the vertebral column. The sympathetic nervous system originates in the thoracic and lumbar spinal cord T1-L3;
therefore, a high thoracic sensory level can cause a complete sympathetic block. The dural sac extends to S2-S3,
not S4-S5. The spinal cord extends to L3 in the infant and L1-L2 in adults (Barash: Clinical Anesthesia, ed 5,
pp 693-694, 708; Miller: Anesthesia, ed 6, pp 585, 589, 1654-1656).
27
Q
- Four days after a left total hip arthroplasty, an obese 62-year-old woman complains of severe back pain in the region
where the epidural was placed. Over the ensuing 72 hours, the back pain gradually worsens and a severe aching pain
that radiates down the left leg to the knee develops. The most likely diagnosis is
A. Epidural abscess
B. Epidural hematoma
C. Anterior spinal artery syndrome
D. Arachnoiditis
E. Meralgia paresthetica
A
- (A) Development of an epidural abscess is fortunately an exceedingly rare complication of spinal and epidural
anesthesia. Most anesthetic related epidural abscesses are associated with epidural catheters. When an epidural
abscess is developing, prompt recognition and treatment are essential if permanent sequelae are to be avoided.
Symptoms from an epidural abscess may not become apparent until several days (mean 5 days) after placement
of the block. There are four clinical stages of epidural abscess symptom progression. Initially, localized back
pain develops. Second stage includes nerve root or radicular pain. The third stage involves motor and sensory
deficits followed by the last stage of paraplegia. Unlike an epidural hematoma, in which severe back pain is the
key feature, patients with epidural abscesses will complain of radicular pain approximately 3 days after development
of the back pain. Anterior spinal artery syndrome is characterized predominantly by motor weakness or
paralysis of the lower extremities. Meralgia paresthetica is related to entrapment of the lateral femoral cutaneous
nerve as it courses below the inguinal ligament and is associated with burning pain over the lateral aspect of the
thigh. It is not a complication of epidural anesthesia (Morgan: Clinical Anesthesia, ed 4, pp 320-321; Raj: Practical
Management of Pain, ed 3, p 649).
28
Q
- Which of the following choices is NOT consistent
with a limb affected by complex regional pain syndrome?
A. Osteoporosis
B. Allodynia
C. Dermatomal distribution of pain
D. Atrophy of the involved extremity
E. Hyperesthesia
A
- (C) Complex regional pain syndromes are associated with trauma. The main feature is burning and continuous pain
that is exacerbated by normal movement, cutaneous stimulation, or stress, usually weeks after the injury. The
pain is not anatomically distributed. Other associated features include cool, red, clammy skin and hair loss in
the involved extremity. Chronic cases may be associated with atrophy and osteoporosis (Barash: Clinical Anesthesia,
ed 5, pp 1456-1458; Miller: Anesthesia, ed 6, pp 2774-2775).
29
Q
- The main advantage of neurolytic nerve blockade with phenol versus alcohol is
A. Denser blockade
B. Blockade is permanent
C. The effects of the block can be evaluated immediately
D. The block is less painful
E. Phenol is selective for sympathetic fibers
A
- (D) Neurolytic blockade with phenol (6% to 10% in glycerine) is painless because phenol has a dual action as
both a local anesthetic and a neurolytic agent. The initial block wears off over a 24-hour period, during which
time neurolysis occurs. For this reason you must wait a day to determine effectiveness of the neurolytic block.
Alcohol (100% ethanol) is painful on injection and should be preceded by local anesthetic injection. Unfortunately,
there is no neurolytic agent that affects only sympathetic fibers (Barash: Clinical Anesthesia, ed 5,
p 1464).
30
Q
817. How much local anesthetic should be administered per spinal segment to patients between 20 and 40 years of age receiving a lumbar epidural anesthetic? A. 0.25 to 0.5 mL B. 0.5 to 1.0 mL C. 1 to 2 mL D. 2 to 3 mL E. 3 to 5 mL
A
- (C) In general, each 1-2 mL of local anesthetic will anesthetize about one spinal segment in the 20 to 40-year-old
patient. Because of the negative intrathoracic pressure transmitted to the epidural space with breathing, about
two thirds of the segments are blocked above the level of the lumbar placement and one third of segments are
blocked below the injection. For example, to achieve a T4 block when an epidural is placed at the L2-L3 space
about 10 segments above and 5 segments below the epidural would be needed (15 segments) or about 20-25 mL.
As one gets older, the dose of local anesthetic mL/segment decreases (e.g., 80 year old may need 0.75-1.5 mL/
segment). Also, pregnant patients are more sensitive to local anesthetics and reduced doses are needed (Barash:
Clinical Anesthesia, ed 5, pp 705-706; Morgan: Clinical Anesthesiology, ed 4, p 312; Stoelting: Basics of Anesthesia,
ed 5, p 266).
31
Q
818. The artery of Adamkiewicz most frequently arises from the aorta at which spinal level? A. T1-T4 B. T5-T8 C. T9-T12 D. L1-L4 E. L5-S3
A
- (C)
The artery of Adamkiewicz is also called the arteria radicularis magna and is one of the “feeder” arteries for the
anterior spinal artery. Damage to this artery can lead to ischemia in the thoracolumbar region and may result in
paraplegia. The origin of this artery is variable (e.g., T9-T12 in 75% of cases, L1-L2 in 10% of cases) (Barash:
Clinical Anesthesia, ed 5, p 958; Miller: Anesthesia, ed 6, p 2087).
32
Q
- The anterior and posterior spinal arteries originate from the
A. Common carotid and vertebral arteries, respectively
B. Internal carotid and vertebral arteries, respectively
C. Internal carotid and posterior cerebral arteries, respectively
D. Vertebral and anterior cerebellar arteries, respectively
E. Vertebral, radicular arteries and the posterior inferior cerebellar arteries, respectively
A
- (E) The one anterior spinal artery supplies about 75% of the blood flow to the spinal cord (motor tracts) and arises
from the vertebral arteries and radicular arteries from the aorta. It descends in front of the anterior longitudinal
sulcus of the spinal cord. The two posterior spinal arteries supply about 25% of the blood flow to the spinal
cord (sensory tracts) and arise from the posterior and inferior cerebellar arteries, the vertebral arteries, and the
radicular arteries (Barash: Clinical Anesthesia, ed 5, p 958; Miller: Anesthesia, ed 6, pp 2086-2087).
33
Q
- Important landmarks for performing a sciatic nerve block (classic approach of Labat) include
A. Iliac crest, sacral hiatus, greater trochanter
B. Iliac crest, coccyx, and greater trochanter
C. Posterior superior iliac spine, coccyx, and greater trochanter
D. Posterior superior iliac spine, greater trochanter and sacral hiatus
E. Posterior superior iliac spine and greater trochanter
A
- (D) To perform a sciatic nerve block, first draw a line from the posterior superior iliac spine to the greater trochanter,
then draw a 5-cm line perpendicular from the midpoint of this line caudally and a second line from the
sacral hiatus to the greater trochanter. The intersection of the second line with the perpendicular line marks the
point of entry (Brown: Atlas of Regional Anesthesia, ed 3, pp 105-110; Miller: Anesthesia, ed 6, p 1700).
34
Q
- A 36-year-old female patient is undergoing thyroidectomy under a deep cervical plexus nerve block. Which of the
following complications would be LEAST likely with this block?
A. Horner’s syndrome
B. Subarachnoid injection
C. Blockade of the recurrent laryngeal nerve
D. Blockade of the spinal accessory nerve
E. Vertebral artery injection
A
- (D) Complications of deep cervical plexus block include injection of the local anesthetic into the vertebral artery,
subarachnoid space, or epidural space. Other nerves that may be anesthetized include the phrenic nerve (which
is why bilateral deep cervical plexus blocks should be performed with caution, if at all), and the recurrent laryngeal
nerve (Barash: Clinical Anesthesia, ed 5, p 723; Brown: Atlas of Regional Anesthesia, ed 3, pp 191-195; Miller:
Anesthesia, ed 6, p 1707).
35
Q
- A retrobulbar block anesthetizes each of the following nerves EXCEPT
A. Ciliary nerves
B. Cranial nerve IV (trochlear nerve)
C. Cranial nerve III (oculomotor nerve)
D. Cranial nerve VI (abducens nerve)
E. Maxillary branch of the trigeminal nerve
A
- (E) A retrobulbar block anesthetizes the three cranial nerves responsible for movement of the eye. The ciliary nerves
are also blocked, providing anesthesia to the conjunctiva, cornea, and uvea. The ophthalmic branch of the trigeminal
nerve provides sensory innervation to the skin of the forehead, cornea, and eyelid. This branch of the
trigeminal nerve may be blocked, but the maxillary branch would be spared (Barash: Clinical Anesthesia, ed 5,
pp 984-986; Brown: Atlas of Regional Anesthesia, ed 3, pp 185-188).
36
Q
823. Which of the following muscles of the larynx is innervated by the external branch of the superior laryngeal nerve? A. Vocalis muscle B. Thyroarytenoid muscles C. Posterior cricoarytenoid muscle D. Oblique arytenoid muscles E. Cricothyroid muscle
A
- (E) The vagus nerve innervates the airway by two branches: the superior laryngeal nerves and the recurrent laryngeal
nerves. All the muscles of the larynx are innervated by the recurrent laryngeal nerve except for the cricothyroid
muscle. The superior laryngeal nerve divides into the internal and external laryngeal branches. The external laryngeal branch innervates the cricothyroid muscle. The internal laryngeal branch provides sensory fibers to the
cords, epiglottis and the arytenoids (Barash: Clinical Anesthesia, ed 5, p 724; Brown: Atlas of Regional Anesthesia,
ed 3, pp 207-211).
37
Q
824. All the following agents are acceptable for use in a Bier block EXCEPT A. 0.5% Lidocaine B. 0.5% Mepivacaine C. 0.5% Procaine D. 0.5% Prilocaine E. 0.25% Bupivacaine
A
- (E) Because of the potential for cardiotoxicity and because bupivacaine has no advantages over other local anesthetics
in this setting, it is no longer recommended for use in intravenous regional anesthesia (Miller: Anesthesia,
ed 6, p 1695).
38
Q
825. The stellate ganglion lies in closest proximity to which of the following vascular structures? A. Common carotid artery B. Internal carotid artery C. Vertebral artery D. Axillary artery E. Aorta
A
- (C)
The stellate ganglion usually lies in front of the neck of the first rib. The vertebral artery lies anterior to the ganglion
as it has just originated from the subclavian artery. After passing over the ganglion, it enters the vertebral
foramen and lies posterior to the anterior tubercle of C6 (Barash: Clinical Anesthesia, ed 5, pp 736-737; Brown:
Atlas of Regional Anesthesia, ed 3, pp 199-203; Raj: Practical Management of Pain, ed 3, pp 655-657).
39
Q
826. Which of the following structures in the antecubital fossa is the most medial? A. Brachial artery B. Radial nerve C. Tendon of the biceps D. Median nerve E. Musculocutaneous nerve
A
- (D) The median nerve is the most medial structure in the antecubital fossa. To block this nerve, first the brachial
artery is palpated at the level of the intercondylar line between the medial and lateral epicondyles, and then a
needle is inserted just medial to the artery and directed perpendicularly to the skin (Brown: Atlas of Regional
Anesthesia, ed 3, pp 73-74; Morgan: Clinical Anesthesia, ed 4, pp 338-339).
40
Q
- During placement of an epidural in a 78-year-old patient scheduled for a total knee arthroplasty, the patient complains
of a sharp sustained pain radiating down his left leg as the catheter is inserted to 2 cm. The most appropriate
action at this time would be
A. Leave the catheter at 2 cm, give test dose
B. Give small dose to relieve pain then advance 1 cm
C. Withdraw the catheter 1 cm, give test dose
D. Withdraw needle and catheter, reinsert in a new position
E. Abandon epidural technique, place long-acting spinal anesthetic
A
- (D) When an epidural catheter is placed without fluoroscopic guidance, the exact location of the needle tip relative
to the anatomic structures of the back can only be surmised. If malposition of either the needle or the catheter
is suspected, it is prudent to withdraw the entire apparatus and reinsert a second time. In this case, it is possible
that the catheter tip has found its way into a nerve root. Under these circumstances, injection of a local anesthetic
or narcotic could produce pressure that would lead to ischemia and possible neurologic damage. During
placement or injection of an epidural catheter, a paresthesia is always a warning sign that should be heeded (Raj:
Practical Management of Pain, ed 3, p 650).
41
Q
828. Cutaneous innervation of the plantar surface of the foot is provided by the A. Sural nerve B. Posterior tibial nerve C. Saphenous nerve D. Deep peroneal nerve E. Superficial peroneal nerve
A
- (B) There are five nerves that supply the ankle and foot: the posterior tibial, sural, superficial and deep peroneal,
and saphenous nerves. These nerves are superficial at the level of the ankle and are easy to block. The posterior
branch of the tibial nerve gives rise to the medial and lateral plantar nerves, which supply the plantar
surface of the foot (Barash: Clinical Anesthesia, ed 5, pp 743-744; Brown: Atlas of Regional Anesthesia, ed 3,
pp 141-143).
42
Q
- Which of the following local anesthetics has the lowest ratio of dosage required for cardiovascular collapse to dosage
required for central nervous system toxicity?
A. Lidocaine
B. Etidocaine
C. Bupivacaine
D. Prilocaine
E. Chloroprocaine
A
- (C) In general, in both in vivo and in vitro studies there is an overall direct correlation between anesthetic’s potency
and its direct depressant effect on myocardial contractility. The ratio of dosage required for cardiovascular collapse
in animal models compared with that required to produce neurologic symptoms is the lowest for bupivacaine,
levo-bupivacaine and ropivacaine (2.0). Ratios for other local anesthetics are as follows: prilocaine, 3.1;
procaine and chloroprocaine, 3.7; etidocaine, 4.4; lidocaine and mepivacaine, 7.1 (Barash: Clinical Anesthesia,
ed 5, pp 462-466).
43
Q
- A 57-year-old patient is scheduled for hemorrhoidectomy. The patient has a history of mild chronic obstructive pulmonary
disease, hypertension, and traumatic foot amputation from a tractor accident. His only hospitalizations were
for two suicide attempts related to phantom limb sensations 10 years ago. He takes phenelzine (Nardil), thiazide, and
potassium. Which of the following anesthetic techniques would be most appropriate for this patient?
A. Spinal anesthetic with 0.5% hyperbaric bupivacaine
B. Epidural anesthetic with 0.5% bupivacaine
C. Local infiltration with lidocaine and epinephrine, sedation with propofol and meperidine
D. General anesthesia with thiopental sodium (Pentothal), succinylcholine, nitrous oxide, isoflurane, meperidine
E. General anesthesia with propofol, succinylcholine, nitrous oxide, fentanyl
A
- (E) Reactivation of phantom limb sensations has been reported in patients who have received both spinal and
epidural anesthetics (90% in some series). In the majority of these cases (80%), phantom limb sensation persisted
until the block receded. With a history of a phantom limb sensations that drove this patient to attempt
suicide, it is probably wise to avoid spinal and epidural anesthetics. Phenelzine (Nardil) is a monoamine oxidase
(MAO) inhibitor that is occasionally used for the treatment of depression. Any anesthetic or combination of
techniques that involves meperidine is contraindicated in patients receiving MAO inhibitors. The combination
of meperidine and MAO inhibitors has been associated with hyperthermia, hypotension, hypertension, ventilatory
depression, skeletal muscle rigidity, seizures, and coma. Because of this unfavorable drug interaction,
meperidine should be avoided in patients receiving MAO inhibitors. Accordingly, the only acceptable choice
in this question would be general anesthesia with propofol, succinylcholine, nitrous oxide, and fentanyl. As an
interesting side point, the drug phenelzine prolongs the duration of action of succinylcholine by decreasing
plasma cholinesterase activity (Miller: Anesthesia, ed 6, pp 423-424; Morgan: Clinical Anesthesiology, ed 4, p 657;
Raj: Practical Management of Pain, ed 3, p 212).
44
Q
- If the recurrent laryngeal nerve were transected bilaterally, the vocal cords would
A. Be in the open position
B. Be in the closed position
C. Be in the intermediate position (i.e., 2-3 mm apart)
D. Not be affected unless the superior laryngeal nerve were also injured
E. Appear exactly the same as if an intubating dose of succinylcholine were given
A
- (C) The recurrent laryngeal nerve innervates all the muscles of the larynx except the cricothyroid muscle, which
tenses the vocal cords and is innervated by the external branch of the superior laryngeal nerve. With bilateral
transections of the recurrent laryngeal nerve, the vocal cords lie within 2 to 3 mm of the midline. The airway
maybe inadequate and a tracheostomy may be needed (Miller: Anesthesia, ed 6, p 2538).
45
Q
832. A 63-year-old woman undergoes total knee arthroplasty under spinal anesthesia. Two days later she complains of a severe headache on the left side of her head. Pain intensity is not related to posture. The LEAST likely cause of this headache is A. Caffeine withdrawal B. Malingering C. Viral illness D. Migraine E. Postdural puncture headache
A
- (E) Postdural puncture headache (PDPH) will have a postural component. When supine, the headache is usually
gone but may be mild in some cases. When the head is elevated the headache may be severe, is bilateral and
may be associated with diplopia, nausea and vomiting. The headache pain is typically frontal and/or occipital in
location (Barash: Clinical Anesthesia, ed 5, p 711; Stoelting: Basics of Anesthesia, ed 5, p 260).
