Transcript Critical / Perioperative Care

ABSITE Review Conference:
Surgical Infection
Neurosurgery
Surgical Infection
The vagus nerve mediates which of the following in the
setting of systemic inflammation?
(A) Enhanced gut motility
(B) Decreased protein production by the liver
(C) Decreased IL-10 production
(D) Increased heart rate to increase cardiac output
Surgical Infection
The vagus nerve mediates which of the following in the
setting of systemic inflammation?
(A) Enhanced gut motility
(B) Decreased protein production by the liver
(C) Decreased IL-10 production
(D) Increased heart rate to increase cardiac output
Surgical Infection
Explanation: The vagus nerve exerts several homeostatic influences,
including enhancing gut motility, reducing heart rate, and regulating
inflammation. Central to this pathway is the understanding of neurally
controlled anti-inflammatory pathways of the vagus nerve.
Parasympathetic nervous system activity transmits vagus nerve efferent
signals primarily through the neurotransmitter acetylcholine. This neurally
mediated anti-inflammatory pathway allows for a rapid response to
inflammatory stimuli and also for the potential regulation of early
proinflammatory mediator release, specifically tumor necrosis factor
(TNF). Vagus nerve activity in the presence of systemic inflammation may
inhibit cytokine activity and reduce injury from disease processes such as
pancreatitis, ischemia and reperfusion, and hemorrhagic shock. This
activity is primarily mediated through nicotinic acetylcholine receptors on
immune mediator cells such as tissue macrophages. Furthermore,
enhanced inflammatory profiles are observed after vagotomy, during
stress conditions.
Surgical Infection
Cytokines are which type of hormone?
(A) Polypeptide
(B) Amino acid
(C) Fatty acid
(D) Carbohydrate
Surgical Infection
Cytokines are which type of hormone?
(A) Polypeptide
(B) Amino acid
(C) Fatty acid
(D) Carbohydrate
Surgical Infection
Explanation: Cytokines are polypeptide hormones. Humans
release hormones in several chemical categories, including
polypeptides (e.g., cytokines, glucagon, and insulin), amino
acids (e.g., epinephrine, serotonin, and histamine), and fatty
acids (e.g., glucocorticoids, prostaglandins, and leukotrienes).
There are no carbohydrate hormones.
Surgical Infection
The primary source of calories during acute starvation
(<5 days fasting) is
(A) Fat
(B) Muscle (protein)
(C) Glycogen
(D) Ketone bodies
Surgical Infection
The primary source of calories during acute starvation
(<5 days fasting) is
(A) Fat
(B) Muscle (protein)
(C) Glycogen
(D) Ketone bodies
Surgical Infection
Explanation: In the healthy adult, principal sources of fuel
during short-term fasting (<5 days) are derived from muscle
protein and body fat, with fat being the most abundant source
of energy.
Surgical Infection
Which of the following is the primary fuel source in
prolonged starvation?
(A) Fat
(B) Muscle (protein)
(C) Glycogen
(D) Ketone bodies
Surgical Infection
Which of the following is the primary fuel source in
prolonged starvation?
(A) Fat
(B) Muscle (protein)
(C) Glycogen
(D) Ketone bodies
Surgical Infection
Explanation: In prolonged starvation, systemic proteolysis is
reduced to approximately 20 g/d and urinary nitrogen
excretion stabilizes at 2 to 5 g/d (Fig. 2-3). This reduction in
proteolysis reflects the adaptation by vital organs (e.g.,
myocardium, brain, renal cortex, and skeletal muscle) to
using ketone bodies as their principal fuel source. In
extended fasting, ketone bodies become an important fuel
source for the brain after 2 days and gradually become the
principal fuel source by 24 days.
Surgical Infection
How many calories per day are required to maintain basal
metabolism in a healthy adult?
(A) 10-15 kcal/kg/day
(B) 20-25 kcal/kg/day
(C) 30-35 kcal/kg/day
(D) 40-45 kcal/kg/day
Surgical Infection
How many calories per day are required to maintain basal
metabolism in a healthy adult?
(A) 10-15 kcal/kg/day
(B) 20-25 kcal/kg/day
(C) 30-35 kcal/kg/day
(D) 40-45 kcal/kg/day
Surgical Infection
Explanation: To maintain basal metabolic needs (i.e., at rest
and fasting), a normal healthy adult requires approximately
22 to 25 kcal/kg per day drawn from carbohydrate, lipid, and
protein sources.
Surgical Infection
A patient presents to the emergency room with a
temperature of 39°C, a heart rate of 115, and a
respiratory rate of 25. There are no localizing
symptoms and the work-up does not reveal any
specific source for the fever. Which of the following
best describes this patient's condition?
(A) Infection
(B) SIRS
(C) Sepsis
(D) Septic shock
Surgical Infection
A patient presents to the emergency room with a
temperature of 39°C, a heart rate of 115, and a
respiratory rate of 25. There are no localizing
symptoms and the work-up does not reveal any
specific source for the fever. Which of the following
best describes this patient's condition?
(A) Infection
(B) SIRS
(C) Sepsis
(D) Septic shock
Surgical Infection
Explanation: This patient meets the criteria for SIRS.
Because there is no identifiable source for the condition, the
criteria for infection and sepsis have not been met. Septic
shock is sepsis with cardiovascular collapse
Surgical Infection
Cortisol is elevated in response to severe injury. How
long can this response persist in a patient with a
significant burn?
(A) 2 days
(B) 1 week
(C) 1 month
(D) 3 months
Surgical Infection
Cortisol is elevated in response to severe injury. How
long can this response persist in a patient with a
significant burn?
(A) 2 days
(B) 1 week
(C) 1 month
(D) 3 months
Surgical Infection
Explanation: Cortisol is a glucocorticoid steroid hormone
released by the adrenal cortex in response to ACTH. Cortisol
release is increased during times of stress and may be
chronically elevated in certain disease processes. For
example, burn-injured patients may exhibit elevated levels for
4 weeks.
Surgical Infection
Overfeeding (RQ >1.0) in a critically ill patient can result
in
(A) Pancreatitis
(B) Increased risk of infection
(C) Atelectasis
(D) Increased risk of DVT
Surgical Infection
Overfeeding (RQ >1.0) in a critically ill patient can result
in
(A) Pancreatitis
(B) Increased risk of infection
(C) Atelectasis
(D) Increased risk of DVT
Surgical Infection
Explanation: Excess glucose from overfeeding, as reflected
by RQs >1.0, can result in conditions such as glucosuria,
thermogenesis, and conversion to fat (lipogenesis).
Excessive glucose administration results in elevated carbon
dioxide production, which may be deleterious in patients with
suboptimal pulmonary function, as well as hyperglycemia,
which may contribute to infectious risk and immune
suppression. Overfeeding may contribute to clinical
deterioration via increased oxygen consumption, increased
carbon dioxide production and prolonged need for ventilatory
support, fatty liver, suppression of leukocyte function,
hyperglycemia, and increased risk of infection.
Surgical Infection
Which is the most commonly cultured hospital acquired
organism in critical care patients with aspiration
pneumonia?
(A) Streptococcus pneumoniae
(B) Staphylococcus aureus
(C) anaerobic species
(D) Pseudomonas aeruginosa
(E) Haemophilus influenzae
Surgical Infection
Which is the most commonly cultured hospital acquired
organism in critical care patients with aspiration
pneumonia?
(A) Streptococcus pneumoniae
(B) Staphylococcus aureus
(C) anaerobic species
(D) Pseudomonas aeruginosa
(E) Haemophilus influenzae
Surgical Infection
When should parenteral antibiotics be given
perioperatively?
(A) the night before
(B) 6 h prior to surgery
(C) 30 min prior to incision
(D) at the time of incision
(E) 30 min after incision
Surgical Infection
When should parenteral antibiotics be given
perioperatively?
(A) the night before
(B) 6 h prior to surgery
(C) 30 min prior to incision
(D) at the time of incision
(E) 30 min after incision
Surgical Infection
Explanation: Wound infections or surgical site infections (SSI) are
markedly reduced with preoperative antibiotic administration as noted
above. Wound infections are classified as superficial or deep incisional
SSIs. One-third of postoperative infections are organ/space SSIs.
Infection occurs within 30 days of operation (or 1 year if an implant is left)
and involves either the skin and subcutaneous tissue or fascia and muscle
layers, respectively. Either pus, evidence of cellulitis, fever, opening of
wound, positive cultures or evidence of abscess, or diagnosis by surgeon
or attending physician must be noted. Bacterial killing by neutrophils is
reduced by approximately 25% and may take as long as 10 days to
recover after surgery. Use of preoperative antibiotics as prophylaxis
reduces the risk of wound infection, endocarditis, or prosthetic material
infection. It has no role in preventing most other types of nosocomial
infections.
Surgical Infection
Wounds can be classified as clean, clean-contaminated, contaminated, or
dirty. The risk of infection is 1.5, 7.5, 15, and 40%, respectively.
Class I or clean wounds are those that are atraumatic or operative incisions with associated
blunt trauma, without associated inflammation. The respiratory, alimentary, genital,
uninfected urinary tract, or biliary tracts are not entered. These are closed primarily with or
without closed drainage systems. An example is a hernia operation.
Class II or clean-contaminated enter the above tracts under controlled conditions and without
unusual contamination. Examples include nonruptured appendix, vaginal hysterectomy, and
cholecystectomy.
Class III or contaminated cases include traumatic wounds, major breaks in sterile
techniques, gross spillage from the gastrointestinal tract, and incisions where acute,
nonpurulent inflammation is encountered. Open cardiac massage is an example.
Class IV or dirty wounds involve old traumatic wounds with retained devitalized tissue and
those that involve existing clinical infection or perforated viscera. An example is a
Hartmann's operation for perforated diverticulitis.
Surgical Infection
Timing of the first dose is critical in relation to skin incision. Administration
is ideally complete, or at least under way, when the patient enters the
operating theatre to achieve appropriate tissue levels. Intravenous
antibiotics should be administered 30 min before the operative incision.
Antibiotics should be dosed every 4 h.
Further maneuvers such as preoperative bathing with disinfectants, proper
skin preparation, careful placement of drapes, protection of the wound
edges from contaminated fluids and viscera, and careful surgical
technique all help reduce the risk of SSIs. Razor shaving of the skin on
the evening before surgery increases wound infections. If hair must be
removed, the following techniques should be used in order of preference:
depilatory creams, hair clipping immediately before prepping, and finally
shaving immediately before prepping. Postoperative wound management
includes protecting the wound with a sterile dressing for 24–48 h
postoperatively (category IB—recommendations are supported by some
experimental, clinical, or epidemiologic studies and strong theoretical
rationale).
Surgical Infection
Length of prophylaxis is controversial; many times no or only one
postoperative dose is necessary. The goal of antibiotic prophylaxis is to
maintain the operative levels of antibiotics during operative exposure of
the tissue and for a short period thereafter. The indication for antibiotic
prophylaxis is based on the surgeon's preoperative prediction of how the
wound will be classified at the end of the operation. Prophylaxis beyond
24 h is not supported.
Surgical Infection
The pathogen most commonly responsible for the onset
of septic shock is
(A) Klebsiella
(B) Pseudomonas
(C) Staphylococcus
(D) Escherichia coli
(E) Bacteroides
Surgical Infection
The pathogen most commonly responsible for the onset
of septic shock is
(A) Klebsiella
(B) Pseudomonas
(C) Staphylococcus
(D) Escherichia coli
(E) Bacteroides
Surgical Infection
Explanation: Sepsis and septic shock have become especially prominent
in this age of high tech intervention in high-risk patients. This condition
afflicts approximately 750,000 individuals and accounts for a mortality of
30–60%. Sepsis represents an unrestrained inflammatory process, arising
in the setting of the SIRS. As defined by a consensus conference in 1991,
SIRS is a generalized inflammatory process associated with a variety of
etiologies, including pancreatitis, multiple trauma, hemorrhagic shock, and
vascular occlusion (Fig. 6-18). Among the criteria for SIRS are a body
temperature >38 or <36°C; a heart rate >90 bpm; a respiratory rate >20 or
a PaCO2 <32 mmHg; a white blood cell count >12,000 or <4000; and a
bandemia >10%. Two of these criteria must be met to fulfill a diagnosis of
SIRS. In the presence of a documented infection, SIRS becomes sepsis.
Surgical Infection
Explanation: The most common pathogen associated with the
bacteremia of sepsis and septic shock is the gram-negative bacilli, most
notably E. coli; however, other gram-negative bacterial species—
Klebsiella, Proteus, and Pseudomonas—as well as the gram-positive
bacteria are often isolated from the blood cultures of septic patients. A
fungemia or viremia also may give rise to sepsis. Positive blood cultures
are obtained in 45% of septic patients. The majority of these infections
emanate from the genitourinary, gastrointestinal, and biliary tracts and the
tracheobronchial tree.
Surgical Infection
A 46-year-old female develops septic shock following an open
cholecystectomy for a gangrenous gallbladder. She remains
intubated after surgery but exhibits persistent hypoxia with
maximal ventilator support. The diagnosis of acute respiratory
distress syndrome (ARDS) is suggested.
Positive end-expiratory pressure (PEEP) is added to this patient's
ventilatory support with an improvement in her oxygenation.
The mechanism by which PEEP functions includes
(A) reduction in the rate of pulmonary edema formation
(B) improvement in the reabsorption of edema fluid
(C) promotion of the opening of collapsed alveoli
(D) prevention of the collapse of alveoli
(E) enhancement of surfactant production
Surgical Infection
A 46-year-old female develops septic shock following an open
cholecystectomy for a gangrenous gallbladder. She remains
intubated after surgery but exhibits persistent hypoxia with
maximal ventilator support. The diagnosis of acute respiratory
distress syndrome (ARDS) is suggested.
Positive end-expiratory pressure (PEEP) is added to this patient's
ventilatory support with an improvement in her oxygenation.
The mechanism by which PEEP functions includes
(A) reduction in the rate of pulmonary edema formation
(B) improvement in the reabsorption of edema fluid
(C) promotion of the opening of collapsed alveoli
(D) prevention of the collapse of alveoli
(E) enhancement of surfactant production
Surgical Infection
Explanation: Treatment of ARDS rests on the support of pulmonary function while
limiting additional lung injury. A majority of patients with ARDS require mechanical
ventilation, with the goal of keeping the PaO2 greater than 60 mmHg or the
oxygen saturation higher than 90%. The ventilation-perfusion mismatch may
prevent an increase in PaO2 despite the administration of supplemental oxygen;
however, a FiO2 of less than 50% is recommended to avoid further lung injury
from oxygen toxicity. The application of PEEP is essential in maximizing oxygen
exchange and, thus, PaO2. Alveoli are predisposed to collapse at end expiration
because of low lung volumes, pulmonary edema, and the deficiency of surfactant.
The application of PEEP prevents this collapse, making more alveoli available for
gas exchange. Additionally, studies have suggested that PEEP may redirect
pulmonary artery circulation to better ventilated areas of the lung, lessening the
ventilation-perfusion mismatch. Yet, PEEP may contribute to lung injury by
inducing barotrauma through alveolar overdistention. Also, cardiac output may be
compromised by the addition of PEEP; consequently, the systemic delivery of
oxygen is reduced. Other strategies for the management of ARDS include inverse
ratio ventilation, high-frequency jet ventilation, and prone positioning. In one study,
corticosteroids improved survival in patients with ARDS: the use of steroids was
associated with a mortality of 38%, significantly less than the 67% mortality in the
nonsteroid group. The utility of corticosteroids in treating ARDS, however, remains
a point of contention.
Surgical Infection
A 42-year-old White female comes to the ER complaining
of RUQ pain for the last 36 h, associated with fever
up to 39°C, bilious emesis, and jaundice. Direct
bilirubin 2.2, alkaline phosphatase 450, WBC 19,000,
AST 24, ALT 19.
The most probable diagnosis is acute cholangitis.
What would be the most appropriate antibiotic therapy
for this patient?
(A) cloxcicillin + tobramycin
(B) piperacillin/tazobactam
(C) Cefazolin
(D) ampicillin + clindamicin
(E) metronidazol + ciprofloxacin
Surgical Infection
A 42-year-old White female comes to the ER complaining
of RUQ pain for the last 36 h, associated with fever
up to 39°C, bilious emesis, and jaundice. Direct
bilirubin 2.2, alkaline phosphatase 450, WBC 19,000,
AST 24, ALT 19.
The most probable diagnosis is acute cholangitis.
What would be the most appropriate antibiotic therapy
for this patient?
(A) cloxcicillin + tobramycin
(B) piperacillin/tazobactam
(C) Cefazolin
(D) ampicillin + clindamicin
(E) metronidazol + ciprofloxacin
Surgical Infection
Explanation: Acute cholangitis is an inflammation/infection process that
develops as a result of bacterial colonization and overgrowth within an
obstructed biliary system. The obstruction and cholangitis result from
impacted stones in 80% of the cases in the Western world. Such stones
most commonly originate from the gallbladder (secondary to CBD stones).
Primary stones, most commonly pigmented are seen in the East Asian
countries. Other causes are benign strictures, neoplasms, papillary
stenosis, sclerosing cholangitis, foreign bodies and so on.
Surgical Infection
Explanation: Fifty to seventy percent of the patients will present with the
Charcot's triad (abdominal pain, fever, and jaundice). The combination of
confusion, hypotension, and the Charcot's triad constitutes the Reynold's
pentad, which is invariably fatal if urgent biliary decompression is not
done.
Chronic biliary obstruction may lead to liver abscesses and secondary
biliary cirrhosis. Organ failure and sepsis, sclerosing cholangitis and
strictures may develop.
Spread of the infection into the portal vein can cause pyelophlebitis and
portal vein thrombosis.
Analysis of the bile and blood in prospective studies showed that E. coli
(27–70%), Klebsiella spp. (17–14%), Enterobacter spp. (5–8%), and
Enteroccocus spp. (17%) were the most common isolated organisms. C.
albicans is the most common fungal cause in immunocompromised
patients.
Surgical Infection
Explanation: A combination of abdominal US, CT scan, and
cholangiography complements and confirm the clinical diagnosis of
cholangitis. Direct cholangiography (ERCP, PTC) is the gold standard for
diagnosing acute cholangitis. ERCP is less invasive and has the
advantage that offers therapeutic measures, including stone extraction
and biliary drainage. PTC is used when ERCP failed or in patients with
previous biloenteric anastamosis.
The management begins with early recognition and aggressive antibiotic
coverage.
Approximately 80% of the patients will improve with conservative therapy.
The 20% remaining will require biliary drainage. Therapeutic endoscopy is
the method of choice for biliary decompression, when it is not available or
unsuccessful. Percutaneous transhepatic biliary decompression or
surgery should be contemplated. High morbidity and mortality of
immediate surgical decompression leaves this option as a last resource.
Once the acute event has resolved, a detailed treatment plan can be
carried out electively to remove the underlying obstruction.
Surgical Infection
Asplenic individuals are at increased risk for severe fatal
infections from all of the following except:
(A) S. pneumoniae
(B) N. meningitidis
(C) H. influenzae
(D) E. coli
(E) Candida albicans
Surgical Infection
Asplenic individuals are at increased risk for severe fatal
infections from all of the following except:
(A) S. pneumoniae
(B) N. meningitidis
(C) H. influenzae
(D) E. coli
(E) Candida albicans
Surgical Infection
Explanation: The spleen plays an important role in defense against a
wide range of microorganisms and its activities are mediated through
multiple peculiarities unique to its anatomy. The immunologic functions of
the spleen cannot be fully duplicated following its removal so that patients
become vulnerable to severe, fulminant, life-threatening infection after
splenectomy, most notoriously because of encapsulated bacteria. This
may be manifested through pneumonia or meningitis; however, in many
cases a focus of infection cannot be identified even in the presence of
high-grade bacteremia.
The greatest risk is posed by encapsulated bacteria such as S.
pneumoniae (Pneumococcus), N. meningitides (Meningococcus), and H.
influenzae, although a multitude of other organisms have been implicated,
including gram-negative rods such as E. coli, Klebsiella, Enterobacter,
Proteus, Pseudomonas, Serratia, and Salmonella species; Enterococcus;
and Staphylococcus and Clostridium species.
Surgical Infection
The antibiotic of choice in a penicillin allergic patient
undergoing a cholecystectomy for acute
cholecystitis is
(A) Ertepenem
(B) Ceftriaxone
(C) Vancomycin + Metronidazole
(D) Fluoroquinolone + Metronidazole
Surgical Infection
The antibiotic of choice in a penicillin allergic patient
undergoing a cholecystectomy for acute
cholecystitis is
(A) Ertepenem
(B) Ceftriaxone
(C) Vancomycin + Metronidazole
(D) Fluoroquinolone + Metronidazole
Surgical Infection
Explanation: Fluoroquinolone plus either metronidazole or
clindamycin (for anaerobic coverage) is indicated in penicillin
allergic patients undergoing biliary tract surgery with active
infection.
Surgical Infection
Which of the following is the most effective dosing of
antibiotics in a patient undergoing elective colon
resection?
(A) A single dose given within 30 min prior to skin incision
(B) A single dose given at the time of skin incision
(C) A single preoperative dose + 24 hours of postoperative
antibiotics
(D) A single preoperative dose + 48 hours of postoperative
antibiotics
Surgical Infection
Which of the following is the most effective dosing of
antibiotics in a patient undergoing elective colon
resection?
(A) A single dose given within 30 min prior to skin incision
(B) A single dose given at the time of skin incision
(C) A single preoperative dose + 24 hours of postoperative
antibiotics
(D) A single preoperative dose + 48 hours of postoperative
antibiotics
Surgical Infection
Explanation: By definition, prophylaxis is limited to the time
before and during the operative procedure; in the vast
majority of cases only a single dose of antibiotic is required,
and only for certain types of procedures. However, patients
who undergo complex, prolonged procedures in which the
duration of the operation exceeds the serum drug half-life
should receive an additional dose or doses of the
antimicrobial agent. Nota bene: There is no evidence that
administration of postoperative doses of an antimicrobial
agent provides additional benefit, and this practice should be
discouraged, as it is costly and is associated with increased
rates of microbial drug resistance.
Surgical Infection
Appropriate duration of antibiotic therapy for most
patients with bacterial peritonitis from perforated
appendicitis is
(A) 3-5 days
(B) 7-10 days
(C) 14-21 days
(D) >21 days
Surgical Infection
Appropriate duration of antibiotic therapy for most
patients with bacterial peritonitis from perforated
appendicitis is
(A) 3-5 days
(B) 7-10 days
(C) 14-21 days
(D) >21 days
Surgical Infection
Explanation: The majority of studies examining the optimal duration of
antibiotic therapy for the treatment of polymicrobial infection have focused
on patients who develop peritonitis. Cogent data exist to support the
contention that satisfactory outcomes are achieved with 12 to 24 hours of
therapy for penetrating GI trauma in the absence of extensive
contamination, 3 to 5 days of therapy for perforated or gangrenous
appendicitis, 5 to 7 days of therapy for treatment of peritoneal soilage due
to a perforated viscus with moderate degrees of contamination, and 7 to
14 days of therapy to adjunctively treat extensive peritoneal soilage (e.g.,
feculent peritonitis) or that occurring in the immunosuppressed host.
In the later phases of postoperative antibiotic treatment of serious intraabdominal infection, the absence of an elevated WBC count, lack of band
forms of PMNs on peripheral smear, and lack of fever [<38.6°C (100.5°F)]
provide close to complete assurance that infection has been eradicated.
Under these circumstances, antibiotics can be discontinued with impunity.
Surgical Infection
Which of the following can be used to mitigate cortisol
effects on wound healing?
(A) Vitamin A
(B) Vitamin B1
(C) Vitamin C
(D) Vitamin E
Surgical Infection
Which of the following can be used to mitigate cortisol
effects on wound healing?
(A) Vitamin A
(B) Vitamin B1
(C) Vitamin C
(D) Vitamin E
Surgical Infection
Explanation: Wound healing also is impaired, because
cortisol reduces transforming growth factor beta (TGF-) and
insulin-like growth factor I (IGF-I) in the wound. This effect
can be partially ameliorated by the administration of vitamin
A.
Surgical Infection
The most common cause of hepatic abscess in the
United States is
(A) GI infection with entoameoba histolytica
(B) Pylephlebitis from appendicitis
(C) Biliary tract procedures
(D) Primary bacterial infection after septicemia
Surgical Infection
The most common cause of hepatic abscess in the
United States is
(A) GI infection with entoameoba histolytica
(B) Pylephlebitis from appendicitis
(C) Biliary tract procedures
(D) Primary bacterial infection after septicemia
Surgical Infection
Explanation: Hepatic abscesses are rare, currently
accounting for approximately 15 per 100,000 hospital
admissions in the United States. Pyogenic abscesses
account for approximately 80% of cases, the remaining 20%
being equally divided among parasitic and fungal forms.
Formerly, pyogenic liver abscesses were caused by
pylephlebitis due to neglected appendicitis or diverticulitis.
Today, manipulation of the biliary tract to treat a variety of
diseases has become a more common cause, although in
nearly 50% of patients no cause is identified.
Surgical Infection
Which of the following best estimates the risk of a
surgical site infection (SSI) in a patient undergoing
an elective low anterior colon resection?
(A) 1-5%
(B) 2-10%
(C) 10-25%
(D) >25%
Surgical Infection
Which of the following best estimates the risk of a
surgical site infection (SSI) in a patient undergoing
an elective low anterior colon resection?
(A) 1-5%
(B) 2-10%
(C) 10-25%
(D) >25%
Surgical Infection
Explanation: The expected infection rate in colorectal
surgery (clean/contaminated) is 9.4 to 25%.
Clean/contaminated wounds (class II) include those in which
a hollow viscus such as the respiratory, alimentary, or
genitourinary tracts with indigenous bacterial flora is opened
under controlled circumstances without significant spillage of
contents. Interestingly, while elective colorectal cases have
classically been included as class II cases, a number of
studies in the last decade have documented higher SSI rates
(9 to 25%). One study identified two thirds of infections
presenting after discharge from hospital, highlighting the need
for careful follow-up of these patients. Infection is also more
common in cases involving entry into the rectal space.
Surgical Infection
Which of the following is most suggestive of a
necrotizing soft tissue infection and would mandate
immediate surgical exploration?
(A) A small amount of grayish, cloudy fluid from a wound
(B) Red, swollen extremity which is tender to palpation
(C) Soft tissue infection with a fever >104°
(D) Induration with pitting edema on the trunk
Surgical Infection
Which of the following is most suggestive of a
necrotizing soft tissue infection and would mandate
immediate surgical exploration?
(A) A small amount of grayish, cloudy fluid from a wound
(B) Red, swollen extremity which is tender to palpation
(C) Soft tissue infection with a fever >104°
(D) Induration with pitting edema on the trunk
Surgical Infection
Explanation: All of the above are suggestive of soft-tissue infection and
may, in the appropriate clinical scenario, support surgical exploration.
Since time from onset of symptoms to surgical debridement is one of the
most critical factors in determination of outcome, the clinician should be
willing to explore a potentially-affected area without a definitive diagnosis.
Careful examination should be undertaken for an entry site such as a
small break or sinus in the skin from which grayish, turbid semipurulent
material ("dishwater pus") can be expressed, as well as for the presence
of skin changes (bronze hue or brawny induration), blebs, or crepitus. The
patient often develops pain at the site of infection that appears to be out of
proportion to any of the physical manifestations. Any of these findings
mandates immediate surgical intervention, which should consist of
exposure and direct visualization of potentially infected tissue (including
deep soft tissue, fascia, and underlying muscle) and radical resection of
affected areas.
Surgical Infection
The appropriate duration of antibiotic therapy for
nosocomial urinary tract infection is
(A) 3-5 days
(B) 7-10 days
(C) 21 days
(D) Until the patient is asymptomatic and the urinalysis
is normal
Surgical Infection
The appropriate duration of antibiotic therapy for
nosocomial urinary tract infection is
(A) 3-5 days
(B) 7-10 days
(C) 21 days
(D) Until the patient is asymptomatic and the urinalysis
is normal
Surgical Infection
Explanation: The presence of a postoperative UTI should be
considered based on urinalysis demonstrating WBCs or
bacteria, a positive test for leukocyte esterase, or a
combination of these elements. The diagnosis is established
after more than 104 CFU/mL of microbes are identified by
culture techniques in symptomatic patients, or more than 105
CFU/mL in asymptomatic individuals. Treatment for 3 to 5
days with a single antibiotic that achieves high levels in the
urine is appropriate. Postoperative surgical patients should
have indwelling urinary catheters removed as quickly as
possible, typically within 1 to 2 days, as long as they are
mobile.
Surgical Infection
A 42-year-old White female comes to the ER complaining
of RUQ abdominal pain for the last 36 h, associated
with fever up to 39°C, bilious emesis, and jaundice.
Direct bilirubin 2.2, alkaline phosphatase 450, WBC
19,000, AST 24, ALT 19.
The most probable diagnosis is acute cholangitis.
What is the most appropriate treatment for this patient?
(A) antibiotics and urgent surgical biliary decompression
(B) antibiotics and endoscopic biliary decompression
(C) antibiotics and percutaneous transhepatic biliary
decompression
(D) antibiotics, surgical decompression, and
cholecystectomy
Surgical Infection
A 42-year-old White female comes to the ER complaining
of RUQ abdominal pain for the last 36 h, associated
with fever up to 39°C, bilious emesis, and jaundice.
Direct bilirubin 2.2, alkaline phosphatase 450, WBC
19,000, AST 24, ALT 19.
The most probable diagnosis is acute cholangitis.
What is the most appropriate treatment for this patient?
(A) antibiotics and urgent surgical biliary decompression
(B) antibiotics and endoscopic biliary decompression
(C) antibiotics and percutaneous transhepatic biliary
decompression
(D) antibiotics, surgical decompression, and
cholecystectomy
Surgical Infection
Which of the following has been shown to decrease the
rate of pancreatic abscess in patients with
necrotizing pancreatitis?
(A) Prophylactic antibiotics
(B) Frequent imaging with percutaneous sampling of new
fluid collections
(C) Enteral nutrition
(D) Parenteral nutrition
Surgical Infection
Which of the following has been shown to decrease the
rate of pancreatic abscess in patients with
necrotizing pancreatitis?
(A) Prophylactic antibiotics
(B) Frequent imaging with percutaneous sampling of new
fluid collections
(C) Enteral nutrition
(D) Parenteral nutrition
Surgical Infection
Explanation: Current care of patients with severe acute pancreatitis
includes staging with dynamic, contrast-enhanced helical CT scan with 3mm tomographs to determine the extent of pancreatic necrosis, coupled
with the use of one of several prognostic scoring systems. Patients who
exhibit significant pancreatic necrosis (grade greater than C, Fig. 6-2)
should be carefully monitored in the ICU and undergo follow-up CT
examination. A recent change in practice has been the elimination of the
routine use of prophylactic antibiotics for prevention of infected pancreatic
necrosis. Early results were promising; however, several randomized
multicenter trials have failed to show benefit and three meta-analyses
have confirmed this finding. In two small studies, enteral feedings initiated
early, using nasojejunal feeding tubes placed past the ligament of Treitz,
have been associated with decreased development of infected pancreatic
necrosis, possibly due to a decrease in gut translocation of bacteria.
Recent guidelines support the practice of enteral alimentation in these
patients, with the addition of parenteral nutrition if nutritional goals cannot
be met by tube feeding alone
Surgical Infection
Which structure is not affected by Fournier gangrene?
(A) Genital
(B) Perineal
(C) Perianal
(D) Periumbilical
(E) none of the above
Surgical Infection
Which structure is not affected by Fournier gangrene?
(A) Genital
(B) Perineal
(C) Perianal
(D) Periumbilical
(E) none of the above
Surgical Infection
Explanation: Fournier gangrene is polymicrobial necrotizing
fascitis of the genital, perianal, or perineal areas. The skin
may be erythematous, gangrenous, or malodorous, and air
may be present on imaging studies. Escherichia coli (most
common aerobe) and Bacteroides (most common anaerobe)
usually cause it. Fournier gangrene is a urologic surgical
emergency requiring aggressive debridement, hyperbaric
oxygen, and intravenous antibiotics. Gas gangrene is caused
by Clostridium perferingens and causes infection that spreads
along muscle planes.
Neurosurgery
A 27-year-old man developed signs and symptoms of
fulminant Cushing's syndrome over 3 months. He has
central obesity, hypertension, and glucose intolerance.
He is likely to have all of the following signs, which are
fairly specific for Cushing's syndrome, except:
(A) enlarged supraclavicular fat pads
(B) purple stria
(C) proximal neuropathy
(D) ecchymosis
Neurosurgery
A 27-year-old man developed signs and symptoms of
fulminant Cushing's syndrome over 3 months. He has
central obesity, hypertension, and glucose intolerance.
He is likely to have all of the following signs, which are
fairly specific for Cushing's syndrome, except:
(A) enlarged supraclavicular fat pads
(B) purple stria
(C) proximal neuropathy
(D) ecchymosis
Neurosurgery
Explanation: Primary Cushing's syndrome occurs when
there is excess secretion of cortisone by the adrenal glands.
The symptoms usually begin insidiously, but occasionally the
signs and symptoms can come on very rapidly. Women are
more frequently involved than men. Most patients present in
the third to the fifth decade of life, but the disorder can occur
in childhood and adolescents. Central weight gain is the
hallmark of the disorder and sometimes can be quite
spectacular; however, some patients only gain a slight
amount, but their body fat is redistributed around their
abdomen. The skin is thin and stretched and purple stria and
easy bruising are suggestive of the diagnosis.
Neurosurgery
Explanation: Many patients with Cushing's have proximal
weakness in the legs, but the weakness is because of a
proximal myopathy rather than a neuropathy. Hypertension
and glucose intolerance are common. Other features of
Cushing's may include a moon facies secondary to deposition
of fat around the ears and cheeks, fat enlargement in the
supraclavicular areas and posterior neck (buffalo hump),
acne and facial hirsutism. Unfortunately there are no signs or
symptoms of Cushing's syndrome to absolutely establish the
diagnosis without a series of supportive laboratory tests.
Neurosurgery
All of the following are classic signs of a basal skull
fracture except:
(A) dilated and nonreactive pupil
(B) bilateral periorbital ecchymosis (Raccoon's eyes)
(C) ecchymosis over mastoids (Battle's sign)
(D) hemotympanum
Neurosurgery
All of the following are classic signs of a basal skull
fracture except:
(A) dilated and nonreactive pupil
(B) bilateral periorbital ecchymosis (Raccoon's eyes)
(C) ecchymosis over mastoids (Battle's sign)
(D) hemotympanum
Neurosurgery
• Explanation: Basal skull fractures are usually diagnosed
by clinical signs. CT scan findings include linear lucencies
through the skull base, pneumocephalus, and opacification
of air sinuses. Clinical signs vary depending on the site of
fracture. Anterior skull base fractures may cause anosmia,
cerebrospinal fliud (CSF) rhinorrhea, and periorbital
ecchymosis (raccoon's eyes). Middle fossa or temporal
bone fractures may result in ecchymosis over the mastoids
(Battle's sign, Fig. 9-6), hemotympanum, CSF otorrhea or
rhinorrhea, and cranial nerve VII or VIII palsies.
Neurosurgery
• Explanation: A dilated and nonreactive pupil is often the
result of compression of cranial nerve III causing
interruption of the sympathetic fibers traveling along this
nerve. This is most often a sign of elevated ICP and not of
a basal skull fracture, although related trauma to the orbit
could result in a dilated and nonreactive pupil. Other
consequences of basal skull fractures include optic nerve
injury, abducens nerve injury, traumatic carotid artery
aneurysms, carotid-cavernous fistulae, CSF fistulae,
meningitis, and cerebral abscess.
Neurosurgery
A patient with a crush injury to the arm has motor and
sensory deficits that indicate a radial nerve injury. The
most appropriate management is
(A) Immediate operative exploration and repair
(B) EMG 5-7 days after injury; surgical exploration if nerve
conduction is decreased
(C) EMG 3-4 weeks after injury; surgical exploration if nerve
conduction is decreased
(D) Surgical exploration if there is no functional improvement
after 3 months
Neurosurgery
A patient with a crush injury to the arm has motor and
sensory deficits that indicate a radial nerve injury. The
most appropriate management is
(A) Immediate operative exploration and repair
(B) EMG 5-7 days after injury; surgical exploration if nerve
conduction is decreased
(C) EMG 3-4 weeks after injury; surgical exploration if nerve
conduction is decreased
(D) Surgical exploration if there is no functional improvement
after 3 months
Neurosurgery
Explanation: The sensory and motor deficits [in a patient
with a peripheral nerve injury] should be accurately
documented. Deficits are usually immediate. Progressive
deficit suggests a process such as an expanding hematoma
and may warrant early surgical exploration. Clean, sharp
injuries may also benefit from early exploration and
reanastomosis. Most other peripheral nerve injuries should be
observed. EMG/NCS studies should be done 3 to 4 weeks
postinjury if deficits persist. Axon segments distal to the site
of injury will conduct action potentials normally until Wallerian
degeneration occurs, rendering EMG/NCS before 3 weeks
uninformative. Continued observation is indicated if function
improves.
Neurosurgery
Explanation: Surgical exploration of the nerve may be
undertaken if no functional improvement occurs over 3
months. If intraoperative electrical testing reveals conduction
across the injury, continue observation. In the absence of
conduction, the injured segment should be resected and endto-end primary anastomosis attempted. However,
anastomoses under tension will not heal. A nerve graft may
be needed to bridge the gap between the proximal and distal
nerve ends. The sural nerve often is harvested, as it carries
only sensory fibers and leaves a minor deficit when resected.
The connective tissue structures of the nerve graft may
provide a pathway for effective axonal regrowth across the
injury.
Neurosurgery
Unilateral loss of visual acuity and pulsatile proptosis is
suggestive of
(A) Retinal artery aneurysm
(B) Carotid-cavernous fistula
(C) Hypertensive crisis
(D) Carotid artery dissection
Neurosurgery
Unilateral loss of visual acuity and pulsatile proptosis is
suggestive of
(A) Retinal artery aneurysm
(B) Carotid-cavernous fistula
(C) Hypertensive crisis
(D) Carotid artery dissection
Neurosurgery
• Explanation: Traumatic vessel wall injury to the portion of
the carotid artery running through the cavernous sinus may
result in a carotid-cavernous fistula (CCF). This creates a
high-pressure, high-flow pathophysiologic blood flow
pattern. CCFs classically present with pulsatile proptosis
(the globe pulses outward with arterial pulsation), retroorbital pain, and decreased visual acuity or loss of normal
eye movement (due to damage to cranial nerves III, IV,
and VI as they pass through the cavernous sinus).
Symptomatic CCFs should be treated to preserve eye
function. Fistulae may be closed by balloon occlusion using
interventional neuroradiology techniques. Fistulae with
wide necks are difficult to treat and may require total
occlusion of the parent carotid artery.
Neurosurgery
Cardinal signs of intracranial hypertension include all of
the following except:
(A) flexor (decorticate) posturing
(B) papilledema
(C) aphasia
(D) dilated and nonreactive pupil
Neurosurgery
Cardinal signs of intracranial hypertension include all of
the following except:
(A) flexor (decorticate) posturing
(B) papilledema
(C) aphasia
(D) dilated and nonreactive pupil
Neurosurgery
Explanation: Intracranial hypertension may be defined as an
ICP greater than 20 cmH2O. Any process that increases the
volume within the intracranial compartment may cause
intracranial hypertension, such as hydrocephalus, cerebral
edema, or a space occupying lesion. The most consistent
and one of the only early signs of intracranial hypertension is
papilledema. The other common signs of elevated ICP
usually develop late and are related to brain herniation.
Aphasia is usually the result of ischemia or a focal mass
lesion interfering with the temporo-parietal area of the
dominant hemisphere. It is not regarded as a hallmark of
intracranial hypertension.
Neurosurgery
Late complications of traumatic brain injury may include
all of the following except:
(A) seizures
(B) communicating hydrocephalus
(C) primary brain tumors
(D) memory impairment
Neurosurgery
Late complications of traumatic brain injury may include
all of the following except:
(A) seizures
(B) communicating hydrocephalus
(C) primary brain tumors
(D) memory impairment
Neurosurgery
Explanation: Well-documented late complications of head
injury include seizures, communicating hydrocephalus,
postconcussion syndrome, and varying degrees of intellectual
impairment. Other documented late complications include
hypogonadotropic hypogonadism and the deposition of
amyloid proteins, which may be related to the development of
Alzheimer's disease. As a recent Swedish study supports,
there is no association between traumatic head injury and
primary brain tumors.
Neurosurgery
A 22-year-old female presents to the emergency
department as a level II trauma after falling off a horse
and hitting her head on the ground. She had brief loss
of consciousness and is now oriented to name and
place only. The patient has no apparent systemic
injuries. A CT scan of the head shows mild generalized
cerebral edema. What is the most appropriate
intravenous fluid for this patient?
(A) Ringer's lactate
(B) 0.225% NS with 20 meq KCl
(C) 0.45% NS with 20 meq KCl
(D) 0.9% NS with 20 meq KCl
Neurosurgery
A 22-year-old female presents to the emergency
department as a level II trauma after falling off a horse
and hitting her head on the ground. She had brief loss
of consciousness and is now oriented to name and
place only. The patient has no apparent systemic
injuries. A CT scan of the head shows mild generalized
cerebral edema. What is the most appropriate
intravenous fluid for this patient?
(A) Ringer's lactate
(B) 0.225% NS with 20 meq KCl
(C) 0.45% NS with 20 meq KCl
(D) 0.9% NS with 20 meq KCl
Neurosurgery
• Explanation: Management of intravenous fluids in headinjured patients is one area where trauma surgeons and
neurosurgeons often disagree. Although reasons to
convert to hypotonic solutions may develop, the initial
choice for head-injured patients is isotonic solution.
Hypotonic solutions should be avoided if possible, because
they may impair cerebral compliance and worsen cerebral
edema. With an intact blood-brain barrier, hypertonic
solutions can establish an osmotic gradient that actually
drives water out of the brain and into plasma. This is the
principal method of action of mannitol, the most wellstudied and proven osmotic diuretic for lowering ICP.
Neurosurgery
• Explanation: In addition to mannitol, hypertonic saline has
been shown in recent studies to lower ICP. A recent
literature review concluded that hypertonic saline has
favorable effects on both systemic hemodynamics and
ICP. The most deleterious side effect of these agents is
renal failure secondary to a hyperosmolar state and renal
hypoperfusion. Therefore, urine output, serum osmolality,
and serum sodium must be monitored closely when using
hypertonic agents. Other basic fluid management
principles to keep in mind when treating a head-injured
patient include the following: provide adequate
resuscitation to avoid hypotension, maintain patient in
euvolemia, and consider pressors over repeated fluid
boluses.
Neurosurgery
A 24-year-old male is taken to the emergency department after being
involved in a motor vehicle accident approximately 3 h ago. The
patient was the unrestrained driver, and he cannot recall the
accident. He complains of a left-sided headache, and you notice
on physical examination that he has a palpable deformity over the
left side of his skull and a boggy temporalis muscle. You order a
CT scan of the head. The nurse calls you 20 min later to see the
patient, because he has suddenly become unresponsive. A CT
scan of the head is most likely to reveal what type of lesion?
(A) chronic subdural hematoma
(B) diffuse subarachnoid hemorrhage
(C) intraventricular hemorrhage
(D) epidural hematoma
Neurosurgery
A 24-year-old male is taken to the emergency department after being
involved in a motor vehicle accident approximately 3 h ago. The
patient was the unrestrained driver, and he cannot recall the
accident. He complains of a left-sided headache, and you notice
on physical examination that he has a palpable deformity over the
left side of his skull and a boggy temporalis muscle. You order a
CT scan of the head. The nurse calls you 20 min later to see the
patient, because he has suddenly become unresponsive. A CT
scan of the head is most likely to reveal what type of lesion?
(A) chronic subdural hematoma
(B) diffuse subarachnoid hemorrhage
(C) intraventricular hemorrhage
(D) epidural hematoma
Neurosurgery
• Explanation: Epidural hematomas comprise about 1% of all head
trauma admissions. An epidural hematoma is defined as a blood clot
that forms between the dura and the inner table of the skull. The
classic presentation of an epidural hematoma, only occurring a minority
of the time, is a young adult who has a brief loss of consciousness
followed by a lucid interval for several hours. This is then followed by
obtundation, contralateral hemiparesis, and ipsilateral pupillary dilation
(signs of uncal herniation as described in question 5). Death may result
from continued compression of the midbrain causing bradycardia and
respiratory distress. Overall mortality from epidural hematomas ranges
from 20 to 55%, with prompt diagnosis and treatment lowering this rate
to 5 to 10%.
Neurosurgery
• Explanation: The most common location for an epidural hematoma is
temporoparietal, and the most common cause is a tear in a branch of
the middle meningeal artery. A temporoparietal skull fracture is the
usual offending injury. Other sources of bleeding include meningeal
veins and dural sinuses. The classic CT finding for an epidural
hematoma is a biconvex, hyperdense area adjacent to the skull. The
hematoma is usually limited to a small area of the skull and does not
cross suture lines. Generally accepted indications for removing an
epidural hematoma in the operating room include any symptomatic
epidural or an acute asymptomatic epidural that is greater than 1 cm at
its widest portion since these tend not to resorb. Additionally, the
threshold for operating on pediatric patients is lower than for adults
since children have less available intracranial space to accommodate a
blood clot.
Neurosurgery
What category of subdural hematoma appears isodense
to brain on CT scans?
(A) acute
(B) subacute
(C) chronic
(D) none of these
Neurosurgery
What category of subdural hematoma appears isodense
to brain on CT scans?
(A) acute
(B) subacute
(C) chronic
(D) none of these
Neurosurgery
• Explanation: The brain is covered by the meninges which include pia
(a thin membrane tightly adherent to the brain), arachnoid, and dura. A
subdural hematoma is a hemorrhage that occurs between the dura and
arachnoid membrane. Subdural hematomas may be divided
radiographically into three categories: acute, subacute, and chronic. An
acute subdural hematoma is seen within 3 days of the initial
hemorrhage and appears hyperdense to brain on CT scans. A
subacute subdural hematoma forms between 4 days and 3 weeks
following the initial hemorrhage and appears isodense to brain on CT
scans. A chronic subdural hematoma may be seen after 3 weeks
following the initial hemorrhage and appears hypodense to brain on CT
scans. All categories of subdural hematomas usually appear as
concave fluid collections that spread out over the convexity of the
brain. Subdural hematomas may also occur along the tentorium
cerebelli, along the interhemispheric fissure, and in the posterior fossa.
Neurosurgery
Neurosurgery
Generally accepted criteria for elevating a depressed
skull fracture in the operating room include all of the
following except:
(A) open fracture
(B) coexistence of other traumatic lesion (i.e., hematoma)
underlying fragment
(C) dural tear with CSF leak
(D) involvement of the anterior wall of the frontal sinus
Neurosurgery
Generally accepted criteria for elevating a depressed
skull fracture in the operating room include all of the
following except:
(A) open fracture
(B) coexistence of other traumatic lesion (i.e., hematoma)
underlying fragment
(C) dural tear with CSF leak
(D) involvement of the anterior wall of the frontal sinus
Neurosurgery
Explanation: Depressed skull fractures are caused by a
significant force being applied to a relatively small area of the
head. The modality of choice for diagnosing depressed skull
fractures is a CT scan of the head. Although recently
disputed, generally accepted criteria for elevating a
depressed skull fracture in the operating room include open
depressed fractures, coexistence of an underlying traumatic
lesion, dural tear with CSF leak, and cosmetic deformity. A
fracture of the anterior wall of the frontal sinus would only
require surgical repair if it caused a significant cosmetic
deformity, and this could be done on an elective basis. A
fracture through the posterior wall, however, is in a different
category because communication between the sinus and
brain increases the risk of developing meningitis or a cerebral
abscess.
Neurosurgery
A 19-year-old male presents to the emergency
department after being shot in the head with a
handgun. Appropriate initial steps in managing this
patient include all of the following except:
(A) begin Solumedrol protocol
(B) control scalp bleeding
(C) elevate HOB to 30–45%
(D) give mannitol 1 g/kg bolus
Neurosurgery
A 19-year-old male presents to the emergency
department after being shot in the head with a
handgun. Appropriate initial steps in managing this
patient include all of the following except:
(A) begin Solumedrol protocol
(B) control scalp bleeding
(C) elevate HOB to 30–45%
(D) give mannitol 1 g/kg bolus
Neurosurgery
• Explanation: Treatment of a GSW to the head include
cardiopulmonary resuscitation as needed, endotracheal
intubation if airway is compromised, cervical spine
precautions, control scalp bleeding, shave the scalp, and
obtain a noncontrast CT scan of the brain. In addition, one
must assume that the ICP is elevated in a patient with a
gunshot wound to the head. Therefore, initial measures
must be taken to control the patient's ICP. These steps are
elevating the head of bed to 30–45%, keeping the head in
midline position, administering a 1 gm/kg bolus of mannitol
as blood pressure permits, and mild hyperventilation
(PCO2 = 35). The efficacy of steroids in penetrating head
injuries is unsubstantiated and is therefore not
recommended.
Neurosurgery
Diffuse axonal injury (DAI) results from what type of force
acting on the brain?
(A) direct impact
(B) axial loading
(C) linear acceleration
(D) rotational acceleration
Neurosurgery
Diffuse axonal injury (DAI) results from what type of force
acting on the brain?
(A) direct impact
(B) axial loading
(C) linear acceleration
(D) rotational acceleration
Neurosurgery
• Explanation: DAI refers to a characteristic brain injury
pattern. The patient presents with unconsciousness and a
lack of a focal mass lesion on CT scanning. Neuronal
damage results from shearing of the axons that is caused
by rotational acceleration forces. These same forces cause
shearing of small blood vessels as well. Skull fractures are
less common in patients with DAI than in those with a focal
lesion. The rotational forces necessary to cause DAI most
commonly occur in motor vehicle accidents. In motor
vehicle accidents, the head makes contact with a relatively
soft, broad surface such as a padded dashboard or
energy-absorbing steering column resulting in a long
period of acceleration within the skull. This longer period of
acceleration translates into greater shearing and
deformation of brain tissue.
Neurosurgery
Neurosurgery
Neurosurgery
Neurosurgery
Neurosurgery
Neurosurgery
The overall mortality rate from deep venous thromboses
in patients with spinal cord injuries is
(A) 1%
(B) 5%
(C) 10%
(D) 20%
Neurosurgery
The overall mortality rate from deep venous thromboses
in patients with spinal cord injuries is
(A) 1%
(B) 5%
(C) 10%
(D) 20%
Neurosurgery
• Explanation: Patients with spinal cord injuries have a
relatively high risk for developing deep venous thrombosis,
especially with higher levels of injury. The overall mortality
from deep venous thromboses in patients with spinal cord
injury is approximately 10%. Death may result from
pulmonary embolus or embolic stroke if the patient has a
patent foramen ovale. Because of this risk, patients with
spinal cord injury should be on some form of deep venous
thrombosis prophylaxis. This may include passive lower
extremity motion, pneumatic compression boots, and
heparin delivered subcutaneously. Additionally, physicians
caring for patients with spinal cord injuries should have a
high index of suspicion and a low threshold for diagnosing
and treating deep venous thromboses in these patients.
Neurosurgery
A painful thoracic compression fracture secondary to the
osteoporosis that accompanies Cushing's disease is
best treated by
(A) prolonged bed rest and narcotics
(B) methylmethacrylate injection
(C) endoscopic transthoracic stabilization
(D) bracing and medical therapy for osteoporosis
Neurosurgery
A painful thoracic compression fracture secondary to the
osteoporosis that accompanies Cushing's disease is
best treated by
(A) prolonged bed rest and narcotics
(B) methylmethacrylate injection
(C) endoscopic transthoracic stabilization
(D) bracing and medical therapy for osteoporosis
Neurosurgery
• Explanation: Vertebroplasty has revolutionized the
management of osteoporotic compression fractures.
Injection of methylmethacrylate into the vertebral body via
a needle introduced through the pedicle is safe and
effective in giving almost immediate relief of pain.