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1. General Principles & Basic Science MCQs

Practice Set 17 of 789

This practice set contains high-yield board review questions covering key concepts in 1. General Principles & Basic Science. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 321

Topic: Physiology & Rehabilitation

A patient sustains a stab wound resulting in a spinal cord hemisection. Below the level of the lesion, what is the expected neurologic deficit pattern?

. Contralateral motor loss and ipsilateral pain/temperature loss
. Ipsilateral motor loss and contralateral pain/temperature loss
. Bilateral motor loss and intact sensation
. Ipsilateral motor, pain, and temperature loss
. Contralateral motor, pain, and temperature loss

Correct Answer & Explanation

. Ipsilateral motor loss and contralateral pain/temperature loss

Explanation

Brown-Sequard syndrome results from a spinal cord hemisection. Patients exhibit ipsilateral loss of motor function and proprioception, combined with a contralateral loss of pain and temperature sensation.

Question 322

Topic: 1. General Principles & Basic Science

Following an anterior cervical corpectomy, a patient develops unilateral ptosis, miosis, and anhidrosis. Retractor placement over which of the following muscles most likely caused this complication?

. Sternocleidomastoid
. Longus colli
. Platysma
. Scalenus anterior
. Omohyoid

Correct Answer & Explanation

. Longus colli

Explanation

Horner's syndrome can occur from injury to the sympathetic chain, which runs longitudinally over the longus colli muscle. Placing self-retaining retractors too far laterally over the longus colli increases the risk of this complication.

Question 323

Topic: 1. General Principles & Basic Science

When placing posterior cervical instrumentation, which of the following screw trajectories carries the highest recognized risk of iatrogenic vertebral artery injury?

. C1 lateral mass screws
. C2 pars/pedicle screws
. C4 lateral mass screws
. C6 lateral mass screws
. C7 pedicle screws

Correct Answer & Explanation

. C2 pars/pedicle screws

Explanation

C2 pedicle and pars screws carry a significant risk of vertebral artery injury due to the artery's medial and superior path through the C2 foramen. Preoperative CT angiography is often used to assess for a 'high-riding' vertebral artery to mitigate this risk.

Question 324

Topic: 1. General Principles & Basic Science

During insertion of C1-C2 transarticular screws, the surgeon must be keenly aware of the vertebral artery anatomy. At which cervical level does the vertebral artery typically enter the transverse foramen?

. C7
. C6
. C5
. C4
. C3

Correct Answer & Explanation

. C6

Explanation

The vertebral artery typically branches from the subclavian artery and enters the transverse foramen at the C6 level in approximately 90% of individuals. Anomalous entry at C7 or higher occurs less frequently.

Question 325

Topic: Physiology & Rehabilitation

A patient involved in a motor vehicle collision sustains a penetrating injury to the right side of the cervical spine, resulting in a Brown-Sequard syndrome. Which of the following neurological deficits will be present?

. Bilateral loss of motor function below the lesion
. Right-sided loss of pain and temperature sensation
. Left-sided loss of proprioception and vibration
. Right-sided loss of motor function and left-sided loss of pain and temperature
. Left-sided loss of motor function and right-sided loss of proprioception

Correct Answer & Explanation

. Right-sided loss of motor function and left-sided loss of pain and temperature

Explanation

Brown-Sequard syndrome involves hemisection of the spinal cord. It presents with ipsilateral loss of motor function and proprioception (corticospinal tract and dorsal columns cross in the medulla) and contralateral loss of pain/temperature (spinothalamic tract crosses near the entry level).

Question 326

Topic: Physiology & Rehabilitation

A 45-year-old male sustains an anterior spinal artery syndrome following a complex thoracoabdominal aortic aneurysm repair. Which of the following sensory modalities will definitively remain intact below the level of the lesion?

. Pain sensation
. Temperature sensation
. Crude touch
. Proprioception
. Motor function

Correct Answer & Explanation

. Pain sensation

Explanation

Anterior spinal artery syndrome causes bilateral loss of motor function, pain, and temperature sensation. The dorsal columns, which mediate proprioception and vibratory sense, are preserved as they are supplied by the posterior spinal arteries.

Question 327

Topic: Infection, Pharmacology & VTE

A 60-year-old poorly controlled diabetic male undergoes an L4-L5 posterior spinal fusion. Three weeks postoperatively, he presents with increasing back pain, incisional erythema, and purulent wound drainage. The most commonly isolated organism in this clinical scenario is:

. Staphylococcus epidermidis
. Staphylococcus aureus
. Pseudomonas aeruginosa
. Escherichia coli
. Cutibacterium acnes

Correct Answer & Explanation

. Staphylococcus aureus

Explanation

Staphylococcus aureus is the most common causative organism in both spontaneous pyogenic vertebral osteomyelitis and acute postoperative spinal surgical site infections.

Question 328

Topic: Infection, Pharmacology & VTE

Which of the following clinical examination findings is most characteristic of a psoas abscess developing as a complication of lumbar vertebral osteomyelitis?

. Pain exacerbated by passive hip flexion
. Pain exacerbated by passive hip extension
. Pain exacerbated by internal rotation of the hip
. A positive straight leg raise test radiating to the foot
. Diminished patellar deep tendon reflex

Correct Answer & Explanation

. Pain exacerbated by passive hip extension

Explanation

A psoas abscess causes inflammation of the psoas muscle, leading to a flexion contracture of the hip. Passive extension of the hip stretches the inflamed muscle, eliciting severe pain (a positive psoas sign).

Question 329

Topic: Infection, Pharmacology & VTE

Which of the following laboratory markers is considered the most sensitive and useful for monitoring the clinical response to antibiotic therapy in a patient being treated for pyogenic vertebral osteomyelitis?

. White blood cell (WBC) count
. Erythrocyte sedimentation rate (ESR)
. C-reactive protein (CRP)
. Procalcitonin
. Serial blood cultures

Correct Answer & Explanation

. C-reactive protein (CRP)

Explanation

C-reactive protein (CRP) is the most reliable marker for tracking treatment response in spinal infections as it normalizes much faster than ESR following successful eradication of the infection.

Question 330

Topic: Infection, Pharmacology & VTE

A 12-year-old boy with a known history of sickle cell anemia develops pyogenic vertebral osteomyelitis. While Staphylococcus aureus remains the most common overall cause, which of the following organisms is classically associated with this patient's underlying condition?

. Klebsiella pneumoniae
. Pseudomonas aeruginosa
. Salmonella species
. Escherichia coli
. Proteus mirabilis

Correct Answer & Explanation

. Salmonella species

Explanation

Patients with sickle cell disease have a uniquely higher risk of osteomyelitis caused by Salmonella species, largely due to functional asplenia and bowel wall ischemia allowing bacterial translocation.

Question 331

Topic: Infection, Pharmacology & VTE

Which of the following represents an absolute indication for surgical intervention in a patient with pyogenic vertebral osteomyelitis?

. An ESR persistently elevated greater than 100 mm/hr
. Persistently positive blood cultures despite 2 weeks of antibiotics
. Development of a progressive neurologic deficit
. Severe localized back pain refractory to NSAIDs
. MRI evidence of extensive disc space enhancement

Correct Answer & Explanation

. Development of a progressive neurologic deficit

Explanation

Absolute indications for surgery in spinal infections include a progressive neurologic deficit, spinal instability, significant deformity, or failure of medical management (clinical deterioration despite appropriate antibiotics).

Question 332

Topic: Infection, Pharmacology & VTE

The "Pons sign," characterized by a step-like anterior erosion of the vertebral body seen on plain lateral radiographs or CT, is a classical finding highly suggestive of which infectious process?

. Tuberculosis
. Pyogenic osteomyelitis
. Spinal Brucellosis
. Fungal osteomyelitis
. Chordoma

Correct Answer & Explanation

. Spinal Brucellosis

Explanation

The Pons sign refers to an anterior step-like defect or focal erosion of the superior or inferior anterior vertebral endplate. It is a hallmark radiographic feature of spinal brucellosis.

Question 333

Topic: Infection, Pharmacology & VTE

To minimize the risk of postoperative wound infection, prophylactic intravenous antibiotics for a routine, clean lumbar microdiscectomy should ideally be administered:

. 2 hours before induction of anesthesia
. Within 60 minutes prior to surgical incision
. Immediately at the time of skin closure
. 24 hours postoperatively as a single dose
. 30 minutes after surgical incision

Correct Answer & Explanation

. Within 60 minutes prior to surgical incision

Explanation

Current guidelines strictly recommend that prophylactic antibiotics (such as cefazolin) be administered within 60 minutes prior to surgical incision to ensure optimal tissue and serum bactericidal concentrations during the procedure.

Question 334

Topic: 1. General Principles & Basic Science

Following an uncomplicated instrumented lumbar fusion, at what postoperative time frame does the C-reactive protein (CRP) typically peak before starting to return to baseline?

. 12-24 hours
. 2-3 days
. 5-7 days
. 10-14 days
. 3-4 weeks

Correct Answer & Explanation

. 2-3 days

Explanation

CRP typically peaks on postoperative days 2 to 3 and begins to fall, usually returning to normal within 1 to 2 weeks. A secondary rise or failure to decrease is highly suspicious for a postoperative infection.

Question 335

Topic: Infection, Pharmacology & VTE

A 45-year-old undergoes a microdiscectomy. Four weeks later, he presents with severe, excruciating back pain and paraspinal spasms. Inflammatory markers are significantly elevated. What is the most appropriate next step in management?

. Immediate surgical debridement
. MRI of the lumbar spine with and without contrast
. CT-guided biopsy followed by 6 weeks of IV antibiotics
. Empiric initiation of vancomycin and ceftriaxone
. Prescription of NSAIDs and physical therapy

Correct Answer & Explanation

. MRI of the lumbar spine with and without contrast

Explanation

The clinical presentation is highly suspicious for postoperative discitis. Gadolinium-enhanced MRI is the diagnostic imaging modality of choice to confirm the diagnosis and assess the extent of infection before any intervention.

Question 336

Topic: Infection, Pharmacology & VTE

In differentiating tuberculous spondylitis from pyogenic vertebral osteomyelitis on MRI, which of the following is most characteristic of tuberculosis?

. Early destruction of the intervertebral disc
. Relative sparing of the intervertebral disc until late in the disease
. Strictly solitary vertebral body involvement
. Sclerotic reactive bone formation early in the disease process
. Absence of paraspinal soft tissue extension

Correct Answer & Explanation

. Relative sparing of the intervertebral disc until late in the disease

Explanation

Tuberculous spondylitis typically involves the anterior-inferior aspect of the vertebral body and spreads subligamentously, sparing the intervertebral disc until late. Pyogenic infections typically originate in the endplates and rapidly destroy the adjacent disc.

Question 337

Topic: Infection, Pharmacology & VTE

What is the primary arterial route of hematogenous spread of pyogenic infection to the adult vertebral body?

. Direct extension from Batson venous plexus
. Nutrient arterioles originating from the segmental artery
. Anastomotic channels of the posterior longitudinal ligament
. Retrograde flow through the basivertebral vein
. Lymphatic spread via the thoracic duct

Correct Answer & Explanation

. Nutrient arterioles originating from the segmental artery

Explanation

Hematogenous spread of pyogenic vertebral osteomyelitis typically occurs via the arterial route in adults. Bacteria lodge in the rich vascular supply of the subchondral bone adjacent to the vertebral endplates, supplied by nutrient branches of the segmental arteries.

Question 338

Topic: Infection, Pharmacology & VTE

A 60-year-old man with confirmed pyogenic vertebral osteomyelitis has been on appropriate intravenous antibiotics for 4 weeks. His CRP has normalized, but he complains of persistent severe back pain and radiographs show progressive local kyphosis of 25 degrees. What is the most appropriate management?

. Switch to oral antibiotics and provide a thoracolumbosacral orthosis (TLSO)
. Continue intravenous antibiotics for an additional 6 weeks
. Perform a CT-guided repeat biopsy
. Posterior laminectomy alone for decompression
. Anterior debridement, strut grafting, and stabilization

Correct Answer & Explanation

. Anterior debridement, strut grafting, and stabilization

Explanation

Indications for surgical intervention in vertebral osteomyelitis include progressive deformity, neurologic deficit, or failure of medical management. Anterior debridement and reconstruction is indicated to correct progressive kyphotic deformity and stabilize the spine.

Question 339

Topic: Infection, Pharmacology & VTE

For a hemodynamically stable patient with native pyogenic vertebral osteomyelitis successfully treated with targeted intravenous antibiotics and demonstrating a good clinical and laboratory response, what is the IDSA recommended total duration of antimicrobial therapy?

. 2 weeks
. 4 weeks
. 6 weeks
. 12 weeks
. 6 months

Correct Answer & Explanation

. 6 weeks

Explanation

The Infectious Diseases Society of America (IDSA) guidelines recommend a total of 6 weeks of targeted antimicrobial therapy (intravenous or highly bioavailable oral agents) for most cases of native vertebral osteomyelitis without extensive complications.

Question 340

Topic: Infection, Pharmacology & VTE

A 65-year-old male presents with severe back pain and elevated ESR 3 weeks after an uncomplicated microdiscectomy. MRI shows fluid in the disc space with endplate edema. What is the most appropriate initial management step prior to starting antibiotics?

. Empiric IV Vancomycin
. CT-guided aspiration of the disc space
. Open debridement and fusion
. Oral broad-spectrum antibiotics
. Repeat MRI with contrast in 2 weeks

Correct Answer & Explanation

. CT-guided aspiration of the disc space

Explanation

In suspected post-operative discitis, a tissue diagnosis is critical before initiating antibiotics. CT-guided aspiration provides the best yield for targeted therapy.

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