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6. Spine MCQs

Practice Set 31 of 379

This practice set contains high-yield board review questions covering key concepts in 6. Spine. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 601

Topic: Cervical Spine

A patient develops severe postoperative dysphagia following a multilevel ACDF. Which of the following intraoperative factors has been most strongly associated with an increased risk of severe prevertebral swelling and chronic dysphagia in this setting?

. Use of an anterior cervical plate
. Use of structural fibular allograft
. Recombinant human bone morphogenetic protein-2 (rhBMP-2) use
. Patient age less than 40 years
. Intraoperative blood loss greater than 100 mL

Correct Answer & Explanation

. Recombinant human bone morphogenetic protein-2 (rhBMP-2) use

Explanation

The use of rhBMP-2 in the anterior cervical spine is notorious for causing robust inflammatory responses leading to severe prevertebral soft tissue swelling, dysphagia, and potentially airway compromise. Its use in ACDF is generally considered off-label and requires extreme caution.

Question 602

Topic: 6. Spine

A patient presents with absent reflexes, profound flaccid paralysis, and absent sensation below the T6 level immediately following a severe MVC. The bulbocavernosus reflex is absent. What is the most likely diagnosis?

. Neurogenic shock
. Complete spinal cord transection
. Spinal shock
. Anterior cord syndrome
. Central cord syndrome

Correct Answer & Explanation

. Spinal shock

Explanation

Spinal shock is a transient physiological state immediately following spinal cord injury, characterized by flaccid paralysis, areflexia, and an absent bulbocavernosus reflex. The definitive completeness of the cord injury cannot be assessed until spinal shock resolves (indicated by the return of the bulbocavernosus reflex).

Question 603

Topic: 6. Spine

During a microscopic lumbar discectomy at L5-S1 for a far-lateral (extraforaminal) disc herniation, the surgeon must carefully decompress the affected nerve root. Which nerve root is most commonly compressed by a far-lateral disc herniation at the L5-S1 level?

. L4
. L5
. S1
. S2
. S3

Correct Answer & Explanation

. L5

Explanation

While a paracentral disc herniation at L5-S1 affects the traversing S1 root, a far-lateral (extraforaminal) disc herniation at L5-S1 compresses the exiting L5 nerve root.

Question 604

Topic: 6. Spine

A patient presents with acute cauda equina syndrome secondary to a massive L4-L5 disc herniation. Which of the following preoperative clinical findings is the strongest predictor of poor postoperative recovery of bladder function?

. Severe bilateral leg pain
. Saddle anesthesia
. Complete loss of perineal sensation and urinary incontinence
. Unilateral foot drop
. Absent Achilles reflexes

Correct Answer & Explanation

. Complete loss of perineal sensation and urinary incontinence

Explanation

The severity of preoperative urinary dysfunction is the most significant predictor of postoperative bladder recovery in cauda equina syndrome. Patients who progress to complete painless urinary retention with overflow incontinence (CES-Retention) have a poorer prognosis than those with incomplete deficits (CES-Incomplete).

Question 605

Topic: 6. Spine

Ossification of the posterior longitudinal ligament (OPLL) is a frequent cause of myelopathy in certain demographics. OPLL most frequently affects which segment of the spine?

. Upper thoracic
. Mid-thoracic
. Lumbar
. Sacral
. Cervical

Correct Answer & Explanation

. Cervical

Explanation

OPLL is most commonly found in the cervical spine, particularly in populations of Asian descent. It leads to progressive spinal canal narrowing and cervical myelopathy.

Question 606

Topic: 6. Spine

The 'K-line' is a critical radiographic parameter used to determine the appropriate surgical approach (anterior vs. posterior) in patients with cervical myelopathy due to OPLL. How is the K-line defined on a neutral lateral cervical radiograph?

. Connects the midpoints of the spinal canal from C2 to C7
. Connects the anterior margins of the vertebral bodies from C2 to C7
. Connects the posterior margins of the spinal canal from C1 to T1
. Connects the tips of the spinous processes from C2 to C7
. Connects the midpoints of the pedicles from C3 to C6

Correct Answer & Explanation

. Connects the midpoints of the spinal canal from C2 to C7

Explanation

The K-line is a straight line connecting the midpoints of the spinal canal at C2 and C7. If the OPLL mass crosses anterior to this line (K-line negative), posterior decompression alone is often insufficient, and an anterior approach is generally indicated.

Question 607

Topic: 6. Spine

How common are spinal infections following penetrating injury to the spine:

. 2%
. 20%
. 60%
. 80%
. 95%

Correct Answer & Explanation

. 2%

Explanation

One study found that 5 of 239 patients with gunshot or stab wounds developed meningitis, paravertebral abscess, vertebral osteomyelitis, or epidural abscess.

Question 608

Topic: 6. Spine

Risk factors implicated in postoperative wound infection following lumbar spine surgery include all of the following except:

. Use of instrumentation
. Presence of spina bifida occulta
. History of smoking
. Longer operative duration
. Obesity

Correct Answer & Explanation

. Use of instrumentation

Explanation

Instrumented cases, preoperative history of smoking or obesity, and longer operating room duration have all been identified as possible risk factors for surgical site infection. Additionally, patient age may be a risk factor or may be associated with a risk factor like medical comorbidity or nutritional depletion.

Question 609

Topic: 6. Spine

The spinal surgical procedure associated with the highest rate of surgical site infection is:

. Neuromuscular scoliosis fusion
. Lumbar spondylolisthesis fusion
. Reduction and fusion of traumatic cervical facet fracture-dislocation
. Lumbar stenosis decompression and fusion
. Cervical laminectomy, foraminotomy, and arthrodesis

Correct Answer & Explanation

. Neuromuscular scoliosis fusion

Explanation

Postoperative infection rates reach 11% for neuromuscular disease indications. For muscular dystrophy scoliosis surgery, the rate may be as high as 23%, for cerebral palsy 18%, and for myelomeningocele 11%.

Question 610

Topic: 6. Spine

Which of the following comprises the middle column in the Denis three- column model of the thoracolumbar spine:

. Posterior longitudinal ligament, spinal canal, pedicles, and facet joints
. Facet joints, intertransverse membrane, and ligamentum flavum
. Vertebral body, posterior longitudinal ligament, and disk
. Posterior half of the vertebral body, posterior half of the disk, and posterior longitudinal ligament
. Interspinous ligament, supraspinous ligament, and ligamentum flavum

Correct Answer & Explanation

. Posterior longitudinal ligament, spinal canal, pedicles, and facet joints

Explanation

The middle column is composed of the posterior half of the vertebral body, posterior half of the disk, and posterior longitudinal ligament. The middle column, according to Denis, is important to determine the stability of a thoracolumbar fracture. There is the potential for instability when the middle column is disrupted.

Question 611

Topic: 6. Spine

Which type of biomechanical force(s) acts on the anterior portion of the thoracolumbar junction (T12-L2) at rest in a standing position:

. C ompression
. C ompression and shear
. C ompression and tension
. Tension
. Shear and torsion

Correct Answer & Explanation

. C ompression

Explanation

The thoracolumbar junction is normally a straight portion of the spine (no lordosis or kyphosis) and the vertebral bodies are subject to compressive forces at rest when the patient is in a standing position. The posteriorosteoligamentous structures are subject to tension along with the paraspinous muscles that help to maintain an upright posture.

Question 612

Topic: 6. Spine

Which of the following statements is true regarding the bulbocavernosus reflex:

. This reflex is a sign of a spinal cord injury.
. This reflex is mediated by the S3 and S4 segments of the spinal cord.
. This reflex may be elicited by pulling on an indwelling catheter that causes a contraction of the cremaster muscle.
. This reflex often means that a spinal cord injury is complete.
. This reflex is mediated by the S3 and S4 segments of the spinal cord, and this reflex often means that a spinal cord injury is complete.

Correct Answer & Explanation

. This reflex is a sign of a spinal cord injury.

Explanation

The bulbocavernosus reflex is mediated by the S3 and S4 regions of the spinal cord. This reflex is elicited by pulling on an indwelling catheter or squeezing the glans penis or clitoris and observing contraction of the anal sphincter. The bulbocavernosus reflex may be absent soon after a spinal cord injury due to spinal shock, but it often returns in 24 to 48 hours and indicates the end of spinal shock. A better sense of prognosis of a spinal cord injury is possible after spinal shock has ended.

Question 613

Topic: 6. Spine
According to the Frankel grading scale for a neurologic injury, what is meant by Frankel C?
. There is an antigravity motor function in some distal muscles below the level of the spinal cord injury.
. There is an antigravity muscle function in the muscles 1 or 2 root levels below the spinal cord injury.
. There is muscle function, but not with adequate power to overcome gravity in some muscles below the level of the spinal cord injury.
. There is muscle function, but not with adequate power to overcome gravity in the muscles 1 or 2 root levels below the spinal cord injury.
. The patient has a chance for further neurologic recovery.

Correct Answer & Explanation

. There is an antigravity motor function in some distal muscles below the level of the spinal cord injury.

Explanation

The Frankel grading scale is used to communicate the extent of neurologic injury in the setting of a spinal cord injury. The A category indicates that there is no motor or sensory function below the level of the injury. The B category indicates that there is only sensory function below the level of the injury. The C category indicates that there is muscle function, but not with adequate power to overcome gravity in some muscles below the level of the spinal cord injury. The D category indicates that there is motor function with at least antigravity power below the level of the injury. The E category indicates that the muscle function below the level of the injury is normal in power. One can see some motor function for 1-2 root levels below the level of a spinal cord injury that is due to 'root escape' and should not be confused with distal motor sparing.

Question 614

Topic: 6. Spine
Which type of thoracolumbar fracture is associated with the highest incidence of intra-abdominal visceral trauma?
. Burst fracture
. Compression fracture
. Flexion-distraction injury
. Fracture dislocation
. Pathologic fracture

Correct Answer & Explanation

. Burst fracture

Explanation

The flexion-distraction injury was originally termed the 'seatbelt injury' or in the case of a fracture proceeding through bone, a 'Chance fracture.' This injury is usually the result of a severe flexion force to the lumbar spine with flexion moment anterior to the spine (e.g., at a lap belt). Due to the severe energy dissipation at the level of the flexion moment, there is a high incidence of intra-abdominal visceral trauma.

Question 615

Topic: 6. Spine

Which type of treatment would be most appropriate for a young, healthy patient with an incomplete spinal cord injury (ASIA C ) 5 days following a T12 burst fracture with 30% canal compromise:

. Bed rest, followed by hyperextension casting
. Posterior distractive instrumentation and fusion
. Posterior fusion in situ
. Anterior T12 corpectomy and strut grafting
. Anterior T12 corpectomy, strut grafting, and instrumentation

Correct Answer & Explanation

. Bed rest, followed by hyperextension casting

Explanation

Surgery is indicated in patients with an incomplete spinal cord injury with spinal cord compression. Although some indirect decompression may be achieved early following the injury using posterior distractive instrumentation, the level of decompression is often better using an anterior approach (especially several days following the fracture). Following anterior decompression, either anterior instrumentation or posterior instrumentation is indicated to stabilize the construct and allow early mobilization.

Question 616

Topic: 6. Spine

Which of the following is the best indication for a laminectomy in a patient who has sustained a thoracolumbar burst fracture with a neurologic deficit:

. Spinal cord compression
. A lamina fracture is present on a computerized tomography scan
. A small epidural hematoma is present on a magnetic resonance image
. Greater than 30° of kyphosis on a lateral radiograph
. Greater than 50% canal compromise on a computerized tomography scan

Correct Answer & Explanation

. Spinal cord compression

Explanation

A laminectomy is never indicated as the sole method of treatment for a thoracolumbar burst fracture. Laminectomy creates additional instability at the level of the fracture and does not effectively decompress the spinal cord, which is compressed anteriorly from the retropulsed bony fragment. When lamina fractures are present on a computerized tomography scan, there is a significant incidence of dural tears and entrapped nerve tissue within the lamina fracture. Surgeons should consider performing a laminectomy in addition to other methods of achieving anterior decompression and stabilization of a burst fracture with a lamina fracture.

Question 617

Topic: 6. Spine

Which recommendations for the pharmacologic treatment of spinal cord injuries resulted from the NASC IS-II trials:

. Treat all patients with a spinal cord injury with methylprednisolone 30 mg/kg over 1 hr followed by a maintenance rate of 5.4 mg/kg/hr for 23 hours.
. Treat only patients who present within the first 8 hours of a spinal cord injury with methylprednisolone 30 mg/kg over 1 hr followed by a maintenance rate of 5.4 mg/kg/hr for 23 hours.
. Treat all patients with a spinal cord injury with decadron 10 mg/kg bolus followed by 1 mg/kg/hr for 23 hours.
. Treat only patients who present within the first 8 hours of a spinal cord injury with decadron 10 mg/kg bolus followed by 1 mg/kg/hr for 23 hours.
. Treat only patients who present with complete spinal cord injuries within the first 8 hours of a spinal cord injury with methylprednisolone 30 mg/kg over 1 hr followed by a maintenance rate of 5.4 mg/kg/hr for 23 hours.

Correct Answer & Explanation

. Treat all patients with a spinal cord injury with methylprednisolone 30 mg/kg over 1 hr followed by a maintenance rate of 5.4 mg/kg/hr for 23 hours.

Explanation

The NASC IS-II recommendations are to treat patients who present with an incomplete spinal cord injury within 8 hours of the injury with methylprednisolone 30 mg/kg over 1 hour followed by a maintenance rate of 5.4 mg/kg/hr for 23 hours. Because it is difficult to tell which patients have a complete or incomplete spinal cord injury in this time frame due to spinal shock, it has generally been accepted to treat all patients with spinal cord injuries with this treatment protocol as long as they present within the first 8 hours of the injury.

Question 618

Topic: 6. Spine

Which of the following statements is true regarding neurogenic shock:

. Neurogenic shock is due to severe blood loss associated with a spinal cord injury.
. Neurogenic shock can be diagnosed when there is hypotension and tachycardia.
. Neurogenic shock is due to increased parasympathetic tone.
. Neurogenic shock is best treated with judicious use of fluids and vasopressors.
. Neurogenic shock is a sign of an incomplete spinal cord injury.

Correct Answer & Explanation

. Neurogenic shock is due to severe blood loss associated with a spinal cord injury.

Explanation

Neurogenic shock is present when there is a spinal cord injury interrupting sympathetic tone to the heart and blood vessels, and it is heralded by bradycardia and hypotension. It is important to maintain a reasonable blood pressure to prevent further damage to the spinal cord due to ischemia. In the absence of significant blood loss from another source, neurogenic shock must be treated with vasopressor medication and atropine. Severe neurogenic shock may require cardiac pacing. Fluids must be used carefully as overzealous use of fluid resuscitation can result in pulmonary edema.

Question 619

Topic: 6. Spine
Which is the best indication for surgical treatment of a patient with a thoracolumbar burst fracture?
. 60% canal compromise by a retropulsed bony fragment
. 25° of kyphosis on the lateral radiograph
. A fracture of the lamina present on a computerized tomography scan
. An incomplete neurologic deficit
. A polytrauma patient

Correct Answer & Explanation

. An incomplete neurologic deficit

Explanation

The exact indications for surgery vs nonoperative management of thoracolumbar burst fractures remains controversial. The best indication is an incomplete neurologic deficit with spinal cord compression. Other considerations include the degree of deformity (greater than 30° is generally considered appropriate to consider surgery) and the other injuries. Although much has been written about canal compromise, in the absence of a neurologic deficit it is not clear that surgery is always indicated due to canal compromise alone. Large canal fragments have been shown to resorb with conservative treatment.

Question 620

Topic: Thoracolumbar Spine & Deformity

Which of the following patients is not at increased risk for isthmic spondylolisthesis:

. Football lineman
. Gymnast
. Eskimo
. Nonambulatory patient
. Weight lifter

Correct Answer & Explanation

. Nonambulatory patient

Explanation

Isthmic spondylolisthesis is most common in white men and least common in black women. It is thought to arise from repetitive hyperextension of the lumbar spine causing a stress fracture of the pars intra-articularis. Sports such as weight lifting, gymnastics, football, and javelin throwing have a particularly high incidence of this condition. Isthmic spondylolisthesis is never present at birth and is rare in nonambulatory patients.

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