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6. Spine MCQs

Practice Set 242 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 4821

Topic: Cervical Spine

A 55-year-old Asian male presents with progressive hand clumsiness and gait disturbance. Examination reveals a positive Hoffmann's sign and bilateral upgoing plantars. Imaging demonstrates continuous ossification along the posterior aspect of the vertebral bodies from C3 to C6.

During preoperative planning for an anterior decompression, which of the following radiographic findings is the most significant predictor of an intraoperative dural tear?

. K-line negative status on a neutral lateral radiograph
. A "double-layer" sign on axial computed tomography (CT)
. Concomitant ossification of the ligamentum flavum (OLF)
. Loss of cervical lordosis greater than 10 degrees
. Pavlov ratio of less than 0.8

Correct Answer & Explanation

. A "double-layer" sign on axial computed tomography (CT)

Explanation

The 'double-layer' sign on a CT scan in patients with Ossification of the Posterior Longitudinal Ligament (OPLL) is highly specific for dural ossification. It appears as an anterior and posterior hyperdense rim separated by a central hypodense area of non-ossified ligament. Its presence alerts the surgeon to a significantly increased risk of dural tear and cerebrospinal fluid (CSF) leak during anterior cervical corpectomy and decompression. While K-line status is important for choosing between an anterior versus posterior approach, the double-layer sign is the specific predictor for dural ossification and tearing.

Question 4822

Topic: 6. Spine

A 52-year-old male with end-stage renal disease on hemodialysis presents with isolated severe midthoracic back pain. He has a low-grade fever. Neurological examination is completely normal with full strength, intact sensation, and normal reflexes. MRI reveals a large ventral epidural abscess spanning T5-T10. His ESR is 110 mm/hr. What is the most appropriate initial management?

. Emergent posterior laminectomy from T5-T10
. Anterior corpectomy and instrumented fusion
. Blood cultures and prompt initiation of empiric intravenous antibiotics
. High-dose intravenous corticosteroids
. Placement of a percutaneous lumbar drain

Correct Answer & Explanation

. Blood cultures and prompt initiation of empiric intravenous antibiotics

Explanation

In a patient with a spinal epidural abscess who is completely neurologically intact, the standard of care is medical management with close neurological monitoring. Immediate surgical decompression is typically reserved for patients presenting with or progressing to neurological deficits, spinal instability, or failure of medical management. Therefore, obtaining cultures (blood or CT-guided aspirate) and starting prompt empiric IV antibiotics is the most appropriate initial step. A posterior laminectomy alone for a purely ventral abscess can also lead to destabilization and inadequate decompression.

Question 4823

Topic: Thoracolumbar Spine & Deformity
A 25-year-old male presents after falling 15 feet from a roof. He complains of back pain but has no motor or sensory deficits. CT imaging reveals an L1 burst fracture. According to the Thoracolumbar Injury Classification and Severity (TLICS) score, which of the following isolated findings is sufficient to strongly recommend operative rather than nonoperative management?
. 40% loss of anterior vertebral body height
. 30% spinal canal compromise by retropulsed bone
. Definitive disruption of the posterior ligamentous complex (PLC)
. Kyphotic angulation of 15 degrees
. Interpedicular widening on the AP radiograph

Correct Answer & Explanation

. Definitive disruption of the posterior ligamentous complex (PLC)

Explanation

The TLICS system scores based on injury morphology, posterior ligamentous complex (PLC) integrity, and neurological status. A score of ≤3 suggests nonoperative management, 4 is a 'surgeon's choice' tie, and ≥5 suggests operative management. A burst fracture (morphology) scores 2 points. If the patient is neurologically intact, that is 0 points. Definitive PLC disruption scores 3 points. Therefore, a burst fracture (2) + PLC disruption (3) = 5 points, which pushes the recommendation unequivocally to operative intervention. Canal compromise and loss of height are not independent drivers of surgery in the TLICS system if neurology is intact and PLC is intact.

Question 4824

Topic: 6. Spine

A 65-year-old female presents with severe neurogenic claudication that limits her walking to 1 block. Radiographs show a grade I degenerative spondylolisthesis at L4-L5.

Based on the findings of the Spine Patient Outcomes Research Trial (SPORT) regarding degenerative spondylolisthesis, what outcome should be expected when comparing surgical (decompression and fusion) versus nonoperative treatment at 4-year follow-up?

. The nonoperative group has a higher rate of progression to cauda equina syndrome.
. Decompression alone was found statistically superior to decompression with fusion.
. Surgical treatment demonstrated significantly greater improvement in pain and physical function.
. There was no statistically significant difference in patient satisfaction between the two groups.
. Crossover from nonoperative to operative treatment was less than 10%.

Correct Answer & Explanation

. Surgical treatment demonstrated significantly greater improvement in pain and physical function.

Explanation

The SPORT trial for degenerative spondylolisthesis demonstrated a clear, statistically significant advantage of surgical treatment (decompression with fusion) over nonoperative treatment in terms of pain relief, physical function, and patient satisfaction at 4-year follow-up (and extending to 8 years). Cauda equina progression in nonoperative treatment is exceptionally rare. The trial also had a very high crossover rate from the nonoperative arm to the surgical arm.

Question 4825

Topic: 6. Spine

A 40-year-old man with a 15-year history of ankylosing spondylitis presents to the emergency department after a low-energy fall from a standing height. He complains of severe neck pain. Neurological examination is normal. Routine plain lateral radiographs of the cervical spine are obscured at the cervicothoracic junction but the visible segments are interpreted as normal.

What is the most appropriate next step in management?

. Discharge with a soft cervical collar and outpatient rheumatology follow-up
. Dynamic flexion-extension cervical spine radiographs
. Electromyography (EMG) of the upper extremities
. CT scan of the entire cervical and upper thoracic spine
. Immediate closed reduction with Gardner-Wells tongs

Correct Answer & Explanation

. CT scan of the entire cervical and upper thoracic spine

Explanation

Patients with ankylosing spondylitis have a rigid, osteopenic spine that acts as a long lever arm, making them extremely susceptible to highly unstable fractures (often extension-type) even from low-energy trauma. Plain radiographs are notoriously inadequate for diagnosing these fractures due to altered anatomy, osteopenia, and obscured junctions. A CT scan of the entire cervical spine (and extending into the thoracic spine) is mandatory for any patient with ankylosing spondylitis presenting with neck or back pain after trauma, regardless of normal-appearing plain films.

Question 4826

Topic: 6. Spine

A 68-year-old man presents with severe lower back pain and a forward-stooped posture. Standing full-length spine radiographs are obtained to evaluate his adult spinal deformity. His measured pelvic incidence (PI) is 60 degrees.

To achieve optimal sagittal balance postoperatively and minimize the risk of adjacent segment disease, his lumbar lordosis (LL) should be surgically corrected to approximately which of the following values?

. 30 degrees
. 40 degrees
. 60 degrees
. 80 degrees
. LL is independent of PI

Correct Answer & Explanation

. 60 degrees

Explanation

In adult spinal deformity surgery, achieving proper sagittal balance is paramount for good clinical outcomes and minimizing hardware failure/adjacent segment disease. The classic rule formulated by Schwab et al. is that the patient's Lumbar Lordosis (LL) should be matched to their fixed Pelvic Incidence (PI) within 9 degrees (Target LL = PI ± 9°). Since the patient's PI is 60 degrees, the ideal target for surgical correction of his LL is approximately 60 degrees.

Question 4827

Topic: 6. Spine

A 45-year-old woman undergoes a C5-C6 anterior cervical discectomy and fusion (ACDF) via a right-sided approach. Postoperatively, she complains of a newly hoarse voice. Direct laryngoscopy reveals a unilateral right vocal cord paralyzed in the paramedian position. Injury to the recurrent laryngeal nerve (RLN) is suspected. Which of the following statements regarding the relevant surgical anatomy is most accurate?

. The right RLN is more vulnerable to injury because it has a more variable, oblique course as it recurs around the subclavian artery.
. The left RLN loops under the brachiocephalic trunk, predisposing it to stretch injuries.
. The RLN travels within the carotid sheath intimately with the internal jugular vein throughout the cervical spine.
. Approaching the cervical spine at C3-C4 increases the risk of RLN injury compared to a C6-C7 approach.
. The right RLN ascends strictly within the tracheoesophageal groove, affording it more protection than the left.

Correct Answer & Explanation

. The right RLN is more vulnerable to injury because it has a more variable, oblique course as it recurs around the subclavian artery.

Explanation

The right recurrent laryngeal nerve loops under the right subclavian artery and ascends in a more variable and oblique path toward the tracheoesophageal (TE) groove. In contrast, the left RLN loops under the aortic arch and ascends vertically, protected within the TE groove. Because of its oblique, less protected path, the right RLN is more vulnerable to direct injury or stretch during a right-sided lower cervical approach. Additionally, a non-recurrent laryngeal nerve (arising directly from the vagus) occurs in roughly 1% of patients and is almost exclusively found on the right side. Lower cervical approaches (e.g., C6-C7) carry a higher risk of RLN injury than upper cervical approaches.

Question 4828

Topic: 6. Spine

A 65-year-old man presents with progressive hand clumsiness and difficulty buttoning his shirt. He has a wide-based gait and a positive Hoffman's sign. MRI of the cervical spine is obtained as shown in Figures 1 and 2.


Which of the following MRI findings is most strongly associated with failure to improve neurologically following surgical decompression?

. Multilevel T2 hyperintensity in the intervertebral discs
. Increased signal intensity on T2-weighted images alone in the spinal cord
. Decreased signal intensity on T2-weighted images in the spinal cord
. Decreased signal intensity on T1-weighted images in the spinal cord
. The presence of Modic type II endplate changes

Correct Answer & Explanation

. Decreased signal intensity on T1-weighted images in the spinal cord

Explanation

T1 hypointensity in the spinal cord represents myelomalacia, cystic cavitation, or permanent cord damage, and is a strong predictor of poor neurologic recovery after surgical decompression for cervical spondylotic myelopathy. A T2 hyperintensity alone indicates edema or gliosis and has a more variable prognostic value. Therefore, combined T1 hypointensity and T2 hyperintensity indicates a poorer prognosis than T2 hyperintensity alone.

Question 4829

Topic: 6. Spine

An 82-year-old woman with a history of osteoporosis falls from a standing height and sustains an isolated Type II odontoid fracture with 2 mm of posterior displacement. She is neurologically intact. In this specific patient population (older than 80 years), what is the primary advantage of utilizing a rigid cervical collar rather than halo vest immobilization?

. Higher rate of bony union
. Lower mortality rate
. Decreased risk of late myelopathy
. Improved long-term cervical range of motion
. Lower rate of fibrous nonunion

Correct Answer & Explanation

. Lower mortality rate

Explanation

Halo vest immobilization in the elderly population (older than 80 years) is associated with a significantly increased mortality rate (up to 40% in some series) primarily due to respiratory complications (e.g., pneumonia) and falls. A rigid cervical collar is associated with lower mortality, and although it carries a higher rate of fibrous nonunion compared to surgery or rigid fixation, most elderly patients remain asymptomatic with a fibrous union.

Question 4830

Topic: 6. Spine

A 55-year-old man with a history of intravenous drug use presents with severe back pain, fevers, and acute onset of bilateral lower extremity weakness (motor strength 3/5 in L4-S1 distributions) along with urinary retention over the last 12 hours. MRI demonstrates a large dorsal epidural abscess from L2 to L5. Which of the following is the most appropriate next step in management?

. CT-guided needle aspiration and targeted intravenous antibiotics
. Immediate emergent surgical decompression and debridement
. Intravenous dexamethasone followed by empiric antibiotics
. Empiric intravenous antibiotics and repeat MRI in 48 hours
. Diagnostic lumbar puncture to identify the organism

Correct Answer & Explanation

. Immediate emergent surgical decompression and debridement

Explanation

A spinal epidural abscess presenting with acute, progressive neurologic deficits (weakness, cauda equina syndrome) is an absolute indication for emergent surgical decompression and debridement. Non-operative management with antibiotics or CT-guided drainage is strictly reserved for patients without neurologic deficits who are clinically stable or those who are medically unfit for surgery.

Question 4831

Topic: 6. Spine

A 45-year-old man with advanced ankylosing spondylitis presents to the emergency department after a low-speed motor vehicle collision. He complains of severe lower neck pain. Neurologic examination is unremarkable. Lateral radiograph and CT scan


show a highly unstable extension-distraction injury at C7-T1. What is the most appropriate definitive management?

. Halo vest immobilization for 12 weeks
. Anterior cervical discectomy and fusion (ACDF) with plating
. Posterior long-segment instrumented fusion
. Combined anterior and posterior short-segment fusion
. Cervical thoracic orthosis (CTO) for 8 weeks

Correct Answer & Explanation

. Posterior long-segment instrumented fusion

Explanation

Fractures of the ankylosed spine act like long-bone fractures due to the fused segments acting as long lever arms. They are highly unstable and frequently involve all three columns (often extension-distraction injuries). The treatment of choice is typically posterior long-segment instrumented fusion (at least 3 points of fixation above and below the injury). Anterior-only constructs or short-segment fusions often fail due to poor bone quality and immense biomechanical forces. Conservative management has high complication rates and fails to control the fracture.

Question 4832

Topic: Thoracolumbar Spine & Deformity

A 15-year-old boy presents with progressive mid-back pain and a noticeable cosmetic deformity. Standing lateral radiographs demonstrate a thoracic kyphosis of 80 degrees. Radiographic criteria (Sorensen's criteria) for typical Scheuermann's kyphosis includes anterior wedging of at least:

. 3 degrees in 3 consecutive vertebrae
. 5 degrees in 3 consecutive vertebrae
. 5 degrees in 2 consecutive vertebrae
. 10 degrees in 3 consecutive vertebrae
. 15 degrees in 2 consecutive vertebrae

Correct Answer & Explanation

. 5 degrees in 3 consecutive vertebrae

Explanation

Sorensen's criteria for the diagnosis of Scheuermann's disease include an abnormally increased thoracic kyphosis (>40 degrees) and anterior wedging of 5 degrees or more in at least three consecutive vertebrae. Other radiographic findings often include Schmorl's nodes, endplate irregularities, and disc space narrowing.

Question 4833

Topic: 6. Spine

A 62-year-old woman with a history of breast cancer presents with severe axial back pain that worsens with movement. Imaging reveals a lytic metastasis in the L3 vertebral body involving 60% of the vertebral body and the left pedicle.

There is a kyphotic deformity of 15 degrees but no epidural spinal cord compression. According to the Spinal Instability Neoplastic Score (SINS), what does a score of 13-18 indicate?

. Stable spine not requiring surgical consultation
. Indeterminate instability requiring bracing only
. Definite instability warranting surgical consultation
. A prediction of tumor response to stereotactic body radiation therapy (SBRT)
. A life expectancy of greater than 6 months justifying surgical intervention

Correct Answer & Explanation

. Definite instability warranting surgical consultation

Explanation

The Spinal Instability Neoplastic Score (SINS) is used to assess spinal stability in patients with neoplastic disease. A score of 0-6 represents a stable spine; 7-12 is potentially unstable; and 13-18 denotes definite instability requiring surgical consultation for stabilization. The SINS score evaluates location, pain with movement, bone lesion quality, radiographic alignment, vertebral body collapse, and posterolateral involvement. It does not evaluate life expectancy or tumor response to radiation (which are assessed by frameworks like NOMS).

Question 4834

Topic: 6. Spine

A 42-year-old man presents with acute back pain, bilateral sciatica, and saddle anesthesia. He reports urinary incontinence that started 12 hours ago. A post-void residual is 400 mL. MRI demonstrates a massive L4-L5 disc herniation compressing the cauda equina. Which of the following factors is most predictive of the recovery of bladder function following emergent surgical decompression?

. Preoperative duration of autonomic dysfunction
. The specific level of the disc herniation
. The presence of unilateral versus bilateral radicular pain
. The size of the disc herniation on MRI
. The choice of laminectomy versus microdiscectomy

Correct Answer & Explanation

. Preoperative duration of autonomic dysfunction

Explanation

In cauda equina syndrome, the most critical predictor of postoperative neurologic recovery, including bladder and bowel function, is the duration and severity of the autonomic dysfunction before surgical decompression. Decompression within 24 to 48 hours of symptom onset is generally recommended to maximize the chances of recovery.

Question 4835

Topic: 6. Spine

A 55-year-old man undergoes an L4-L5 transforaminal lumbar interbody fusion (TLIF) for degenerative spondylolisthesis.

Five years later, he presents with new-onset neurogenic claudication. Imaging reveals symptomatic spinal stenosis at L3-L4. Which of the following is the most significant surgeon-controlled risk factor for the development of adjacent segment disease (ASD) in this patient?

. Smoking history
. Postoperative sagittal imbalance
. Use of interbody cages instead of posterolateral fusion alone
. Patient age under 50 at the time of index surgery
. The use of bone morphogenetic protein (BMP) during index surgery

Correct Answer & Explanation

. Postoperative sagittal imbalance

Explanation

Adjacent segment disease (ASD) refers to new degenerative changes causing symptoms at a spinal level adjacent to a previous fusion. While patient factors like age and pre-existing degeneration play a role, the most significant surgeon-controlled risk factor for ASD is postoperative sagittal imbalance (especially failure to restore lumbar lordosis and pelvic incidence-lumbar lordosis mismatch). Violation of the adjacent facet capsule during screw placement is another major modifiable risk factor.

Question 4836

Topic: 6. Spine

A 38-year-old male construction worker presents with persistent lower back pain and right-sided L5 radiculopathy that has failed 6 months of conservative treatment. Radiographs

demonstrate a Grade 2 L5-S1 isthmic spondylolisthesis. What is the most common anatomic source of the L5 nerve root compression in this specific condition?

. Hypertrophic facet joints compressing the exiting root
. The pars interarticularis defect with a fibrocartilaginous mass (Gill body)
. A herniated nucleus pulposus at L5-S1
. Pedicle subsidence causing central canal stenosis
. The ligamentum flavum compressing the traversing root

Correct Answer & Explanation

. The pars interarticularis defect with a fibrocartilaginous mass (Gill body)

Explanation

In adult isthmic spondylolisthesis at L5-S1, the L5 nerve root (exiting root) is most commonly compressed in the neural foramen by a fibrocartilaginous mass known as a Gill body, which forms at the site of the pars interarticularis nonunion. Treatment typically involves decompression of the root by removing the Gill body along with a stabilization procedure.

Question 4837

Topic: Cervical Spine

During a revision anterior cervical discectomy and fusion (ACDF) at C6-C7 on the right side, the surgeon notes postoperative hoarseness in the patient. Indirect laryngoscopy confirms a vocal cord paralysis. Which of the following best describes the anatomical basis for the variable risk to the recurrent laryngeal nerve (RLN) during a right-sided versus left-sided anterior cervical approach?

. The right RLN loops under the aortic arch, making it more protected than the left.
. The right RLN has a more variable, oblique course after looping under the subclavian artery.
. The left RLN does not enter the tracheoesophageal groove, making it more vulnerable to retractor injury.
. The left RLN loops under the brachiocephalic artery, causing it to cross the surgical field obliquely.
. The right RLN is embedded within the carotid sheath, requiring division of the sheath for mobilization.

Correct Answer & Explanation

. The right RLN loops under the aortic arch, making it more protected than the left.

Explanation

The right recurrent laryngeal nerve (RLN) loops under the right subclavian artery and ascends into the neck with a more variable, oblique course before entering the tracheoesophageal groove. This makes it more susceptible to surgical injury or retractor stretch during a right-sided anterior cervical approach, particularly at the lower cervical levels (C6-T1). The left RLN loops under the aortic arch and ascends vertically within the protective tracheoesophageal groove, making its location more predictable.

Question 4838

Topic: 6. Spine

A 48-year-old man presents with acute bilateral radicular leg pain, severe lower back pain, saddle anesthesia, and overflow urinary incontinence following a heavy lifting injury. An MRI confirms a massive central disc herniation at L4-L5 compressing the cauda equina. Emergent surgical decompression is planned. Which of the following is the most consistent and significant predictor of the extent of his postoperative bladder function recovery?

. Timing of surgical decompression (less than 12 hours vs. less than 48 hours)
. The preoperative degree and severity of bladder dysfunction (retention vs. incontinence)
. The exact size of the herniated disc volume on preoperative MRI
. Presence of bilateral rather than unilateral Achilles reflex absence
. Administration of high-dose intravenous steroids prior to decompression

Correct Answer & Explanation

. The preoperative degree and severity of bladder dysfunction (retention vs. incontinence)

Explanation

While early decompression (ideally within 24-48 hours) is critical in Cauda Equina Syndrome (CES), multiple studies have shown that the preoperative degree of bladder dysfunction—specifically whether the patient has progressed to overflow incontinence (CES-Retention complete) versus purely retention with preserved sphincter tone (CES-Incomplete)—is the single most important prognostic factor for eventual bladder recovery. Patients with complete loss of voluntary control and overflow incontinence have a significantly poorer prognosis for full sphincter recovery regardless of exact surgical timing.

Question 4839

Topic: 6. Spine

A 62-year-old Japanese male presents with progressive hand clumsiness and broad-based gait. Imaging confirms cervical myelopathy secondary to multi-level Ossification of the Posterior Longitudinal Ligament (OPLL). The surgeon is considering a posterior cervical laminoplasty. Which of the following preoperative radiographic findings is the strongest predictor of a poor neurologic outcome if a posterior-only motion-preserving operation (laminoplasty) is performed?

. A Pavlov ratio of less than 0.8
. An occupation ratio of the spinal canal of 30%
. A positive (anterior) K-line on a neutral lateral radiograph
. A negative (posterior) K-line on a neutral lateral radiograph
. T2-weighted hyperintensity confined to a single cervical level

Correct Answer & Explanation

. A negative (posterior) K-line on a neutral lateral radiograph

Explanation

The K-line is a straight line connecting the midpoints of the spinal canal at C2 and C7 on a neutral lateral radiograph. It evaluates cervical alignment and the size of the OPLL mass. If the OPLL mass crosses the K-line (a 'negative' K-line), a posterior procedure like laminoplasty will not allow sufficient posterior shift of the spinal cord to decompress it adequately over the anterior mass. These patients often require an anterior approach or a posterior decompression with fusion to halt kyphosis. A positive K-line indicates the OPLL does not cross the line, making laminoplasty a viable option.

Question 4840

Topic: 6. Spine

Based on the 4-year and 8-year follow-up data from the Spine Patient Outcomes Research Trial (SPORT) for degenerative spondylolisthesis, which of the following statements most accurately describes the outcomes comparing surgical intervention to non-operative treatment?

. Surgical patients showed initially better outcomes at 1 year, but non-operative patients equalized by 4 years.
. Non-operative treatment showed superior functional outcomes due to high rates of adjacent segment disease in the surgical group.
. Surgical intervention maintained a statistically significant advantage in pain relief and functional improvement over non-operative treatment.
. The incidence of permanent neurologic injury was significantly higher in the surgically treated cohort.
. Surgical treatment had no significant benefit over conservative management on intent-to-treat analysis due to crossover, but actual treatment analysis showed conservative care was superior.

Correct Answer & Explanation

. Surgical intervention maintained a statistically significant advantage in pain relief and functional improvement over non-operative treatment.

Explanation

The SPORT trial for degenerative spondylolisthesis demonstrated that patients who underwent surgical decompression and fusion had significantly greater improvements in pain and function (SF-36, ODI) compared to those treated non-operatively, and this advantage was maintained at 4-year and 8-year follow-ups. While intent-to-treat analyses were often confounded by high crossover rates, the 'as-treated' analysis robustly favored surgical intervention.

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