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6. Spine MCQs

Practice Set 90 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 1781

Topic: 6. Spine

A 60-year-old male is diagnosed with pyogenic spondylodiscitis at L4-L5 growing Methicillin-susceptible Staphylococcus aureus (MSSA). He is hemodynamically stable without epidural abscess or neurologic deficit. What is the minimum recommended duration of appropriate antimicrobial therapy?

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

Correct Answer & Explanation

. 6 weeks

Explanation

For uncomplicated pyogenic spondylodiscitis, current IDSA guidelines recommend a minimum of 6 weeks of targeted antimicrobial therapy to ensure eradication and prevent recurrence.

Question 1782

Topic: 6. Spine

A 45-year-old male presents with right arm pain, numbness in his long finger, and weakness with elbow extension and wrist flexion. An MRI of the cervical spine is most likely to show a posterolateral disc herniation at which of the following levels?

. C4-C5
. C5-C6
. C6-C7
. C7-T1
. T1-T2

Correct Answer & Explanation

. C5-C6

Explanation

The patient's symptoms (triceps weakness, wrist flexion weakness, and long finger numbness) are classic for a C7 radiculopathy. In the cervical spine, exiting nerve roots exit above the correspondingly named pedicle, meaning a C6-C7 disc herniation compresses the C7 nerve root.

Question 1783

Topic: 6. Spine

A 52-year-old female presents with severe right leg pain radiating to her anterior thigh and medial leg, along with weakness in knee extension. MRI reveals a far lateral disc herniation at the L4-L5 level. Which nerve root is most likely compressed?

. L3 exiting root
. L4 exiting root
. L5 exiting root
. L4 traversing root
. L5 traversing root

Correct Answer & Explanation

. L3 exiting root

Explanation

Far lateral (extraforaminal) disc herniations in the lumbar spine typically compress the exiting nerve root at that level, whereas central/paracentral herniations compress the traversing root. A far lateral disc at L4-L5 will compress the exiting L4 nerve root, causing quadriceps weakness and anterior thigh pain.

Question 1784

Topic: 6. Spine

A 14-year-old female undergoes a posterior spinal fusion for adolescent idiopathic scoliosis. On postoperative day 5, she develops severe nausea, bilious emesis, and abdominal distension. What is the most likely pathophysiologic mechanism for her complication?

. Iatrogenic bowel perforation from a malpositioned pedicle screw
. Opiate-induced paralytic ileus
. Compression of the third portion of the duodenum by the superior mesenteric artery
. Acute cholecystitis exacerbated by surgical stress
. Retroperitoneal hematoma compressing the large intestine

Correct Answer & Explanation

. Compression of the third portion of the duodenum by the superior mesenteric artery

Explanation

Superior mesenteric artery (SMA) syndrome is a known complication of scoliosis surgery, resulting from the lengthening of the spine which decreases the angle between the SMA and the aorta. This leads to mechanical compression of the third portion of the duodenum, presenting with bilious emesis and feeding intolerance.

Question 1785

Topic: 6. Spine

During a physical exam for suspected cervical myelopathy, tapping the distal brachioradialis tendon results in reflexive flexion of the fingers without elbow flexion. What is this clinical sign called, and what level of spinal cord compression does it indicate?

. Hoffmann sign; C4-C5 compression
. Inverted brachioradialis reflex; C5-C6 compression
. Babinski sign; T1-T2 compression
. Lhermitte sign; C6-C7 compression
. Wartenberg sign; C7-T1 compression

Correct Answer & Explanation

. Inverted brachioradialis reflex; C5-C6 compression

Explanation

The inverted brachioradialis reflex occurs when tapping the brachioradialis tendon produces finger flexion (a lower cord response) and an absent normal brachioradialis reflex (elbow flexion). It is highly specific for cervical myelopathy with compression at the C5-C6 level.

Question 1786

Topic: 6. Spine

A 55-year-old male undergoes an uneventful C3-C6 laminectomy and fusion for cervical myelopathy. On postoperative day 2, he develops profound new weakness in bilateral deltoids and biceps, with preserved strength in his hands and legs. What is the most widely accepted mechanism for this postoperative complication?

. Intraoperative injury to the recurrent laryngeal nerve
. Posterior drift of the spinal cord resulting in tethering of the nerve roots
. Unrecognized epidural hematoma compressing the anterior spinal artery
. Ischemia of the anterior horn cells at the C8-T1 level
. Inadequate decompression of the C7 neural foramina

Correct Answer & Explanation

. Posterior drift of the spinal cord resulting in tethering of the nerve roots

Explanation

Postoperative C5 palsy is a known complication of cervical decompressive surgery, particularly laminectomy. The most widely accepted etiology is the posterior drift (tethering effect) of the spinal cord following decompression, which places traction on the short, horizontally oriented C5 nerve roots.

Question 1787

Topic: 6. Spine

A 68-year-old female presents with low back pain and severe neurogenic claudication. Flexion-extension radiographs show a Grade 1 degenerative spondylolisthesis at L4-L5. Which of the following is the most accurate statement regarding the typical neurologic compromise in this condition?

. The exiting L4 nerve root is compressed in the lateral recess
. The traversing L5 nerve root is compressed in the lateral recess
. The exiting L5 nerve root is compressed by a hypertrophic facet
. The traversing S1 nerve root is compressed by a paracentral disc
. Neurogenic claudication is relieved by extension of the lumbar spine

Correct Answer & Explanation

. The traversing L5 nerve root is compressed in the lateral recess

Explanation

In degenerative spondylolisthesis, facet hypertrophy and ligamentum flavum infolding cause severe lateral recess and central stenosis. This typically compresses the traversing nerve root (L5 at the L4-L5 level), whereas isthmic spondylolisthesis frequently causes foraminal compression of the exiting root.

Question 1788

Topic: 6. Spine

An 8-month-old male is evaluated for infantile idiopathic scoliosis. Radiographs demonstrate a left thoracic curve of 28 degrees. Measurement of the rib-vertebra angle difference (RVAD) at the apical vertebra is 25 degrees. What is the most likely natural history for this patient's deformity?

. Spontaneous resolution without intervention
. Progression requiring casting or surgical intervention
. Stable curve magnitude until the adolescent growth spurt
. Improvement with aggressive physical therapy
. Rapid progression to neurological compromise

Correct Answer & Explanation

. Progression requiring casting or surgical intervention

Explanation

In infantile idiopathic scoliosis, a rib-vertebra angle difference (RVAD) of greater than 20 degrees is highly predictive of curve progression (Phase II curve). These patients require early intervention, typically beginning with Mehta casting.

Question 1789

Topic: Thoracolumbar Spine & Deformity

A 70-year-old male undergoes evaluation for a significant adult spinal deformity. Standing full-length radiographs reveal a pelvic incidence (PI) of 60 degrees, a lumbar lordosis (LL) of 30 degrees, and a sagittal vertical axis (SVA) of +8 cm. If surgical correction is planned, what is the primary radiographic goal to improve postoperative health-related quality of life (HRQOL)?

. Achieve a lumbar lordosis (LL) of at least 80 degrees
. Correct the SVA to less than +5 cm and PI-LL mismatch to less than 10 degrees
. Reduce the pelvic incidence (PI) to match the lumbar lordosis (LL)
. Increase the pelvic tilt (PT) to greater than 25 degrees
. Ensure the thoracic kyphosis equals the pelvic incidence

Correct Answer & Explanation

. Correct the SVA to less than +5 cm and PI-LL mismatch to less than 10 degrees

Explanation

In adult spinal deformity, restoring sagittal balance is critical for optimizing patient outcomes. The key radiographic goals are an SVA < 50 mm, a Pelvic Tilt (PT) < 20 degrees, and a PI-LL mismatch of less than 10 degrees. Pelvic incidence is a fixed morphologic parameter and cannot be changed surgically.

Question 1790

Topic: 6. Spine

A 40-year-old man has a 6-week history of right-sided sciatica due to an extruded L5-S1 disc herniation. He has normal motor function but severe pain. He elects for continued conservative management. Which of the following best describes the physiological process by which spontaneous disc resorption occurs?

. Fibroblastic replacement and ossification of the nucleus pulposus
. Apoptosis of annular fibrosus cells leading to scar contraction
. Neovascularization and macrophage-mediated phagocytosis of the extruded disc material
. Osmotic fluid shift driven by highly sulfated glycosaminoglycans
. Chondrocytic proliferation resulting in cartilaginous encapsulation

Correct Answer & Explanation

. Neovascularization and macrophage-mediated phagocytosis of the extruded disc material

Explanation

Spontaneous resorption of herniated disc material, particularly extruded or sequestered fragments, is highly common. The pathophysiological mechanism involves an inflammatory response characterized by neovascularization and macrophage-mediated phagocytosis of the disc material.

Question 1791

Topic: 6. Spine
A 50-year-old female presents with acute profound lower extremity weakness, sensory loss below the umbilicus, and urinary retention. MRI reveals a massive central, calcified T8-T9 disc herniation severely compressing the spinal cord. Which of the following surgical approaches is contraindicated in the management of this patient?
. Costotransversectomy
. Lateral extracavitary approach
. Anterior transthoracic approach
. Simple posterior laminectomy
. Transpedicular approach

Correct Answer & Explanation

. Simple posterior laminectomy

Explanation

A simple posterior laminectomy is strictly contraindicated for a central thoracic disc herniation. Removing the posterior elements eliminates the tether, allowing the spinal cord to bowstring posteriorly over the calcified disc, which frequently results in devastating and permanent neurological injury.

Question 1792

Topic: 6. Spine

A 16-year-old male with adolescent idiopathic scoliosis undergoes a posterior spinal fusion. During the deformity correction, the neuromonitoring technician reports a sudden, complete loss of motor evoked potentials (MEPs) in the lower extremities, while somatosensory evoked potentials (SSEPs) remain perfectly intact. Which neural pathway and associated vascular supply are most likely compromised?

. Dorsal columns; Posterior spinal arteries
. Anterior corticospinal tract; Anterior spinal artery
. Spinothalamic tract; Artery of Adamkiewicz
. Rubrospinal tract; Radicular arteries
. Lateral corticospinal tract; Posterior spinal arteries

Correct Answer & Explanation

. Anterior corticospinal tract; Anterior spinal artery

Explanation

Motor evoked potentials (MEPs) monitor the anterior/lateral corticospinal tracts, which are supplied by the anterior spinal artery. A selective loss of MEPs with intact SSEPs strongly suggests ischemia or injury to the anterior spinal cord, which is highly sensitive to hypotension or over-distraction.

Question 1793

Topic: 6. Spine

A 48-year-old male presents with bilateral lower extremity radicular pain, saddle anesthesia, and urinary overflow incontinence. A post-void residual (PVR) ultrasound shows 400 mL of retained urine. MRI confirms a massive L4-L5 disc extrusion. Which of the following is the most critical factor in maximizing the recovery of his bladder function?

. Administration of high-dose methylprednisolone within 8 hours
. Surgical decompression within 48 hours of symptom onset
. Immediate insertion of a suprapubic catheter
. Surgical approach utilizing a minimally invasive tubular retractor
. Performing a concomitant lumbar fusion

Correct Answer & Explanation

. Surgical decompression within 48 hours of symptom onset

Explanation

Cauda equina syndrome is a surgical emergency. The most critical factor for optimizing outcomes, particularly for bladder, bowel, and sexual function, is urgent surgical decompression, ideally within 48 hours of the onset of autonomic symptoms.

Question 1794

Topic: Thoracolumbar Spine & Deformity

A 14-year-old elite gymnast presents with progressive low back pain worsened by extension. Radiographs reveal a Grade 2 isthmic spondylolisthesis at L5-S1. Despite 6 months of rest and core strengthening, she has persistent severe pain. If surgical intervention is chosen, what is the most appropriate procedure?

. L5-S1 microdiscectomy
. L5 pars interarticularis repair (e.g., Scott wiring)
. L5 laminectomy without fusion
. L5-S1 posterior instrumented fusion
. Total disc replacement at L5-S1

Correct Answer & Explanation

. L5-S1 posterior instrumented fusion

Explanation

In a skeletally immature patient with symptomatic isthmic spondylolisthesis that fails conservative management, an in situ posterior spinal fusion is the treatment of choice. Direct pars repair is generally reserved for L4 or above with a defect but minimal slip, while L5-S1 defects with slips require fusion.

Question 1795

Topic: 6. Spine



During posterior instrumentation of the thoracic spine, pedicle screws are being placed. Which of the following anatomic landmarks is most accurate for identifying the starting point for a mid-thoracic pedicle screw?

. The superolateral corner of the facet joint
. The junction of the bisected transverse process and the lateral border of the superior articular process
. 1 mm inferior to the pars interarticularis
. The base of the spinous process
. The inferior border of the inferior articular facet

Correct Answer & Explanation

. The junction of the bisected transverse process and the lateral border of the superior articular process

Explanation

The classic starting point for a thoracic pedicle screw is at the junction of a line bisecting the transverse process and a vertical line drawn along the lateral border of the superior articular facet. The medial-lateral angulation decreases as one moves from T1 to T12.

Question 1796

Topic: 6. Spine

A 42-year-old female is diagnosed with a C5-C6 soft disc herniation causing medically refractory radiculopathy. She is considering cervical disc replacement (CDR) versus anterior cervical discectomy and fusion (ACDF). Which of the following is a recognized absolute contraindication for CDR in this patient?

. Presence of a C5-C6 disc extrusion rather than a protrusion
. A preoperative C5-C6 range of motion of 5 degrees
. Significant facet joint arthropathy at the C5-C6 level
. A history of 6 weeks of failed conservative management
. Tobacco use within the last 3 months

Correct Answer & Explanation

. Significant facet joint arthropathy at the C5-C6 level

Explanation

Cervical disc replacement is contraindicated in the presence of significant facet arthropathy, instability, or severe spondylosis. Preserving motion at a segment with arthritic, painful facets will lead to continued pain and poor clinical outcomes.

Question 1797

Topic: 6. Spine

A 22-year-old patient with an acute posterior sternoclavicular dislocation is undergoing closed reduction under general anesthesia. Traction is applied to the arm in abduction and extension, but the medial clavicle fails to reduce. What is the most appropriate next step in the reduction maneuver?

. Apply direct posterior pressure on the medial clavicle
. Hyperflex and adduct the arm aggressively across the chest
. Use a sterile towel clip to grasp the medial clavicle percutaneously and pull anteriorly
. Perform an immediate open resection of the medial clavicle
. Apply longitudinal superior traction to the cervical spine

Correct Answer & Explanation

. Use a sterile towel clip to grasp the medial clavicle percutaneously and pull anteriorly

Explanation

If traction combined with extension and abduction fails to unlock a posterior SC dislocation, the surgeon should prep the chest and percutaneously grasp the medial clavicle with a sterile towel clip to provide direct anterior traction.

Question 1798

Topic: 6. Spine

A 45-year-old male presents with severe shoulder pain after a motorcycle accident. Radiographs reveal lateral displacement of the intact scapula relative to the thoracic spine, an intact clavicle, and significant soft tissue swelling. What devastating concomitant injury is highly associated with this pattern?

. Esophageal rupture
. Tension pneumothorax
. Complete brachial plexus avulsion and subclavian artery disruption
. Tracheobronchial tree laceration
. Aortic transection

Correct Answer & Explanation

. Complete brachial plexus avulsion and subclavian artery disruption

Explanation

The scenario describes a scapulothoracic dissociation, characterized by lateral displacement of the scapula. This high-energy injury carries a massive risk of severe neurovascular compromise, particularly complete brachial plexus avulsion and subclavian artery disruption.

Question 1799

Topic: 6. Spine

A 25-year-old motorcyclist sustains severe high-energy blunt trauma to his shoulder. Radiographs reveal marked lateral displacement of the scapula. Which associated injury must be urgently ruled out as it represents the highest risk of immediate mortality?

. Brachial plexus avulsion
. Pneumothorax
. Subclavian artery disruption
. Axillary nerve transection
. Cervical spine fracture

Correct Answer & Explanation

. Subclavian artery disruption

Explanation

Scapulothoracic dissociation involves a complete disruption of the scapulothoracic articulation. It is highly associated with life-threatening subclavian or axillary artery injuries, requiring urgent vascular evaluation.

Question 1800

Topic: 6. Spine

A 28-year-old male is brought to the trauma bay after a diving accident, presenting with a bilateral C4-C5 facet dislocation and an ASIA A complete spinal cord injury. He is intubated and sedated, making a reliable neurological examination impossible. Which of the following is the most appropriate next step in his management regarding imaging and potential reduction?

. Immediately attempt closed reduction with Gardner-Wells tongs, monitoring for changes in vital signs.
. Proceed directly to the operating room for emergent open reduction and stabilization without further imaging.
. Obtain a magnetic resonance imaging (MRI) of the cervical spine prior to any reduction attempt.
. Perform a computed tomography angiography (CTA) to rule out vertebral artery injury before considering reduction.
. Administer high-dose methylprednisolone and observe for neurological improvement before any intervention.

Correct Answer & Explanation

. Obtain a magnetic resonance imaging (MRI) of the cervical spine prior to any reduction attempt.

Explanation

Correct Answer: CThe timing of magnetic resonance imaging (MRI) in relation to closed reduction is critical. For awake, alert, and cooperative patients, rapid closed reduction via cranial traction can be attempted prior to MRI, provided serial neurological examinations are performed. However, if the patient is uncooperative, intoxicated, or comatose (as in this intubated and sedated patient with an ASIA A injury), MRI must be obtained prior to any reduction attempt. This is to evaluate for a traumatic disc herniation, which occurs in 30-60% of cases. If a massive disc herniation is present, an anterior cervical discectomy must be performed before reduction to prevent catastrophic cord compression from retropulsed disc material.Option A is incorrect because attempting closed reduction in an obtunded patient without prior MRI carries a high risk of iatrogenic neurological deterioration. Option B is incorrect as further imaging is crucial for surgical planning and safety. Option D (CTA) is important if there's suspicion of vertebral artery injury, but MRI for disc herniation takes precedence before reduction in this scenario. Option E (methylprednisolone) is no longer routinely recommended for acute spinal cord injury due to lack of clear benefit and potential side effects.

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