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6. Spine MCQs

Practice Set 315 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 6281

Topic: 6. Spine

A 68-year-old male presents to the emergency department after falling forward and striking his chin, sustaining a hyperextension injury to his cervical spine. On examination, he exhibits bilateral upper extremity weakness (motor grade 2/5) but is able to move his lower extremities against resistance (motor grade 4/5). He also has patchy sensory deficits. Which spinal cord syndrome is most likely, and what is its typical prognosis for future ambulation?

. Anterior cord syndrome; poor prognosis for ambulation.
. Central cord syndrome; good prognosis for ambulation.
. Brown-Sequard syndrome; good prognosis for ambulation.
. Posterior cord syndrome; poor prognosis for ambulation.
. Conus medullaris syndrome; fair prognosis for ambulation.

Correct Answer & Explanation

. Anterior cord syndrome; poor prognosis for ambulation.

Explanation

This classic presentation represents Central Cord Syndrome, which typically occurs in elderly patients with pre-existing cervical spondylosis who sustain a hyperextension injury. It affects the centrally located cervical tracts supplying the upper extremities more than the peripherally located tracts supplying the lower extremities. The prognosis for ambulation is generally good, with most patients regaining the ability to walk, although fine motor function in the hands often remains impaired.

Question 6282

Topic: 6. Spine

The modified Tokuhashi scoring system is a widely utilized tool to predict life expectancy in patients with metastatic spine disease and to guide surgical decision-making. Which of the following parameters is specifically evaluated in this scoring system?

. Patient's chronologic age
. Primary tumor site
. Spine bone mineral density (DEXA T-score)
. History of previous chemotherapy
. Serum calcium and alkaline phosphatase levels

Correct Answer & Explanation

. Patient's chronologic age

Explanation

The modified Tokuhashi score evaluates six parameters: 1) General condition (Karnofsky performance status), 2) Number of extraspinal bone metastases, 3) Number of vertebral metastases, 4) Metastases to major internal organs, 5) Primary tumor site (e.g., thyroid/breast/prostate score higher than lung/stomach), and 6) Severity of spinal cord palsy. Age, BMD, and chemotherapy history are not specific components of the score.

Question 6283

Topic: 6. Spine

A 15-year-old male presents with a progressive rounding of his back. Lateral radiographs are taken to evaluate for Scheuermann's kyphosis. According to the classic Sorensen criteria, which of the following radiographic findings confirms the diagnosis?

. Thoracic kyphosis > 40 degrees and at least one wedged vertebra of 5 degrees.
. Thoracic kyphosis > 45 degrees and at least three consecutive wedged vertebrae of 5 degrees each.
. Thoracic kyphosis > 50 degrees with the presence of multiple Schmorl's nodes.
. Thoracic kyphosis > 45 degrees and at least two consecutive wedged vertebrae of 10 degrees each.
. Any degree of kyphosis associated with a symptomatic syrinx.

Correct Answer & Explanation

. Thoracic kyphosis > 40 degrees and at least one wedged vertebra of 5 degrees.

Explanation

The classic Sorensen criteria for the diagnosis of Scheuermann's disease include a thoracic kyphosis greater than 45 degrees and the presence of anterior wedging of at least 5 degrees in three or more consecutive vertebrae. Other findings like Schmorl's nodes and endplate irregularities are common but are not the primary defining diagnostic criteria.

Question 6284

Topic: 6. Spine

A 55-year-old female undergoes a complex 10-hour posterior spinal fusion for degenerative scoliosis. During the surgery, there is significant estimated blood loss requiring massive transfusion, and prolonged hypotensive anesthesia is maintained. Upon waking in the recovery room, she complains of bilateral, painless vision loss. What is the most common cause of postoperative vision loss (POVL) in this specific clinical scenario?

. Central retinal artery occlusion
. Cortical blindness
. Ischemic optic neuropathy
. Acute angle-closure glaucoma
. Retinal detachment

Correct Answer & Explanation

. Central retinal artery occlusion

Explanation

Ischemic Optic Neuropathy (ION) is the most common cause of postoperative vision loss (POVL) following major prone spine surgery. Risk factors include prolonged surgical time, large blood loss, intraoperative hypotension, and prone positioning which increases venous pressure in the head. Central retinal artery occlusion is less common and is typically unilateral due to direct globe compression.

Question 6285

Topic: 6. Spine

Ossification of the posterior longitudinal ligament (OPLL) is a frequent cause of myelopathy. Which of the following describes the most common anatomical location and the most characteristic patient demographic for this condition?

. Lumbar spine in patients of African descent
. Cervical spine in patients of East Asian descent
. Thoracic spine in patients of Caucasian descent
. Cervical spine in patients of Hispanic descent
. Lumbar spine in patients of Caucasian descent

Correct Answer & Explanation

. Lumbar spine in patients of African descent

Explanation

OPLL is most prevalent in East Asian populations (particularly Japanese, where the prevalence can be 2-3%). It predominantly affects the cervical spine, leading to cervical myelopathy due to progressive anterior compression of the spinal cord by the ossified ligament.

Question 6286

Topic: 6. Spine

A 30-year-old male is evaluated in the trauma bay following a high-speed rollover motor vehicle collision. AP and lateral cervical radiographs reveal a unilateral facet dislocation at C5-C6 on the right side. What is the primary mechanism of injury, and what is the typical radiographic appearance on the AP view?

. Flexion and distraction; the spinous process points toward the dislocated side.
. Flexion and rotation; the spinous process points toward the dislocated side.
. Extension and rotation; the spinous process points away from the dislocated side.
. Vertical compression; the spinous process points away from the dislocated side.
. Lateral bending; the spinous process remains midline.

Correct Answer & Explanation

. Flexion and distraction; the spinous process points toward the dislocated side.

Explanation

Unilateral facet dislocations are primarily caused by a flexion-rotation mechanism. On an AP radiograph, the spinous process of the dislocated vertebra appears deviated toward the side of the dislocated facet. This is because the anterior vertebral body rotates away from the dislocated side, causing the posterior elements (spinous process) to swing toward the dislocated side.

Question 6287

Topic: 6. Spine

Recombinant human bone morphogenetic protein-2 (rhBMP-2) possesses potent osteoinductive properties and is used off-label in various spinal fusion procedures. If utilized in anterior cervical spine surgery (e.g., ACDF), what is a well-documented, potentially life-threatening complication that prompted an FDA warning?

. Recurrent laryngeal nerve palsy
. Severe dysphagia and prevertebral soft-tissue swelling
. Pseudoarthrosis at the operated level
. Vertebral artery thrombosis
. Esophageal perforation

Correct Answer & Explanation

. Recurrent laryngeal nerve palsy

Explanation

The off-label use of rhBMP-2 in anterior cervical spine surgery has been strongly linked to exaggerated prevertebral soft-tissue swelling and severe dysphagia, which can precipitate airway compromise. Consequently, the FDA issued a public health advisory warning against its routine use in the anterior cervical spine.

Question 6288

Topic: Cervical Spine
According to the Fielding and Hawkins classification for atlantoaxial rotatory subluxation (AARS) in pediatric patients, what radiographic parameter defines a Type II injury?
. Rotatory fixation with an atlantodens interval (ADI) less than 3 mm
. Rotatory fixation with anterior displacement and an ADI of 3 to 5 mm
. Rotatory fixation with anterior displacement and an ADI greater than 5 mm
. Rotatory fixation combined with posterior displacement of the atlas
. Rotatory fixation with significant vertical translation

Correct Answer & Explanation

. Rotatory fixation with anterior displacement and an ADI of 3 to 5 mm

Explanation

The Fielding and Hawkins classification for AARS is: Type I: Rotatory fixation with no anterior displacement (ADI < 3 mm); transverse ligament intact. Type II: Rotatory fixation with anterior displacement of 3-5 mm; transverse ligament ruptured but alar ligaments intact. Type III: Anterior displacement > 5 mm; rupture of transverse and alar ligaments. Type IV: Posterior displacement of the atlas.

Question 6289

Topic: Thoracolumbar Spine & Deformity
A 14-year-old female gymnast presents with insidious onset lower back pain. Imaging confirms an L5-S1 spondylolisthesis secondary to bilateral stress fractures of the pars interarticularis. According to the Wiltse classification of spondylolisthesis, which type does this represent?
. Type I (Dysplastic)
. Type II (Isthmic)
. Type III (Degenerative)
. Type IV (Traumatic)
. Type V (Pathologic)

Correct Answer & Explanation

. Type II (Isthmic)

Explanation

The Wiltse classification categorizes spondylolisthesis by etiology. Type I is Dysplastic (congenital anomaly). Type II is Isthmic (lesion in the pars interarticularis, common in gymnasts). Type III is Degenerative. Type IV is Traumatic (fracture in areas other than the pars). Type V is Pathologic (generalized or localized bone disease). Type VI is Iatrogenic (post-surgical).

Question 6290

Topic: 6. Spine

Pyogenic spondylodiscitis is a serious spinal infection that most frequently affects the lumbar spine in adult patients. What is the most common route of pathogen dissemination leading to this condition?

. Retrograde spread through Batson's venous plexus
. Hematogenous spread via the arterial system
. Direct contiguous spread from a psoas abscess
. Lymphatic spread from the genitourinary tract
. Direct inoculation from previous spinal surgery

Correct Answer & Explanation

. Retrograde spread through Batson's venous plexus

Explanation

While retrograde venous spread via Batson's plexus was historically emphasized in older literature, contemporary understanding establishes that hematogenous spread via the arterial system is the most common route for pyogenic spondylodiscitis in adults. The infection typically lodges in the highly vascularized subchondral bone adjacent to the endplate before spreading to the disc.

Question 6291

Topic: Thoracolumbar Spine & Deformity

A 40-year-old male presents with severe mechanical back pain. Standing lateral radiographs reveal an isthmic spondylolisthesis at L5-S1. The L5 vertebral body has slipped anteriorly by 60% of the width of the S1 endplate. According to the Meyerding classification, what grade is this slip?

. Grade 1
. Grade 2
. Grade 3
. Grade 4
. Grade 5 (Spondyloptosis)

Correct Answer & Explanation

. Grade 1

Explanation

The Meyerding classification grades spondylolisthesis based on the percentage of anterior slip: Grade 1 (0-25%), Grade 2 (26-50%), Grade 3 (51-75%), Grade 4 (76-100%), and Grade 5 (>100%, also known as spondyloptosis). A 60% slip falls into the Grade 3 category.

Question 6292

Topic: 6. Spine

A 45-year-old male presents with severe radiating leg pain. MRI of the lumbar spine reveals a far lateral (extraforaminal) disc herniation at the L4-L5 level. Which nerve root is predominantly compressed by a herniation in this specific location?

. L3
. L4
. L5
. S1
. S2

Correct Answer & Explanation

. L3

Explanation

In the lumbar spine, a far lateral (extraforaminal) disc herniation compresses the exiting nerve root at that level. Therefore, at L4-L5, a far lateral disc herniation will compress the L4 nerve root. In contrast, a central or paracentral disc herniation at L4-L5 would compress the traversing L5 nerve root.

Question 6293

Topic: 6. Spine

A 65-year-old male with long-standing, advanced ankylosing spondylitis presents to the emergency department after a low-energy mechanical fall. He complains of severe neck pain but has a normal neurological examination. Radiographs and CT reveal a highly unstable, extension-type fracture through the C5-C6 disc space extending into the posterior elements. What is the most appropriate definitive management?

. Rigid cervical collar immobilization for 12 weeks
. Halo-vest application
. Long-segment posterior cervical fusion
. Single-level anterior cervical discectomy and fusion (ACDF)
. Cervical laminectomy without fusion

Correct Answer & Explanation

. Rigid cervical collar immobilization for 12 weeks

Explanation

Spinal fractures in patients with ankylosing spondylitis are highly unstable, often traversing all three columns, and the fused spine acts as a long lever arm. Conservative management (collar or halo) has a high failure rate and significant complication profile in these patients. The gold standard treatment is rigid internal fixation, typically involving a long-segment posterior fusion (often 3 levels above and below the fracture) to resist the extreme lever-arm forces.

Question 6294

Topic: 6. Spine

Degenerative spondylolisthesis most commonly occurs at the L4-L5 level in older adults, particularly females. Which anatomical feature is most strongly associated with the predisposition for developing degenerative spondylolisthesis at this specific level?

. Coronal orientation of the facet joints
. Sagittal orientation of the facet joints
. Spina bifida occulta at L5
. Transitional lumbosacral vertebra (sacralization)
. Dysplastic pedicles at L4

Correct Answer & Explanation

. Coronal orientation of the facet joints

Explanation

The development of degenerative spondylolisthesis is strongly associated with a more sagittal orientation of the facet joints at the L4-L5 level. Normally, L4-L5 facet joints have a more coronal orientation, which biomechanically resists anterior translation. A more sagittally oriented facet joint provides less resistance to shear forces, predisposing the segment to anterior slippage as the disc degenerates.

Question 6295

Topic: 6. Spine

A 40-year-old trauma patient requires the application of a halo-vest for a cervical spine injury. To minimize the risk of iatrogenic injury to the supraorbital and supratrochlear nerves, what is the optimal anatomical placement for the anterior halo pins?

. Medial to the supraorbital notch
. Directly over the frontal sinus
. Lateral one-third of the eyebrow, approximately 1 cm superior to the orbital rim
. Posterior to the external auditory meatus
. Directly at the glabella

Correct Answer & Explanation

. Medial to the supraorbital notch

Explanation

Safe placement of anterior halo pins requires positioning them in the lateral one-third of the eyebrow (or lateral to the supraorbital notch), approximately 1 cm superior to the orbital rim. This location avoids the supratrochlear and supraorbital nerves, which run medially. Placing pins medially risks nerve injury, and placing them over the frontal sinus or glabella risks penetration of the thin bone and sinus.

Question 6296

Topic: Cervical Spine

Fractures of the odontoid process (dens) are classified into three types by Anderson and D'Alonzo. Type II fractures are notorious for having a high rate of nonunion. What is the primary anatomical reason for this high nonunion rate?

. They occur through the area of highest biomechanical stress at the tip.
. They directly sever the primary blood supply from the vertebral artery.
. The fracture line passes through a watershed vascular zone at the base of the dens.
. There is constant interposition of the transverse ligament in the fracture gap.
. Disruption of the alar ligaments leaves the proximal fragment entirely avascular.

Correct Answer & Explanation

. They occur through the area of highest biomechanical stress at the tip.

Explanation

Type II odontoid fractures occur at the base (junction) of the dens and the body of C2. This region represents a vascular watershed zone between the blood supply provided by the apical arcade (via the alar ligaments) and the vessels supplying the body of C2. This tenuous blood supply, combined with the small surface area and high mobility of the segment, leads to a high rate of nonunion if not adequately immobilized or surgically fixed.

Question 6297

Topic: 6. Spine

A 25-year-old male is involved in a high-speed motor vehicle collision while wearing only a lap belt. He sustains a classic Chance fracture of the L2 vertebra. Based on the Denis three-column classification of the spine, which columns are involved in the pathomechanics of a classic Chance fracture?

. Anterior and middle columns
. Posterior and middle columns
. Anterior, middle, and posterior columns
. Posterior column only
. Middle column only

Correct Answer & Explanation

. Anterior and middle columns

Explanation

A classic Chance fracture (seatbelt fracture) is a flexion-distraction injury. The axis of rotation is anterior to the vertebral body (at the abdominal wall where the seatbelt sits). This causes tension failure extending through the posterior, middle, and anterior columns of the spine. Therefore, all three Denis columns are disrupted (typically bony failure through the spinous process, pedicles, and vertebral body).

Question 6298

Topic: 6. Spine

In the evaluation of adult spinal deformity, achieving neutral global sagittal balance is a key surgical objective. What is the generally accepted threshold for a normal Sagittal Vertical Axis (SVA), measured as the distance from the C7 plumb line to the posterior superior corner of S1?

. Less than 0 cm (a negative SVA is required)
. Less than 5 cm
. Less than 10 cm
. Less than 15 cm
. Less than 20 cm

Correct Answer & Explanation

. Less than 0 cm (a negative SVA is required)

Explanation

The Sagittal Vertical Axis (SVA) is a measure of global sagittal alignment. A normal or well-compensated SVA is generally considered to be less than 5 cm (i.e., the C7 plumb line falls within 5 cm anterior or posterior to the posterior-superior corner of the S1 endplate). An SVA greater than 5 cm indicates positive sagittal malalignment, which correlates strongly with poor health-related quality of life (HRQOL) scores.

Question 6299

Topic: 6. Spine

A 24-year-old male arrives at the trauma bay following a high-speed motor vehicle collision. Neurologic examination reveals no voluntary motor function or sensation below the T4 dermatome. His rectal tone is flaccid, and the bulbocavernosus reflex is absent. Which of the following statements regarding his neurologic prognosis is most accurate?

. The patient has a complete spinal cord injury (ASIA A) and is unlikely to recover function.
. The administration of high-dose methylprednisolone within 8 hours will significantly improve motor recovery.
. An accurate prediction of neurologic recovery cannot be established until the bulbocavernosus reflex returns.
. The presence of spinal shock indicates a higher likelihood of long-term spasticity.
. Immediate surgical decompression within 4 hours is mandatory to reverse the flaccid paralysis.

Correct Answer & Explanation

. The patient has a complete spinal cord injury (ASIA A) and is unlikely to recover function.

Explanation

The absence of the bulbocavernosus reflex indicates the patient is in a state of spinal shock. During spinal shock, the true extent of the spinal cord injury cannot be accurately determined. Prognostication and ASIA classification must be deferred until the reflex returns, marking the resolution of spinal shock.

Question 6300

Topic: 6. Spine

A 45-year-old female presents with sharp, radiating right arm pain. Examination demonstrates significant weakness in right wrist extension, numbness over the dorsal aspect of the thumb and index finger, and a diminished brachioradialis reflex. 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

. C4-C5

Explanation

The patient's findings (weak wrist extension, numbness in the thumb/index finger, diminished brachioradialis reflex) correspond to a C6 radiculopathy. In the cervical spine, exiting nerve roots exit above their corresponding pedicle. Therefore, a C5-C6 posterolateral disc herniation impinges the exiting C6 nerve root.

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