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6. Spine MCQs

Practice Set 37 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 721

Topic: 6. Spine

A 62-year-old Asian man presents with signs of progressive thoracic myelopathy. Sagittal CT imaging demonstrates beak-like osseous excrescences projecting anteriorly from the posterior elements at the T10-T11 level. What is the most likely diagnosis?

. Ossification of the posterior longitudinal ligament
. Ossification of the ligamentum flavum
. Thoracic disc herniation
. Epidural lipomatosis
. Spinal meningioma

Correct Answer & Explanation

. Ossification of the ligamentum flavum

Explanation

Ossification of the ligamentum flavum (OLF) predominantly affects the lower thoracic spine (T10-T12) and is a well-known cause of thoracic myelopathy. It occurs most frequently in populations of East Asian descent and presents with posterior cord compression.

Question 722

Topic: 6. Spine

A 15-year-old boy presents with back pain and increasing thoracic kyphosis. Lateral radiographs of the thoracic spine demonstrate distinct anterior wedging of the vertebral bodies. According to the Sorensen criteria, what is required to confirm a diagnosis of Scheuermann kyphosis?

. Anterior wedging of >5 degrees in at least three consecutive vertebrae
. Anterior wedging of >10 degrees in two consecutive vertebrae
. Intervertebral disc space widening with endplate sclerosis
. Posterior wedging of >5 degrees in at least three consecutive vertebrae
. Cobb angle of >45 degrees with isolated Schmorl nodes

Correct Answer & Explanation

. Anterior wedging of >5 degrees in at least three consecutive vertebrae

Explanation

The classic Sorensen criteria for diagnosing Scheuermann kyphosis mandate anterior wedging of 5 degrees or more in at least three consecutive vertebral bodies. Associated findings often include Schmorl nodes and irregular vertebral endplates.

Question 723

Topic: 6. Spine

A 25-year-old man is brought to the trauma bay following a high-speed motor vehicle collision where he was wearing only a lap belt. Radiographs show a transverse fracture through the vertebral body, pedicles, and spinous process of T12. Which of the following is most commonly associated with this injury pattern?

. Axial loading mechanism associated with burst fractures
. Hyperextension injury associated with spinal epidural hematomas
. Flexion-distraction injury associated with hollow viscus intra-abdominal injuries
. Rotational injury mechanism resulting in unilateral facet dislocations
. Shear force injury predominantly failing the anterior longitudinal ligament

Correct Answer & Explanation

. Flexion-distraction injury associated with hollow viscus intra-abdominal injuries

Explanation

A Chance fracture is a flexion-distraction injury typically caused by a lap belt acting as a fulcrum. It is highly associated with concomitant hollow viscus intra-abdominal injuries (up to 50% of cases), requiring careful general surgical evaluation.

Question 724

Topic: 6. Spine

A 68-year-old man presents with chronic stiffness in his middle and upper back. Radiographs reveal diffuse flowing ossification along the anterolateral aspect of the thoracic spine. To formally diagnose Diffuse Idiopathic Skeletal Hyperostosis (DISH), the Resnick criteria require which of the following?

. Flowing ossification of the ALL across at least two contiguous levels
. Flowing ossification of the ALL across at least four contiguous levels with preserved disc heights
. Continuous ossification of the posterior longitudinal ligament with canal stenosis
. Marginal syndesmophytes bridging three consecutive disc spaces with SI joint fusion
. Anterior wedging of three consecutive vertebrae with anterior osteophytes

Correct Answer & Explanation

. Flowing ossification of the ALL across at least four contiguous levels with preserved disc heights

Explanation

The Resnick criteria for DISH require flowing ossification of the anterior longitudinal ligament across at least four contiguous vertebral bodies. Furthermore, disc heights must be relatively preserved, and there should be an absence of sacroiliac joint sclerosis or fusion.

Question 725

Topic: 6. Spine

When planning for posterior instrumented fusion of the thoracic spine, pre-operative computed tomography (CT) is utilized to evaluate pedicle morphology. In the normal adult spine, the narrowest pedicle diameters are typically found at which levels?

. T1-T3
. T4-T6
. T7-T9
. T10-T12
. L1-L3

Correct Answer & Explanation

. T4-T6

Explanation

The narrowest pedicle diameters in the thoracic spine are typically located at the T4 to T6 levels. Preoperative CT planning is essential to ensure safe pedicle screw placement and to determine if alternative fixation, such as hooks or extrapedicular screws, is needed.

Question 726

Topic: 6. Spine

A patient undergoes an anterior approach for the excision of a symptomatic thoracic disc herniation. Post-operatively, the patient is noted to have ipsilateral ptosis, miosis, and anhidrosis. The surgery was most likely performed at which of the following thoracic levels?

. Upper thoracic (T1-T2)
. Mid-thoracic (T5-T6)
. Lower thoracic (T9-T10)
. Thoracolumbar junction (T12-L1)
. Mid-lumbar (L3-L4)

Correct Answer & Explanation

. Upper thoracic (T1-T2)

Explanation

Anterior surgical approaches to the upper thoracic spine (T1-T2) risk injury to the stellate ganglion or the upper sympathetic chain. This iatrogenic injury results in Horner syndrome, clinically presenting as ptosis, miosis, and anhidrosis.

Question 727

Topic: 6. Spine

A 40-year-old immigrant presents with chronic back pain, low-grade fevers, and an increasing gibbus deformity. Imaging demonstrates anterior vertebral body destruction with disc space narrowing. In spinal tuberculosis (Pott disease), what is the most common anatomic location of involvement?

. Upper cervical spine
. Thoracolumbar junction
. Mid-lumbar spine
. Lumbosacral junction
. Sacroiliac joint

Correct Answer & Explanation

. Thoracolumbar junction

Explanation

Spinal tuberculosis (Pott disease) most commonly affects the lower thoracic and upper lumbar spine (thoracolumbar junction). The infection classically begins in the anterior vertebral metaphysis and spreads under the anterior longitudinal ligament, leading to anterior collapse and gibbus deformity.

Question 728

Topic: 6. Spine

A 16-year-old boy presents with severe mid-back pain that is worse at night. The pain is consistently relieved by ibuprofen. A CT scan of the thoracic spine is obtained. Based on his likely diagnosis, where is the lesion most commonly located anatomically?

. Night pain unrelieved by NSAIDs, located in the vertebral body
. Radicular pain worsened by extension, located in the intervertebral disc
. Unremitting night pain relieved by NSAIDs, located in the posterior elements
. Painful scoliosis with the lesion located on the concavity of the curve
. Asymptomatic incidental finding, located in the spinous process

Correct Answer & Explanation

. Unremitting night pain relieved by NSAIDs, located in the posterior elements

Explanation

Osteoid osteomas of the spine classically present with nocturnal pain that is dramatically relieved by NSAIDs. When occurring in the spine, they are almost exclusively located in the posterior elements (e.g., lamina, pedicle, pars).

Question 729

Topic: 6. Spine

A 45-year-old man presents with progressive lower extremity weakness and myelopathy. Imaging reveals a large, central, heavily calcified thoracic disc herniation at T8-T9. Why is a standard posterior laminectomy contraindicated in this clinical scenario?

. It causes unacceptable postsurgical kyphosis.
. It fails to decompress the thoracic nerve roots adequately.
. It is associated with catastrophic neurological deterioration.
. It necessitates an unnecessary dural opening.
. It significantly increases the risk of spinal epidural hematoma.

Correct Answer & Explanation

. It is associated with catastrophic neurological deterioration.

Explanation

Standard posterior laminectomy for central thoracic disc herniations is absolutely contraindicated due to a high rate of catastrophic neurological deterioration. Retraction of the thoracic spinal cord to access a central disc is poorly tolerated due to its limited mobility and tenuous blood supply.

Question 730

Topic: 6. Spine

A surgeon is planning a left-sided anterior transthoracic approach to decompress a symptomatic T10-T11 disc herniation. Which critical vascular structure is at greatest risk during the exposure on the left side of the lower thoracic spine?

. Thoracic duct
. Azygos vein
. Artery of Adamkiewicz
. Superior vena cava
. Recurrent laryngeal nerve

Correct Answer & Explanation

. Artery of Adamkiewicz

Explanation

The Artery of Adamkiewicz provides the major arterial supply to the lower two-thirds of the spinal cord. It typically originates from the left side between T8 and L1, making it highly vulnerable during left-sided anterior approaches to the lower thoracic spine.

Question 731

Topic: 6. Spine

What is the most common initial presenting symptom in patients with a symptomatic thoracic disc herniation?

. Lower extremity paresis
. Bowel and bladder incontinence
. Band-like chest radiculopathy
. Axial thoracic back pain
. Sensory ataxia

Correct Answer & Explanation

. Axial thoracic back pain

Explanation

Axial thoracic back pain is the most common presenting symptom in patients with thoracic disc herniations. Although myelopathic symptoms or band-like radicular pain often prompt surgical intervention, localized axial pain is frequently the earliest manifestation.

Question 732

Topic: 6. Spine

Which of the following radiographic characteristics of a thoracic disc herniation is most strongly associated with intradural extension?

. Gas in the disc space (Vacuum phenomenon)
. Heavy disc calcification
. Bridging spondylophytes
. Modic Type 1 endplate changes
. Decreased intervertebral disc height

Correct Answer & Explanation

. Heavy disc calcification

Explanation

Disc calcification is strongly associated with intradural extension and dural adherence in thoracic disc herniations. Calcified thoracic discs are often termed "hard discs" and carry a higher risk of dural tears during surgical resection.

Question 733

Topic: 6. Spine

A 35-year-old woman presents with severe right-sided band-like chest pain radiating along the T7 dermatome. MRI reveals a soft, right-sided far-lateral disc herniation at T7-T8 with no myelopathy. What is the most appropriate surgical approach if conservative measures fail?

. Anterior transthoracic approach
. Posterolateral transpedicular approach
. Standard posterior laminectomy
. Anterior corpectomy and fusion
. Video-assisted thoracoscopic surgery (VATS)

Correct Answer & Explanation

. Posterolateral transpedicular approach

Explanation

The posterolateral transpedicular approach is ideal for lateral and foraminal soft thoracic disc herniations. It avoids the morbidity of a transthoracic approach while safely decompressing the nerve root without manipulating the spinal cord.

Question 734

Topic: 6. Spine

The thoracic spinal cord is particularly vulnerable to ischemic injury due to a vascular "watershed" area. This zone of precarious blood supply is typically located between which vertebral levels?

. C7 to T2
. T4 to T9
. T10 to T12
. T12 to L2
. L3 to L5

Correct Answer & Explanation

. T4 to T9

Explanation

The upper thoracic spine receives blood from the radicular arteries of the neck, and the lower cord from the Artery of Adamkiewicz. The mid-thoracic region (T4-T9) serves as a vascular watershed zone, making it highly susceptible to ischemic insults.

Question 735

Topic: 6. Spine

A 52-year-old man presents with acute onset of saddle anesthesia, bowel incontinence, and bilateral leg weakness. MRI demonstrates a large, extruded disc herniation. Given the clinical presentation, at which of the following thoracic levels is the herniation most likely located?

. T4-T5
. T6-T7
. T8-T9
. T11-T12
. L2-L3

Correct Answer & Explanation

. T11-T12

Explanation

A herniation at T11-T12 or T12-L1 compresses the conus medullaris, resulting in conus medullaris syndrome. This presents with mixed upper and lower motor neuron signs, saddle anesthesia, and early bowel/bladder dysfunction.

Question 736

Topic: 6. Spine

Following a right-sided transthoracic approach for a T8-T9 disc herniation, the patient is noted to have an asymmetric umbilicus that deviates upward upon flexing the neck (positive Beevor's sign). What is the most likely cause?

. Spinal cord infarction
. Injury to the T8 and T9 intercostal nerves
. Iatrogenic diaphragmatic palsy
. Injury to the sympathetic chain
. Postoperative epidural hematoma

Correct Answer & Explanation

. Injury to the T8 and T9 intercostal nerves

Explanation

Beevor's sign occurs when the lower abdominal muscles are paralyzed, causing the umbilicus to deviate upward during abdominal contraction. This indicates injury or dysfunction of the lower thoracic nerve roots (T10-T12) or, as in this case, selective denervation of the T8/T9 intercostal nerves supplying the rectus abdominis.

Question 737

Topic: 6. Spine

Which of the following represents an absolute contraindication to Video-Assisted Thoracoscopic Surgery (VATS) for the treatment of a thoracic disc herniation?

. Previous thoracotomy with extensive pleural adhesions
. Morbid obesity (BMI > 40)
. Presence of a calcified disc
. Concurrent thoracic myelopathy
. Multilevel disc degeneration

Correct Answer & Explanation

. Previous thoracotomy with extensive pleural adhesions

Explanation

Extensive pleural adhesions, typically from previous thoracotomy, severe empyema, or pleurodesis, represent an absolute contraindication to VATS. The adhesions prevent safe lung deflation and endoscopic visualization of the spine.

Question 738

Topic: 6. Spine

Why are clinical thoracic disc herniations significantly less common than those in the cervical and lumbar regions?

. The thoracic discs completely lack a nucleus pulposus.
. The thoracic spine is hypermobile, preventing disc desiccation.
. The rib cage and coronal facet joints provide rigid stabilization.
. Thoracic discs possess a higher concentration of proteoglycans.
. The thoracic spinal canal is significantly wider than the lumbar canal.

Correct Answer & Explanation

. The rib cage and coronal facet joints provide rigid stabilization.

Explanation

The splinting effect of the rib cage and the coronal orientation of the facet joints severely limit flexion, extension, and rotation in the thoracic spine. This rigid stabilization dramatically reduces the mechanical stress placed on thoracic intervertebral discs.

Question 739

Topic: 6. Spine

Within the thoracic spinal canal, what is the most common anatomical location for a symptomatic disc herniation to occur?

. Far lateral (extraforaminal)
. Foraminal
. Central or paracentral
. Anterior to the anterior longitudinal ligament
. Posterior to the ligamentum flavum

Correct Answer & Explanation

. Central or paracentral

Explanation

Unlike lumbar disc herniations, which are typically posterolateral, approximately 75% of symptomatic thoracic disc herniations occur in the central or paracentral location. This directly contributes to their high propensity for causing myelopathy.

Question 740

Topic: 6. Spine

What anatomical feature of the thoracic spinal canal contributes significantly to the high risk of myelopathy from a central disc herniation?

. It is triangular with a low cord-to-canal ratio.
. It is circular with a high cord-to-canal ratio.
. It is oval with extremely wide lateral recesses.
. It is trefoil with a low cord-to-canal ratio.
. It is triangular with absent epidural fat.

Correct Answer & Explanation

. It is circular with a high cord-to-canal ratio.

Explanation

The thoracic spinal canal is circular and has a very high cord-to-canal ratio, meaning the spinal cord occupies most of the available space. This "tight fit" leaves minimal reserve capacity, allowing even small disc herniations to cause significant cord compression.

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