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6. Spine MCQs

Practice Set 83 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 1641

Topic: 6. Spine

When performing a Wiltse paraspinal muscle-splitting approach for a far lateral L4-L5 disc herniation, the deep dissection plane is developed between which two muscles?

. Multifidus and Longissimus
. Iliocostalis and Longissimus
. Psoas and Quadratus lumborum
. Multifidus and Spinalis
. Longissimus and Spinalis

Correct Answer & Explanation

. Multifidus and Longissimus

Explanation

The Wiltse paraspinal approach utilizes the natural intermuscular cleavage plane between the multifidus (medial) and longissimus (lateral) muscles. This provides direct access to the extraforaminal zone and facet joint while minimizing muscle devascularization.

Question 1642

Topic: 6. Spine

Dysplastic (Type I) spondylolisthesis is characterized by congenital deficiency of the superior sacral facet or L5 inferior facet. Which of the following radiographic findings is most characteristic of high-grade dysplastic spondylolisthesis?

. "Scotty dog" with a collar sign
. Bamboo spine
. Dome-shaped sacrum
. Vacuum disc phenomenon
. Ivory vertebra

Correct Answer & Explanation

. Dome-shaped sacrum

Explanation

Dysplastic (Type I) spondylolisthesis is frequently associated with a dome-shaped sacrum, a trapezoidal L5 vertebral body, and a high propensity for progression. The "Scotty dog" collar sign is indicative of an isthmic (Type II) pars defect.

Question 1643

Topic: 6. Spine



A 45-year-old male presents with acute severe back pain, bilateral sciatica, and new-onset urinary retention. Imaging confirms a massive L4-L5 central disc extrusion. What is the most appropriate next step in management?

. High-dose intravenous corticosteroids
. Emergent surgical decompression
. Lumbar epidural steroid injection
. Urodynamic studies
. Catheterization and observation for 24 hours

Correct Answer & Explanation

. Emergent surgical decompression

Explanation

Cauda equina syndrome is a surgical emergency. Emergent surgical decompression, ideally within 24 to 48 hours of symptom onset, is required to optimize neurological recovery, particularly for bowel and bladder function.

Question 1644

Topic: 6. Spine

A patient with an L4-L5 paracentral disc herniation will most likely exhibit weakness in which of the following movements during a physical examination?

. Hip flexion
. Knee extension
. Ankle dorsiflexion
. Great toe extension
. Ankle plantarflexion

Correct Answer & Explanation

. Great toe extension

Explanation

An L4-L5 paracentral disc herniation compresses the traversing L5 nerve root. This typically results in weakness of the extensor hallucis longus (great toe extension) and sensory loss over the first dorsal web space.

Question 1645

Topic: 6. Spine

A 35-year-old female underwent a successful L5-S1 microdiscectomy 6 months ago but now presents with recurrent, severe S1 radiculopathy. MRI with contrast confirms a recurrent disc herniation at the same level. What is the expected recurrence rate after a primary lumbar microdiscectomy?

. 1-2%
. 5-10%
. 15-20%
. 25-30%
. 40-50%

Correct Answer & Explanation

. 5-10%

Explanation

The rate of recurrent symptomatic disc herniation following a primary lumbar microdiscectomy is generally reported in the literature to be between 5% and 10%.

Question 1646

Topic: Thoracolumbar Spine & Deformity
Which of the following anatomic and biomechanical changes is most directly responsible for the development of degenerative (Wiltse Type III) spondylolisthesis?
. Pars interarticularis stress fracture
. Sagittal orientation of the facet joints
. Congenital sacral dysplasia
. Pathologic tumor infiltration
. Iatrogenic pars resection

Correct Answer & Explanation

. Sagittal orientation of the facet joints

Explanation

Degenerative spondylolisthesis is most commonly associated with a sagittal orientation of the lumbar facet joints. This anatomic variant provides less resistance to anterior shear forces, leading to progressive slipping.

Question 1647

Topic: 6. Spine
A 50-year-old presents with progressive myelopathy and is found to have a large, calcified central disc herniation at T8-T9. Which of the following surgical approaches is universally contraindicated?
. Anterior transthoracic approach
. Costotransversectomy
. Lateral extracavitary approach
. Standard posterior laminectomy
. Thoracoscopic microdiscectomy

Correct Answer & Explanation

. Standard posterior laminectomy

Explanation

A standard posterior laminectomy is absolutely contraindicated for central thoracic disc herniations. Attempting to retract the thoracic spinal cord to access an anteriorly located disc carries an unacceptably high risk of catastrophic cord injury.

Question 1648

Topic: Thoracolumbar Spine & Deformity

A 10-year-old female gymnast is diagnosed with a Grade II L5-S1 isthmic spondylolisthesis. Which of the following is the most significant radiographic risk factor for further anterior progression of her slip?

. Slip angle greater than 45 degrees
. Age greater than 16 years
. Male gender
. Participation in contact sports
. Absence of spina bifida occulta

Correct Answer & Explanation

. Slip angle greater than 45 degrees

Explanation

A high slip angle (typically greater than 45-50 degrees) is a strong radiographic predictor of slip progression in pediatric isthmic spondylolisthesis. Young age (prior to the adolescent growth spurt) and female gender are also significant risk factors.

Question 1649

Topic: Thoracolumbar Spine & Deformity

A 19-year-old college football lineman presents with chronic mechanical low back pain. Radiographs show a Grade I L5-S1 isthmic spondylolisthesis. Which diagnostic test is most useful to confirm that the pars defect is the primary source of his pain prior to performing a direct pars repair?

. MRI without contrast
. CT myelogram
. Technetium-99m bone scan
. Fluoroscopically guided pars intra-articular/defect injection
. Electromyography (EMG)

Correct Answer & Explanation

. Fluoroscopically guided pars intra-articular/defect injection

Explanation

A fluoroscopically guided injection of local anesthetic into the pars defect can help isolate the defect as the primary pain generator. A positive response supports the decision for a direct pars repair in young patients without significant disc degeneration.

Question 1650

Topic: 6. Spine

A 45-year-old male presents with severe lower back pain, bilateral lower extremity weakness, and perineal numbness. A post-void residual (PVR) bladder volume is measured. Which of the following PVR volumes is most strongly indicative of cauda equina syndrome?

. < 50 mL
. 50 - 100 mL
. 100 - 200 mL
. > 200 mL
. PVR is not useful in evaluating cauda equina syndrome

Correct Answer & Explanation

. > 200 mL

Explanation

A post-void residual (PVR) > 200 mL is highly sensitive and specific for urinary retention associated with cauda equina syndrome. Volumes < 100 mL are generally considered normal, while intermediate volumes may require clinical correlation.

Question 1651

Topic: 6. Spine

A 52-year-old male presents with acute severe left leg pain. Physical examination reveals weakness in left ankle dorsiflexion and great toe extension, but normal ankle plantarflexion. He has numbness over the dorsal web space between the first and second toes. Which of the following disc herniations is most likely responsible?

. Far-lateral L3-L4 disc herniation
. Paracentral L4-L5 disc herniation
. Far-lateral L4-L5 disc herniation
. Paracentral L5-S1 disc herniation
. Central L5-S1 disc herniation

Correct Answer & Explanation

. Paracentral L4-L5 disc herniation

Explanation

The patient exhibits a classic L5 radiculopathy (weak toe extension/ankle dorsiflexion, numbness in the first dorsal web space). In the lumbar spine, a paracentral disc herniation at L4-L5 typically compresses the traversing L5 nerve root.

Question 1652

Topic: Thoracolumbar Spine & Deformity

Which of the following anatomic factors has been most strongly correlated with the development of degenerative spondylolisthesis at the L4-L5 level?

. Coronal orientation of the facet joints
. Sagittal orientation of the facet joints
. Increased pelvic incidence
. Decreased sacral slope
. Elongated pars interarticularis

Correct Answer & Explanation

. Sagittal orientation of the facet joints

Explanation

Sagittal orientation of the L4-L5 facet joints (sagittal tropism) is a primary anatomic risk factor for degenerative spondylolisthesis. This orientation provides less resistance to anterior shear forces, leading to progressive slip.

Question 1653

Topic: Thoracolumbar Spine & Deformity
A 16-year-old high school football lineman complains of chronic low back pain. Radiographs demonstrate an isthmic spondylolisthesis. Advanced imaging reveals an elongated, but intact, pars interarticularis without a frank fracture. According to the Wiltse classification, which subtype does this represent?
. Type IIA
. Type IIB
. Type IIC
. Type III
. Type IV

Correct Answer & Explanation

. Type IIB

Explanation

Wiltse Type II isthmic spondylolisthesis is divided into three subtypes: IIA (lytic/stress fracture), IIB (elongated but intact pars due to healed repeated microfractures), and IIC (acute pars fracture). Type IIB correctly describes an elongated, intact pars.

Question 1654

Topic: 6. Spine

A 40-year-old male has an MRI demonstrating a lumbar disc herniation. He elects for nonoperative management. Based on the natural history of lumbar disc herniations, which morphologic type has the highest rate of spontaneous resorption?

. Disc bulge
. Disc protrusion
. Disc extrusion
. Sequestrated disc
. Schmorl's node

Correct Answer & Explanation

. Sequestrated disc

Explanation

Sequestrated (free fragment) disc herniations have the highest rate of spontaneous resorption due to increased exposure to the epidural vascular supply and a vigorous macrophage-mediated inflammatory response.

Question 1655

Topic: 6. Spine

A 35-year-old male presents with severe right leg pain radiating to the plantar aspect of his foot. On examination, he has an absent Achilles reflex and 4/5 strength in ankle plantarflexion. A paracentral disc herniation at which level is the most likely cause?

. L3-L4
. L4-L5
. L5-S1
. S1-S2
. Far-lateral L5-S1

Correct Answer & Explanation

. L5-S1

Explanation

The patient has an S1 radiculopathy (absent Achilles reflex, weak plantarflexion, plantar numbness). An L5-S1 paracentral disc herniation compresses the traversing S1 nerve root.

Question 1656

Topic: Thoracolumbar Spine & Deformity

A 12-year-old female undergoes surgical reduction and instrumented fusion for a Meyerding Grade IV isthmic spondylolisthesis at L5-S1. Postoperatively, she exhibits new-onset weakness in foot dorsiflexion and great toe extension. Which nerve root is most commonly injured during the reduction maneuver for a high-grade slip?

. L3
. L4
. L5
. S1
. S2

Correct Answer & Explanation

. L5

Explanation

The L5 nerve root is at the highest risk for stretch injury during the surgical reduction of a high-grade L5-S1 spondylolisthesis. This is due to the tethering of the nerve as it exits the L5-S1 foramen during the restoration of disc height and slip reduction.

Question 1657

Topic: Thoracolumbar Spine & Deformity

In the evaluation of spinopelvic parameters for a patient with adult spinal deformity and spondylolisthesis, which of the following equations accurately defines Pelvic Incidence (PI)?

. PI = Pelvic Tilt (PT) - Sacral Slope (SS)
. PI = Pelvic Tilt (PT) + Sacral Slope (SS)
. PI = Sacral Slope (SS) - Pelvic Tilt (PT)
. PI = Lumbar Lordosis (LL) + Pelvic Tilt (PT)
. PI = Lumbar Lordosis (LL) - Sacral Slope (SS)

Correct Answer & Explanation

. PI = Pelvic Tilt (PT) + Sacral Slope (SS)

Explanation

Pelvic incidence (PI) is a fixed morphologic parameter defined as the sum of Pelvic Tilt (PT) and Sacral Slope (SS). Therefore, PI = PT + SS.

Question 1658

Topic: 6. Spine

A patient with a massive central L4-L5 disc herniation develops acute urinary retention, fecal incontinence, and saddle anesthesia. Compression of which specific nerve roots is primarily responsible for the saddle anesthesia?

. L4, L5, S1
. L5, S1, S2
. S1, S2, S3
. S2, S3, S4
. S4, S5, Coccygeal

Correct Answer & Explanation

. S2, S3, S4

Explanation

Saddle anesthesia in cauda equina syndrome is caused by the compression of the S2, S3, and S4 nerve roots. These roots provide sensory innervation to the perineum, perianal area, and medial aspects of the buttocks.

Question 1659

Topic: 6. Spine

Based on the results of the Spine Patient Outcomes Research Trial (SPORT) regarding degenerative spondylolisthesis, which of the following statements is true regarding outcomes at the 4-year follow-up?

. Nonoperative treatment demonstrated superior pain relief compared to surgery.
. Surgical treatment showed significantly greater improvement in pain and function compared to nonoperative treatment.
. There was no significant difference in outcomes between surgical and nonoperative cohorts in the as-treated analysis.
. Surgery had a higher rate of severe permanent neurological deterioration.
. Epidural steroid injections provided equivalent long-term functional improvement as surgical decompression.

Correct Answer & Explanation

. Surgical treatment showed significantly greater improvement in pain and function compared to nonoperative treatment.

Explanation

The SPORT trial for degenerative spondylolisthesis demonstrated that patients treated surgically had significantly greater improvements in pain and function compared to those treated nonoperatively at the 4-year follow-up (in the as-treated analysis).

Question 1660

Topic: 6. Spine

A 48-year-old female presents to the emergency department with acute onset of bilateral sciatica, severe perianal numbness, and loss of bowel control following a heavy lifting event. MRI confirms a massive central L5-S1 disc extrusion. To optimize the potential for full neurologic recovery of sphincter function, surgical decompression should ideally be performed within what maximum time frame from symptom onset?

. 12 hours
. 24 hours
. 48 hours
. 72 hours
. 1 week

Correct Answer & Explanation

. 48 hours

Explanation

Surgical decompression for cauda equina syndrome should optimally be performed within 48 hours of symptom onset. Intervening within this critical window significantly improves the likelihood of recovering bladder and bowel function.

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