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6. Spine MCQs

Practice Set 190 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 3781

Topic: 6. Spine

In the cervical spine, the vertebral artery typically enters the transverse foramen at which vertebral level?

. C2
. C4
. C6
. C7
. T1

Correct Answer & Explanation

. C6

Explanation

The vertebral artery typically enters the transverse foramen at the C6 level, although anatomical variations can occur. It ascends through the transverse foramina of C6 to C1 before entering the foramen magnum.

Question 3782

Topic: 6. Spine

A surgeon is placing pedicle screws in the L4 vertebra during a lumbar fusion. A breach of the inferior cortex of the L4 pedicle places which of the following structures at highest immediate risk of injury?

. Exiting L3 nerve root
. Traversing L4 nerve root
. Exiting L4 nerve root
. Traversing L5 nerve root
. Exiting L5 nerve root

Correct Answer & Explanation

. Exiting L4 nerve root

Explanation

The L4 nerve root exits the neural foramen immediately inferior to the L4 pedicle. Therefore, an inferior breach of the L4 pedicle directly endangers the exiting L4 nerve root.

Question 3783

Topic: Cervical Spine

During an anterior cervical discectomy and fusion (ACDF), excessive lateral dissection carries the risk of vertebral artery injury. At which cervical level does the vertebral artery typically enter the transverse foramen from the neck?

. C7
. C6
. C5
. C4
. C3

Correct Answer & Explanation

. C6

Explanation

The vertebral artery typically enters the transverse foramen at the level of C6 in about 90% of individuals. It bypasses the transverse foramen of C7, making it vulnerable to injury anteriorly at the cervicothoracic junction.

Question 3784

Topic: 6. Spine

During anterior cervical spine surgery, knowledge of vertebral artery anatomy is crucial. The vertebral artery typically enters the transverse foramen at which cervical level?

. C7
. C6
. C5
. C4
. C3

Correct Answer & Explanation

. C6

Explanation

The vertebral artery typically arises from the subclavian artery and enters the transverse foramen at the C6 vertebral level in over 90% of individuals.

Question 3785

Topic: 6. Spine

In the lumbar spine, a central-posterolateral disc herniation at the L4-L5 level will most likely impinge which of the following nerve roots?

. L3
. L4
. L5
. S1
. S2

Correct Answer & Explanation

. L5

Explanation

In the lumbar spine, a typical posterolateral disc herniation impinges the traversing nerve root rather than the exiting one. Therefore, an L4-L5 herniation affects the L5 nerve root.

Question 3786

Topic: 6. Spine

A 14-month-old boy is diagnosed with infantile idiopathic scoliosis. Radiographs demonstrate a left-sided thoracic curve of 35 degrees. The rib-vertebra angle difference (RVAD) is calculated at 28 degrees. What is the most appropriate management?

. Observation with radiographs in 6 months
. Physical therapy and core strengthening
. Mehta cast application
. Growing rod instrumentation
. Posterior spinal fusion

Correct Answer & Explanation

. Mehta cast application

Explanation

In infantile scoliosis, an RVAD greater than 20 degrees strongly predicts curve progression (Mehta's criteria). Serial casting is the gold standard treatment for progressive infantile idiopathic scoliosis to delay or prevent the need for surgery.

Question 3787

Topic: 6. Spine
A 2-year-old girl is found to have a fully segmented hemivertebra at T8 on spine radiographs. Which of the following imaging studies is mandatory in the initial diagnostic workup of this patient?
. CT scan of the chest
. Renal ultrasound
. Brain MRI
. Bone scintigraphy
. Pelvic ultrasound

Correct Answer & Explanation

. Renal ultrasound

Explanation

Congenital scoliosis is frequently associated with VACTERL anomalies, with genitourinary anomalies occurring in up to 30% of patients. A renal ultrasound and an MRI of the entire spine to evaluate for intraspinal anomalies are mandatory in the initial workup.

Question 3788

Topic: 6. Spine

A 1-year-old boy presents with an infantile early-onset idiopathic scoliosis measuring 25 degrees in the thoracic spine. Which of the following radiographic parameters indicates a high likelihood of curve progression?

. A left-sided curve direction
. A Rib-Vertebral Angle Difference (RVAD) of Mehta greater than 20 degrees
. Phase I rib head morphology bilaterally
. An associated lumbar curve of 10 degrees
. Absence of syringomyelia on MRI

Correct Answer & Explanation

. A Rib-Vertebral Angle Difference (RVAD) of Mehta greater than 20 degrees

Explanation

In infantile idiopathic scoliosis, a Rib-Vertebral Angle Difference (RVAD) greater than 20 degrees, as described by Mehta, strongly predicts progressive disease. Phase II rib heads (overlapping the vertebral body) also indicate progression risk.

Question 3789

Topic: 6. Spine

A 6-month-old infant is incidentally noted to have a 20-degree left-sided thoracic scoliosis. The rib-vertebra angle difference (RVAD) of Mehta is measured at 12 degrees, and there is no vertebral rotation. What is the most likely natural history of this curve?

. Spontaneous resolution
. Steady progression requiring a TLSO brace
. Rapid progression requiring growing rods (VEPTR)
. Stable curve magnitude throughout adolescence
. Development of restrictive lung disease by age 5

Correct Answer & Explanation

. Spontaneous resolution

Explanation

Infantile idiopathic scoliosis with a curve under 25 degrees and a Mehta's Rib-Vertebral Angle Difference (RVAD) less than 20 degrees has a high likelihood of spontaneous resolution.

Question 3790

Topic: 6. Spine

A newborn is diagnosed with congenital scoliosis secondary to a fully unsegmented unilateral bar with a contralateral hemivertebra. Renal ultrasound is normal. Before planning any surgical intervention, which imaging modality is strictly indicated?

. Echocardiogram
. Total spine MRI
. High-resolution CT of the chest
. Brain MRI
. Positron emission tomography (PET)

Correct Answer & Explanation

. Total spine MRI

Explanation

Up to 30% of patients with congenital scoliosis have associated neural axis abnormalities (e.g., tethered cord, diastematomyelia, syringomyelia). A total spine MRI is mandatory before surgical intervention.

Question 3791

Topic: 6. Spine

A 13-year-old boy with Duchenne muscular dystrophy recently became wheelchair-dependent. He has developed a rapidly progressive thoracolumbar scoliosis that currently measures 45 degrees. His forced vital capacity (FVC) is 45% of predicted. What is the most appropriate management strategy?

. TLSO bracing to allow completion of spinal growth
. Seating modifications and observation until FVC falls below 30%
. Posterior spinal fusion from the upper thoracic spine to the pelvis
. Anterior spinal fusion with instrumentation
. Insertion of vertical expandable prosthetic titanium ribs (VEPTR)

Correct Answer & Explanation

. Posterior spinal fusion from the upper thoracic spine to the pelvis

Explanation

In Duchenne muscular dystrophy, scoliosis progresses rapidly once the child is wheelchair-bound. Bracing is ineffective and poorly tolerated. Posterior spinal fusion to the pelvis is indicated to maintain sitting balance and should be performed before the FVC drops below 30%.

Question 3792

Topic: 6. Spine

A 2-year-old boy presents with a 55-degree left thoracic curve. A complete neuroaxial MRI is unremarkable. What is the most appropriate initial treatment for this early-onset idiopathic scoliosis?

. Observation with radiographs every 6 months
. Thoracolumbosacral orthosis (TLSO)
. Serial elongation-derotation-flexion (EDF) casting
. Implantation of magnetically controlled growing rods
. Definitive posterior spinal fusion

Correct Answer & Explanation

. Serial elongation-derotation-flexion (EDF) casting

Explanation

For progressive Early-Onset Scoliosis (EOS) with a curve of this magnitude, serial casting (Mehta/EDF casting) is the initial treatment of choice. It can delay surgical intervention and, in some idiopathic infantile cases, completely resolve the curve.

Question 3793

Topic: 6. Spine
A 3-year-old female is diagnosed with congenital scoliosis secondary to a fully segmented unilateral hemivertebra at T8. Which of the following screening tests is mandatory as part of her initial comprehensive workup due to common associated anomalies?
. Echocardiogram and Renal Ultrasound
. CT scan of the chest without contrast
. Bone scintigraphy
. DEXA scan
. Dynamic fluoroscopy of the cervical spine

Correct Answer & Explanation

. Echocardiogram and Renal Ultrasound

Explanation

Congenital scoliosis is highly associated with VACTERL anomalies. Renal anomalies (found in 20-30% of patients) and cardiac anomalies require mandatory screening with a renal ultrasound and an echocardiogram, respectively.

Question 3794

Topic: 6. Spine

A 6-month-old infant is evaluated for a left-sided thoracic spinal curve. Radiographs demonstrate a Cobb angle of 28 degrees. The rib-vertebra angle difference (RVAD) of Mehta at the apical vertebra is 25 degrees, and the rib head overlaps the vertebral body (Phase 2). What is the most appropriate management?

. Observation with repeat radiographs in 6 months
. Application of a Milwaukee brace
. Serial derotational casting
. Insertion of a vertical expandable prosthetic titanium rib (VEPTR)
. Posterior spinal fusion

Correct Answer & Explanation

. Serial derotational casting

Explanation

In infantile idiopathic scoliosis, an RVAD of Mehta greater than 20 degrees with a Phase 2 rib indicates a high likelihood of rapid progression. Serial elongating derotational casting is the gold standard of treatment for progressive infantile curves.

Question 3795

Topic: 6. Spine

A 14-year-old boy with Duchenne muscular dystrophy is non-ambulatory and uses a motorized wheelchair. He has developed a progressive neuromuscular scoliosis, currently measuring 55 degrees with significant pelvic obliquity. His forced vital capacity (FVC) is 40% of predicted. What is the recommended surgical management?

. Anterior spinal fusion without instrumentation
. Insertion of growing rods
. Posterior spinal fusion extending to the pelvis
. Observation until FVC drops below 20%
. Thoracolumbosacral orthosis (TLSO) bracing

Correct Answer & Explanation

. Posterior spinal fusion extending to the pelvis

Explanation

In non-ambulatory patients with Duchenne muscular dystrophy and progressive scoliosis, posterior spinal fusion from the upper thoracic spine to the pelvis is indicated to correct pelvic obliquity, improve sitting balance, and halt respiratory decline.

Question 3796

Topic: 6. Spine

A 3-year-old child is evaluated for a spinal deformity noted by the pediatrician. Radiographs reveal congenital scoliosis. Which of the following anatomic anomalies carries the highest risk for rapid curve progression?

. A single fully segmented hemivertebra
. A block vertebra
. A unilateral unsegmented bar with a contralateral hemivertebra at the same level
. A wedge vertebra
. An incarcerated hemivertebra

Correct Answer & Explanation

. A unilateral unsegmented bar with a contralateral hemivertebra at the same level

Explanation

A unilateral unsegmented bar with a contralateral hemivertebra represents the highest risk of rapid curve progression in congenital scoliosis. This combination causes an extreme tethering effect on one side and unchecked growth on the opposite side.

Question 3797

Topic: 6. Spine
Figure 24 shows the sitting AP and lateral spinal radiographs of a nonambulatory 12.5-year-old boy with Duchenne muscular dystrophy who is being evaluated for scoliosis. The lumbar curve from T12 to L5 measures 36 degrees, and the thoracic curve from T3 to T12 measures 24 degrees on the AP radiograph. He has 5 degrees of pelvic obliquity. His forced vital capacity is 45% of predicted for height and weight. What is the most appropriate treatment for the spinal deformity?
. Posterior spinal fusion from T2 to L5 with segmental instrumentation
. Anterior spinal fusion from L1 to L4, followed by posterior spinal fusion from T2 to the sacrum with segmental instrumentation including iliac fixation
. Custom-molded spinal orthosis worn 23 hours per day until skeletal maturity
. A spinal orthosis until age 14 years, followed by posterior spinal fusion with segmental instrumentation
. Adapted wheelchair seating with a custom-molded back support to correct scoliosis and kyphosis

Correct Answer & Explanation

. Posterior spinal fusion from T2 to L5 with segmental instrumentation

Explanation

Posterior spinal fusion is the treatment of choice for scoliosis in patients with Duchenne muscular dystrophy once they are no longer able to walk. This treatment improves quality of life and upright wheelchair positioning. Its effect on pulmonary function is less clear, as pulmonary function will continue to decline because of the underlying muscle disease. While bracing and wheelchair modifications may slow the progression of the curve, progression will continue. Surgical intervention at this stage does not have to include the pelvis, which, in general, is indicated in curves of greater than 40 degrees, and when pelvic obliquity is greater than 10 degrees. Fixation to the pelvis should also be considered in lumbar curves where the apex is lower than L1. Surgical treatment usually can be safely performed if the vital capacity is greater than 35%.

Question 3798

Topic: Thoracolumbar Spine & Deformity

A 9-month-old boy is referred for a 25-degree left thoracic scoliosis.

Radiographs demonstrate a rib-vertebral angle difference (RVAD) of 25 degrees. What is the most likely natural history and appropriate treatment?

. Likely to resolve spontaneously; observation only
. Likely to resolve spontaneously; nighttime bracing
. High risk of progression; serial Mehta casting
. High risk of progression; immediate growth-friendly instrumentation
. Requires immediate MRI to rule out syringomyelia before intervention

Correct Answer & Explanation

. High risk of progression; serial Mehta casting

Explanation

This is infantile idiopathic scoliosis. According to Mehta's criteria, an RVAD greater than 20 degrees indicates a high likelihood of curve progression. The gold standard for progressive infantile curves is early serial derotational casting.

Question 3799

Topic: 6. Spine

A 12-year-old boy with Duchenne muscular dystrophy presents with a 45-degree sweeping thoracolumbar neuromuscular scoliosis. His forced vital capacity (FVC) is 40% of predicted. What is the most appropriate management?

. Full-time TLSO bracing
. Observation until the curve reaches 60 degrees
. Posterior spinal fusion from the upper thoracic spine to the pelvis
. Anterior spinal fusion only
. Growth-friendly tethering procedures

Correct Answer & Explanation

. Posterior spinal fusion from the upper thoracic spine to the pelvis

Explanation

Bracing is ineffective in halting curve progression in Duchenne muscular dystrophy. Posterior spinal fusion to the pelvis is indicated for curves over 20-30 degrees to halt progressive respiratory decline, maintain sitting balance, and prevent severe pelvic obliquity.

Question 3800

Topic: 6. Spine

A 10-year-old boy presents with a 30-degree left-sided thoracic scoliosis.

His neurological examination is normal. What is the most appropriate next step in his diagnostic workup?

. Immediate application of a TLSO brace
. CT scan of the thoracic spine
. MRI of the entire neuroaxis
. Skeletal survey to rule out systemic dysplasia
. Dynamic flexion-extension radiographs

Correct Answer & Explanation

. MRI of the entire neuroaxis

Explanation

Left-sided thoracic curves, particularly in juvenile patients or males, have a higher association with intraspinal anomalies such as syringomyelia or Chiari malformations. An MRI of the neuroaxis is indicated to rule out underlying neural axis abnormalities prior to treatment.

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