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6. Spine MCQs

Practice Set 62 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 1221

Topic: Thoracolumbar Spine & Deformity
Which of the following patients with infantile idiopathic scoliosis can be observed without a magnetic resonance image (MRI)?
. A patient with a curve less than 20°
. A patient with a normal neurologic examination
. A patient with a right thoracic curve
. A patient younger than 2 years old
. A patient without any pain

Correct Answer & Explanation

. A patient younger than 2 years old

Explanation

Patients with idiopathic infantile scoliosis have a 22% incidence of abnormalities that can be viewed on MRI. Syrinx and Chiari malformation are the most common abnormalities, with a similar rate as that found in patients with juvenile idiopathic scoliosis. The left thoracic curve pattern is most commonly seen in infantile patients, but a right thoracic curve is not protective. Age, freedom from pain, or a normal neurologic examination are also not protective. Magnetic resonance imaging is recommended for all infantile curves larger than 20°.

Question 1222

Topic: 6. Spine

What is the primary force applied to the spine during a C hance (seatbelt) fracture:

. Flexion
. C ompression
. Rotation
. Distraction
. Flexion and rotation

Correct Answer & Explanation

. Distraction

Explanation

The primary force applied to the spine during a C hance fracture is distraction. The body is flexed forward around an axis in front of the body (often a seatbelt), but the spine is subject to distraction because it is posterior to this axis. This motion results in a characteristic distraction of bony or ligamentous elements with minimal crush.

Question 1223

Topic: 6. Spine

Motion artifact in magnetic resonance imaging of the pediatric spine is caused by all of the following except:

. Patient movement
. C ardiac activity
. C erebrospinal fluid flow
. Respiration
. A flexible titanium rod in the femur

Correct Answer & Explanation

. A flexible titanium rod in the femur

Explanation

Motion artifact affects magnetic resonance imaging of the spine and can result from patient movement (common in children under 8 years old), cardiac activity, respiration, and cerebrospinal fluid flow. Presence of a titanium rod in a childs femur, while causing a local signal void, does not affect spinal imaging.

Question 1224

Topic: 6. Spine

Which of the following is considered the most sensitive clinical indicator of early cauda equina syndrome?

. Loss of Achilles reflex
. Saddle anesthesia
. Urinary retention
. Fecal incontinence
. Bilateral foot drop

Correct Answer & Explanation

. Urinary retention

Explanation

Urinary retention is the most sensitive early clinical sign of cauda equina syndrome, often evaluated objectively by measuring post-void residual volume. Saddle anesthesia and fecal incontinence are typically later findings.

Question 1225

Topic: 6. Spine

What is the most sensitive early clinical finding in patients developing cauda equina syndrome?

. Bilateral sciatica
. Saddle anesthesia
. Urinary retention
. Fecal incontinence
. Decreased anal sphincter tone

Correct Answer & Explanation

. Urinary retention

Explanation

Urinary retention is typically the first and most sensitive sign of cauda equina syndrome. A post-void residual volume of less than 100 mL practically rules out the diagnosis in suspected cases.

Question 1226

Topic: 6. Spine

In a patient with cervical spondylotic myelopathy, the "finger escape sign" is characterized by the inability to maintain which digits in a fully extended and adducted position?

. Thumb and index fingers
. Index and middle fingers
. Middle and ring fingers
. Ring and small fingers
. Thumb and small fingers

Correct Answer & Explanation

. Ring and small fingers

Explanation

The finger escape sign is a classic myelopathic finding where the patient cannot keep the ulnar digits (ring and small fingers) extended and adducted. They spontaneously drift into flexion and abduction.

Question 1227

Topic: 6. Spine

The phenomenon of spinal cord injury without radiographic abnormality in children may be due to any one of the following except:

. Increased longitudinal stretch of the skeletal elements compared to the spinal cord
. Increased physiologic translation of the cervical vertebrae
. Apophyseal injury
. Transverse ligament injury of the atlas
. Lack of neural myelination in children

Correct Answer & Explanation

. Increased physiologic translation of the cervical vertebrae

Explanation

In most cases, spinal cord injury without radiographic abnormality, or SC IWORA, is due to the greater elasticity or translation of the skeletal elements. Apophyseal or transverse ligament injuries are other explanations. Myelination of the cord is complete after birth so this is not an explanation.

Question 1228

Topic: 6. Spine
A 6-year-old girl is seriously injured in an automobile accident. She remains unconscious and intubated 6 days after the injury due to head and pulmonary injuries. She is expected to survive. A firm cervical collar was placed on her neck at the time of rescue and remains in place. Plain radiographs show no cervical abnormalities. At this time, recommended treatment includes:
. Removing the collar
. Leaving the collar in place until she awakens
. Passive flexion and extension radiographs by the physician to clear the spine of injury
. Ultrasound of the cervical spine to clear it of injury
. Magnetic resonance imaging to clear the spine of injury

Correct Answer & Explanation

. Magnetic resonance imaging to clear the spine of injury

Explanation

Spinal cord injury without radiographic abnormality (SCIWORA) may occur in children. Motor vehicle accidents and head injury are two risk factors for this. The neck collar cannot be left on indefinitely or it may cause pressure sores. Therefore, it is most prudent to evaluate the cervical spine with MRI if the patient's neck cannot be cleared by physical exam. Passive range of the neck is risky, and ultrasound is not used for this purpose.

Question 1229

Topic: Cervical Spine

Which of the following structures is the primary stabilizer of the atlantoaxial segment against anterior atlantal translation:

. Apical ligament
. Alar ligament
. Anterior atlantodental ligament
. Transverse ligament
. Ligamentum nuchae

Correct Answer & Explanation

. Transverse ligament

Explanation

The transverse ligament is the primary stabilizer of the atlantoaxial segment against anterior atlantal translation. The transverse ligament runs between the lateral masses of C1 and behind the odontoid process. The apical ligament is attached to the tip of the odontoid and the occiput, but not C1. The paired alar ligaments run obliquely and are secondary restraints, as is the anterior atlantodental ligament. The ligamentum nuchae is a strong condensation of fibers extending from the external occipital protuberance to the tips of the spinous processes C2-C 7.

Question 1230

Topic: Cervical Spine

The radiographic line delimiting the foramen magnum that is used in determining basilar invagination is the:

. McGregor line
. McRae line
. Chamberlain line
. Ranawat line
. Swischuk line

Correct Answer & Explanation

. McRae line

Explanation

The McRae line is from the anterior to the posterior lip of the foramen magnum. Protrusion of the odontoid above this line indicates basilar invagination. The McGregor and Ranawat lines are also used to evaluate basilar invagination. The Swischuk line is from the posterior cortex of C1 to C3 lamina and is used in evaluating pseudosubluxation.

Question 1231

Topic: 6. Spine

A 4-year-old girl with achondroplasia presents with progressively worsening lower extremity weakness and hyperreflexia. What is the most likely anatomic site of neurologic compression in this patient?

. Foramen magnum
. Cervical spine (C5-C6)
. Thoracic spine (T10-T12)
. Lumbar spine (L4-L5)
. Sacral plexus

Correct Answer & Explanation

. Foramen magnum

Explanation

Children with achondroplasia are at high risk for foramen magnum stenosis, which can cause cervicomedullary compression leading to hyperreflexia, weakness, central apnea, or even sudden death. Urgent decompression is required if symptomatic.

Question 1232

Topic: Thoracolumbar Spine & Deformity

For a patient who has thoracic idiopathic scoliosis of the surgical range, the distance between the thecal sac and the apical thoracic pedicle on the concave side is:

. Less than 1 mm
. 2 mm
. 3 mm
. 4 mm
. 5 mm

Correct Answer & Explanation

. Less than 1 mm

Explanation

The distance between the apical thoracic pedicle and the thecal sac is less than 1 mm on the concave side.

Question 1233

Topic: 6. Spine

Which region (vertebral body) of the spine is the closest to the aorta:

. T4
. T9
. T1
. T6
. T12

Correct Answer & Explanation

. T9

Explanation

The aorta is on the left side of the vertebra in the upper and midthoracic spine. The aorta moves to an anterior location in the lower thoracic spine. The distance from the aorta to the vertebral body is 6 mm to 7 mm in skeletally mature patients with idiopathic scoliosis between the fourth and ninth vertebral bodies. The distance becomes less than 5 mm in the thoracolumbar junction and lumbar spine. The aortic arch does not extend to the first thoracic vertebral.

Question 1234

Topic: 6. Spine

The width of the pedicles in a patient with idiopathic scoliosis in the surgical range is narrowest in the:

. Thoracic spine on the convex side
. Lumbar spine on the convex side
. Sacral spine
. Thoracic spine on the concave side
. Lumbar spine on the concave side

Correct Answer & Explanation

. Thoracic spine on the concave side

Explanation

The width of the pedicles is less in the thoracic spine than in the lumbar or sacral spine, and less on the concavity than on the convexity. The mean width of the thoracic pedicles on the concave side at the apex in skeletally mature patients is only 3 mm.

Question 1235

Topic: 6. Spine

The angle of the pedicle with the midsagittal plane at T11 is closest to:

. 0°
. 5°
. 15°
. 20°
. 25°

Correct Answer & Explanation

. 15°

Explanation

The angle of the pedicles is greatest in the upper thoracic and lumbar spines (approximately 15°). The angle decreases to approximately 7° at the thoracolumbar junction.

Question 1236

Topic: Thoracolumbar Spine & Deformity

A 1-year-old boy presents with an infantile idiopathic scoliosis curve measuring 30 degrees. Which radiographic measurement is the most reliable prognostic indicator for curve progression?

. Cobb angle magnitude alone
. Nash-Moe rotation
. Rib-vertebral angle difference (RVAD) of Mehta
. Risser sign
. Apical vertebral translation

Correct Answer & Explanation

. Rib-vertebral angle difference (RVAD) of Mehta

Explanation

Mehta's Rib-Vertebral Angle Difference (RVAD) is the most critical prognostic factor for infantile idiopathic scoliosis. An RVAD greater than 20 degrees strongly predicts curve progression.

Question 1237

Topic: Thoracolumbar Spine & Deformity

A 14-year-old gymnast complains of chronic lower back pain. Radiographs show a grade II spondylolisthesis at L5-S1. What radiographic parameter is most predictive of future slip progression?

. Pelvic incidence
. Sacral slope
. Slip angle (sagittal roll)
. Lumbar lordosis
. Intervertebral disc height

Correct Answer & Explanation

. Slip angle (sagittal roll)

Explanation

The slip angle (sagittal roll or kyphosis) is the most important radiographic predictor for the progression of a dysplastic spondylolisthesis. High slip angles indicate greater instability.

Question 1238

Topic: 6. Spine

A 14-month-old boy is evaluated for infantile idiopathic scoliosis. Radiographs reveal a left thoracic curve of 25 degrees. Which of the following radiographic parameters is the most reliable predictor of curve progression in this patient?

. Rib-vertebra angle difference (RVAD) greater than 20 degrees
. Risser sign of 0
. Nash-Moe rotation of grade 1
. Cobb angle magnitude at presentation alone
. Apical vertebral translation greater than 2 cm

Correct Answer & Explanation

. Rib-vertebra angle difference (RVAD) greater than 20 degrees

Explanation

Mehta described the rib-vertebra angle difference (RVAD) for infantile idiopathic scoliosis. An RVAD greater than 20 degrees strongly correlates with progressive curves requiring intervention.

Question 1239

Topic: 6. Spine

A 15-year-old male with achondroplasia presents with progressively worsening lower extremity weakness and neurogenic claudication. What is the primary anatomical cause of this complication in achondroplastic patients?

. Atlantoaxial instability
. Intervertebral disc herniation
. Shortened pedicles leading to spinal stenosis
. High-grade isthmic spondylolisthesis
. Syringomyelia

Correct Answer & Explanation

. Shortened pedicles leading to spinal stenosis

Explanation

Achondroplasia causes impaired endochondral ossification, which leads to abnormally short and thickened pedicles. This results in severe central canal stenosis and neurogenic claudication.

Question 1240

Topic: 6. Spine

A 4-year-old girl is evaluated for a high-riding, hypoplastic left scapula (Sprengel deformity). During surgical correction via the Woodward procedure, the surgeon must identify and resect an anomalous structure that frequently connects the medial border of the scapula to the cervical spine. What is this structure called?

. Cervical rib
. Os odontoideum
. Omovertebral bone
. Coracoclavicular ossification
. Bifid spinous process

Correct Answer & Explanation

. Omovertebral bone

Explanation

The omovertebral bone (or cartilaginous/fibrous band) connects the cervical spine to the superior medial border of the scapula in about 30% to 50% of patients with Sprengel deformity. Its resection is required to effectively lower the scapula.

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