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6. Spine MCQs

Practice Set 369 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 7361

Topic: 6. Spine

A 13-year-old boy presents with an atypical left thoracic scoliosis curve and absence of abdominal reflexes. MRI confirms a large syringomyelia. What pathomechanism is most commonly responsible for curve progression in this setting?

. Asymmetrical weakness of the paraspinal musculature
. Congenital hemivertebra formation
. Wedging of the epiphyseal plates due to gravity
. Direct tethering of the spinal cord to the dura
. Disruption of the anterior spinal artery

Correct Answer & Explanation

. Asymmetrical weakness of the paraspinal musculature

Explanation

Syringomyelia disrupts the anterior horn cells and descending tracts, leading to asymmetrical weakness and neuromuscular imbalance of the paraspinal muscles. This drives the rapid and atypical progression of the scoliotic curve.

Question 7362

Topic: 6. Spine

Which of the following clinical curve patterns is considered an absolute indication for obtaining a total spine MRI to rule out syringomyelia in a patient presenting with scoliosis?

. Right thoracic curve in a 14-year-old girl
. Left thoracic curve in an 11-year-old boy
. Right lumbar curve of 20 degrees
. Double major curve with a right thoracic component
. Thoracolumbar curve in a 16-year-old girl

Correct Answer & Explanation

. Left thoracic curve in an 11-year-old boy

Explanation

Atypical curve patterns, such as a left-sided thoracic curve, early onset, or rapid progression, are strong indications for an MRI. This imaging is crucial to rule out intraspinal abnormalities like a syrinx or tumor.

Question 7363

Topic: 6. Spine

A 10-year-old girl presents with a rapidly progressive left-sided thoracic scoliosis. Her neurologic examination is completely normal. Which of the following is the most appropriate next step in evaluation?

. Immediate bracing with a TLSO
. MRI of the entire neuraxis
. CT scan of the thoracic spine
. Observation with radiographs in 6 months
. Posterior spinal fusion

Correct Answer & Explanation

. MRI of the entire neuraxis

Explanation

Left-sided thoracic curves, rapid progression, or abnormal neurologic findings are red flags for intraspinal anomalies like syringomyelia or Chiari malformation. These findings strongly warrant an MRI of the entire neuraxis prior to any intervention.

Question 7364

Topic: 6. Spine

A central spinal cord syrinx typically causes early neurologic deficits by initially compressing which specific neural structure?

. Dorsal columns
. Corticospinal tract
. Anterior horn cells
. Crossing spinothalamic fibers in the anterior white commissure
. Spinocerebellar tract

Correct Answer & Explanation

. Crossing spinothalamic fibers in the anterior white commissure

Explanation

A syrinx centrally expands and initially damages the crossing fibers of the spinothalamic tract in the anterior white commissure. This results in the classic bilateral "cape-like" loss of pain and temperature sensation in the upper extremities.

Question 7365

Topic: 6. Spine

A 12-year-old patient presents with a 45-degree right thoracic scoliosis curve and an MRI revealing a large cervical syrinx associated with a Chiari I malformation. What is the most appropriate sequence of management?

. Spinal fusion followed by syrinx decompression
. Syrinx decompression followed by observation of the curve
. Simultaneous posterior spinal fusion and posterior fossa decompression
. Bracing followed by syrinx decompression
. Insertion of a vertical expandable prosthetic titanium rib (VEPTR)

Correct Answer & Explanation

. Syrinx decompression followed by observation of the curve

Explanation

Neurosurgical decompression of the syrinx/Chiari malformation should always precede scoliosis surgery to reduce the high risk of intraoperative neurologic injury. Furthermore, the scoliosis curve may stabilize or even improve following neurosurgical decompression.

Question 7366

Topic: 6. Spine

A 16-year-old girl presents with back pain and L3 radiculopathy. Imaging shows an expansile lytic lesion in the L3 posterior elements with fluid-fluid levels. To minimize intraoperative complications, which preoperative intervention is highly recommended?

. Intravenous bisphosphonates
. Preoperative selective arterial embolization
. Neoadjuvant chemotherapy
. Preoperative external beam radiation therapy
. Administration of desmopressin

Correct Answer & Explanation

. Preoperative selective arterial embolization

Explanation

Spinal ABCs commonly involve the posterior elements and can be extremely vascular. Preoperative selective arterial embolization is strongly recommended to significantly decrease the risk of massive intraoperative hemorrhage.

Question 7367

Topic: 6. Spine

A 15-year-old male with an atypical left-sided thoracic scoliosis undergoes an MRI revealing a holocord syrinx. He has no gross neurologic deficits. Why is immediate surgical correction of the scoliosis strictly contraindicated prior to neurosurgical evaluation?

. The curve will spontaneously resolve entirely without surgery.
. There is an unacceptably high risk of acute spinal cord injury during curve correction.
. Spinal hardware will inevitably become infected due to abnormal CSF flow.
. Bone healing and fusion are permanently impaired in patients with syringomyelia.
. Syringomyelia causes severe local osteopenia preventing adequate screw purchase.

Correct Answer & Explanation

. There is an unacceptably high risk of acute spinal cord injury during curve correction.

Explanation

Performing spinal deformity correction in the presence of an untreated syrinx carries a massive risk of acute neurologic injury or paraplegia. The syrinx limits the cord's compliance and space to adapt to the mechanical shifts of deformity correction.

Question 7368

Topic: 6. Spine

A 12-year-old girl presents with a rapidly progressive left thoracic scoliotic curve. Physical exam reveals absent superficial abdominal reflexes. Which of the following is the most appropriate next step in evaluation?

. CT scan of the thoracic spine
. Total spine MRI
. Genetic testing for GNAS mutation
. Electromyography (EMG)
. Scoliosis bracing

Correct Answer & Explanation

. Total spine MRI

Explanation

A left-sided thoracic curve and absent abdominal reflexes are atypical findings for adolescent idiopathic scoliosis and highly suggestive of a neural axis abnormality, such as syringomyelia. A total spine MRI is the gold standard for evaluating neuroaxial anomalies prior to any intervention.

Question 7369

Topic: 6. Spine

An 11-year-old boy is diagnosed with a large syringomyelia and an associated Chiari I malformation, along with a 50-degree thoracic scoliotic curve. What is the recommended treatment sequence?

. Posterior spinal fusion followed by posterior fossa decompression
. Anterior spinal tethering followed by syrinx observation
. Bracing for 6 months followed by spinal fusion
. Posterior fossa decompression prior to scoliosis correction
. Simultaneous posterior fossa decompression and spinal fusion

Correct Answer & Explanation

. Posterior fossa decompression prior to scoliosis correction

Explanation

In patients with a large syrinx and a surgically significant scoliosis curve, neurosurgical decompression of the syrinx/Chiari malformation should be performed before spinal deformity correction. This reduces the risk of neurologic injury during spinal correction and may result in curve stabilization or improvement.

Question 7370

Topic: 6. Spine

An orthopedic surgeon is evaluating a 20-year-old patient with an atypical scoliotic curve. An MRI of the spine reveals a fluid-filled cavity within the spinal cord extending from C5 to T8. Which associated finding is most likely to be seen on a sagittal MRI of the head and neck?

. Agenesis of the corpus callosum
. Downward displacement of the cerebellar tonsils
. Enlargement of the pituitary gland
. Meningioma of the optic nerve
. Cystic hygroma

Correct Answer & Explanation

. Downward displacement of the cerebellar tonsils

Explanation

Syringomyelia is frequently associated with Chiari I malformation, which is characterized by the downward displacement (ectopia) of the cerebellar tonsils through the foramen magnum. This obstruction of CSF flow is thought to drive syrinx formation.

Question 7371

Topic: 6. Spine

An 18-year-old male with an untreated, symptomatic Chiari I malformation and a large cervicothoracic syrinx presents for scoliosis correction due to a progressive 65-degree curve. If spinal fusion is performed prior to neurosurgical decompression, what is the most significant risk?

. Pseudarthrosis
. Hardware failure
. Neurologic deficit during curve correction
. Postoperative wound infection
. Superior mesenteric artery syndrome

Correct Answer & Explanation

. Neurologic deficit during curve correction

Explanation

Performing scoliosis correction on a patient with an untreated syrinx carries an unacceptably high risk of neurologic injury (e.g., paraplegia) during curve correction due to altered spinal cord compliance. Neurosurgical decompression must precede deformity correction to mitigate this risk.

Question 7372

Topic: 6. Spine

An infant is diagnosed with achondroplasia, exhibiting rhizomelic short stature, frontal bossing, and midface hypoplasia. During the first two years of life, which of the following spinal complications warrants the most vigilant screening due to its potential for sudden mortality?

. Thoracolumbar kyphosis
. Foramen magnum stenosis
. Lumbar spinal stenosis
. Atlantoaxial instability
. High-grade spondylolisthesis

Correct Answer & Explanation

. Foramen magnum stenosis

Explanation

Foramen magnum stenosis is a critical and potentially fatal complication in infants with achondroplasia, leading to cervicomedullary compression, central apnea, and sudden death. Screening with sleep studies and MRI is essential, whereas lumbar stenosis typically becomes problematic in adulthood.

Question 7373

Topic: 6. Spine

An 18-year-old male presents with a painful scoliosis. Imaging reveals a small sclerotic lesion in the pedicle of a lumbar vertebra.

In patients with an osteoid osteoma of the spine causing scoliosis, where is the lesion typically located relative to the scoliotic curve?

. On the convexity at the apex
. On the concavity at the apex
. Three levels above the apex
. Unrelated to the curve apex
. Causing purely a hyperkyphotic deformity

Correct Answer & Explanation

. On the concavity at the apex

Explanation

Osteoid osteoma of the spine causes asymmetric muscle spasm due to local inflammation, leading to a scoliotic deformity. The lesion is characteristically located on the concavity of the curve at the apex of the deformity.

Question 7374

Topic: Thoracolumbar Spine & Deformity
A 15-year-old female gymnast presents with chronic low back pain. Radiographs demonstrate a grade II anterior translation of L5 on S1 with an identifiable defect in the pars interarticularis. According to the Wiltse classification, what type of spondylolisthesis does this patient have?
. Type I (Dysplastic)
. Type II (Isthmic)
. Type III (Degenerative)
. Type IV (Traumatic)
. Type V (Pathologic)

Correct Answer & Explanation

. Type II (Isthmic)

Explanation

Type II (Isthmic) spondylolisthesis involves a defect in the pars interarticularis (spondylolysis). It is the most common type in adolescents and athletes, such as gymnasts, who undergo repetitive hyperextension. Type I is dysplastic, Type III is degenerative (common in older adults), Type IV is traumatic (fracture other than the pars), and Type V is pathologic.

Question 7375

Topic: 6. Spine

A 5-year-old girl presents with a visibly elevated and hypoplastic left scapula.

She is diagnosed with Sprengel's deformity. What is the embryological failure that results in this condition?

. Failure of formation of the clavicle
. Failure of descent of the scapula
. Failure of segmentation of the cervical spine
. Failure of fusion of the scapular body
. Failure of neural tube closure

Correct Answer & Explanation

. Failure of descent of the scapula

Explanation

Sprengel's deformity is caused by an arrest in the embryological descent of the scapula from the cervical region to its normal thoracic position during the 9th to 12th weeks of gestation.

Question 7376

Topic: 6. Spine

A 6-year-old boy with Sprengel's deformity is undergoing radiographic evaluation. In approximately 30% of these patients, what cartilaginous or osseous structure tethers the scapula to the cervical spine?

. Cervical rib
. Omovertebral bone
. Coracoclavicular ligament
. Os acromiale
. Bipartite clavicle

Correct Answer & Explanation

. Omovertebral bone

Explanation

The omovertebral bone is a fibrous, cartilaginous, or osseous connection between the superomedial border of the scapula and the spinous processes or lamina of the lower cervical spine.

Question 7377

Topic: 6. Spine

During surgical correction of a Sprengel's deformity, an omovertebral bone is identified. Where does this structure typically attach?

. Between the inferior angle of the scapula and the iliac crest
. Between the coracoid process and the first rib
. Between the superomedial angle of the scapula and the cervical spinous processes or lamina
. Between the acromion and the clavicle
. Between the glenoid and the humerus

Correct Answer & Explanation

. Between the superomedial angle of the scapula and the cervical spinous processes or lamina

Explanation

The omovertebral bone is a cartilaginous or osseous connection found in up to 40% of Sprengel's deformity cases. It spans from the superomedial angle of the scapula to the posterior elements of the lower cervical spine.

Question 7378

Topic: 6. Spine

A 6-year-old girl presents with a high-riding, hypoplastic left scapula and limited shoulder abduction. Radiographs show a bony connection between the superomedial angle of the scapula and the cervical spine.

What is this anatomical structure called?

. Os acromiale
. Omovertebral bone
. Cervical rib
. Scapular exostosis
. Coracoclavicular bar

Correct Answer & Explanation

. Omovertebral bone

Explanation

The omovertebral bone is a fibrous, cartilaginous, or osseous connection present in roughly 30% of patients with Sprengel's deformity. It links the cervical spine to the superomedial scapula and restricts motion.

Question 7379

Topic: 6. Spine

During surgical correction of a severe Sprengel's deformity, the surgeon isolates an omovertebral connection. When present, this structure typically bridges the superior-medial angle of the scapula to which of the following structures?

. The spinous process, lamina, or transverse process of the cervical spine
. The posterior arch of the first rib
. The middle third of the clavicle
. The acromion process
. The occiput

Correct Answer & Explanation

. The spinous process, lamina, or transverse process of the cervical spine

Explanation

The omovertebral bone (or cartilaginous/fibrous band) connects the superior medial angle of the scapula to the posterior elements (spinous process, lamina, or transverse process) of the lower cervical vertebrae. It must be resected during corrective surgery.

Question 7380

Topic: 6. Spine

Sprengel's deformity is a congenital failure of descent of the scapula. The presence of an omovertebral bone is noted in approximately 30% of cases.

When present, this structure typically connects the cervical spine to which anatomical region of the scapula?

. Acromion
. Coracoid process
. Superomedial angle
. Inferior angle
. Glenoid neck

Correct Answer & Explanation

. Superomedial angle

Explanation

The omovertebral bone or fibrous band typically connects the spinous processes or laminae of the lower cervical vertebrae to the superomedial angle of the scapula, restricting its movement.

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