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6. Spine MCQs

Practice Set 276 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 5501

Topic: Cervical Spine

Which of the following is the most common underlying cause of atlantoaxial instability in a patient with Spondyloepiphyseal Dysplasia Congenita (SEDC)?

. Rupture of the transverse ligament
. Congenital absence of the C1 anterior arch
. Odontoid hypoplasia
. Degenerative facet arthropathy
. Assimilation of the atlas

Correct Answer & Explanation

. Odontoid hypoplasia

Explanation

Patients with SEDC (a COL2A1 defect) frequently exhibit defective ossification of the odontoid process, resulting in odontoid hypoplasia. This structural defect directly leads to significant atlantoaxial instability.

Question 5502

Topic: 6. Spine

A 45-year-old male with achondroplasia presents with neurogenic claudication. The spinal stenosis typical of this condition is primarily due to which of the following anatomical abnormalities?

. Hypertrophy of the ligamentum flavum
. Shortened pedicles and decreased interpedicular distance
. Spondylolisthesis at L4-L5
. Herniated nucleus pulposus
. Congenital facet joint absence

Correct Answer & Explanation

. Shortened pedicles and decreased interpedicular distance

Explanation

Spinal stenosis in achondroplasia is driven by premature closure of the neurocentral synchondroses. This results in short, thickened pedicles and a progressive narrowing of the interpedicular distance from L1 to L5.

Question 5503

Topic: 6. Spine

A 3-year-old child with diastrophic dysplasia is found to have a severe, progressive cervical kyphosis of 60 degrees. What is the recommended management?

. Observation as it typically resolves spontaneously
. Halo gravity traction followed by anterior and posterior spinal fusion
. Isolated anterior cervical discectomy and fusion
. Cervical collar wear until skeletal maturity
. Posterior wiring and bracing

Correct Answer & Explanation

. Halo gravity traction followed by anterior and posterior spinal fusion

Explanation

While mild cervical kyphosis in diastrophic dysplasia may resolve, severe progressive curves (>50 degrees) carry a high risk of quadriparesis or sudden death. Treatment usually involves halo traction followed by anterior and posterior fusion.

Question 5504

Topic: 6. Spine

A 5-year-old boy with Morquio syndrome (MPS IV) requires intubation for dental surgery. What is the most significant anesthetic concern regarding his spine?

. Severe thoracolumbar kyphosis restricting lung volume
. Atlantoaxial instability due to odontoid hypoplasia
. Fixed cervical kyphosis making positioning difficult
. High incidence of basilar invagination
. Risk of malignant hyperthermia

Correct Answer & Explanation

. Atlantoaxial instability due to odontoid hypoplasia

Explanation

Patients with Morquio syndrome frequently have severe odontoid hypoplasia and ligamentous laxity leading to life-threatening atlantoaxial instability. Preoperative cervical flexion/extension radiographs are mandatory to evaluate this risk before intubation.

Question 5505

Topic: 6. Spine

A 10-year-old patient with metatropic dysplasia presents for follow-up. Which spinal deformity is most characteristic of the natural history of this specific dysplasia?

. Spontaneous resolution of infantile scoliosis
. Rapidly progressive, severe kyphoscoliosis
. Progressive basilar invagination
. Multiple cervical spine hemivertebrae
. Isolated lumbar hyperlordosis

Correct Answer & Explanation

. Rapidly progressive, severe kyphoscoliosis

Explanation

Metatropic dysplasia is characterized by a "changing" phenotype, where infants present with a long trunk and short limbs, but rapidly develop severe, progressive kyphoscoliosis that makes the trunk appear short later in life.

Question 5506

Topic: 6. Spine
A 12-year-old female with osteogenesis imperfecta type III complains of worsening headaches, dysphagia, and lower cranial nerve deficits. What is the most likely spinal complication?
. Atlantoaxial rotatory subluxation
. Thoracic burst fracture
. Basilar invagination
. Dural ectasia
. Spondylolysis

Correct Answer & Explanation

. Basilar invagination

Explanation

Basilar invagination (upward migration of the odontoid into the foramen magnum) is a serious complication in severe OI due to skull base softening. It presents with brainstem and lower cranial nerve compression symptoms.

Question 5507

Topic: 6. Spine

A 6-month-old infant with achondroplasia presents with sleep apnea, hyperreflexia, and hypotonia. An MRI confirms severe foramen magnum stenosis. What is the most appropriate surgical intervention?

. Cervicomedullary decompression with dural patch
. Anterior odontoidectomy
. Posterior cervical fusion C1-C2
. Ventriculoperitoneal shunt placement alone
. Suboccipital craniectomy without dural opening

Correct Answer & Explanation

. Cervicomedullary decompression with dural patch

Explanation

Symptomatic foramen magnum stenosis in achondroplasia, presenting with sleep apnea or myelopathy, requires urgent cervicomedullary decompression. This typically involves a suboccipital craniectomy, C1 laminectomy, and duraplasty.

Question 5508

Topic: 6. Spine

A 2-year-old child with Hurler syndrome presents with a prominent lower thoracic gibbus deformity. Radiographs show a hypoplastic, wedge-shaped vertebra with an anterior beak. Where is the vertebral beak typically located in Hurler syndrome?

. Anterosuperiorly
. Anteroinferiorly
. Centrally
. Posterosuperiorly
. Posteroinferiorly

Correct Answer & Explanation

. Anteroinferiorly

Explanation

In Hurler syndrome (MPS I), the characteristic radiographic finding of the spine is a hypoplastic, wedge-shaped vertebra with an anteroinferior beak. In contrast, Morquio syndrome (MPS IV) typically presents with a central anterior beak.

Question 5509

Topic: 6. Spine

A newborn is diagnosed with Conradi-Hunermann syndrome (X-linked dominant chondrodysplasia punctata). Which of the following spinal anomalies is most commonly associated with this condition?

. Severe cervical kyphosis due to absent C2-C4 vertebral bodies
. Scoliosis related to asymmetric stippling and early fusion of ossification centers
. Lumbar spinal stenosis due to short pedicles
. Basilar invagination secondary to skull base softening
. Atlantoaxial instability due to odontoid hypoplasia

Correct Answer & Explanation

. Scoliosis related to asymmetric stippling and early fusion of ossification centers

Explanation

Chondrodysplasia punctata is characterized by stippled epiphyses. Asymmetric involvement of the vertebral ossification centers can lead to tethering, early fusion, and a rapidly progressive congenital-type scoliosis.

Question 5510

Topic: 6. Spine

A patient with delayed closure of cranial sutures, absent clavicles, and multiple supernumerary teeth is evaluated. Which spinal condition is highly associated with this syndrome?

. Severe rigid kyphoscoliosis
. Syringomyelia
. Spina bifida occulta in the cervical or upper thoracic spine
. Premature fusion of the neurocentral synchondrosis
. Atlantoaxial subluxation

Correct Answer & Explanation

. Spina bifida occulta in the cervical or upper thoracic spine

Explanation

Cleidocranial dysplasia, caused by a mutation in RUNX2, is characterized by delayed ossification of midline structures. This frequently manifests as spina bifida occulta, particularly in the cervical or upper thoracic spine.

Question 5511

Topic: 6. Spine

A 6-year-old child with achondroplasia has a fixed thoracolumbar kyphosis of 65 degrees with wedging of the L1 vertebra. Conservative measures have failed. What is the most appropriate surgical strategy?

. Posterior spinal fusion alone without decompression
. Anterior and posterior spinal fusion with decompression if neurologic deficit is present
. Growing rods insertion
. Vertebral column resection (VCR)
. Laminectomy alone

Correct Answer & Explanation

. Anterior and posterior spinal fusion with decompression if neurologic deficit is present

Explanation

Fixed, severe progressive thoracolumbar kyphosis (>50-60 degrees) with apical vertebral wedging in achondroplasia requires anterior and posterior spinal fusion. Laminectomy alone is contraindicated as it exacerbates kyphotic instability.

Question 5512

Topic: 6. Spine

A neonate presents with bowed lower limbs, pretibial skin dimples, and ambiguous genitalia. Radiographs reveal hypoplastic scapulae and non-mineralized thoracic pedicles. Which cervical spine abnormality is critical to monitor in this patient?

. Atlantoaxial subluxation
. Severe cervical kyphosis
. Odontoid aplasia
. Cervical stenosis
. Basilar invagination

Correct Answer & Explanation

. Severe cervical kyphosis

Explanation

Campomelic dysplasia (SOX9 mutation) is often lethal due to respiratory failure, but survivors frequently develop severe, rigid cervical kyphosis resulting from hypoplasia or absence of the cervical vertebrae.

Question 5513

Topic: Cervical Spine

A 7-year-old girl with Morquio syndrome has documented atlantoaxial instability with 8 mm of translation and early myelopathic signs. What is the recommended surgical management?

. Anterior odontoidectomy only
. Posterior C1-C2 fusion with rigid instrumentation
. Occipitocervical fusion
. Cervical laminectomy C1-C4
. Halo gravity traction alone

Correct Answer & Explanation

. Occipitocervical fusion

Explanation

In Morquio syndrome, generalized ligamentous laxity, odontoid hypoplasia, and a dysplastic C1 arch make isolated C1-C2 fusion highly prone to failure. Occipitocervical fusion is the most reliable method to achieve stability and decompress the neuraxis.

Question 5514

Topic: 6. Spine

A 6-month-old infant with diagnosed diastrophic dysplasia is noted to have a moderate mid-cervical kyphosis on lateral radiographs, along with spina bifida occulta at the same level. The neurological examination is normal. What is the most appropriate management of the cervical spine deformity at this time?

. Immediate posterior spinal fusion
. Observation with serial radiographs
. Halo-gravity traction
. Anterior cervical discectomy and fusion
. Bracing with a Minerva orthosis

Correct Answer & Explanation

. Observation with serial radiographs

Explanation

Cervical kyphosis in diastrophic dysplasia typically resolves spontaneously with growth, unlike the progressive kyphosis seen in Larsen syndrome. Surgical intervention is generally reserved for deformities that demonstrate strict progression or if neurological deficits develop.

Question 5515

Topic: 6. Spine

A 6-month-old infant with achondroplasia presents with profound hypotonia, brisk lower extremity deep tendon reflexes, and a history of central sleep apnea. What is the most likely anatomic etiology of these clinical findings?

. Odontoid hypoplasia leading to atlantoaxial instability
. Foramen magnum stenosis causing cervicomedullary compression
. Apical vertebral hypoplasia leading to severe thoracic kyphosis
. Congenital tethered spinal cord
. Lumbar spinal stenosis due to shortened pedicles

Correct Answer & Explanation

. Foramen magnum stenosis causing cervicomedullary compression

Explanation

Infants with achondroplasia are at high risk for foramen magnum stenosis due to abnormal endochondral ossification of the cranial base. This can cause cervicomedullary compression leading to central sleep apnea, hypotonia, hyperreflexia, and even sudden death, warranting prompt MRI evaluation and possible suboccipital decompression.

Question 5516

Topic: 6. Spine

A newborn is diagnosed with Larsen syndrome, presenting with bilateral knee, hip, and elbow dislocations, along with a prominent forehead and depressed nasal bridge. Which of the following spinal deformities is most characteristic of this syndrome and requires urgent evaluation due to the high risk of catastrophic spinal cord injury?

. Lumbar hyperlordosis
. Progressive thoracolumbar scoliosis
. Cervical kyphosis
. Basilar invagination
. High-grade L5-S1 dysplastic spondylolisthesis

Correct Answer & Explanation

. Cervical kyphosis

Explanation

Larsen syndrome is highly associated with a dangerous, progressive cervical kyphosis resulting from hypoplastic vertebral bodies. Because this deformity rarely resolves spontaneously and can lead to tetraplegia, it requires early identification and often early posterior spinal fusion to prevent catastrophic spinal cord injury.

Question 5517

Topic: 6. Spine

A 16-year-old male presents with persistent mid-back pain not completely relieved by NSAIDs and a new-onset painful structural scoliosis. Radiographs of the spine are evaluated.

What is the most appropriate definitive management for the most likely diagnosis?

. Radiofrequency ablation
. Observation with bracing
. Intralesional curettage and bone grafting
. En bloc resection with wide margins
. Systemic chemotherapy

Correct Answer & Explanation

. Intralesional curettage and bone grafting

Explanation

Osteoblastoma typically presents in the posterior elements of the spine and can cause painful scoliosis. Unlike osteoid osteoma, it is >2cm, less responsive to NSAIDs, and usually treated with intralesional curettage or marginal excision.

Question 5518

Topic: 6. Spine

A 6-year-old child with normal intelligence, corneal clouding, and severe platyspondyly presents with progressive cervical myelopathy. Radiographs reveal severe odontoid hypoplasia and atlantoaxial instability. What is the accumulated metabolite in this syndrome?

. Heparan sulfate
. Dermatan sulfate
. Keratan sulfate
. Chondroitin-6-sulfate
. Hyaluronic acid

Correct Answer & Explanation

. Keratan sulfate

Explanation

Morquio syndrome (MPS Type IV) is an autosomal recessive disorder caused by a defect in galactose-6-sulfatase, leading to keratan sulfate accumulation. Patients typically have normal intelligence but severe skeletal dysplasia, notably odontoid hypoplasia causing profound atlantoaxial instability.

Question 5519

Topic: 6. Spine

A 6-year-old boy with Morquio Syndrome (Mucopolysaccharidosis Type IV) is scheduled for elective bilateral osteotomies for severe genu valgum. Preoperatively, which of the following evaluations is absolutely critical to prevent catastrophic neurologic injury during intubation?

. Echocardiogram to assess for aortic root dilation
. Flexion-extension radiographs of the cervical spine to assess for atlantoaxial instability
. Pulmonary function testing to evaluate restrictive lung disease
. Renal ultrasound to check for progressive nephropathy
. Ophthalmologic exam to evaluate for corneal clouding

Correct Answer & Explanation

. Flexion-extension radiographs of the cervical spine to assess for atlantoaxial instability

Explanation

Patients with Morquio Syndrome frequently have odontoid hypoplasia leading to severe atlantoaxial instability. Flexion-extension cervical spine radiographs are mandatory before any procedure requiring anesthesia or neck manipulation to prevent spinal cord injury.

Question 5520

Topic: Thoracolumbar Spine & Deformity

A 16-year-old boy presents with painful scoliosis. Radiographs demonstrate an expansile lesion in the posterior elements of the lumbar spine.

What is the characteristic scoliotic curve pattern associated with this type of lesion?

. Scoliosis with the apex directed towards the lesion
. Scoliosis with the apex directed away from the lesion
. Progressive structural thoracic kyphosis
. Reversal of cervical lordosis without coronal plane deformity
. Scoliosis with compensatory contralateral hemivertebrae

Correct Answer & Explanation

. Scoliosis with the apex directed away from the lesion

Explanation

Painful lesions like osteoblastoma and osteoid osteoma in the posterior elements cause unilateral paravertebral muscle spasm. This spasm creates a concavity on the side of the lesion, causing the apex of the scoliotic curve to be directed away from the lesion.

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