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6. Spine MCQs

Practice Set 288 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 5741

Topic: 6. Spine

A 9-year-old boy with Neurofibromatosis type 1 (NF1) presents with a rapidly progressive spinal deformity. Radiographs demonstrate a short-segment, sharp angular curve in the thoracic spine with severe apical rotation, vertebral scalloping, and 'penciling' of the ribs. What is the most appropriate surgical management strategy for this specific type of curve?

. Bracing until skeletal maturity
. Posterior spinal fusion alone with pedicle screws
. Combined anterior and posterior spinal fusion
. Growing rod construct without fusion
. Observation with serial radiographs every 6 months

Correct Answer & Explanation

. Combined anterior and posterior spinal fusion

Explanation

Correct Answer: Combined anterior and posterior spinal fusionThe clinical and radiographic description is classic for dystrophic scoliosis in Neurofibromatosis type 1 (NF1). Dystrophic curves are characterized by short, sharp angular deformities, vertebral scalloping, rib penciling, and severe rotation. They have a very high rate of progression and a high incidence of pseudarthrosis if treated with posterior fusion alone. Therefore, the gold standard surgical treatment for dystrophic NF1 scoliosis is a robust, combined anterior and posterior spinal fusion (360-degree fusion) to ensure stability and prevent curve progression or implant failure.

Question 5742

Topic: 6. Spine

A 6-year-old child with short-trunk dwarfism presents with a progressively waddling gait. Examination reveals a flat face, myopia, and normal intelligence. Radiographs show severe coxa vara. What critical cervical spine abnormality must be screened for prior to any surgical procedure requiring anesthesia?

. Foramen magnum stenosis
. Odontoid hypoplasia causing atlantoaxial instability
. Progressive cervical kyphosis
. Klippel-Feil anomaly
. Basilar invagination

Correct Answer & Explanation

. Odontoid hypoplasia causing atlantoaxial instability

Explanation

Spondyloepiphyseal dysplasia congenita (SEDC) is a type II collagenopathy characteristically associated with odontoid hypoplasia. Preoperative flexion-extension cervical spine radiographs are mandatory to rule out atlantoaxial instability.

Question 5743

Topic: Thoracolumbar Spine & Deformity

A 3-month-old infant presents with severe shortening of all limbs, hitchhiker thumbs, and cystic swelling of the external ears. Radiographs reveal short, thick tubular bones and a characteristic cleft palate. Which of the following spinal deformities poses the most critical risk of severe neurological compromise in the natural history of this disorder?

. Progressive thoracic scoliosis
. Cervical kyphosis
. Atlantoaxial rotatory subluxation
. Lumbar hyperlordosis
. Lumbosacral spondylolisthesis

Correct Answer & Explanation

. Cervical kyphosis

Explanation

This patient has diastrophic dysplasia (SLC26A2 mutation). Severe cervical kyphosis is common and, while it can resolve spontaneously, it may rapidly progress and cause lethal or severe neurological compromise, requiring close monitoring.

Question 5744

Topic: Cervical Spine

A 6-year-old girl is evaluated for severe knock-knees, short-trunk dwarfism, and corneal clouding. Radiographs show platyspondyly with central anterior beaking of the vertebrae and hypoplastic odontoid. Laboratory testing reveals urinary excretion of keratan sulfate. What is the specific enzymatic deficiency in this patient?

. Alpha-L-iduronidase
. Iduronate-2-sulfatase
. Arylsulfatase B
. N-acetylgalactosamine-6-sulfatase
. Glucocerebrosidase

Correct Answer & Explanation

. N-acetylgalactosamine-6-sulfatase

Explanation

This clinical picture describes Mucopolysaccharidosis Type IVA (Morquio Syndrome). It is caused by a deficiency in N-acetylgalactosamine-6-sulfatase (GALNS), resulting in keratan sulfate accumulation and severe skeletal dysplasia.

Question 5745

Topic: 6. Spine

A 6-month-old infant with confirmed achondroplasia is noted to have brisk deep tendon reflexes, clonus, and central apnea during sleep studies. Which of the following represents the most urgent diagnostic step and its rationale?

. MRI of the craniocervical junction to evaluate for foramen magnum stenosis
. Flexion-extension cervical spine radiographs to rule out atlantoaxial instability
. CT of the chest to assess for restrictive lung disease secondary to a small rib cage
. MRI of the lumbar spine to evaluate for severe central spinal stenosis
. Echocardiogram to evaluate for cor pulmonale

Correct Answer & Explanation

. MRI of the craniocervical junction to evaluate for foramen magnum stenosis

Explanation

Infants with achondroplasia are at high risk for foramen magnum stenosis causing cervicomedullary compression, which presents with hyperreflexia, sleep apnea, or sudden death. Urgent MRI of the craniocervical junction is required for surgical planning.

Question 5746

Topic: 6. Spine

An 18-month-old boy is diagnosed with Hurler syndrome (MPS IH). He has progressive kyphosis (gibbus deformity), coarse facial features, and developmental delay. Which of the following systemic treatments is most appropriate at this age to prevent progressive cognitive decline and extend survival, despite having limited efficacy on the skeletal dysostosis multiplex?

. Hematopoietic stem cell transplantation
. Intravenous bisphosphonates
. Recombinant human growth hormone
. Bilateral total hip arthroplasties
. Oral enzyme replacement therapy with keratanase

Correct Answer & Explanation

. Hematopoietic stem cell transplantation

Explanation

Hurler syndrome (alpha-L-iduronidase deficiency) is treated with early Hematopoietic Stem Cell Transplantation (HSCT) prior to age 2 to cross the blood-brain barrier and preserve cognition, though orthopaedic issues like spinal deformity often continue to progress.

Question 5747

Topic: 6. Spine

A 6-year-old boy presents with short-trunk dwarfism, a barrel chest, and a waddling gait due to progressive coxa vara. He has a history of a cleft palate and severe myopia. Which of the following conditions is most critical to screen for prior to administering general anesthesia to this patient?

. Central sleep apnea due to foramen magnum stenosis
. Malignant hyperthermia
. Atlantoaxial instability due to odontoid hypoplasia
. Restrictive lung disease from severe rib anomalies
. Aortic root dilation

Correct Answer & Explanation

. Atlantoaxial instability due to odontoid hypoplasia

Explanation

Spondyloepiphyseal dysplasia congenita (SEDC) is a type II collagenopathy (COL2A1 mutation) presenting with short-trunk dwarfism, coxa vara, and myopia. Odontoid hypoplasia is a frequent complication, making flexion-extension cervical spine radiographs mandatory to rule out atlantoaxial instability before intubation.

Question 5748

Topic: 6. Spine

A 12-year-old female presents with a rapidly progressive left-sided thoracic scoliosis. Neurological examination reveals a loss of pain and temperature sensation in her bilateral upper extremities with preserved fine touch and proprioception. What is the most likely primary etiology of her spinal deformity?

. Idiopathic adolescent scoliosis
. Tethered cord syndrome
. Type 1 neurofibromatosis
. Syringomyelia associated with Chiari I malformation
. Diastematomyelia

Correct Answer & Explanation

. Syringomyelia associated with Chiari I malformation

Explanation

A left-sided thoracic curve and rapidly progressive scoliosis are 'atypical' features warranting an MRI. The cape-like loss of pain and temperature sensation is pathognomonic for syringomyelia, which is most commonly associated with a Chiari I malformation.

Question 5749

Topic: 6. Spine

A 9-year-old boy presents with an atypical right thoracic scoliosis curve of 45 degrees. MRI confirms a large syringomyelia spanning C5 to T8 and a Chiari I malformation. What is the most appropriate initial surgical intervention?

. Immediate posterior spinal fusion from T2-L2
. Anterior tethering of the convex side of the curve
. Neurosurgical decompression of the posterior fossa
. Bracing with a thoracolumbosacral orthosis (TLSO)
. Growing rod instrumentation without neurological intervention

Correct Answer & Explanation

. Neurosurgical decompression of the posterior fossa

Explanation

In patients with scoliosis secondary to syringomyelia/Chiari I, neurosurgical decompression is the recommended first step. Decompression often halts curve progression and may even improve the scoliosis in younger children with flexible curves.

Question 5750

Topic: 6. Spine

Which specific spinal cord tract is initially compromised in syringomyelia, leading to the classic 'cape-like' neurological deficit?

. Dorsal columns
. Lateral corticospinal tract
. Anterior spinothalamic tract
. Anterior white commissure
. Spinocerebellar tract

Correct Answer & Explanation

. Anterior white commissure

Explanation

Syringomyelia begins as a central dilation of the spinal canal. It first compresses the crossing pain and temperature fibers of the spinothalamic tract located in the anterior white commissure.

Question 5751

Topic: Thoracolumbar Spine & Deformity

A 14-year-old female presents with scoliosis. On physical exam, stroking the skin around the umbilicus fails to elicit an umbilical deviation toward the stimulus on the left side. What is the significance of this finding in the context of adolescent idiopathic scoliosis?

. It is a normal finding in 50% of healthy adolescents
. It indicates tethered cord syndrome necessitating detethering
. It suggests an underlying syrinx or neuroaxis abnormality, warranting an MRI
. It predicts rapid curve progression requiring immediate bracing
. It confirms a diagnosis of poliomyelitis

Correct Answer & Explanation

. It suggests an underlying syrinx or neuroaxis abnormality, warranting an MRI

Explanation

Asymmetric or absent abdominal reflexes are an objective 'hard' neurological sign in a patient with scoliosis. This finding strongly suggests an underlying intraspinal anomaly, such as syringomyelia, and mandates an MRI of the entire neuroaxis.

Question 5752

Topic: 6. Spine

A 10-year-old girl is evaluated for a new-onset scoliosis. Physical examination reveals an atypical left-sided thoracic curve. Neurological examination reveals a loss of pain and temperature sensation in a cape-like distribution over her shoulders. What is the most appropriate next step in evaluation?

. CT scan of the thoracic spine
. Skeletal survey
. Total spine and brain MRI
. EMG and nerve conduction studies
. Bracing with a Boston brace

Correct Answer & Explanation

. Total spine and brain MRI

Explanation

A left-sided thoracic curve or a curve associated with neurologic deficits (such as the classic cape-like distribution of sensory loss) is highly suspicious for syringomyelia. A total spine MRI and brain MRI are required to evaluate for a syrinx and associated Chiari malformation.

Question 5753

Topic: 6. Spine

A patient with a known history of an expanding syringomyelia in the cervical and thoracic spine begins to experience progressive flaccid paralysis and significant muscle atrophy in the intrinsic muscles of the hands. This specific physical finding indicates extension of the syrinx into which spinal cord structure?

. Anterior white commissure
. Anterior horn
. Posterior columns
. Lateral spinothalamic tract
. Corticospinal tract

Correct Answer & Explanation

. Anterior horn

Explanation

While central cord expansion initially damages the crossing spinothalamic fibers (causing loss of pain/temp), further expansion into the anterior horns damages lower motor neurons. This results in flaccid paralysis, atrophy, and fasciculations in the upper extremities.

Question 5754

Topic: 6. Spine

A 13-year-old girl is found to have a 60-degree progressive thoracic scoliosis associated with a large, symptomatic syringomyelia and a Chiari I malformation. What is the recommended surgical sequencing for her treatment?

. Spinal fusion followed by neurosurgical decompression 6 months later
. Simultaneous spinal fusion and posterior fossa decompression
. Neurosurgical decompression of the Chiari/syrinx, followed by spinal fusion at a later date
. Spinal fusion only, as correcting the deformity resolves the syrinx
. Syrinx-to-pleural shunt placement only

Correct Answer & Explanation

. Neurosurgical decompression of the Chiari/syrinx, followed by spinal fusion at a later date

Explanation

In a patient with scoliosis secondary to a syrinx/Chiari malformation, neurosurgical decompression is indicated first to decompress the neural axis. Spinal fusion performed without prior decompression carries an unacceptably high risk of neurologic injury during deformity correction.

Question 5755

Topic: 6. Spine

A 45-year-old female presents with progressive, painless swelling and instability of her right shoulder. Examination reveals massive crepitus and a loss of pain and temperature sensation over her shoulders and upper back. What is the most appropriate imaging modality to confirm the underlying etiology of her joint pathology?

. Ultrasound of the right shoulder
. CT arthrogram of the right shoulder
. MRI of the cervical and thoracic spine
. Non-contrast CT of the brain
. Electromyography (EMG) of the upper extremities

Correct Answer & Explanation

. MRI of the cervical and thoracic spine

Explanation

The patient has a Charcot (neuropathic) shoulder secondary to syringomyelia, indicated by her "cape-like" distribution of dissociated sensory loss. MRI of the cervical and thoracic spine is the gold standard to visualize the syrinx cavity.

Question 5756

Topic: 6. Spine

A 32-year-old male with a known Chiari I malformation presents with weakness in his intrinsic hand muscles and multiple painless burn scars on his forearms. What is the precise pathophysiological mechanism responsible for his sensory deficit?

. Compression of the posterior columns
. Destruction of the anterior horn cells
. Disruption of the decussating spinothalamic fibers in the anterior white commissure
. Demyelination of the lateral corticospinal tracts
. Ischemia to the dorsal root ganglia

Correct Answer & Explanation

. Disruption of the decussating spinothalamic fibers in the anterior white commissure

Explanation

The patient has syringomyelia, common in Chiari I malformations. The syrinx expands centrally in the spinal cord, first damaging the decussating spinothalamic fibers in the anterior white commissure, causing bilateral loss of pain and temperature sensation.

Question 5757

Topic: 6. Spine

An 8-year-old male presents with a rapidly progressive left thoracic scoliosis curve of 45 degrees. On neurological examination, he has absent superficial abdominal reflexes on the left side but normal lower extremity motor strength. What is the most appropriate next step in management?

. Immediate custom thoracolumbosacral orthosis (TLSO) bracing
. Surgical posterior spinal fusion from T4 to L2
. MRI of the entire neuraxis
. Electromyography and nerve conduction studies
. Observation and repeat standing radiographs in 6 months

Correct Answer & Explanation

. MRI of the entire neuraxis

Explanation

A left-sided thoracic scoliosis curve and asymmetric/absent abdominal reflexes in a young child are "red flags" indicating a potential underlying intraspinal anomaly, such as syringomyelia or Chiari malformation. An MRI of the entire spine and hindbrain is mandatory before considering any deformity correction.

Question 5758

Topic: 6. Spine

In the pediatric population, a symptomatic syrinx (syringomyelia) causing a rapidly progressive scoliosis is most commonly associated with which of the following underlying cranial abnormalities?

. Dandy-Walker malformation
. Chiari II malformation
. Chiari I malformation
. Arachnoid cyst of the posterior fossa
. Encephalocele

Correct Answer & Explanation

. Chiari I malformation

Explanation

Syringomyelia in children is predominantly associated with a Chiari I malformation, where the cerebellar tonsils herniate through the foramen magnum. This alters CSF dynamics, leading to the formation of a syrinx within the spinal cord.

Question 5759

Topic: Thoracolumbar Spine & Deformity

A 12-year-old girl with syringomyelia and an associated Chiari I malformation presents with a 60-degree progressive thoracic scoliosis. Which of the following describes the recommended sequence of surgical interventions?

. Suboccipital decompression/syrinx decompression prior to scoliosis correction
. Simultaneous scoliosis correction and syrinx shunting
. Scoliosis correction first, followed by syrinx decompression 6 months later
. Scoliosis correction only, as the syrinx usually resolves spontaneously
. Non-operative management with a Boston brace indefinitely

Correct Answer & Explanation

. Suboccipital decompression/syrinx decompression prior to scoliosis correction

Explanation

To minimize the risk of devastating neurological complications during deformity correction, neurosurgical intervention (suboccipital decompression) for the Chiari malformation/syrinx must be performed before addressing the scoliosis.

Question 5760

Topic: 6. Spine

A 40-year-old male presents with cape-like pain and temperature sensory loss in the upper extremities. MRI of the cervical spine reveals a syrinx extending from C2 to T2. However, there is no evidence of a Chiari malformation, spinal tumor, or tethered cord. What is the most likely anamnestic finding in this patient's history?

. Family history of neurofibromatosis type 1
. Prior severe spinal cord trauma or meningitis
. Exposure to ionizing radiation in childhood
. History of congenital scoliosis
. Recent severe viral upper respiratory infection

Correct Answer & Explanation

. Prior severe spinal cord trauma or meningitis

Explanation

When a syrinx is found without an associated congenital anomaly (like Chiari malformation) or tumor, it is often acquired. Prior severe spinal cord trauma or an inflammatory process (meningitis/arachnoiditis) alters normal CSF dynamics, leading to secondary syrinx formation.

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