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6. Spine MCQs

Practice Set 289 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 5761

Topic: 6. Spine

A 28-year-old female presents with a progressive left-sided thoracic scoliosis and decreased pain and temperature sensation in her bilateral upper extremities. Light touch and proprioception remain intact. Which of the following is the most appropriate next step in her evaluation?

. Electromyography and nerve conduction studies (EMG/NCS)
. Magnetic resonance imaging (MRI) of the entire neuroaxis
. Computed tomography (CT) myelogram of the cervical spine
. Genetic testing for Neurofibromatosis type 1
. Diagnostic joint aspiration of the shoulder

Correct Answer & Explanation

. Magnetic resonance imaging (MRI) of the entire neuroaxis

Explanation

Dissociated sensory loss (loss of pain/temperature with preserved dorsal column function) and an atypical left-sided thoracic scoliotic curve strongly suggest syringomyelia. An MRI of the entire neuroaxis is required to evaluate for a syrinx and associated congenital anomalies like a Chiari malformation.

Question 5762

Topic: 6. Spine

A 12-year-old boy presents with a rapidly progressive right thoracic scoliosis measuring 55 degrees. An MRI demonstrates a large cervicothoracic syrinx and a Chiari I malformation. What is the most appropriate recommended treatment sequence?

. Posterior spinal fusion followed by posterior fossa decompression
. Posterior fossa decompression followed by observation or spinal fusion if progression continues
. Simultaneous posterior fossa decompression and instrumented spinal fusion
. Bracing for 6 months, followed by spinal fusion if the curve exceeds 60 degrees
. Syrinx shunting followed by anterior vertebral body tethering

Correct Answer & Explanation

. Posterior fossa decompression followed by observation or spinal fusion if progression continues

Explanation

In patients with a syrinx and significant scoliosis, neurosurgical decompression of the Chiari malformation/syrinx must precede orthopedic spinal deformity correction. Decompression alone may halt progression or even improve the scoliotic curve, particularly in younger patients.

Question 5763

Topic: 6. Spine

A 35-year-old male with a known history of a skeletal dysplasia caused by an FGFR3 mutation presents with neurogenic claudication and bilateral lower extremity weakness. Which of the following radiographic findings is the primary anatomical basis for his symptoms?

. Progressive widening of the interpedicular distance from L1 to L5
. Decreased interpedicular distance from L1 to L5 with short pedicles
. Atlantoaxial instability due to odontoid hypoplasia
. Severe thoracic kyphoscoliosis with vertebral wedging
. Spondylolisthesis at the L5-S1 junction

Correct Answer & Explanation

. Decreased interpedicular distance from L1 to L5 with short pedicles

Explanation

Correct Answer: Decreased interpedicular distance from L1 to L5 with short pediclesThe patient has achondroplasia. A hallmark radiographic feature of achondroplasia is the narrowing (rather than the normal widening) of the interpedicular distance from L1 to L5, combined with congenitally short pedicles. This severely compromises the spinal canal diameter, predisposing these patients to symptomatic spinal stenosis in adulthood, often presenting as neurogenic claudication.

Question 5764

Topic: 6. Spine

A 45-year-old male with a known skeletal dysplasia characterized by rhizomelic shortening and a mutation in the FGFR3 gene presents with bilateral lower extremity neurogenic claudication. Radiographs of the spine show narrowing of the interpedicular distances from L1 to L5. What is the primary anatomical cause of his symptoms?

. Hypertrophy of the ligamentum flavum
. Congenital short pedicles
. Spondylolisthesis
. Disc herniation
. Facet joint arthropathy

Correct Answer & Explanation

. Congenital short pedicles

Explanation

Correct Answer: Congenital short pediclesAchondroplasia is the most common rhizomelic dwarfism, caused by an FGFR3 mutation. A classic spinal manifestation is congenital spinal stenosis due to short, thickened pedicles and a progressive decrease in the interpedicular distance from the upper to the lower lumbar spine (the opposite of normal anatomy). This predisposes them to severe neurogenic claudication in adulthood.

Question 5765

Topic: 6. Spine

An adult patient with achondroplasia presents with severe neurogenic claudication. Radiographs of the lumbar spine are obtained. Which of the following anatomical features is the primary congenital contributor to spinal stenosis in this condition?

. Progressive increase in interpedicular distance from L1 to L5
. Progressive decrease in interpedicular distance from L1 to L5
. Congenital absence of the pars interarticularis
. Severe degenerative lumbar scoliosis
. Hypertrophy of the anterior longitudinal ligament

Correct Answer & Explanation

. Progressive decrease in interpedicular distance from L1 to L5

Explanation

Correct Answer: Progressive decrease in interpedicular distance from L1 to L5In a normal spine, the interpedicular distance gradually increases from the upper lumbar spine (L1) down to the lower lumbar spine (L5). A hallmark radiographic finding in achondroplasia is the abnormal progressive decrease in the interpedicular distance from L1 to L5. This congenital narrowing of the spinal canal, combined with short, thickened pedicles and exaggerated lumbar lordosis, severely predisposes these patients to symptomatic lumbar spinal stenosis in adulthood, often requiring extensive laminectomies.

Question 5766

Topic: 6. Spine

A 2-year-old girl with disproportionate short stature and fine, sparse, light-colored hair is diagnosed with a metaphyseal chondrodysplasia. She has a history of recurrent severe respiratory infections. Which of the following gastrointestinal conditions is most strongly associated with her underlying skeletal dysplasia?

. Celiac disease
. Crohn disease
. Hirschsprung disease
. Biliary atresia
. Pyloric stenosis

Correct Answer & Explanation

. Hirschsprung disease

Explanation

Correct Answer: Hirschsprung diseaseThe patient has Cartilage-Hair Hypoplasia (McKusick type metaphyseal chondrodysplasia), which is characterized by short-limbed dwarfism, fine/sparse hair, and immunodeficiency (often T-cell or combined). It is caused by mutations in theRMRPgene. A known and significant association with this syndrome is Hirschsprung disease (aganglionic megacolon), as well as an increased risk of malignancies such as lymphomas.

Question 5767

Topic: 6. Spine

A 45-year-old male with achondroplasia presents with progressive neurogenic claudication and lower extremity weakness. Radiographs of the lumbar spine demonstrate narrowing of the interpedicular distances from L1 to L5. Which of the following anatomical abnormalities is the primary cause of his spinal stenosis?

. Hypertrophy of the ligamentum flavum
. Congenitally short pedicles
. Severe degenerative spondylolisthesis
. Herniation of the nucleus pulposus
. Ossification of the posterior longitudinal ligament

Correct Answer & Explanation

. Congenitally short pedicles

Explanation

Correct Answer: Congenitally short pediclesSpinal stenosis is a hallmark complication in adults with achondroplasia. The primary anatomical basis for this stenosis is congenitally short, thickened pedicles and a decreased interpedicular distance that typically worsens from L1 to L5 (the opposite of the normal spine). While degenerative changes like disc bulging and ligamentum flavum hypertrophy can exacerbate the stenosis later in life, the fundamental underlying cause is the abnormal pedicle morphology due to defective endochondral ossification.

Question 5768

Topic: 6. Spine

An infant with achondroplasia is noted to have central apnea, hyperreflexia, and delayed motor milestones. An MRI of the brain and cervical spine is ordered. What is the most likely finding responsible for these symptoms?

. Hydrocephalus due to aqueductal stenosis
. Cervicomedullary compression at the foramen magnum
. Atlantoaxial instability
. Tethered cord syndrome
. Syringomyelia

Correct Answer & Explanation

. Cervicomedullary compression at the foramen magnum

Explanation

Correct Answer: Cervicomedullary compression at the foramen magnumInfants with achondroplasia are at high risk for foramen magnum stenosis due to abnormal endochondral ossification of the skull base. This can lead to cervicomedullary compression, presenting with central apnea, hyperreflexia, hypotonia, delayed motor milestones, and even sudden death. Prompt evaluation with MRI and potential neurosurgical decompression are critical.

Question 5769

Topic: 6. Spine

In a patient with achondroplasia, which of the following radiographic findings is most characteristic of the lumbar spine?

. Progressive widening of the interpedicular distance from L1 to L5
. Anterior beaking of the lumbar vertebral bodies
. Coronal clefts in the vertebral bodies
. Progressive narrowing of the interpedicular distance from L1 to L5
. Atlantoaxial instability due to odontoid hypoplasia

Correct Answer & Explanation

. Progressive narrowing of the interpedicular distance from L1 to L5

Explanation

Correct Answer: Progressive narrowing of the interpedicular distance from L1 to L5A hallmark radiographic feature of achondroplasia is the progressive narrowing of the interpedicular distance from the upper to the lower lumbar spine (L1 to L5). In a normal spine, this distance widens. This narrowing, combined with short pedicles and thickened ligamentum flavum, strongly predisposes these patients to severe spinal stenosis later in life. Anterior beaking is characteristic of mucopolysaccharidoses (like Hurler or Morquio syndrome), and coronal clefts are seen in chondrodysplasia punctata.

Question 5770

Topic: 6. Spine

A 35-year-old male with achondroplasia presents with neurogenic claudication, progressive leg weakness, and hyperreflexia in the lower extremities. Which anatomical feature of his skeletal dysplasia most directly contributes to this presentation?

. Decreased interpedicular distance in the lumbar spine
. Atlantoaxial instability
. Odontoid hypoplasia
. Thoracolumbar kyphosis
. Pedicle lengthening

Correct Answer & Explanation

. Decreased interpedicular distance in the lumbar spine

Explanation

Achondroplasia is characterized by narrowing of the interpedicular distances from the upper to lower lumbar spine. This anatomical defect severely predisposes adults to central spinal canal stenosis and neurogenic claudication.

Question 5771

Topic: Thoracolumbar Spine & Deformity

A 6-year-old is evaluated for short-trunk short stature, scoliosis, and generalized joint laxity. Radiographs demonstrate platyspondyly, delayed epiphyseal ossification, and irregular, flared metaphyses. A mutation in the TRPV4 gene is identified. This gene encodes for an ion channel primarily permeable to which of the following?

. Chloride
. Potassium
. Calcium
. Sodium
. Magnesium

Correct Answer & Explanation

. Calcium

Explanation

Spondyloepimetaphyseal dysplasia (SEMD), Maroteaux type, is caused by mutations in the TRPV4 gene. TRPV4 functions as a calcium-permeable, non-selective cation channel essential for normal chondrocyte function.

Question 5772

Topic: 6. Spine

A 3-year-old Amish child presents with disproportionate short stature, sparse light-colored hair, and a history of recurrent severe respiratory infections. Radiographs demonstrate flaring and irregularity of the metaphyses. This patient is at the highest risk for developing which of the following complications?

. Hypercalcemic crisis
. Non-Hodgkin lymphoma
. Foramen magnum stenosis
. Exocrine pancreatic insufficiency
. Cranial nerve deafness

Correct Answer & Explanation

. Non-Hodgkin lymphoma

Explanation

This clinical picture describes Cartilage-Hair Hypoplasia (McKusick type), caused by an RMRP gene mutation. Patients have impaired T-cell immunity, predisposing them to recurrent infections and malignancies such as non-Hodgkin lymphoma.

Question 5773

Topic: 6. Spine

A 17-year-old boy with achondroplasia complains of progressive bilateral leg weakness, numbness, and neurogenic claudication after walking short distances. He has a normal upper extremity neurological examination. Which of the following is the most likely cause of his symptoms?

. Foramen magnum stenosis
. Cervical myelopathy
. Thoracolumbar kyphosis
. Lumbar spinal stenosis
. Tethered cord syndrome

Correct Answer & Explanation

. Lumbar spinal stenosis

Explanation

In older children and adults with achondroplasia, neurogenic claudication is typically due to lumbar spinal stenosis caused by congenitally short pedicles and decreased interpedicular distance. Foramen magnum stenosis usually presents in infancy with central apnea or high cervical myelopathy.

Question 5774

Topic: 6. Spine

A 35-year-old male with achondroplasia presents with progressively worsening bilateral leg pain and weakness brought on by walking and relieved by sitting. Neurological examination reveals hyperreflexia in the lower extremities. Imaging confirms severe lumbar spinal stenosis. Which anatomic abnormality is the primary driver of central canal stenosis in this patient?

. Hypertrophy of the ligamentum flavum
. Severe facet joint arthrosis
. Shortened pedicles and narrowed interpedicular distance
. Isthmic spondylolisthesis
. Ossification of the posterior longitudinal ligament

Correct Answer & Explanation

. Shortened pedicles and narrowed interpedicular distance

Explanation

In achondroplasia, premature closure of the neurocentral synchondroses results in congenitally shortened pedicles and a narrowed interpedicular distance. This developmental anomaly strictly limits the spinal canal diameter, making minor degenerative changes highly symptomatic.

Question 5775

Topic: 6. Spine

A 38-year-old male with classic achondroplasia presents with neurogenic claudication, complaining of bilateral leg pain and heaviness that worsens with walking and improves when sitting. What is the primary anatomical basis for his spinal stenosis?

. Severe spondylolisthesis at L5-S1
. Congenitally short pedicles and thickened ligamentum flavum
. Massive central disc extrusions
. Ossification of the posterior longitudinal ligament
. Thoracolumbar kyphosis causing anterior cord compression

Correct Answer & Explanation

. Congenitally short pedicles and thickened ligamentum flavum

Explanation

Adults with achondroplasia frequently develop symptomatic lumbar spinal stenosis. The stenosis is driven by underlying osseous anatomy, specifically congenitally shortened pedicles and decreased interpedicular distances, compounded by a thickened ligamentum flavum.

Question 5776

Topic: 6. Spine

A 6-year-old girl presents with progressive mid-back pain. Neurological examination is unremarkable. Radiographs reveal a uniform collapse of the T7 vertebral body with preservation of the adjacent intervertebral disc spaces, consistent with vertebra plana. Which of the following is the most appropriate initial management?

. Anterior corpectomy and structural grafting
. Posterior spinal fusion with instrumentation
. Radiation therapy
. Observation and symptomatic treatment with or without bracing
. Systemic multidrug chemotherapy

Correct Answer & Explanation

. Observation and symptomatic treatment with or without bracing

Explanation

Vertebra plana in a child is highly characteristic of eosinophilic granuloma (Langerhans cell histiocytosis). Without neurologic deficit, the condition is typically self-limiting, and the vertebral body often spontaneously reconstitutes over time, making observation and symptomatic care the treatment of choice.

Question 5777

Topic: 6. Spine

A 6-year-old boy presents with back pain but intact neurology. Radiographs reveal a 'coin-on-edge' appearance of the T8 vertebral body (vertebra plana). MRI confirms a solitary lesion confined to the vertebral body. What is the most appropriate initial management?

. Anterior corpectomy and strut grafting
. Posterior spinal fusion
. High-dose systemic chemotherapy
. Observation and symptomatic management
. Radiation therapy

Correct Answer & Explanation

. Observation and symptomatic management

Explanation

Vertebra plana in a child without neurologic compromise is a classic presentation of eosinophilic granuloma (LCH). These solitary lesions are typically self-limiting and tend to reconstitute height over time, making observation and symptomatic care the best initial approach.

Question 5778

Topic: 6. Spine

A 6-year-old boy is evaluated for mild, progressive back pain. Radiographs reveal an isolated, completely flattened vertebral body (vertebra plana) at T8 with no associated soft tissue mass or kyphotic deformity. The patient is neurologically intact. What is the most appropriate initial management?

. Urgent posterior spinal instrumentation and fusion
. Observation and symptomatic management with NSAIDs
. Intralesional injection of methylprednisolone
. Excisional biopsy and curettage
. Multi-agent systemic chemotherapy

Correct Answer & Explanation

. Observation and symptomatic management with NSAIDs

Explanation

Isolated vertebra plana in a pediatric patient is the classic presentation of Eosinophilic Granuloma (LCH) of the spine. In the absence of neurologic deficits or severe instability, these typically reconstitute height over time, making observation and symptomatic management the standard of care.

Question 5779

Topic: 6. Spine

In the staging and prognosis of Langerhans Cell Histiocytosis (LCH), which of the following clinical scenarios carries the worst prognosis?

. A 5-year-old with multiple lytic skull lesions
. A 10-year-old with isolated vertebra plana and mild diabetes insipidus
. A 14-year-old with a solitary femoral diaphyseal lesion
. A 1-year-old with diffuse rash, hepatosplenomegaly, and cytopenias
. An 8-year-old with bilateral clavicular and rib lesions

Correct Answer & Explanation

. A 1-year-old with diffuse rash, hepatosplenomegaly, and cytopenias

Explanation

The worst prognosis in LCH is seen in children under 2 years of age who have disseminated disease with multi-organ involvement, particularly involving 'risk organs' such as the liver, spleen, and bone marrow.

Question 5780

Topic: 6. Spine

An 8-year-old boy presents with back pain. Radiographs reveal a severe compression fracture of the T6 vertebral body (vertebra plana). Biopsy of the lesion shows sheets of eosinophils and mononuclear cells. Electron microscopy reveals tennis-racket shaped intracytoplasmic organelles. Which immunohistochemical marker will be definitively positive?

. CD99
. S-100 and CD1a
. Cytokeratin
. EMA
. Vimentin only

Correct Answer & Explanation

. S-100 and CD1a

Explanation

The clinical presentation of vertebra plana with "tennis-racket" Birbeck granules on electron microscopy is pathognomonic for Langerhans Cell Histiocytosis (LCH). These histiocytic cells characteristically stain positive for CD1a, S-100, and Langerin (CD207).

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