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 7221
Topic: 6. Spine
A 5-year-old with Morquio syndrome (MPS IV) is scheduled for elective bilateral lower extremity osteotomies for severe genu valgum. Prior to intubation and anesthesia, which of the following is the most critical radiographic screening required?
Correct Answer & Explanation
. Flexion-extension cervical spine radiographs
Explanation
Patients with Morquio syndrome have severe odontoid hypoplasia and ligamentous laxity, leading to atlantoaxial instability. Flexion-extension C-spine radiographs are mandatory prior to any procedure requiring intubation to prevent catastrophic spinal cord injury.
Question 7222
Topic: Cervical Spine
A 6-year-old girl with Morquio syndrome (MPS IV) presents with progressive weakness and clumsiness in her hands. Cervical spine flexion-extension radiographs demonstrate severe atlantoaxial instability. What is the primary anatomic cause of this instability in Morquio syndrome?
Correct Answer & Explanation
. Odontoid hypoplasia combined with ligamentous laxity
Explanation
Atlantoaxial instability in Morquio syndrome (MPS IV) is driven by a combination of severe odontoid hypoplasia and profound ligamentous laxity. This places patients at high risk for fatal cervicomedullary compression if not addressed with surgical fusion.
Question 7223
Topic: Thoracolumbar Spine & Deformity
A patient with Hurler syndrome develops a severe thoracolumbar kyphosis (gibbus deformity). What is the primary radiographic abnormality of the vertebrae causing this deformity?
Correct Answer & Explanation
. Anteroinferior vertebral body beaking
Explanation
In Hurler syndrome (MPS I), the vertebrae typically exhibit anteroinferior beaking, which leads to anterior wedging and progressive thoracolumbar kyphosis. In contrast, Morquio syndrome (MPS IV) classically features central anterior beaking.
Question 7224
Topic: 6. Spine
A 6-year-old child with normal intelligence presents with short stature, severe genu valgum, and a barrel chest. Radiographs reveal platyspondyly with central anterior vertebral beaking.
Which of the following is the most critical screening evaluation prior to any surgical intervention?
Correct Answer & Explanation
. Flexion-extension cervical spine radiographs
Explanation
The clinical presentation and central vertebral beaking are classic for Morquio syndrome (MPS IV). These patients are at high risk for fatal atlantoaxial instability due to odontoid hypoplasia, necessitating cervical spine screening prior to anesthesia.
Question 7225
Topic: Cervical Spine
A 6-year-old child presents with severe disproportionate short-trunk dwarfism, knock-knees, and normal intelligence. Radiographs reveal platyspondyly and odontoid hypoplasia. Laboratory analysis confirms a diagnosis of Morquio syndrome (MPS IV). Which of the following is the deficient enzyme in Type A of this disorder?
Correct Answer & Explanation
. Galactosamine-6-sulfatase
Explanation
Morquio syndrome Type A is an autosomal recessive mucopolysaccharidosis caused by a deficiency in galactosamine-6-sulfatase. Unlike most other MPS types, intelligence is preserved, but severe skeletal deformities and atlantoaxial instability are hallmarks.
Question 7226
Topic: 6. Spine
A 1-year-old infant presents with corneal clouding, hepatosplenomegaly, mental retardation, and a noticeable gibbus deformity of the thoracolumbar spine. What is the deficient enzyme responsible for this clinical presentation?
Correct Answer & Explanation
. Alpha-L-iduronidase
Explanation
This presentation is classic for Hurler syndrome (MPS I), an autosomal recessive disorder. It is caused by a deficiency in alpha-L-iduronidase, leading to the accumulation of dermatan and heparan sulfate.
Question 7227
Topic: 6. Spine
A 5-year-old child with a known deficiency of galactosamine-6-sulfatase requires general anesthesia for a hernia repair. Which pre-operative orthopedic evaluation is absolutely critical before intubation?
Correct Answer & Explanation
. Flexion-extension cervical spine radiographs
Explanation
Patients with Morquio syndrome (MPS IV) frequently have odontoid hypoplasia resulting in severe atlantoaxial instability. Flexion-extension cervical spine radiographs are mandatory before any procedure requiring intubation to prevent spinal cord injury.
Question 7228
Topic: 6. Spine
A 6-year-old boy presents with short trunk dwarfism, normal intelligence, and severe genu valgum. Spine radiographs demonstrate universal platyspondyly with central anterior vertebral beaking. He is diagnosed with Mucopolysaccharidosis Type IV (Morquio syndrome). Which specific enzyme is deficient in this patient?
Correct Answer & Explanation
. Galactosamine-6-sulfatase
Explanation
Morquio syndrome (MPS IV) is caused by a deficiency in Galactosamine-6-sulfatase (Type A) or Beta-galactosidase (Type B), leading to keratan sulfate accumulation. It uniquely features normal intelligence and central anterior vertebral beaking.
Question 7229
Topic: 6. Spine
A 2-year-old girl is evaluated for coarse facial features, corneal clouding, developmental delay, and severe kyphosis. Spine radiographs show anterior-inferior vertebral body beaking.
The accumulation of which glycosaminoglycans is primarily responsible for her clinical presentation?
Correct Answer & Explanation
. Heparan sulfate and Dermatan sulfate
Explanation
The patient has Hurler syndrome (MPS I), caused by alpha-L-iduronidase deficiency. This leads to the toxic accumulation of heparan sulfate and dermatan sulfate, resulting in severe skeletal dysplasia, corneal clouding, and mental retardation.
Question 7230
Topic: 6. Spine
An 8-year-old boy with known Morquio syndrome (MPS IV) is scheduled for bilateral lower extremity corrective osteotomies to address severe genu valgum. Before general anesthesia is administered, which of the following is the most critical pre-operative orthopedic evaluation?
Correct Answer & Explanation
. Flexion-extension radiographs of the cervical spine
Explanation
Patients with Morquio syndrome (MPS IV) classically suffer from odontoid hypoplasia and ligamentous laxity, making them highly susceptible to atlantoaxial instability. Flexion-extension cervical radiographs (or MRI) are critical prior to intubation to prevent catastrophic spinal cord injury.
Question 7231
Topic: 6. Spine
A 5-year-old boy with a known iduronate-2-sulfatase deficiency (Hunter syndrome) undergoes a comprehensive skeletal survey. Which of the following radiographic findings is most characteristic of the spinal deformities seen in this patient?
Correct Answer & Explanation
. Central anterior vertebral body beaking
Explanation
Hunter syndrome (MPS II) is characterized radiographically by anterior-inferior vertebral body beaking, similar to Hurler syndrome (MPS I). Central anterior beaking is the hallmark of Morquio syndrome (MPS IV).
Question 7232
Topic: Cervical Spine
A 6-year-old girl presents with short-trunk dwarfism, severe genu valgum, and generalized joint hyperlaxity. She has normal intelligence but exhibits corneal clouding. Cervical spine radiographs reveal odontoid hypoplasia with significant atlantoaxial instability.
Which of the following glycosaminoglycans abnormally accumulates in this patient's specific syndrome?
Correct Answer & Explanation
. Keratan sulfate
Explanation
The patient's presentation of short-trunk dwarfism, normal intelligence, joint hyperlaxity, and odontoid hypoplasia is classic for Morquio syndrome (Mucopolysaccharidosis Type IV). This condition is caused by a deficiency in galactosamine-6-sulfatase or beta-galactosidase, leading to the specific accumulation of keratan sulfate.
Question 7233
Topic: 6. Spine
A 6-year-old child presents with severe genu valgum, prominent chest deformity, and normal intelligence. Radiographs demonstrate central anterior beaking of the vertebral bodies and platyspondyly. Which of the following is the most critical orthopedic screening required for this patient to prevent catastrophic neurological injury?
Correct Answer & Explanation
. Cervical spine flexion-extension radiographs
Explanation
This patient has Morquio syndrome (MPS IV), characterized by central vertebral beaking, normal intelligence, and severe skeletal dysplasia. Odontoid hypoplasia and atlantoaxial instability are hallmarks, necessitating careful cervical spine screening to prevent myelopathy.
Question 7234
Topic: 6. Spine
A 3-year-old girl is diagnosed with a mucopolysaccharidosis. Radiographs of her thoracolumbar spine demonstrate severe kyphosis (gibbus deformity). Which of the following radiographic features of the spine best distinguishes Hurler syndrome from Morquio syndrome?
Correct Answer & Explanation
. Location of the vertebral body anterior beak
Explanation
In Hurler syndrome (MPS I), the anterior vertebral beak is typically located at the anteroinferior aspect of the vertebral body. In contrast, Morquio syndrome (MPS IV) classically presents with a central anterior vertebral beak.
Question 7235
Topic: 6. Spine
A 4-year-old girl with achondroplasia presents to the clinic with progressive clumsiness, bilateral lower extremity hyperreflexia, and occasional apneic episodes during sleep. Radiographs confirm normal sagittal and coronal alignment of the thoracolumbar spine. What is the most likely cause of her progressive neurological symptoms?
Correct Answer & Explanation
. Foramen magnum stenosis causing cervicomedullary compression
Explanation
In young children with achondroplasia, abnormal endochondral ossification leads to poor development of the skull base, frequently causing foramen magnum stenosis. This can lead to cervicomedullary compression, presenting with hyperreflexia, sleep apnea, central hypotonia, and potentially sudden death if untreated.
Question 7236
Topic: 6. Spine
A 45-year-old man presents with recurrent right-sided sciatica 6 months after a right L4-L5 microdiscectomy. He had initial relief of symptoms, but the pain returned 4 weeks ago. To differentiate between epidural fibrosis (scar tissue) and a recurrent disk herniation, an MRI with gadolinium contrast is ordered. Which of the following best describes the expected MRI findings?
Correct Answer & Explanation
. Epidural fibrosis will enhance with gadolinium, whereas a recurrent disk herniation will not enhance.
Explanation
Correct Answer: Epidural fibrosis will enhance with gadolinium, whereas a recurrent disk herniation will not enhance.Differentiating between a recurrent disk herniation and epidural fibrosis (scar tissue) in a patient with recurrent radiculopathy after a microdiscectomy is a common clinical challenge. MRI with intravenous gadolinium contrast is the imaging modality of choice. Epidural fibrosis is highly vascularized and will enhance with gadolinium. In contrast, a recurrent disk fragment is avascular and will not enhance centrally, although there may be a thin rim of peripheral enhancement due to surrounding inflammatory granulation tissue.
Question 7237
Topic: 6. Spine
A 45-year-old man presents with recurrent right-sided sciatica 2 years after an L4-L5 microdiscectomy. An MRI with gadolinium contrast is ordered to evaluate his symptoms. What is the expected enhancement pattern that differentiates a recurrent disc herniation from epidural scar tissue?
Correct Answer & Explanation
. Scar tissue enhances uniformly, while a recurrent disc herniation shows only peripheral enhancement.
Explanation
Correct Answer: CMRI with gadolinium contrast is the gold standard for differentiating epidural fibrosis (scar tissue) from a recurrent disc herniation in a patient with prior spine surgery. Epidural scar tissue is highly vascularized and will enhance uniformly after gadolinium administration. In contrast, a recurrent disc fragment is avascular and will not enhance centrally, although it may exhibit a thin rim of peripheral enhancement due to the surrounding inflammatory response.
Question 7238
Topic: 6. Spine
A 45-year-old man presents with recurrent right-sided L5 radicular leg pain 6 months after an L4-L5 microdiscectomy. To differentiate between a recurrent disc herniation and postoperative epidural fibrosis, an MRI with gadolinium contrast is ordered. Which of the following MRI findings is most characteristic of a recurrent disc herniation?
Correct Answer & Explanation
. A mass in the anterior epidural space with peripheral enhancement and a non-enhancing center
Explanation
Correct Answer: BDifferentiating recurrent disc herniation from epidural fibrosis (scar tissue) is a common clinical challenge following lumbar discectomy. MRI with intravenous gadolinium contrast is the imaging modality of choice. Epidural fibrosis is vascularized tissue and will therefore enhance homogeneously with gadolinium. In contrast, a recurrent disc fragment is avascular and will not enhance centrally. However, the disc fragment is often surrounded by vascularized granulation tissue or scar, leading to a characteristic pattern of peripheral enhancement with a dark, non-enhancing center. Therefore, a mass with peripheral enhancement and a non-enhancing center is diagnostic of a recurrent disc herniation.
Question 7239
Topic: 6. Spine
A 45-year-old man presents with recurrent right-sided sciatica 6 months after a right L4-L5 microdiscectomy. He had complete relief of his leg pain immediately postoperatively, but the pain returned gradually over the past month. Which of the following imaging modalities is the most specific for differentiating a recurrent disc herniation from postoperative epidural fibrosis?
Correct Answer & Explanation
. MRI of the lumbar spine with intravenous gadolinium
Explanation
Correct Answer: BDifferentiating a recurrent disc herniation from postoperative epidural fibrosis (scar tissue) is critical in a patient with recurrent radiculopathy after a discectomy. MRI with intravenous gadolinium contrast is the imaging modality of choice. Epidural fibrosis is highly vascularized and will enhance uniformly after gadolinium administration. In contrast, a recurrent disc fragment is avascular and will not enhance centrally, although it may demonstrate a thin rim of enhancement from surrounding inflammatory scar tissue. Non-contrast MRI cannot reliably distinguish between the two entities, as both can appear as intermediate signal intensity on T1 and T2-weighted images.
Question 7240
Topic: 6. Spine
A 45-year-old man presents with recurrent right-sided L5 radiculopathy 18 months after an L4-L5 microdiscectomy. To differentiate between a recurrent disc herniation and epidural fibrosis, an MRI with gadolinium is ordered. Which of the following MRI findings is most indicative of a recurrent disc herniation rather than epidural fibrosis?
Correct Answer & Explanation
. Peripheral enhancement of the mass with a non-enhancing central core on T1-weighted images
Explanation
Correct Answer: BDifferentiating between a recurrent disc herniation and epidural fibrosis (scar tissue) is critical in a patient presenting with recurrent radiculopathy after a prior discectomy. MRI with intravenous gadolinium contrast is the imaging modality of choice. Epidural fibrosis is vascularized tissue and will demonstrate homogeneous enhancement following gadolinium administration. In contrast, a recurrent disc fragment is avascular and will not enhance centrally. However, the inflammatory granulation tissue surrounding the recurrent disc fragment will enhance, leading to a characteristic peripheral enhancement with a non-enhancing central core on T1-weighted images.
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