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Cervical Spine MCQs

Practice Set 24 of 24

This practice set contains high-yield board review questions covering key concepts in Cervical Spine. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 461

Topic: Cervical Spine

A 7-year-old child with short trunk dwarfism, corneal clouding, and normal intelligence presents for orthopedic evaluation. Cervical spine radiographs reveal severe odontoid hypoplasia and atlantoaxial instability. Which enzyme is deficient in this specific syndrome?

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

Correct Answer & Explanation

. Galactosamine-6-sulfatase

Explanation

Morquio syndrome (Mucopolysaccharidosis Type IV) is caused by a deficiency in galactosamine-6-sulfatase (Type A) or beta-galactosidase (Type B). It is uniquely characterized by severe odontoid hypoplasia leading to life-threatening atlantoaxial instability, while maintaining normal intelligence.

Question 462

Topic: Cervical Spine

A 6-year-old child with normal intelligence presents with short stature, severe knock-knees, and a waddling gait. Radiographs reveal platyspondyly and a hypoplastic odontoid.

Which of the following enzyme deficiencies is the primary cause of this condition?

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

Correct Answer & Explanation

. N-acetylgalactosamine-6-sulfatase

Explanation

The patient has Morquio syndrome (MPS IV), characterized by normal intelligence, severe skeletal dysplasia (platyspondyly, odontoid hypoplasia), and joint laxity. It is caused by a deficiency of N-acetylgalactosamine-6-sulfatase (Type A) or Beta-galactosidase (Type B).

Question 463

Topic: Cervical Spine

A 6-year-old boy with normal intelligence presents with severe genu valgum, short trunk dwarfism, and a waddling gait. Radiographs reveal platyspondyly with central anterior beaking of the vertebrae and severe odontoid hypoplasia. Urine spot testing is positive for keratan sulfate. Which enzyme is most likely deficient in this patient?

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

Correct Answer & Explanation

. Galactosamine-6-sulfatase

Explanation

The clinical presentation of normal intelligence, severe skeletal dysplasia, atlantoaxial instability, central vertebral beaking, and keratan sulfate accumulation is classic for Morquio syndrome A (MPS IVA). This is caused by a deficiency of the enzyme galactosamine-6-sulfatase.

Question 464

Topic: Cervical Spine

A 6-year-old boy with short trunk dwarfism and normal intelligence presents for evaluation. Radiographs demonstrate severe platyspondyly, anterior central vertebral beaking, and odontoid hypoplasia. What is the underlying enzyme deficiency?

. Alpha-L-iduronidase
. Iduronate-2-sulfatase
. N-acetylgalactosamine-6-sulfate sulfatase
. Glucocerebrosidase
. Sphingomyelinase

Correct Answer & Explanation

. N-acetylgalactosamine-6-sulfate sulfatase

Explanation

The clinical picture describes Morquio syndrome (MPS IV), uniquely characterized by normal intelligence, severe platyspondyly, and odontoid hypoplasia. It is caused by a deficiency in N-acetylgalactosamine-6-sulfate sulfatase (Type IVA) or beta-galactosidase (Type IVB).

Question 465

Topic: Cervical Spine

A 6-year-old boy with normal intelligence presents with a disproportionately short trunk, severe genu valgum, and progressive corneal clouding. Flexion-extension cervical spine radiographs show pronounced atlantoaxial instability secondary to profound odontoid hypoplasia. Which of the following metabolites is accumulating in this patient's tissues?

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

Correct Answer & Explanation

. Keratan sulfate

Explanation

Morquio syndrome (Mucopolysaccharidosis Type IV) is caused by a deficiency in N-acetylgalactosamine-6-sulfatase (Type IVA) or beta-galactosidase (Type IVB), leading to the accumulation of keratan sulfate. It uniquely causes severe odontoid hypoplasia and atlantoaxial instability, requiring careful monitoring and potential cervical fusion.

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