ARRS Case of the Week- Oct 2, 2017

From http://www.arrs.org/ARRSLIVE/CaseOfTheWeek.

PEDIATRIC RADIOLOGY: Musculoskeletal Radiology

Case Author: Ricardo Restrepo, MD, Miami Children’s Hospital

History

8-year-old girl with dysmorphic features and short stature who reports difficulty walking.

Imaging Findings

Frontal radiograph of the right hand (A) shows short, squat metacarpals that are widened distally and tapered proximally (arrows). Wide radioulnar articular ends also are evident. Lateral radiograph of the spine (B) shows platyspondyly with central anterior beaking (arrow). Sagittal reconstruction CT image of the cervical spine (C) shows diffuse platyspondyly with a hypoplastic dens (arrow). Sagittal T2-weighted MR image (D) shows severe narrowing of the spinal canal with a focal area of myelomalacia (arrow) at C2.

Achondroplasia
Hurler syndrome
Morquio syndrome

Diagnosis

Morquio syndrome

Teaching Points

Achondroplasia is the most common type of short-limb dwarfism characterized by abnormal formation of endochondral bone. Spinal features include bullet-shaped vertebral bodies and a decrease in interpedicular distance in the lumbar spine, thoracolumbar kyphosis, stenosis of the spinal canal and foramen magnum with secondary hydrocephalus, and progressive neurological deficits, such as paraplegia and nerve root compression. Mucopolysaccharidosis is a lysosomal storage disorder caused by a deficiency in the enzyme involved in metabolism of glycosaminoglycans. It is classified as types I–IV, VI, VII, and IX. The types are differentiated by their clinical features, age at presentation, and associated specific enzyme deficiency. The radiologic workup of mucopolysaccharidosis is a skeletal survey. The types of mucopolysaccharidosis share imaging features. Morquio syndrome has distinctive manifestations mainly involving the spine (universal platyspondyly, central anterior vertebral beaking, odontoid hypoplasia, atlantooccipital instability, spinal canal stenosis, and progressive cervical myelopathy). In Hurler syndrome, there is no platyspondyly, and the vertebral beaking is anteroinferior. In patients with Morquio syndrome with spinal cord compression and spinal instability, early posterior fusion is helpful in preventing neurologic deterioration.

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