Cervicomedullary Cord Compression in Young Children with Achondroplasia: Value of Comprehensive Neurologic and Respiratory Evaluation
While the majority of individuals with achondroplasia have few serious complications, affected infants and children are at risk for both respiratory and neurologic complications due to certain anatomic characteristics of the disorder (1–3). In the young child, the ribs are short and straight, causing a constricted thoracic cage with a flattened anteroposterior diameter. Dysplasia of the cranial base and upper cervical spine result in a shortened and narrowed nasopharynx as well as a constricted craniocervical junction (Fig. 1). Both restrictive lung disease and obstructive sleep apnea have been documented in young children with achondroplasia (3,4). Compression of the upper cervical spinal cord and distal medulla because of a stenotic foramen magnum is well documented as a cause of quadriplegia in achondroplasia (5), but has been recently reemphasized as a cause of respiratory compromise, apnea and sudden death in infants with the disorder (6). Compression of the anterior spinal artery, traction on the medullary respiratory center and paresis of respiratory muscles have each been suggested as causes of hypoventilation in infants with cervicomedullary compression (5,6). Some young patients with documented cord compression have had findings suggesting a chronic respiratory disorder, such as right ventricular hypertrophy, but have had few, if any, upper motor neuron signs (1). Because both primary and neurogenic respiratory problems may coexist, interpretation of respiratory problems in a given patient is difficult, especially when there are few neurologic signs. We hypothesized that respiratory problems in some achondroplastic infants and children might be due to occult cervicomedullary compression, and that some patients with signs of compression might have occult respiratory abnormalities. We therefore undertook a prospective clinical study to evaluate achondroplastic infants and children for both respiratory and neurologic abnormalities.
KeywordsObstructive Sleep Apnea Somatosensory Evoke Potential Odontoid Process Craniocervical Junction Foramen Magnum
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