A 5-month-old boy was referred by a community pediatrician to clinical genetics at our facility for short stature and macrocephaly. His delivery had been normal, although his parents had noticed snoring from the age of 4 months. He had shortened proximal limb lengths (humerus and femur), bifrontal bossing and a large, flat fontanelle suspicious for achondroplasia. Neurologic examination was normal.
The patient had moderate central sleep apnea diagnosed on polysomnography. Genetic testing confirmed fibroblast growth factor 3 (FGFR3) gene mutation and we diagnosed achondroplasia. When he was 10 months old, we performed craniospinal imaging, which showed severe foramen magnum stenosis with cervicomedullary compression (Figure 1). Because of the severe compression with signal change and central sleep apnea, we performed a suboccipital craniectomy and C1 laminectomy. At 2 months' follow-up, the patient's neurologic examination was still normal and developmental milestones were progressing appropriately....