Centrally mediated obstructive apnoea and restenosis of the foramen magnum in an infant with achondroplasia

Achondroplasia is associated with foramen magnum stenosis. We report a male infant with achondroplasia and centrally mediated obstructive apnoea who underwent two foramen magnum decompression due to bone regrowth. He presented at six weeks of age with breath holding and apnoeic episodes associated with significant desaturation, requiring non-invasive ventilation. Craniospinal imaging revealed a narrow foramen magnum without signal change in the spinal cord. Sleep studies showed obstructive, but not central, apnoea. Respiratory abnormalities persisted and reimaging at two months showed development of significant signal changes at the cervicomedullary junction (CMJ). He underwent emergency foramen magnum decompression with initial clinical improvement. Ten days later he relapsed with further apnoeic episodes requiring respiratory support. After extensive re-investigations including CT and MRI, incomplete initial decompression and foramen magnum restenosis were considered and confirmed with a CT head scan 15 weeks after the initial operation. Repeat decompression of bone and removal of thickened dural bands resulted in complete resolution of the apnoeic episodes. Obstructive sleep apnoea can be centrally mediated and further decompression of foramen magnum stenosis should be considered, especially if significant respiratory compromise persists or recurs.