LAUSR

Spinal cord compression at the craniocervical junction can cause central sleep apnea (CSA) in children, due to mechanical disruption of respiratory control centers. Polysomnography (PSG) pre/post surgical decompression is indicated to evaluate treatment response. A 5-year-old with Wolf-Hirschhorn syndrome, developmental delay, partial agenesis of the corpus callosum, hypotonia, incomplete segmentation of C1 with subluxation leading to stenosis, cleft palate, and obstructive sleep apnea (OSA) presented for post-surgical PSG. Prior PSGs revealed oAHI 55/hr and 7/hr, cAHI 3/hr and 2/hr at 1 and 10 months of age, respectively. At 46 months, patient underwent suboccipital decompression at C1 for severe craniocervical stenosis. Post-operative PSG revealed emergence of CSA with cAHI 8/hr and stability of OSA with an oAHI 8/hr. Positional analysis revealed worsening in lateral position (lateral cAHI 10.6/hr, supine cAHI 4.6/hr). Central events were up to 33 seconds long with nadir desaturation of 76% in lateral position compared to 20 seconds and nadir 88% in supine position. Head CT and MRI showed incomplete ossification of the C1 vertebra with subluxation of the left lateral mass leading to absence of CSF flow at the craniocervical junction. Repeat decompression and fixation is planned by neurosurgery; in the interim supine sleep was recommended and family declined BiPAP. In our case, CSA worsened with left lateral positioning and improved with supine positioning. Lateral positioning likely increased subluxation of the left lateral mass seen on CT/MRI, and eased subluxation in supine sleep causing position-dependent dynamic impingement of the respiratory control centers at the level of subluxation. The absence of findings prior to decompression may reflect increased instability after decompression or increased stenosis with growth. Our case highlights the importance of positional analysis for central as well as the more conventional obstructive sleep apnea to understand pathogenesis and guide therapy.