MRI findings and sleep apnea in children with Chiari I malformation.

Chiari I malformation is characterized by downward herniation of the cerebellar tonsils through the foramen magnum. Scant data are available on the clinical course, relationship to the extent of herniation on magnetic resonance imaging in Chiari I malformation and the presence of sleep-disordered breathing on polysomnography. Retrospective analysis was performed looking at polysomnographic findings of children diagnosed with Chiari I malformation. Details on how Chiari I malformation was diagnosed, brainstem magnetic resonance imaging findings, and indications for obtaining the polysomnogram in these patients were reviewed. We also reviewed available data on children who had decompression surgery followed by postoperative polysomnography findings. Twenty-two children were identified in our study (11 males, median age 10 years, range 1 to 18). Three had central sleep apnea, five had obstructive sleep apnea, and one had both obstructive and central sleep apnea. Children with sleep-disordered breathing had excessive crowding of the brainstem structures at the foramen magnum and were more likely to have a greater length of herniation compared with those children without sleep-disordered breathing (P = 0.046). Patients with central sleep apneas received surgical decompression, and their conditions were significantly improved on follow-up polysomnography. These data suggest that imaging parameters may correlate with the presence of sleep-disordered breathing in children with Chiari I malformation.