Brain Malformation Surgery Reduces Sleep Apnea

In Arnold-Chiari malformation, abnormalities cause the cerebellum portion of the brain to protrude through the bottom of the skull against the spinal cord. This protrusion can cause compression on the brain stem, including the areas that control breathing. People with this brain defect often develop sleep apnea, a disorder that causes breathing interruptions during sleep and can lead to daytime sleepiness.

The study involved 16 people with Arnold-Chiari malformation type I and a related condition called syringomyelia. In syringomyelia, cerebrospinal fluid enters the spinal cord. The fluid then forms a cavity in the spinal cord known as a syrinx. All of the participants underwent an overnight sleep study.

Out of the 16 people, 12 had sleep apnea. Of those, half had a rare type of sleep apnea called central sleep apnea, caused by problems with the brain's mechanisms that control breathing. Eight of the 12 people with sleep apnea had decompression surgery. Six of these had another overnight sleep study about seven months after the surgery. This showed that the number of central sleep apnea occurrences decreased by more than 90%, from an average of 15 episodes per hour of sleep to an average of one episode per hour of sleep. Incidences that involved micro-arousals also dropped by 30%. The results were published in the January 10, 2006, issue of Neurology.

"Our study shows that more than 70% of people with Chiari malformations have sleep apnea and problems with daytime sleepiness,” said study author Frédéric Gagnadoux, M.D., of Central University Hospital (Angers, France). "These problems can be significantly improved by surgery.”