Laryngeal stridor associated with the Chiari II malformation.

Twelve patients with Chiari II malformation developed laryngeal stridor and respiratory distress. This may develop when there is acute downward or upward displacement of the malformed brain stem secondary to increased or decreased intracranial pressure. Rapidly progressive hydrocephalus and compression of the lower portion of the IV ventricle are more important factors than the size of the head at birth. For the treatment of these symptoms relief of the increase in intracranial pressure, relief of the pressure difference between intracranial and intraspinal compartments, and selection of a shunt system with a proper flow rate are important. Posterior fossa decompression did not show a favorable effect.