Associated Disorders of Chiari Type I Malformations

A Review

Marios Loukas, M.D., Ph.D.; Brian J. Shayota, B.S.; Kim Oelhafen, B.S.; Joseph H. Mill er, M.D.; Joshua J. Chern, M.D., Ph.D.; R. Shane Tubbs, M.S., P.A.-C., Ph.D.; W. Jerry Oakes, M.D.


Neurosurg Focus. 2011;31(3):e3 

In This Article


Hans Chiari's aforementioned original theory regarding the causative association between hydrocephalus and hindbrain herniation has not allowed for an all-encompassing explanation into the pathophysiology of CM-I. Nonetheless, hydrocephalus is noted in approximately 4%–18% of patients with CM-I.[3,70] Tubbs et al.,[65] in a review of 500 patients with CM-I treated between 1989 and 2010, demonstrated that 9.8% of patients had concomitant hydrocephalus. These patients all required CSF diversion in addition to an operative posterior fossa decompression. This association is likely secondary to fourth ventricular outflow tract obstruction or concurrent aqueductal stenosis. As a result, endoscopic third ventriculostomy has been used with success in this patient population.