ACQUIRED CHIARI-I MALFORMATION SECONDARY TO SPONTANEOUS SPINAL CEREBROSPINAL-FLUID LEAKAGE AND CHRONIC INTRACRANIAL HYPOTENSION SYNDROME IN7 CASES

Object. Spontaneous spinal cerebrospinal fluid (CSF) leakage with deve lopment of the intracranial hypotension syndrome and acquired Chiari I malformation due to lumbar spinal CSF diversion procedures have both been well described. However, concomitant presentation of both syndrom es has rarely been reported. The object of this paper is to present da ta in seven cases in which both syndromes were present. Three illustra tive cases are reported in detail. Methods. The authors describe seven symptomatic cases of spontaneous spinal CSF leakage with chronic intr a cranial hypotension syndrome in which magnetic resonance (MR) images depicted dural enhancement, brain sagging, loss of CSF cisterns, and acquired Chiari I malformation. Conclusions. This subtype of intracran ial hypotension syndrome probably results from chronic spinal drainage of CSF or high-flow CSF shunting and subsequent loss of brain buoyanc y that results in brain settling and herniation of hindbrain structure s through the foramen magnum. Of 35 cases of spontaneous spinal CSF le akage identified in the authors' practice over the last decade, MR ima ging evidence of acquired Chiari I malformation has been shown in seve n. Not to be confused with idiopathic Chiari I malformation, ideal the rapy requires recognition of the syndrome and treatment directed to th e site of the spinal CSF leak.