INCREASED BRAIN WATER SELF-DIFFUSION IN PATIENTS WITH IDIOPATHIC INTRACRANIAL HYPERTENSION

PURPOSE: To investigate changes in brain water diffusion in patients w ith idiopathic intracranial hypertension. METHODS: A motion-compensate d MR pulse sequence was used to create diffusion maps of the apparent diffusion coefficient (ADC) in 12 patients fulfilling conventional dia gnostic criteria for idiopathic intracranial hypertension and in 12 he althy volunteers. RESULTS: A significant larger ADC was found within s ubcortical white matter in the patient group (mean, 1.16 x 10(-9) m(2) /s) than in the control group (mean, 0.75 X 10(-9) m(2)/s), whereas no significant differences were found within cortical gray matter, the b asal nuclei, the internal capsule, or the corpus callosum. Four of 7 p atients with increased ADC in subcortical white matter also had increa sed ADC within gray matter. CONCLUSION: Measurement of diffusion coeff icients in vivo demonstrated increased local water mobility within sub cortical white matter in 7 patients with idiopathic intracranial hyper tension that otherwise appeared normal on conventional MR imaging. Fur ther studies are necessary to assess the clinical significance of thes e observations.