The neuroanatomy of 11 females with Rett syndrome (RS) and 15 control subjects investigated in vivo with quantitative MRI is reported from Johns Hopkins University, Baltimore, MD. Compared to age- and gender-matched controls, RS patients had 1) significantly reduced cerebral volume; 2) reduction in brain tissue volumes, especially affecting gray matter; 3) regional variation in cortical gray matter, frontal regions showing the largest decrease; 4) volume reduction of caudate nucleus and midbrain; and 5) increased CSF volume. There was no evidence of an ongoing degenerative process in these patients. 
COMMENT. These findings are consistent with one previous neuro-pathological report, whereas cerebellar pathology was emphasized in another autopsy report of 5 patients. See Progress in Pediatric Neurology, PNB Publ, 1991.