ASSOCIATION OF CHIARI-I MALFORMATION AND WILLIAMS-SYNDROME

Two Williams syndrome patients are presented who had neurologic sympto ms secondary to Chiari malformation type I, Both patients had many of the well-known medical problems found in Williams syndrome, In additio n, Patient 1 developed headache, diplopia, and tinnitus at 26 years of age, Neurologic examination revealed intermittent nystagmus and brisk reflexes. Magnetic resonance imaging demonstrated Chiari malformation type I; neurologic symptoms abated following surgery, Patient 2 had a normal neurologic examination at 2 years of age except for hyperrefle xia and tight heel cords, At age 10 years, she had generalized contrac tures, decreased strength and wasting of hand musculature, and hyperre flexia. Magnetic resonance imaging documented Chiari malformation type I, Both patients have significant dysphagia and fusion of cervical sp ine segments noted on radiography. Morphometric analyses of intracrani al contents based on midsagittal magnetic resonance images were perfor med, This analysis suggests that, compared to age-matched controls, th e posterior fossa size is selectively diminished in Williams syndrome, whereas the cerebellum is normal in size, This ''mismatch'' between t he size of the posterior fossa bony compartment and its neural content s may place Williams syndrome patients at high risk for developing Chi ari malformation type I.