[Type I Chiari malformation: report of 2 cases with unusual clinical presentation]. / Malformação de Chiari tipo. I. Relato de dois casos com apresentações clínicas pouco usuais.

We describe two patients with Chiari type I malformation with unusual clinical presentation. The first one with clinical picture of acute respiratory insufficiency and the second one with vestibular and mild cerebellar syndrome and headache. In both cases the neurological examination demonstrated the presence of "down-beating nystagmus". We emphasize the value of neurological semiology, determining a correct complementary evaluation and effective treatment.