A case of type I Arnold-Chiari malformation of anomalous onset.

A case of type I Arnold-Chiari malformation, with onset of diplopia, without associated medullar alteration, is presented. The symptomatology remained unique and had transitory presentation for many years with negative ophthalmic examinations. Attention is drawn to the great variability of the syndrome's presenting symptoms confirming the importance of MR in the diagnostic course and of evoked potentials of the brain stem to follow progress of the illness.