[Trigeminal involvement and peripheral facial paralysis caused by Arnold-Chiari malformation with hydrocephalus].

The case of a 26 years old woman who presented with hydrocephalus from an Arnold-Chiari malformation is described. The first signs were a left trigeminal disorder and a left facial paresis as false localizing signs. Symptomatology was secondary to decompensation of the hydrocephalus, and was associated with aqueductal stenosis. Complete and rapid regression of the symptomatology after ventriculo-caval shunt was observed. Type 1 Arnold-Chiari malformation can manifest itself clinically in a number of ways. Cranial nerve abnormalities are uncommon, and may be false localizing signs. Unsuccessful investigations can delay the diagnosis and the treatment.