Kinking of the aqueduct of Sylvius in the absence of posterior fossa masses.

The kinked or "hockey stick" deformity of the aqueduct of Sylvius has long been considered pathognomonic of a mass in the posterior fossa. Five patients with kinking of the aqueduct of Sylvius are described. All had intracranial abnormalities but none had a mass in the posterior fossa.