Giant posterior inferior cerebellar artery aneurysm associated with foramen magnum syndrome.

The case of a giant distal posterior inferior cerebellar artery (PICA) aneurysm which caused foramen magnum syndrome is presented. A 67-year-old male was referred for evaluation of a posterior fossa mass lesion on MRI scan. Craniotomy was performed which revealed a giant and completely thrombosed aneurysm of the distal PICA, which was subsequently excised intact. This report adds giant aneurysm of the PICA to the list of posterior fossa lesions reported which cause foramen magnum syndrome.