Association of "top of the basilar" syndrome with megadolichobasilar artery. Clinical and neuroimaging evaluation.

We describe the case of a patient with a history of trigeminal neuralgia who suddenly developed the "top of the basilar" syndrome. MRI disclosed ischemic lesions in the left paramedian mesencephalic tectum, in the left ventral thalamus, in the left occipital lobe and a megadolichobasilar artery (MDBA). The association of MDBA with the top of the basilar syndrome is rarely reported. We discuss the possible hemodynamic mechanism producing a top of the basilar syndrome in the presence of MDBA.