[The Schmidt and Vernet classical syndrome. Alternating brain stem syndromes that do not exist?]

In contrast to the majority of classic brainstem syndromes, the interpretation of Schmidt's syndrome (ipsilateral palsy of the IX, X, XI, and XII cranial nerves with contralateral hemiparesis) and Vernet's syndrome (ipsilateral palsy of the IX, X, and XI nerves with contralateral hemiparesis) is controversial. They are sometimes addressed as crossed brainstem syndromes but also as syndromes due to multiple cranial nerve lesions without contralateral hemiparesis. In this study, the historic descriptions and recent publications about Schmidt's and Vernet's syndromes were reviewed and critically analysed. We conclude that historic descriptions and later publications describe exclusively patients with extracerebral lesions of multiple cranial nerves. "Central" syndromes of Schmidt and Vernet caused by brainstem lesion appear not to exist. An extremely extensive lesion explaining these hypothetical unilateral brainstem syndromes is theoretically possible but, however, was apparently never observed in any of the known unilateral brainstem diseases.