One and a half syndrome

Abstract

One and a half syndrome is an infrequent condition characterized by conjugate horizontal gaze palsy and ipsilateral medial longitudinal fasciculus alteration secondary to various etiologies, including cerebrovascular disease and multiple sclerosis. Clinically, it presents with exotropia and abduction nystagmus. Its diagnosis may be established during exploration, due to the typical eye movement alterations, whereas brain magnetic resonance imaging is indispensable for differential and etiological diagnosis. A bibliographic review was conducted to obtain updated information about the characteristics, diagnosis and treatment of one and a half syndrome. Use was made of the databases available in Infomed, Google Scholar and Pubmed.

Key words: One and a half syndrome; diplopia; nystagmus; exotropia.