The use of onabotulinum toxin A in the treatment of see-saw nystagmus.

See-saw nystagmus (SSN) is an uncommon disorder that consists of cycles in which one eye rises and intorts while the other depresses and extorts, followed by reversal of the pattern. It typically causes debilitating symptoms including oscillopsia that interfere with activities of daily living. There are myriad etiologies, including stroke, tumors, trauma, and multiple sclerosis. Treatment options are limited and are often unsatisfactory. The authors report a case in which targeted injections of onabotulinum toxin A were used to decrease the torsional component of SSN and thus significantly improve the subjective symptoms of oscillopsia in a patient with acquired SSN.