Edrophonium infrared optokinetic nystagmography in the diagnosis of myasthenia gravis.

Horizontal optokinetic nystagmus was measured by an infrared eye movement recording technique before and after the administration of intravenous edrophonium chloride in 16 patients wtih proved myasthenia gravis. All the patients, even those without clinically apparent ophthalmoparesis, demonstrated an increased amplitude of optokinetic nystagmus after administration of the drug. None of 12 control patients, many with ophthalmoparesis, showed increased optokinetic nystagmographic amplitude. The superiority of infrared recording techniques to electro-ocuography was discussed. Edrophonium infrared optokinetic nystagmography proved to be a sensitive and specific test of myasthenic weakness in extraocular muscles.