Ocular myasthenia mimicking a one-and-a-half syndrome.

A 52-year-old patient developed an eye movement disorder first resembling a left internuclear ophthalmoplegia and subsequently a "one-and-a-half syndrome" as the presenting symptoms of ocular myasthenia gravis. No accompanying myasthenic features were present except for the fluctuation in the amplitude of dissociated nystagmus. This patient shows that an oculomotor disorder considered a typical pontine lesion may instead be caused by myasthenia gravis, even in the absence of other clinical and electrophysiologic features of neuromuscular deficit.