Isolated Bilateral Fascicular Sixth Cranial Palsies as Initial Presentations of Multiple Sclerosis

A 41 year old male presented with acute onset binocular horizontal diplopia of two weeks duration. Diplopia was described as greater at distance and present in both right and left gaze. Mild paresthesias affecting the distal aspects of the upper extremities, left greater than right, had been noted for several weeks. Over the preceding several years the patient had noted increasing difficulty in sporting activities. There were no other symptoms. Past medial history was notable only for depression. The patient took no medication. Visual acuity measured 20/20 in each eye. Color vision, pupillary response, funduscopic appearance, general, neurologic and slit lamp examinations were normal. Examination of extra-ocular movements demonstrated left esotropia and mild bilateral paresis of abduction, confirmed by red glass cover test. Oculovestibular maneuver failed to achieve a greater degree of abduction than that obtained by testing of versions and ductions. Saccadic velocities and smooth pursue~ were otherwise judged o be normal in horizontal and vertical planes. There was subtle non-sustained, gaze dependent, conjugate horizontal nystagmus. There was no evidence of internuclear ophthalmoplegia. Near response was intact.