Ocular movement and nystagmus: basics and clinical diagnosis

Background: Eye movements are one of the most complex motor functions of the central nervous system (CNS). Eye movement disorders including nystagmus occur in diseases of the CNS and the vestibular system. A systematic clinical examination often allows a topodiagnostic classification of the lesion.

Objective: The basics of eye movements, the role of the cerebellum, the clinical examination of the oculomotor system, and the most important forms of nystagmus and their diagnostic implications are described.

Methods: A literature analysis assessing eye movements, cerebellar control of eye movements, clinical examination of eye movement, and nystagmus was performed.

Results: In disorders of eye movement, diseases of the oculomotor cranial nerves and the central nervous structures are to be distinguished from diseases of the orbit, eye muscles, and motor end plates. The former result in cranial nerve-related paralysis of extraocular muscles, disturbances of saccadic and smooth pursuit eye movements, vertical or horizontal gaze palsy, internuclear ophthalmoplegia, or impaired gaze holding. Nystagmus in combination with other disturbances of ocular movement is highly related to a lesion within the CNS. Intense nystagmus with a rotatory component that decreases during fixation usually has a peripheral vestibular cause.

Conclusions: Clinical examination of eye movements and nystagmus enables the diagnosis of typical eye movement disorders with a strong relation to distinct lesions of the CNS or the peripheral vestibular pathway.