Downbeat and Upbeat Nystagmus
Authors Strupp et al. convincingly explained the importance of central oculomotor disturbances (1). I wish to add that occasionally, downbeat nystagmus (DBN) and upbeat nystagmus may be present depending on the person’s gaze direction. Pronounced DBN can sometimes occur in all directions of gaze, even when looking upwards (2).
Numerous causes for DBN are known. Familial DBN subsequent to spinocerebellar degeneration is among the most common causes of DBN. In addition to hereditary causes, causes of acquired DBN include brain stem infarctions, toxic adverse effects of medication (for example, phenytoin, carbamazepine, lithium, morphine derivates), brain tumors, paraneoplastic syndrome, alcoholism, trauma, encephalitis, and multiple sclerosis (3). In addition to the medications listed by Strupp et al., the literature also mentions prism treatment and Kestenbaum eye muscle surgery among the therapeutic options.
Prof. Dr. med. Dieter Schmidt
|1.||Strupp M, Hüfner K, Sandmann R, et al.: Central oculomotor disturbances and nystagmus: a window into the brainstem and cerebellum. Dtsch Arztebl Int 2011; 108(12): 197–204. VOLLTEXT|
|2.||Schmidt D: Downbeat nystagmus an upgaze. Neuro-Ophthalmology 1991; 11: 223–7.|
|3.||Schmidt D: Downbeat-Nystagmus. A clinical review. Neuro-Ophthalmology 1991; 11: 247–62.|