Timothy C. Hain, MD. Page last modified: December 26, 2015
Video of opsoclonus in young woman, developed after the West Nile outbreak in Chicago. See the site DVD page for a list of more movies like this one.
Opsoclonus denotes chaotic back-back saccadic eye movements. It is a dramatic syndrome, sometimes due to cancer or a brainstem encephalitis such as West-Nile or Dengue. There is an immense literature about opsoclonus, probably because it is so dramatic.
Opsoclonus in young children is drastically different than in older persons -- we think it best to designate opsoclonus by the age group - -pediatric, or adult at least.
Opsoclonus differs from ocular flutter in that opsoclonus changes rapidly in any direction (horizontal, vertical, torsion) -- i.e. the eye movement vector is chaotic, while flutter is generally always purely horizontal. It may look like a a chaotic "shimmer" on direct observation.
Opsoclonus is generally best visualized by using a video-frenzel goggle system, having a large screen. Opsoclonus may be difficult to record. A general rule is that the bandwidth (samples per second) of the device that you are using to record an eye movement should be at least twice the bandwidth of the eye movement. Because opsoclonus occurs so quickly -- that it cannot be captured very well by low-bandwith devices such as clinical EOG or VNG systems. Videotaping may also have trouble capturing this rapid movement as the frame rate may be only 30 fps.
In all age groups, opsoclonus is rare. The common causes of opsoclonus depend on age.
The causes of opsoclonus in children is drastically different than in older groups. Opsoclonus in children is often caused by a neural tumor (a neuroblastoma). The median age in children is about 18 months. In very young children there is a vigorous effort to find and remove a potential tumor as well as treatment with powerful immune suppressant medications. (Toyoshima et al, 2015). Paraneoplastic syndromes -- opsoclonus associated with another tumor -- also occur in children (see comment below about adults). (Singhi et al, 2014).
In adolescents through roughly the 60's, generally no cause is found and opsoclonus is blamed on the usual mysterious suspects -- viruses, autoimmune disorders and genetic defects. Of course when this syndrome follows a viral infection such as a cold, it is difficult to be sure that this is more than a coincidence. Adolescents have more psychiatric disorders than other age groups, and it is possible that in some cases these are teens who have learned to produce an unusual variety of voluntary nystagmus. Adolescent opsoclonus often resolves without any treatment, after the child is kept out of school and tutored or home schooled for a year.
In persons older than roughly 60, a common cause of opsoclonus is a paraneoplastic syndrome (a tumor elsewhere in the body). In older adults, a full-scale workup for neoplasm is generally indicated and often productive in persons with opsoclonus. Lung cancer, especially small cell, is the commonly found tumor (Laroumange et al, 2014). Thus a chest-Xray or CT scan of the chest (rather than an MRI of the brain) is usually the most productive first test. PET scanning has also been used to diagnose occult cancers in this situation (Bataller et al, 2003). Although antibodies such as anti-Hu, Yo, and Ri among others may occasionally be positive, commercial testing for antibodies is often of little diagnostic value. Research studies have implicated autoantibodies to a large assortment of miscellaneous neural antigens (Blaes, Fuhlhuber et al. 2005; Panzer et al, 2015; Player et al, 2015). We are dubious as to the utility of antibody testing in most situations.
Opsoclonus may also be caused by a viral infection of the brainstem or cerebellum, as well as autoimmune processes. A huge surge in opsoclonus appeared in Chicago, after the West Nile Virus outbreak of 2003. It has now vanished again, as have most of the West Nile cases. There have also been many reports of opsoclonus after dengue virus infection. Note that West Nile and Dengue are both members of the flavivirus family. Nevertheless, this is usually a "wastebasket" type diagnosis, arrived at after screening for cancer has been unproductive.
Opsoclonus is classically attributed to malfunction of the pause-cells in the midline brainstem. However, functional MRI suggest increased activation in the deep cerebellar nuclei in opsoclonus (Helmchen et al, 2003; Mustafa et al, 2015). The fastigial oculomotor region projects to the burst neurons, omnipause neurons, and the local feedback loop of the brainstem saccade generator. The fastigial oculomotor region is inibited by the vermis. Thus the fundamental underlying problem in opsoclonus may relate to decrease activation in the posterior vermal lobule VII.
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