| Opsoclonus | |
|---|---|
| Classification and external resources | |
| ICD-9 | 379.59 |
Opsoclonus refers to uncontrolled eye movement. Opsoclonus consists of rapid, involuntary, multivectorial (horizontal and vertical), unpredictable, conjugate fast eye movements without intersaccadic intervals. It is also referred to as saccadomania or reflexive saccade. The movements of opsoclonus may have a very small amplitude, appearing as tiny deviations from primary position.
Possible etiologies of opsoclonus include neuroblastoma and encephalitis in children, and breast, lung, or ovarian cancer in adults. Other considerations include multiple sclerosis, toxins, or medication effects. It can also be caused by a lesion in the omnipause neurons which tonically inhibit initiation of saccadic eye movement (until signaled by the superior colliculus) by blocking paramedian pontine reticular formation (PPRF) burst neurons in the midbrain. It frequently occurs along with myoclonus in opsoclonus myoclonus syndrome.