Isolated Horner syndrome and syringomyelia in a child.

Horner syndrome can be caused by a variety of etiologies that interrupt the sympathetic innervation of the eye, including but not limited to central mass lesions. Recently, it has been debated whether neuroimaging has a place in the diagnostic algorithm of isolated pediatric Horner syndrome given the low incidence of neuroblastoma. We present a case of a 19-month-old girl with an isolated Horner syndrome, likely caused by a lower cervical syrinx, that was diagnosed by magnetic resonance imaging.