Unnoticed dysautonomic syndrome of the face: Harlequin syndrome.

Harlequin sign and harlequin syndrome, which are used interchangeably in the literature, are characterized by sudden onset of hemifacial sweating and flushing, induced by exercise and heat. Hemifacial sweating and flushing with normal ocular sympathetic innervation, known as harlequin syndrome, is rarely associated with tonic pupils, parasympathetic oculomotor lesion and pre- or postganglionic sudomotor sympathetic deficit. In the literature, hemifacial sweating and flushing in patients with apparently abnormal ocular sympathetic innervation has been defined as harlequin sign. To date, a few reports of excessive hemifacial sweating and flushing in structural lesion have been documented. Herein, we report five patients with excessive hemifacial sweating and flushing, two of whom had a syrinx. In presenting the patients, we have attempted to distinguish harlequin syndrome from harlequin sign. With this in mind, Case 1 can be described as harlequin syndrome resembling Ross syndrome, Case 2 as harlequin syndrome with normal ocular sympathetic innervation, Case 3 as harlequin sign with congenital Horner syndrome, Case 4 as harlequin sign with sympathetic and parasympathetic denervation sensitivity, and Case 5 as harlequin syndrome associated with occult sympathetic denervation sensitivity. These cases are discussed together with a review of the literature.