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.