Harlequin syndrome in a pediatric population: a case series.

Harlequin syndrome is a rare condition, presenting with unilateral facial flushing and hyperhidrosis in response to physical exercise, heat or emotional stressors and has scarcely been reported in pediatric patients. It is caused by a dysfunction of vasomotor and sudomotor sympathetic fiber activity inhibiting the ability to flush on the affected side, causing the neurologically intact side to appear red. We present three pediatric cases of this uncommon syndrome, each of them of different origin and displaying distinct associated (neurological) symptoms, and review medical literature. Insight into the anatomical structure of the thoracocervical and facial sympathetic nervous system is pivotal as it dictates symptomatology. About half of Harlequin syndrome cases are complicated with ocular symptoms and a minority may be part of more extensive partial dysautonomias affecting facial sudomotor, vasomotor and pupillary responses, such as Holmes-Adie syndrome and Ross syndrome. Etiology is generally idiopathic, however, cases secondary to surgery, trauma or infection have been described. Considering its predominantly self-limiting nature, treatment is usually unnecessary and should be restricted to incapacitating cases.