Harlequin Syndrome Caused by Multinodular Goitre

Harlequin syndrome is a rare neurological disorder characterised by hemifacial flushing and sweating. We present a case of Harlequin syndrome with evidence of compression of the sympathetic trunk due to a non-toxic multinodular goitre. We review the neuroanatomy of this fascinating condition, particularly in relation to the more common and often sinister Horner's syndrome, to convey a deeper understanding of the nuances of sympathetic facial innervation to the keen physician.