THE HARLEQUIN SIGN AND CONGENITAL HORNERS-SYNDROME

When trying to establish the likely anatomical site (preganglionic or postganglionic) of a lesion causing congenital Horner's syndrome, the distribution of facial flushing (the ''harlequin'' sign), may be seen. In babies and young children, facial flushing is a relatively simple clinical sign to demonstrate, compared with facial sweating. In unilat eral facial flushing the areas that do not flush are almost always ide ntical to the anhidrotic areas. However, neither facial flushing nor t esting the pupil reactions with pholedrine or hydroxyamphetamine can b e relied on to predict the probable site of any lesion causing congeni tal Horner's syndrome. Two patients with congenital Homer's syndrome a re presented which demonstrated the ''harlequin'' sign and in whom cli nical examination and pharmacological testing gave conflicting evidenc e for localisation of the site of the causative lesion. The presentati on of congenital Horner's syndrome should be investigated and include MRI or CT to exclude a serious underlying cause.