Does Horner's syndrome in infancy require investigation?

Aims-To evaluate whether isolated Horner's syndrome presenting in the first: year of life warrants investigation. Method-Retrospective review of 23 children presenting with Horner's syndrome in the first year of life. Results-In 16 patients (70%) no cause was identified. Birth trauma was the most common identifiable cause (four patients). Twenty one children (91%) urinary vanillylmandelic acid (VMA) measured and 13 patients (57%) under went either computed tomography or magnetic resonance imaging of the chest and neck. These investigations revealed previously undisclosed pathology in only two-one ganglioneuroma of the left pulmonary apex and one cervical neuroblastoma. A further patient was known to have abdominal neuroblastoma before presenting with Horner's syndrome. There were no cases of Horner's syndrome occurring after cardiothoracic surgery. Long term follow up of the patients (mean 9.3 years) has not revealed further pathology. Conclusions-Routine diagnostic imaging of isolated Horner's syndrome in infancy is unnecessary. Infants should be examined for cervical or abdominal masses and involvement of other cranial nerves. If the Horner's syndrome is truly isolated then urinary VMA levels and follow up in conjunction with a paediatrician should detect any cases associated with neuroblastoma. Further investigation is warranted if the Horner's syndrome is acquired or associated with other signs such as increasing heterochromia, a cervical mass, or cranial nerve palsies.