A case of Horner's syndrome attributable to chest tube injury to the o
culosympathetic pathway is reported, and determination of the diagnosi
s and etiology of Horner's syndrome is summarized. The patient sustain
ed a traumatic pneumothorax for which a chest tube was inserted into t
he second intercostal space. Horner's syndrome was noted the day after
chest tube removal, and it completely resolved within 13 days. Chest
tube injury to the oculosympathetic pathway should be considered as a
possible etiology of Horner's syndrome in any patient with a concurren
t or recent history of chest tube placement, particularly if the chest
tube has been located higher than the third posterior rib. Judicious
chest tube placement can prevent Horner's syndrome, which can be misle
ading in a patient with multiple injuries because of the anisocoria, a
nd it can be associated with unacceptable cosmesis and/or chronic use
of the frontalis muscle to raise the ptotic eyelid.