Horner’s syndrome = small pupil, ipsilateral ptosis +/- reduced sweating.  Compare Holmes Adie pupil.

Anhidrosis localizes lesion to preganglionic branch.

Turn down the lights to make it more obvious!  Look for associated Klumpke’s.

In babies usually congenital or related to birth trauma, rarely it can be due to:

• cervical or mediastinal neuroblastoma (look for mass in neck or abdomen, heterochromia (eye changes colour!), panda eyes, Dancing eye syndrome, or
• carotid vascular lesion or
• apical pulmonary abnormality.

Other cranial nerve involvement clearly points to brainstem problem.

[British Journal of Ophthalmology 1998;82:51-54. ]