Understanding the associated and not-associated features of CN3 palsies can help localize the disease. Because partial CN3 palsy is often associated with other life-threatening or highly-morbid disease, urgent neuroimaging is recommended in all cases of suspected partial CN3 palsy.
The Oculosympathetic Pathway
The Light Reflex Pathway
Horner Syndrome: Pharmacologic Diagnosis
Horner syndrome describes the constellation of findings associated with a lesion affecting the oculosympathetic pathway. Clinically, ipsilateral miosis, ptosis, and anhidrosis form the classic triad, with other features potentially being present.
Without getting into too much detail about the sympathetic pathways and differential diagnosis of Horner syndrome (those will be covered in other articles), I will attempt to highlight the 3 pharmaceutical agents used in the diagnosis of Horner syndrome, discuss the tests, and point out the key ideas that often find themselves in tests.