What pathologic cause could be indicated by the finding of anisocoria in a patient?

Anisocoria, or unequal pupil size, can have various causes, and identifying the underlying pathology is essential for proper diagnosis and management. The finding of anisocoria can indicate Horner's syndrome, which results from disruption of sympathetic pathways to the eye. This syndrome is characterized by a triad of symptoms: ptosis (drooping of the eyelid), miosis (constricted pupil), and anhidrosis (lack of sweating) on the affected side of the face.

In Horner's syndrome, the affected pupil is typically smaller (miosis) and reacts poorly to light. This occurs due to the loss of sympathetic innervation, leading to unopposed parasympathetic activity, which causes constriction of the pupil. Recognizing this association is crucial since Horner’s syndrome can indicate significant underlying pathology, such as a tumor or lesion affecting the sympathetic pathways.

Benign anisocoria, while a common and generally non-urgent condition, does not have the same implications as Horner's syndrome and is usually not associated with other concerning symptoms. Differing light intensities for each eye may lead to anisocoria but is not a pathologic cause on its own; rather, it is a circumstance that might produce unequal pupil