Transdermal and Powdered Scopolamine-Induced Anisocoria: A Report of Two Cases.

Abstract

Introduction: In this case report, we present 2 cases of sudden-onset anisocoria caused by accidental exposure to scopolamine in 2 young female patients.

Case presentation: Two patients presented with unilateral anisocoria. One patient experienced unilateral mydriasis accompanied by neurological symptoms from a transdermal scopolamine patch, while the other, exposed to powdered scopolamine, presented with unilateral mydriasis without additional neurological symptoms. Both cases showed gradual resolution of symptoms over several days without intervention. Initially, Adie's pupil (tonic pupil) was high in the differential diagnosis, but a comprehensive history taking revealed scopolamine exposure as the more likely cause. In the first case, pilocarpine did not result in miosis, while in the second case, pilocarpine initially induced miosis but was followed by a return to mydriasis. Although current literature suggests that mydriasis caused by an anticholinergic substance presents as pupil dilation unresponsive to pilocarpine, our case series shows its inconsistency in clinical presentation.

Conclusion: This report presents 1 case of systemic scopolamine toxicity, alongside unilateral mydriasis, adding confusion to the case given the expected bilateral mydriasis in systemic toxicity, and another case of pharmacological anisocoria secondary to exposure to scopolamine with an atypical reaction to pilocarpine. These cases highlight the importance of thorough history taking and the need to consider pharmacological causes in the differential diagnosis of acute anisocoria.