Anisocoria after Posterior Spine Surgery: A Rare but Disastrous Complication - A Case Report and Literature Review.

Introduction: Ocular complications after spine surgery in prone position are very rare and are described centrally in elective surgeries with long duration. The most well-known ocular complications are vision loss and acute angle-closure glaucoma. To the best of our knowledge, anisocoria after prone spinal surgery has never been reported previously in literature.

Case Report: We present a very rare case of a transient harmless anisocoria in a 23-year-old otherwise healthy female patient, who underwent in the traditionally prone position lumbosacral spinal fractures stabilization and calcaneal fracture reduction and external fixation. We describe step by step the diagnosis algorithm and we discuss detaily the differential diagnosis of the unilaterally fixed and dilated pupil. Careful stepwise medical history and examination are mandatory to establish correct diagnosis and avoid unnecessary, expensive, and potentially hazardous or invasive diagnostic testing.

Conclusion: The wrong position during prone spine surgery can cause iris sphincter muscle tears and transient or permanent dilation of the affected pupil. Fixed dilated pupil is a permanent abnormality of the iris, causing irregular cosmetic appearance, especially in young females, and requires further conservative or surgical intervention. Positioning of the patient and duration of surgery should be taken into consideration both by spine surgeons and anesthesiologists.