Can Pupil Changes Detect Autonomic Dysregulation After Spinal Cord Injury? A Systematic Review.

Abstract

Objectives: The autonomic neural circuitry of the pupil makes it a unique target for identifying impaired autonomic regulation following spinal cord injury (SCI). This systematic review characterizes the evidence on pupillary changes after SCI.

Methods: A systematic search was conducted in MEDLINE, Embase, and CINAHL. Articles were independently assessed by 2 reviewers and included studies reporting on pupillary changes (e.g., miosis, mydriasis, anisocoria) following traumatic or nontraumatic SCI at any level. Data on study design, patient demographics, injury characteristics, and pupillary changes were extracted. We used the Joanna Briggs Institute Critical Appraisal checklists for quality assessments and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

Results: We identified 486 studies, of which 37 articles (36 case reports and 1 cross-sectional study) were included and primarily of medium quality. All studies reported anisocoria, with 81% involving unilateral miosis, 16% involving unilateral mydriasis, and 3% unspecified. Pupillary dysfunction predominantly occurred in people with cervical or high thoracic SCI acutely (<20 days after injury) or in the intermediate-to-chronic phase of SCI (>4 months post injury).

Conclusion: Most studies identified in this review were case reports describing pupil abnormalities likely related to trauma of autonomic pathways-either central or peripheral-resulting from SCI or associated injuries (e.g., brain injury) during the acute phase. In the intermediate-to-chronic phase, autonomic dysreflexia was often reported alongside pupil changes. Larger cohorts and quantitative pupil detection technologies are needed to validate the utility of pupil data in SCI research and clinical care.