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  • Abuse-Related Head Trauma May Raise IOP

    By Lynda Seminara
    Selected by Richard K. Parrish II, MD
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    Journal Highlights

    American Journal of Ophthalmology, August 2022

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    Minckler et al. investigated orthograde axonal transport of amyloid precursor protein (APP-A4) in the retina and the lamina cribrosa (LC) portion of the optic nerve in the eyes of children believed to be victims of abusive head trauma (AHT). They found that nearly all globes with nerve heads available for analysis were positive for LC accumu­lation of the APP-A4 marker, empha­sizing the importance of measuring and monitoring IOP in victims of head trauma.

    For this case-control study, 36 pairs of cadaveric eyes from infants and toddlers with and without AHT were obtained from the Los Angeles coroner. Shaken baby syndrome was suspected in the AHT cohort. All eyes underwent immunohistochemistry, and axonal transport was assessed by light mi­croscopy after paraffin processing. A proprietary biomicroscopy imaging software was used to estimate LC APP-A4 blockage in a subset of patients who survived their head injuries (n = 21).

    In AHT eyes, accumulation of APP-A4 was found in retinal gangli­on cell (RGC) bodies, in nerve fiber layer axons around the ends of Bruch membrane, and in LC optic nerve axon bundles. These observations indicate that the obstruction of axonal transport likely was caused by elevated IOP. Most of the 21 AHT suspects who survived at least one day (range: 1-1,588 days) exhibited accumulation of APP-A4.

    Although seldom recorded and not previously reported in the litera­ture, IOP may be elevated in AHT for various reasons, said the authors. These include frequent retinal and vitreous hemorrhages and possible clogging of outflow pathways by red cells, mac­rophages, or fibrin, as noted in other studies. Other contributors may be constriction of ocular venous outflow by subdural blood expanding the optic nerve sheath, inflammation from retinal trauma debris, vitreous hemorrhage, angle contusion injury, and tears in an­terior segment structures or the retina. Despite substantial artifactitious retinal fragmentation and detachment, APP-A4 labeling of RGCs was a consistent find­ing in most AHT suspects in this study, as was the accumulation of APP-A4 re­action product in the LC of the anterior optic nerve.

    In light of these findings and evidence from previous studies, the authors advise IOP assessment of patients with suspected AHT. They also encourage further pathologic studies of AHT.

    The original article can be found here.