Abstract
Purpose: :
Pediatric abusive head trauma is characterized by intracranial and/or retinal hemorrhages (RH). Mechanisms of traumatic brain injury have been elucidated through carefully controlled animal models, but no such model exists for RH. In the preliminary stages of developing a pediatric rotational acceleration-deceleration model of RH, we sought to characterize ocular hemorrhages in neonatal piglets resulting from rotations of the head.
Methods: :
3-5 day old anesthetized piglets (n=35) underwent a single, rapid (160-200 rad/s) head rotation in sagittal (n=6), coronal (n=2), or horizontal (n=27) planes; 5 additional piglets were controls. Six hours post injury the animals were euthanized and perfusion fixed. Brains and eyes were harvested for gross and histologic examination, evaluated by masked neuro- and ocular pathologists.
Results: :
Ocular hemorrhage was found in 69% of animals. Intraocular hemorrhage was primarily located near the vitreous base (66% of animals had ciliary body hemorrhage, 9% had peripheral RH). Hemorrhages were also found in the anterior chamber (11%), or optic nerve (disc 9%, nerve sheath 51%). Animals undergoing a rapid horizontal head rotation had a significantly higher occurrence of ciliary body hemorrhage than coronal or sagittal. All but one animal had large collections of subdural blood, but that animal still had ciliary body hemorrhage. Controls had no ocular or intracranial injuries.
Conclusions: :
Optic nerve and ciliary body hemorrhages were common in single rapid rotations of the piglet head. Intraocular hemorrhages were located primarily in regions of strong vitreous attachment in the pig. This preliminary model involved a single high velocity rotation to the head; future studies with this model will investigate the effect of low velocity cyclic head motion (shaking) on ocular hemorrhages.
Keywords: trauma • retina • infant vision