Optical clearing of the dura mater using glycerol: a reversible process to aid the post-mortem investigation of infant head injury
Abstract
Purpose
In cases of suspected abusive head trauma, a thorough and systematic study of the cranium and its contents is essential, preferably using the best available methods for observing the brain and its coverings. Building upon recent developments in skull bone removal techniques in infant autopsies, we have assessed the use of two optical clearing agents (OCAs), glycerol and mannitol, on pediatric dura mater in an attempt to increase the transparency of this tissue and thereby enhance the post-mortem assessment of infant head injuries, particularly subdural hematomas.
Methods
Extracorporeal testing revealed glycerol to be the more effective OCA. Therefore, in situ investigations were commenced using glycerol during 33 pediatric post-mortem examinations.
Results
An increase in the transparency of the dura was observed in 32 of the 33 cases, within 1 min of application of the OCA. In a 2 year old with cerebral palsy, only partial optical clearance of the dura was seen, most likely due to a significantly atrophic brain, prominent gelatinous leptomeninges, and abnormally thickened dura. This technique allowed for detection of minimal amounts of subdural bleeding over the convexities, before dissection of the dura, avoiding post-mortem blood spillage from artifactually disrupted bridging veins. Optical clearing of the dura aided in the evaluation of patterns of subdural hemorrhage in three cases of non-accidental head injury, three cases of peri-natal head injury and one case of overlaying, apparently resulting in minor crush injury to the head.
Conclusions
We have demonstrated that glycerol is an effective and easy-to-use OCA to effect the readily reversible optical clearing of human infant calvarial dura at autopsy.
Keywords
Post-mortem Infant Head injury Dura mater Glycerol Optical clearingNotes
Acknowledgments
This article presents independent research funded by the Home Office Science Secretariat, Science Group. The views expressed in this publication are those of the author(s) and not necessarily those of the Home Office Pathology Unit in Home Office Science. We would like to thank volunteers from the staff of the East Midlands Forensic Pathology Unit who took part in the visual assessment of tissue clearance.
Compliance with Ethical Standards
Conflict of interest
None.
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