Diffuse axonal injury in infants with nonaccidental craniocerebral trauma - Enhanced detection by beta-amyloid precursor protein immunohistochemical staining

Objective.-Accurate identification of diffuse axonal injury is important in the forensic investigation of infants who have died from traumatic brain i njury. beta-Amyloid precursor protein (beta-APP) immunohistochemical staini ng is highly sensitive in identifying diffuse axonal injury. However the ef fectiveness of this method in brain-injured infants has not been well estab lished. The present study was undertaken to assess the utility of beta-APP immunohistochemistry in detecting diffuse axonal injury in infants with eit her shaken baby syndrome or blunt head trauma. Materials and Methods.-Archival formalin-fixed, paraffin-embedded blocks fr om infants (<1 year old) with shaken baby syndrome (7 cases) and blunt head trauma (3) and blocks from 7 control cases that included nontraumatic cere bral edema (1), acute hypoxic-ischemic encephalopathy (1), and normal brain (5) were immunostained for beta-APP. A semiquantitative assessment of the severity of axonal staining was made. Corresponding hematoxylin-eosin-stain ed sections were examined for the presence of axonal swellings. Results.-Immunostaining for beta-APP identified diffuse axonal injury in 5 of 7 infants with shaken baby syndrome and 2 of 3 infants with blunt head t rauma. Immunoreactive axons were easily identified and were present in the majority of the sections examined. By contrast, hematoxylineosin staining r evealed axonal swellings in only 3 of 7 infants with shaken baby syndrome a nd 1 of 3 infants with blunt head trauma. Most of these sections had few if any visible axonal swellings, which were often overlooked on initial revie w of the slides. No beta-APP immunoreactivity was observed in any of the 7 control cases. Conclusions.-Immunostaining for beta-APP can easily and reliably identify d iffuse axonal injury in infants younger than 1 year and is considerably mor e sensitive than routine hematoxylin-eosin staining. We recommend its use i n the forensic evaluation of infants with fatal craniocerebral trauma.