At present, there are multiple theories regarding the source of subdural bleeding in infants who have suffered accidental or non-accidental (NAHI) traumatic head injury (previously known as the ‘Shaken baby syndrome’). One controversial subject concerns the mechanism of how violently shaking an infant causes subdural bleeding. Cases of suspected NAHI often present with a triad of injuries, including subdural haematoma (SDH), retinal haemorrhages and encephalopathy. Historically, the most widely assumed source of subdural bleeding in these cases is the rupture of bridging veins which extend through the subarachnoid space to penetrate the dural margin of the major venous sinuses. This theory has been questioned due to biomechanical models which have suggested that the amount of force required to shear bridging veins is estimated to be greater than that of inertial forces (such as those produced by vigorous shaking). Direct demonstration of disrupted bridging veins by imaging of surviving patients, during surgery or at autopsy has also been limited.
Establishing a diagnosis of NAHI is a very challenging, complex, controversial and emotive process, often deliberated over at length in Court. Without accompanying evidence of inflicted trauma, such as unexplained bruises or fractures, convictions based on the triad alone have been called into question, resulting in numerous appeals. This study will consider alternative hypotheses for the source of bleeding related to infant SDHs. Our research will focus on the anatomy of the dura mater, a membrane that has a very rich and intricate vasculature, a fact not often alluded to in the SDH literature. The aim of this area of work is ultimately to aid health, law enforcement and legal professionals in the correct recognition of cases of abusive infant head injury, based on detailed scientific study and not on unproven theory.
This prospective, consented, autopsy-based study will include a cohort of 1 month to 1 year old human infants (the most common age range for NAHI victims). A minimally destructive technique for removal of the skull vault bones will be used at autopsy. The vessels within the intact dura mater will be visualised using various imaging techniques, including optical coherence tomography (similar to a CT scan only using near-infrared light instead of x-rays). This will allow measurement of the calibre of vessels within and around the dura mater as well as anatomical mapping of the vessels in relation to the brain surface.