Its a Stitch-Up: The Function of Subarachnoid Trabeculae

The Shaken Baby Hypothesis assumes the brain can slide in the skull, but trabeculae (thin strips of collagen reinforced tissue that link across the subarachnoid space) appear to prevent this. They are so thin that they are undetectable by ultrasound or MRI imaging systems. Pediatricians in the 1970s were unaware of their existence. The Shaken Baby Syndrome hypothesis ignores them. The purpose of this study was to investigate whether omitting the trabecular structures from the SBS hypothesis would have made any difference to the legal validity of cases based on it. When the Shaken Baby Syndrome concept was created in the 1970s it was believed that there was a layer of fluid between the Dura and Arachnoid Maters (a “Subdural Space”) which allowed the brain cortex to slide. Electron microscopy has since shown that the Subdural Space does not exist. Electron microscopy has shown a “Cob-Web” of tissue (Trabeculae) linking the Arachnoid and Pia Maters. There is no subarachnoid space in the “Shaken Baby” model so no subarachnoid trabeculae are considered. Collagen fibres within these subarachnoid trabeculae are continuous with bundles of collagen in the inner aspect of the arachnoid and with collagen bundles in the subpial space, effectively “stitching” the pia and arachnoid membranes together. By implanting radio-opaque markers in cadaver heads and using high speed X-ray recorders vehicle accident researchers established that fresh brain is softly elastic. Under impact various regions move over different loci at different speeds. This trabecular stitching causes the cerebral cortex surface to follow skull movement closely. The cortex cannot slide, it reversibly deforms to take up movements. Therefore the bridging veins cannot be strained as was assumed in the 1970s and the Shaken Baby Syndrome hypothesis is invalid.