Shaken baby syndrome (abusive head trauma) produces its characteristic injuries primarily through which biomechanical mechanism?

• A Direct impact fracture of skull from blunt force applied to the occiput
• B Hypoxic ischaemic injury from airway obstruction during shaking episode
• C Cervical spinal cord contusion from hyperflexion of the unsupported infant neck
• D Rotational acceleration-deceleration forces causing subdural haematoma from bridging vein rupture and diffuse axonal injury ✓

Explanation

Abusive head trauma (shaken baby syndrome) results from violent repetitive rotational (angular) acceleration-deceleration of the infant's disproportionately large head on a weak neck. This creates shear forces causing: (1) tearing of bridging veins between the cortical surface and dural venous sinuses → bilateral subdural haematomas; (2) diffuse axonal injury from shear strain; (3) retinal haemorrhages from vitreoretinal traction. The triad (subdural haematoma, retinal haemorrhage, encephalopathy) without sufficient external evidence of impact characterises non-accidental injury. No single finding is diagnostic in isolation; biomechanical analysis includes injury pattern dating.

Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.

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Written and medically reviewed by the StethoPrep medical team.