Tuesday May 25, 2010

Q: What is the modus operandi of Subdural Hematomas (SDH)?

Answer: Contrary to popular belief that SDH happens due to direct trauma, Subdural hematomas actually are most often caused by rapidly changing velocities within the skull which may stretch and tear small bridging veins. In other words, subdural hematomas generally result from shearing injuries due to various rotational or linear forces.

Due to above modus operandi, SDH is a classic finding in shaken baby syndrome, in which similar shearing forces classically cause intra- and pre-retinal hemorrhages. Cerebral atrophy - commonly seen in the elderly and in alcoholics - increases the length the bridging veins have to traverse between the two meningeal layers, hence increasing the likelihood of shearing forces causing a tear.