Shaken Baby Syndrome “Science” (Really ??)

I’ve been reading lately about biomechanical studies that have been, and are being, done to try to quantify the physical forces and accelerations required to inflict damage inside the human infant skull sufficient to cause “triad” symptoms (subdural hematoma, retinal hemorrhage, diffuse edema or diffuse axonal injury).

Dr. Carole Jenny, queen of the SBS protagonists, has dedicated her career to doing research with “bio-fidelic” dummies in search the answers to these questions.  Other researchers have attempted to use the power of computer modelling, employing the technique of finite element analysis, to answer the same questions.

If I may, let me mount the editorial pulpit, and draw on my personal knowledge, training, education, and experience.  I spent a 42-year career deeply immersed in a broad range of the physical sciences.  I have a profound understanding of mechanics (statics and dynamics), thermo-dynamics, fluid-dynamics, materials science, the laws of physics, computer software, and computer modelling.  I can say, without reservation, that the accuracy and integrity of the data produced by any simulation or model will be absolutely limited by the accuracy and integrity of the model or simulation itself.  It doesn’t matter whether the “model” is a bio-fidelic dummy or a finite element simulation.

We have yet to even come close to being able to model the intricacies of the mass and fluid dynamics inside the skull.  We really don’t understand tissue density distributions and gradients, fluid densities and distributions, fluid flow characteristics, tissue shear and tensile strengths, tissue compressibility, and on and on.  In short, we are just not currently capable of building an accurate model.

Unfortunately, research in this area is necessarily limited to modelling and simulation, because we cannot shake 1,000 babies to death, and drop 1,000 babies on a hard surface from different heights, and then do autopsies.  I’m also not aware that any babies have been shaken or abused to death while having accelerometers implanted in their brains and on their retinas.  So the results of biomechanical studies and computer simulations are really nothing more than somebody’s best guess.

Dummies and simulations are great for designing seat belts and airbags, and I won’t go so far as to say these SBS efforts are useless.  Certainly, we learn something, but in terms of actually explaining the intra-cranial medico-physical impacts of various forces and accelerations on the skull, the scientist in me doesn’t buy it.  I look very skeptically upon the biomechanical studies in this field.

Phil Locke