Objective: Decompressive craniectomy (DC) is efficient in reducing the intracranial pressure in several complicated disorders such as traumatic brain injury (TBI) and stroke. The neurosurgical procedure has indeed reduced the number of deaths. However, parallel with the reduced fatal cases, the number of vegetative patients has increased significantly. Mechanical stretching in axonal fibers has been suggested to contribute to the unfavorable outcome. Thus, there is a need for improving treatment procedures that allow both reduced fatal and vegetative outcomes. The hypothesis is that by performing the DC at the non-injured side of the head, stretching of axonal fibers at the injured brain tissue can be reduced, thereby having the potential to improve patient outcome.
Methods: Six patients, one with TBI and five with stroke, were treated with DC and where each patient's pre- and postoperative computerized tomography (CT) were analyzed and transferred to a finite element (FE) model of the human head and brain to simulate DC both at the injured and non-injured sides of the head. Poroelastic material was used to simulate brain tissue.
Results: The computational simulation showed slightly to substantially increased axonal strain levels over 40 % on the injured side where the actual DC had been performed in the six patients. However, when the simulation DC was performed on the opposite, non-injured side, there was a substantial reduction in axonal strain levels at the injured side of brain tissue. Also, at the opposite, non-injured side, the axonal strain level was substantially lower in the brain tissue. The reduced axonal strain level could be verified by analyzing a number of coronal sections in each patient. Further analysis of axial slices showed that falx may tentatively explain part of the different axonal strain levels between the DC performances at injured and opposite, non-injured sides of the head.
Conclusions: By using a FE method it is possible to optimize the DC procedure to a non-injured area of the head thereby having the potential to reduce axonal stretching at the injured brain tissue. The postoperative DC stretching of axonal fibers may be influenced by different anatomical structures including falx. It is suggested that including computational FE simulation images may offer guidance to reduce axonal strain level tailoring the anatomical location of DC performance in each patient.