Unlocking in COVID Times: The Neurosurgical Way

The humankind is facing one of the worst nightmares in the form of the ongoing Corona crisis. The pandemic has spread all across the globe and we are struggling to deal with its might. All nations have made their own strategies to deal with this situation and mainly a phase of lockdown has been the savior in most countries, especially India, where it was enforced early and well in time. After a successful lockdown, there is a phase of unlocking, which is equally important. One should exercise caution in that this should be done gradually and phased, with all the precautions in place and without any complacency. Neurosurgeons are faced with a situation pertaining to those afflicted by posterior fossa lesions with hydrocephalus. They are treated with ventriculoperitoneal shunt, but sometimes they develop reverse tentorial herniation. This needs prompt evaluation and intervention and carries a poor prognosis if untreated. Another situation is where bifrontal contusions need decompressive surgery; some patients develop encephaloceles and extradural hematomas following successful surgery and complicate the prognosis. Both situations emerge due to sudden decompression, leading to quick changes in brain pressure and perfusion. The solution is slow and careful decompression, with all precautions in place despite the temptation of eureka moments. A similar response could be desirous over the course of our unlocking period. Hope this wisdom brings us good results in these Corona times.

Brain Pressure Wave Propagation during Baseball Impact

Keywords: baseball; brain injury; novel surrogate head; finite element method; pressure wave propagation

Traumatic Brain Injury Caused by +Gz Acceleration

Traumatic brain injury (TBI) has long been known as one of the most anonymous reasons for death around the world. This phenomenon has been under study for many years and yet it remains a question due to physiological, geometrical and computational complexity. Although the modeling facilities for soft tissue have improved, the precise CT-imaging of human head has revealed novel details of the brain, skull and meninges. In this study a 3D human head including the brain, skull, and meninges is modeled using CT-scan and MRI data of a 30-year old human. This model is named “Sharif University of Technology Head Trauma Model (SUTHTM)”. By validating SUTHTM, the model is then used to study the effect of +Gz acceleration on the human brain. Damage threshold based on loss of consciousness in terms of acceleration and time duration is developed using Maximum Brain Pressure criteria. Results revealed that the Max. Brain Pressure ≥3.1 are representation of loss of consciousness. 3D domains for the loss of consciousness are based on Max. Brain Pressure is developed.

Untangling the Effect of Head Acceleration on Brain Responses to Blast Waves

Multiple injury-causing mechanisms, such as wave propagation, skull flexure, cavitation, and head acceleration, have been proposed to explain blast-induced traumatic brain injury (bTBI). An accurate, quantitative description of the individual contribution of each of these mechanisms may be necessary to develop preventive strategies against bTBI. However, to date, despite numerous experimental and computational studies of bTBI, this question remains elusive. In this study, using a two-dimensional (2D) rat head model, we quantified the contribution of head acceleration to the biomechanical response of brain tissues when exposed to blast waves in a shock tube. We compared brain pressure at the coup, middle, and contre-coup regions between a 2D rat head model capable of simulating all mechanisms (i.e., the all-effects model) and an acceleration-only model. From our simulations, we determined that head acceleration contributed 36–45% of the maximum brain pressure at the coup region, had a negligible effect on the pressure at the middle region, and was responsible for the low pressure at the contre-coup region. Our findings also demonstrate that the current practice of measuring rat brain pressures close to the center of the brain would record only two-thirds of the maximum pressure observed at the coup region. Therefore, to accurately capture the effects of acceleration in experiments, we recommend placing a pressure sensor near the coup region, especially when investigating the acceleration mechanism using different experimental setups.