Transient, powerful pressures are generated in the brain by a rotational acceleration impulse to the head

Abstract

A rotational acceleration impulse to a head, as occurs at traffic accidents, sport injuries, assaults and falls, induces a diffuse brain damage that eventually could result in persistent neuropsychiatric deficits and neurodegeneration. Emphasis has been concentrated on the relative motion of the brain inside the skull during head impact, whereas less attention has been paid to whether intracranial pressure changes are generated and, if so, the implications thereof. In the present experimental study we investigated in an animal model system, based on rabbits, if a sagittal, anterior-posterior rotational acceleration of a head generated intracranial pressure changes, recorded by fibre optic pressure sensors, inserted ipsilaterally in the parieto-temporal and the occipital lobes. Two levels of rotational acceleration were used in the experiments; one higher, corresponding to the threshold limit for moderate diffuse brain injury, and one lower, close to being noninjurious. Several pressure recordings were performed in each rabbit at the two acceleration levels. The pressure recordings invariably revealed the same general characteristics of rapid, positive and negative pressures within the brain, with variations in amplitude and duration, lasting for up to 10 ms. A major finding was the generation of powerful negative pressures, as low as 0.3 bars in absolute pressure. The most prominent difference in amplitudes of the negative peak pressures between the two applied acceleration levels was demonstrated at the parieto-temporal location. The presented pressure recordings are the first to disclose the generation of transient, powerful intracerebral pressures at rotational acceleration of the head, which must be considered in studies of brain injury generation and distribution as well as prevention.

Towards clinical management of traumatic brain injury: a review of models and mechanisms from a biomechanical perspective

“…These models have been developed for larger animals, including non-human primates (Gennarelli et al, 1981; Gennarelli et al, 1982), pigs (Smith et al, 1997; Smith et al, 2000; Browne et al, 2011) and rabbits (Gutierrez et al, 2001; Runnerstam et al, 2001; Hamberger et al, 2003; Krave et al, 2005; Krave et al, 2011), as well as for small animals such as rats (Davidsson and Risling, 2011). In these models, the animal head is often secured onto the mechanical system with a snout clamp or a skull-fixation plate.…”

A New Model to Produce Sagittal Plane Rotational Induced Diffuse Axonal Injuries

“…Despite the higher accelerations, the rats suffered from classical concussion injuries with minimal histological abnormalities. A series of publications have presented a model in which rabbits are exposed to rotational acceleration in the sagittal plane (Gutierrez et al, 2001; Runnerstam et al, 2001; Hamberger et al, 2003; Hansson et al, 2003; Krave et al, 2005, 2011). Due to the size of the rabbit brain as compared to the rat brain, the rabbit has become the preferred choice.…”

Development of a large-animal model to measure dynamic cerebrospinal fluid pressure during spinal cord injury

“…Such transducers have been applied to intracranial fluid pressure measurement in various traumatic brain injury models such as fluid percussion, cortical impact, contusion, acceleration, and blast wave models. 16,17,51 However, they have not been used in the spinal intrathecal space or for studying SCI, partly due to the lack of an SCI model with an appropriately large intrathecal sac dimension. The objectives of this study were to establish an in vivo porcine model of SCI suitable for studying the mechanics of CSF pressure during injury and to determine changes in pressure magnitude at several locations cranial and caudal to the injury site during the SCI event.…”