Penetrating gunshots to the head and lack of immediate incapacitation

Abstract

There are two distinct mechanisms of ballistic injury. Crushing of tissue resulting in a permanent tract is the primary factor in wounding of most tissues and most body regions. Temporary cavitation causes radial tissue displacement and subsequent shearing, compression and especially stretching of tissue analogous to blunt trauma. In contrast to the effect in elastic tissue, temporary cavitation can contribute substantially to wounding of inelastic tissue, such as the brain. This is the case in penetrating gunshot wounds to the head. Additionally, the penetration of the bony cranium can produce secondary missiles in the form of bone or bullet fragments and a tendency of the bullet to deformation and early yaw. Most important, wounding resulting from temporary cavitation is greatly augmented by the confined space provided by the unyielding walls of the skull. Bone contact and enhanced effects of temporary cavitation result in an enlarged zone of disintegrated tissue and in high intracranial peak pressures. Morphological signs of powerful intracranial pressure effects are cortical contusion zones, indirect skull fractures and perivascular haemorrhages remote from the tract. Depending on ballistic and anatomical parameters, the intracranial effect varies from slightly more severe injury than in isolated soft tissue to an "explosive" type of injury with comminuted fractures of the skull and laceration of the brain. Incapacitation is the physiologically based inability to perform complex and longer lasting movements independent of consciousness or intention. Immediate incapacitation is possible following cranio-cerebral gunshot wounds or wounds that disrupt the upper cervical spinal cord only. Rapid incapacitation can be produced by massive bleeding from major vessels or the heart. Immediate incapacitation is the result of primary intracranial effects of the bullet. A mechanism similar to commotion cerebri applied extracranially does not exist in cases of penetrating gunshot wounds to the head.

Suicídio atípico com dois ou mais disparos efetivos de arma de fogo: casuística do Instituto Médico Legal de Belo Horizonte e implicações periciais

“…Ressalta-se que lesões dessas regiões mais nobres do SNC também podem ocorrer sem que o projétil as atinja diretamente, através da transmissão radial de energia produzida pela cavitação temporária dos projéteis [30]. Entretanto, esta situação é mais comum e fisiologicamente importante com projéteis de alta energia, que produzem cavitações temporárias de maiores diâmetros e que são de uso pouco comum para suicídios na maioria das cidades brasileiras.…”

“…O exame pericial da arma e dos projéteis recuperados no local do ato ou no corpo dos indivíduos durante a autopsia pode permitir a avaliação das situações nas quais mais de uma lesão de entrada de PAF serão produzidas, tais quais: a utilização de uma arma com mais de um cano [6,30], a utilização de uma arma automática [36] e a realização de dois disparos simultâneos com duas AF [37,38]. Em um relato de caso de suicídio com um fuzil automático AK-47 havia três lesões de entrada de PAF localizadas no tronco, com grande espaçamento entre as mesmas [39].…”

A case of orbitocranial foreign body

“…However, most of the damage in the target tissue is caused by the radially redirected kinetic energy of the expanding tissue itself. 5 Studies of craniocerebral gunshot victims demonstrate mortality twice as high as in patients after road accidents and threefold higher than other penetrating head traumas. 6,7 In our case, the potentially devastating effects of this penetrating injury were decreased as the projectile did not dislodge large portions of the bone and did not cause fatal bleeding from adjacent vessels.…”

Deaths resulting from the use of firearms by police against motor vehicles: Study of cases in Porto, Portugal

“…26,27 Case 3 is also to be noted. The victim was quickly disabled, which is expected when the major vessels are hit, 12,27 the aortic arch in this specific case, and the consequent loss of large volumes of blood within seconds. 12 Besides, it was proven that the victim's death occurred immediately after he lost consciousness.…”