Pathophysiology of Brain Injury

Brain function most likely be immediately impaired by direct damage (eg, crush, laceration) of brain tissue. Further damage may happen shortly thereafter from the cascade of events triggered by the initial injury.

TBI of any sort can produce cerebral edema and decrease blood flow to the brain. The cranial vault is fixed in size (constrained by the skull) and filled by non compressible CSF and minimally compressible brain tissue; consequently, any swelling from edema or an intracranial hematoma has nowhere to go and thus increases ICP. Cerebral blood flow is proportional to the cerebral perfusion pressure (CPP), which is the difference between mean arterial pressure (MAP) and mean ICP.. So, as ICP increases (or MAP decreases), CPP decreases. When CCP falls below 50 mm Hg, the brain may become ischemic. Ischemia and edema may trigger various secondary mechanisms of injury ( release of excitatory neurotransmitters, intracellular Ca, free radicals, and cytokines), causing further cell damage, further edema, and further increases in ICP. Systemic complications from the trauma (eg, hypotension, hypoxia) can also contribute to cerebral ischemia and are called secondary brain insults.

Excessive ICP initially causes global cerebral dysfunction. If excessive ICP goes untreated, it can push brain tissue across the tentorium or through the foramen magnum, causing herniation (see Coma and Impaired Consciousness: Pathophysiology) and increased morbidity and death. If ICP increases to equal MAP, CPP becomes zero, resulting in complete brain ischemia and brain death; absent cranial blood flow is objective evidence of brain death (see Coma and Impaired Consciousness: Brain Death).

Hyperemia and increased brain blood flow may result from concussive injury in teens or children. Second impact syndrome is a very rare and debated entity defined by sudden increased ICP and death after a second traumatic insult that follows a usually minor head injury. It is attributed to loss of autoregulation of cerebral blood flow that leads to vascular engorgement, increased ICP, and herniation.

At Sam Harding Law Firm, The Good Guy, we want our client to be aware of the physiology of Brain Injury. We understand the problems suffered by people who have sustained "mild" Traumatic Brain Injuries. We know that insurance companies often try to take advantage of unrepresented clients. We work hard for our clients to get them the money they deserve without their having to go to court. We work to get medical bills, lost income and money for pain and suffering. However, should your case require us to litigate, we are prepared to take your case to court. We are an ABOTA and AV rated Martindale Hubbel law firm.