Pathophysiology of Brain Injuries
A mild head trauma may result in cortical contusions resulting from coup or contrecoup injuries. Axonal fracture due to shear and tensile forces can happen during a severe head injury. Central nervous system resident and peripherally derived inflammatory cells are involved. There are moderate levels of axonal damage that can result in a milder traumatic brain injury. Interference of the axonal neurofilament system diminishes axonal transport leading to axonal swelling, Wallerian degeneration and transection. What may contribute to a minor injury is the release of excitatory neurotransmitters acetylcholine, glutamate, aspartate and a generation of free radicals.
Blast accodents may or transfer kinetic energy through the vascular system, to the brain and lead to a traumatic brain injury (TBI) without a direct head injury. Evidence of microscopic axonal injury, axon reaction bulbs and microglial sets, has been found in pathological examinations of patients with minor head traumas, that died from other injuries. Dispersal tensor MRI studies of the corpus callosum in patients with mild TBI revealed increased limited anisotropy and diffusivity suggestive of a cytotoxic edema. In patients with mild head traumas, the neuroimaging studies have shown that certain patients may develop frequent and extensive areas of abnormality as ascertained by the SPECT, PET and MRI that is revealed on a CT scan. The findings have shown an individual more prone to becoming more psychologically unbalanced and may display signs of mild psychosis.
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Clinical Characteristics
Concussions produce confusion, amnesia, irritability, and lack of concentration. The signs of a concussion may show up immediately after the head trauma or a short time after. Amnesia often includes forgetting the traumatic event and the events before and after the head injury occurred. Athletes who have suffered a head injury are a prime example of what can occur during and after a head trauma. The inability to recall the event that caused the head trauma is common. The individual is unaware of his or her environment, being unable to recall the details of the game. Further evidence of amnesia after a head trauma is the patient repeating questions already answered and sometimes displaying certain phobias.
A person with amnesia may be confused and lose consciousness. Close monitoring of the patient after a head injury can reveal information about the severity of head traumas and the timeframe in which mild to severe brain damage can occur.
The signs of amnesia can show up anytime from moments after the injury to days later. Early indications of a concussion are headaches, dizziness and lack of coordination, vertigo, being unaware of the surroundings, not recognizing family members or friends, nausea and vomiting. Patients may display mood swings and complain of sensitivity to light and sound. The taste of certain foods and liquids are displeasurable and the head trauma victim may become hypersensitive to noise and may start experiencing sleep deprivation. The phenomena experienced during sleep may be horrific nightmares or even hallucinations while awake.
