Traumatic Brain Injury and Cell Death
Traumatic brain injury is the leading cause of death and disability for those who are under 44. Societal cost is 40-80 billion dollars/year.
Head injury event usually lasts for 200msec.
Three types:
Inertia injury-brain trauma causes diffused axonal injury due to acceleration and deceleration injury
Impact Injury-lead to hematomas
Penetrating Injury-associated with post-traumatic epilepsy.
Glasgow Coma Scale-international grading scale for grading the severity of TBI based on patients response to
1) eye opening (spontaneous-4, verbal command-3, no response-1)
2) motor response (verbal-6, localize pain-5, flexion-4, no response-1)
3) verbal response (converses-6, incomprehensible-4, No response-1)
Grading of Glasgow scale (add values of three aforesaid tests)
1) mild, 13-15
2) moderate 9-12
3) severe, 3-8
Neurological Dysfunction implies a defect of both cognition and behavior. Hallmark symptom of TBI… loss of consciousness. Concussion… alteration in consciousness
Coma results from severe damage to the cerebral hemispheres and to the brainstem reticular formation. Symptoms = confusion, disorientation and retrograde amnesia
Sites of Injury
-Frontal Lobe Injury
-highest level of cortical development
-compromise decision-making and foresight/social conduct
-attention and cognitive abilities impaired
-Occipital Lobe Damage
-alters visual perception
-Parietal Lobe Damage
-neglect of visual hemispheres particularly in left hemifield
-focal injury to dominant side… decrease mathematical ability
-calculation skills impaired
-Temporal Lobe Damage
-long and short term memory affected
-posttraumatic amnesia have more residual cognitive impairment
-more post-traumatic injury… more severe brain trauma
Speech and Language and Olfaction
-traumatic aphasia results in anomia or inability to name common objects
-Broca’s aphasia is the most common in TBI
-Olfactory dysfunction common in 7% of individuals with TBI, most common cranial nerve injury
-severe loss of smell (anosmia) occurs by ripping of olfactory bulb
Epilepsy
-occurs in 5% of all people with TBI
-epileptic zone exists around the site of injury, upon stimulation seizure occurs
-retraction of dura from site of injury induces seizure as well
-dural penetration to brain leads to formation of scar tissue between brain and dura mater and subsequent pulling ipsilateral and contralateral hemispheres toward the lesion
-blood breakdown products also contribute to seizure activity (hemosiderin)
-subpial iontophoresis of Fe+2 compounds are responsible for the phenomenon
Cell/Neuronal Death
-uncontrolled rise of intracellular calcium… destructive changes in cells
-cause excessive release of excitatory AA
-NMDA receptor binds glycine/glutamate activates IP3 to increase intracellular Ca+2
-formation of destructive O2 radicals also induces cellular poisoning during TBI
(no antioxidant enzymes)
-TREATMENT: hypothermia increases Glasgow Coma Score
Tags: Aphasia, Broca's aphasia, cell death, coma, diffused axonal injury, epilepsy, frontal lobe, Glasgow Coma, hypothermia, Neurological Dysfunction, neuronal death, occipital lobe, olfaction, parietal lobe, posttraumatic amnesia, traumatic brain injury
