bisp194_midterm - Head Trauma Classification o Glasgow Coma...

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Unformatted text preview: Head Trauma Classification o Glasgow Coma Scale (GCS): severity as mild, moderate, or severe o Should also look at o Mechanism of injury: closed or penetrating o Intracranial (skull) consequence: diffuse brain injury or focal hematoma (blood clot caused by broken blood vessel) Anatomy & Physiology o Adult cranium sutures fuse to form rigid vault with constant intracranial volume o Major contents: brain, blood, cerebrospinal fluid (CSF) o Monro-Kellie hypothesis o Sum volume of major intracranial contents remain constant o Any increase in one (or addition of space occupying lesion, ex. hematoma) must be accompanied by an equal decrease in the others o Brain has some pressure buffering capacity o Squeeze venous blood into jugular veins o CSF into spinal canal Blood enters brain via carotid arteries and vertebral arteries . o Blood brain barrier (BBB) o Limits and regulates diffusion of solutes, toxins, and water o Tight junctions o Limit passive movement of substances into brain o Maintains diffusion gradient Head trauma o BBB disrupted increased capillary permeability o Blood plasma, H 2 O diffuse into brain parenchyma causing vasogenic cerebral edema (cerebral edema in white matter: swelling of organ/tissue due to accumulation of excess lymph fluid) Herniation Dural Folds (scaffold to limit movement) o Falx cerebri extends from frontal to occipital lobes separates two hemispheres o Tentorium cerebelli Separates occipital lobes from posterior fossa (cerebellum and brainstem) Incisura (opening that surrounds rostral brain stem) Intracranial Pressure (ICP) Elevations (Mass Effect) o Brain shift o Eventually herniate beneath dural folds injure brain/cranial nerves o Shifts may obstruct normal drainage pathyways of CSF hydrocephalus (abnormal accumulation of CSF in brain causes ICP elevation in skull) 1 Head Injury Requiring Operation Anatomy and Physiology Dura Mater (“dura”) o Separates brain from surrounding skull o “Hemorrhage” can occur above/below dura, above/within brain Epidural hematoma (extra dural hematoma) o accumulation of blood in space between inner table of skull and dura mater o occur due to tearing of: o middle meningeal artery o bridging temporal veins o linear skull fracture (90%) – squamous portion (region of temporal bone in front of/above ear) Subdural Hematoma o accumulation of blood in subdural space under dura/ immediately above arachnoid covering of brain o occur due to: o torn surface vein, esp. in region of Sylvian fissure or at vertex o venous sinus/arterial bleeding o of all ages: frequency increases with advancing age o elderly after falls o infants: result of perinatal birth trauma o based on time in which it occurs after injury: acute, subacute, chronic Aneurysms (Ruptured vs. Unruptured) Ruptured Aneurysm o Presents with subarachnoid hemorrhage (SAH)- bleeding over surface of brain in spinal fluid space that bathes arteries/veins- cause vasospasm (blood vessels spasm, lead to vasoconstriction, then tissue ischemia and death) and/...
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This note was uploaded on 02/02/2009 for the course BISP bisp 194 taught by Professor J during the Fall '07 term at UCSD.

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bisp194_midterm - Head Trauma Classification o Glasgow Coma...

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