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Closed Head Trauma
Clinical Medicine II
Question | Answer |
---|---|
How do we fix a head lac, and what must we do prior to this | fix in layers, often staple, must palpate inside the lac for bony crepitus or stepoffs |
Fxn of the tentorium cerebelli and falx cerebri | tentorium divides cerebral hemispheres from cerebellum/ brainstem and falx: divides R and L cerebral hemispheres |
Fxn of CSF | cushions brain and spinal cord against trauma |
What makes CSF? How much | 150cc, made in choroid plexus in ventricles |
What % of cardiac output does the cerebrum get | 15% and only 2% mass of body |
What is Cerebral Blood flow influenced by? How does it respond | CO2 and some O2, Hypercapnia: vasodilation, Hypocapnia: vasoconstriction Hypoxia: vasodilation |
What can we do with ↑ICP | hyperventilate them to ↓CBF |
What is CPP | Cerebral perfusion pressure: mean arterial BP-Intracranial pressure MAP-ICP |
The ability of the brain to maintain constant cerebral BF despite changes in CPP | Autoregulation Range: 45-160mmHg |
How does the brain autoregulate | vasodilation and vasoconstriction of cerebral vessels |
What does ICP depend on | Brain+Blood+CSF <15mmHg (-FB)\ |
What happens when the brain begins to swell | CSF leaves cavity to cords, then blood, the results in brain herniation’s |
What are causes of ↑ICP | mass lesion, hematoma, cerebral edema (anything ↓ the space in the skull) |
What is a transtentorial herniation | epidural hematoma, can medial force the temporal lobe (uncus) through tentorium opening |
What are the two main structures compressed d/t an uncal herniation | compressed CN III and corticospinal tract |
Clinical findings of an uncal herniation | Ipsilateral fixed, dilated pupil, contralateral weakness of arm/leg, ↓ LOC |
Two types of closed head injuries | Diffuse and focal |
What are Diffuse lesions? Focal? | concussion, diffuse axonal injury Focal: skull fx, cerebral contusion, intracerbral hemorrhage, epidural hematoma, subdural hematoma |
What is a concussion | transient LOC or alteration following blunt impact to dead : sec-mins (maybe hrs) |
What is residual of a concussion | post-concussive syndrome: HA, memory problems, anxiety, insomnia, dizziness last weeks to months |
Tearing/shearing of n. fibers at time of impact | diffuse axonal injury |
Clinical signs of diffuse axonal injury | CT may be nl, but profound neurological deficits, comas and 33% death d/t cerebral edema |
Tx of isolated skull frx | conservative follow up, no tx needed |
Tx of a depressed skull frx | palpate to identify, require surgery to elevate fragment, Abx if open |
Fracture across base of temporal bone | basilar skull fracture |
4 signs of a basilar skull fracture | hemotypanum, raccoon’s eyes, battle’s sign, CFS rhinorrhea/otorrhea |
How do we dx a basilar skull frx | usually clinically, CT hard to pick up this |
Focal hemorrhagic area on brain: CT, often surrounded by edema | cerebral contusion |
What is a contrecoup lesion | cerebral contusion on opposite side of the injury |
What does a cerebral contusion look like | an intracerebral hemorrhage or brain bleed |
Parenchymal hemorrhage d/t torn BV’s, onset? | intracerebral Hemorrhage (can be delayed for days) |
Bleeding b/w skull and dura, characteristics | epidural hematoma, “lenticular” on CT, no damage to actual brain, rapid deterioration |
MOI of epidural hematoma | d/t (temporal) skull fx. Which tears the middle meningeal artery |
What is a subdural hematoma and chracteristics | bw dura and arachnoid/brain Sickle-shaped, d/t veins |
Where are subdural hematomas normally seen | elderly and alcoholics d/t brain atrophy: veins span greater distance and more easily torn |
What does a subacute and chronic subdural hematoma look like | S: gray (still can see brain shifting) C: black still some shifting and disappearance of the lateral ventricles |
What are assessment steps for head injury | maintain O2/ventilation, Cushing’s reflex, neuro exam, films, |
What Is the mechanism of the Cushing reflex | ↑ICP takes ↑MAP to perfuse brain, baroreceptors notice ↑ BP→↓HR |
Do we get plain skull XR’s | no CT will show both. |
What calls for a CT | prolonged LOC >1m, persistant ↓ mental status, clinical suspicion of skull frx, persistent vomiting (>x1), sz, focalneuro defici |
When wouldn’t we get a CT | mild MOI, nl neuro, glascow of 15, someone to monitor them |
Management of severe head injury | ABC’s, c-spine immob. Intubate/hyperventilate to ↓CO2, elevate head to 30 degrees, correct hypotension, give IV diuretic to ↓ ICP, rapid neuro surgery evacuation |
When would you admit a person w/ head injury | persistent ↓ LOC, focal nneuro deficit, Sz, unreliable pt with hx of LOC |
When can we discharge pt | minor injury, neuro intact, reliable fam member to observe |
When do sz’s occur post-traumatic | immediate, early, late ↑ incidence of epilepsy. Aggressively treat! |