neurosurgical emergencies Flashcards
GCS score components (3)
- eye;
- motor;
- verbal
what is the GCS eye response component
4.eyes open spontaneously
3.eyes open to verbal command
2.eyes open to pain
1.no eye opening
what is the GCS motor response component
6.obeys command
5.localises pain
4.withdraws from pain
3.flexion response to pain
2.extension response to pain
1.no motor response
what is the GCS voice response component
5.orientated
4.confused
3.inappropriate words
2.incomprehensible sounds
1.no verbal response
what does a GCS of <8 indicate
coma
what GCS is worrying
<12
what examination is essential when assessing for brain injury and why
pupil examination -> mass effect can compress the tentorium cerebelli where CN III sits resulting in pupil abnormalities -> usually unilateral but bad sign if bilateral
what is the monroe-kellie doctrine
the principle of homeostatic intracerebral volume regulation, which stipulates that the total volume of the parenchyma, cerebrospinal fluid, and blood remains constant i.e. if the volume of one component increases it must come at the expense of the others
when does the brain enter the decompensatory phase (raised ICP)
when the limit of compensation by the other 2 components is reached e.g. haemorrhage may cause CSF to decrease in volume but this can only be up until a point and the brain cant compensate anymore
cerebral pressure perfusion equation
CPP = MAP (mean arterial pressure) - ICP (intercranial pressure)
what is normal and ischaemic cerebral perfusion pressure
70-100 is normal
<60 is ischaemic
what is normal ICP
7-15 mmHg
what is cerebral auto regulation
the ability of the cerebral vasculature to maintain stable blood flow despite changes in blood pressure (within a certain range) -> ICP is maintained
when might auto regulation not be maintained
traumatic brain injuries
why is drowsiness seen in COPD pts
hypercapnia (CO2 retention) results in venous dilation -> raised ICP
CT appearance of extra dural haematoma
biconvex (lemon) shape in specified region (the dura is adhered tightly to sutures -> blood cannot cross suture lines)
extradural haemorrhage treatment
emergency surgery to drain + repair source of bleed
what usually causes an extradural haemorrhage
clear head trauma to temporal/parietal areas, esp pterion -> MMA ruptured
subdural haematoma CT presentation
cresent shaped rostral to caudal laterally-> crosses suture lines as beneath the dura
what can a microdyalisis device be used to measure (3)
- O2 levels
- glucose levels
- exciatory NT levels
why might a pt be put into a deep coma
to decrease the metabolic demand of the cells in the brain
what is a chronic subdural haematoma
an old collection of blood in the subdural space that irritated the bvs and initatees inflammatory responses-> bvs become leaky and allow fluid to be secreted resulting in mass effect and even midline shift
epi of chronic subdural haematoma
elderly pts on blood thinners w Hx of head trauma weeks ago
what kind of pts does haemorrhage in the BG and internal capsule usually occur in and why
hypertensive pts -> lenticulo striate arterries are easily ruptured due to HTN
why should haemorrhage in the BG/internal capsule not be operated on (unless massive)
to reach this area, lots of healthy brain must be damaged -> harm may be worse than the good outcome
what is the fisher scale
the best known system of classifying the amount of subarachnoid haemorrhage on CT scans, and is useful in predicting the occurrence and severity of cerebral vasospasm
fisher scale categories (4)
grade 1:
no subarachnoid (SAH) or intraventricular haemorrhage (IVH) detected;
incidence of symptomatic vasospasm: 21% ;
grade 2:
diffuse thin (<1 mm) SAH;
no clots;
incidence of symptomatic vasospasm: 25%;
grade 3:
localised clots and/or layers of blood >1 mm in thickness;
no IVH;
incidence of symptomatic vasospasm: 37%;
grade 4:
diffuse or no SAH;
ICH or IVH present;
incidence of symptomatic vasospasm: 31%;
what causes rebleeding of SAH
rupture of fibrin cap on aneuyrsm -> most don’t survive this second rebleed
common complication of SAH
hydrocephalus
communicating (3) vs obstructive (4) hydrocephalus
communicating :
- all 4 ventricles are enlarged
- lumbar puncture can be done
- may be caused by IVH, aneurysmal SAH, meningitis
obstructuve:
- dilation of lateral and 3rd ventricles with small, compressed or normal sized 4th
- asymmetry or enlargement of lateral ventricles when obstruction is at foramen of Monro
- may be caused by posterior fossa mass lesions, intraventricuar mass lesions, aqueductal stenosis
- NO LUMBAR PUNCTURE
