surgery - NEURO flow and pressure Flashcards
what is hydrocephalus?
accumulation of CSF in cerebral ventricles
ventricular dilatation occurs which can lead to white matter damage, gliotic scarring and death if untreated
pathophysiology of hydrocephalus?
causes of obstructive hydrocephalus
Obstructing tumour or cyst
Congenital (e.g. congenital aqueduct stenosis)
causes of communicating hydrocephalus
Infective meningitis
Subarachnoid haemorrhage
Congenital (e.g. Dandy-Walker syndrome)
Normal Pressure Hydrocephalus
what is normal pressure hydrocephalus
ventricular dilatation present in the absence of raised CSF pressure
causes are idiopathic, with the remainder due to SAH, meningitis, head injury, or malignancy.
how does normal pressure hydrocephalus present?
triad of Parkinsonian gait, urinary incontinence, and dementia
ix for normal pressure hydrocephalus?
CT = ventricular enlargement, which is in excess to sulcal atrophy and periventricular lucency.
CSF pressures on lumbar puncture will be normal
mx of normal pressure hydrocephalus
surgical insertion of a CSF shunt
features of hydrocephalus?
nausea & vomiting
headache, worse in the morning
altered GCS
blurred vision
gait abnormalities
incontinence
papilloedema
what are causes of congenital hydrocephalus
Bickers-Adams syndrome, Dandy-Walker malformation, or Arnold-Chiari malformation
features of congenital hydrocephalus
Rapid increase in head circumference, with dilated scalp veins
Bulging of the fontanelles
Eyes pointing downwards with the upper lids retracted (termed ‘sunset sign’)
ix of hydrocephalus
CT = enlargement of ventricles, loss of the sulcal gyral pattern
mx of hydrocephalus
1st = insertion of an external ventricular drain
definitive - debulking tumour, endoscopic third ventriculostomy or choroid plexis resection
VP shunt to reduce CSF pressured
normal ICP?
5-15mmHg
average intracranial volume
1700ml
composed of the brain 1400ml + CSF 150ml + blood 150ml
CSF production
500 – 600ml per day
what principle describes the pressure-volume relationship in skull?
Monro-Kellie doctrine
VIntracranial = VBrain + VCSF + VBlood
what is cerebral perfusion pressure?
Cerebral perfusion pressure (CPP) drives oxygenation and metabolite transfer to cerebral tissues.
CSF is produced by ependymal cells within the choroid plexus, reabsorbed via arachnoid granulations
equilibrium between CSF production and absorption, however when this relationship is disrupted, a raised ICP can occur
features of raised ICP
morning headache (worse upon coughing, exertion or moving head), vomiting (with no associated nausea), and lethargy or altered mental status.
cular palsies, papilloedema, or pupil irregularities, including unilateral dilation or pupillary light defects
persistent vomiting, Cushing’s triad*, ophthalmoplegia
indications for ICP monitoring?
traumatic brain injury (TBI), hydrocephalus or conditions at high risk of developing hydrocephalus (e.g. space-occupying lesions or subarachnoid haemorrhage), idiopathic intracranial hypertension, or Reye’s syndrome
contraindications to ICP monitoring?
coagulopathies or anti-coagulation medication, scalp infections, or brain abscess.
complications of ICP monitoring?
infection (meningitis, ventriculitis, wound infection), intracranial haemorrhage, device malfunction or difficulty with placement, and ventricular collapse (potentially leading to tentorial herniation)
what is brain herniation?
tumour continues to grow without intervention causing brain parenchyma to shift + be displaced
