CSF, hydrocephalus and lumbar puncture Flashcards
What is hydrocephalus?
General condition whereby there is excess CSF in the intracranial space and specifically, interventricular spaces within the brain causing dilation of ventricles and a wide range of symptoms
What ventricles is the majority of CSF produced and by which structure?
lateral, 3rd, 4th
choroid plexus
Briefly describe CSF production
metabolically active
sodium pumped into subarachnoid space and water follows
How much on average does an adult brain make of CSF per day?
450-600 cc’s
At any moment how much CSF is present and with how much being in the ventricles?
150cc
25cc
CSF pathway
lateral ventricle - foramen of munro - 3rd ventricle - cerebral aqueduct - 4th ventricle - foramina of Luschka or foramen of Magendie - subarachnoid space - over and around brain and spinal cord - arachnoid granulations
Where are the arachnoid granulations found?
Along dural venous sinuses
Is CSF resorption active or passive and what does it rely on?
passive
pressure
Difference between communicating and non communicating hydrocephalus
Non communicating - obstruction in CSF pathway
What is the main problem in communicating hydrocephalus?
CSF resorption
What happens to the ventricular system and ICP in CoH?
dilates
increases
Signs in children with CoH
failure to thrive, head disproportionate to body
Signs/symptoms in adults with CoH
headache, papilloedema, gait disturbance, 6th nerve palsy , upgaze difficulty
Causes of CoH
infection - bacterial meningitis
subarachnoid haemorrhage
post-operative, head trauma
Causes of NCoH
aqueductal stenosis tumours/cysts/cancers/masses infection haemorrhage/haematoma congenital malformations/conditions
3 findings on radiography with hydrocephalus
Dilation of temporal horn of lateral ventricle
3rd ventricle balloons
peripheral sulci wiped out
What is Evan’s ratio used for?
ventriculomegaly
Main treatment method for hydrocephalus ie medical or surgical?
surgical
What does acute hydrocephalus require for treatment?
EVD - external ventricular drain
What is usually required after an EDV?
permanent shunt
Main treatment for CoH
shunt placement
Main treatment for NCoH
remove obstruction
What is 3rd ventriculostomy and what type of hydrocephalus can it be used in?
hole between 3rd and 4th ventricle
NCoH
Why do VP shunts fail?
infection, over/under drainage, occlusion, skin erosion
Why is normal pressure hydrocephalus important?
Rare and preventable/reversible cause of dementia
Classic triad of normal pressure hydrocephalus
wet - incontinence
wobbly - gait disturbance
whacky - progressive dementia
How does normal pressure hydrocephalus appear in scans?
CoH
Investigations of normal pressure hydrocephalus
MMSE
gait assessment
Lumbar puncture
Treatment of normal pressure hydrocephalus - why is a LP shunt not used?
programmable VP shunt
tend to overdrain
Most likely symptoms to improve in normal pressure hydrocephalus
gait - incontinence - memory
Indications for lumbar puncture
Meningitis, meningoencephalitis
malignancy
subarachnoid haemorrhage
infusion of drugs/contrasts ETC
Some contraindications of lumbar puncture
unstable patient with CVS and resp instability localised infection over puncture site unstable bleeding disorder Raised ICP CT to rule out cerebral mass
List some equipment needed for a lumbar puncture (do not need to be specific)
anaesthetic eg topical, lidocaine drapes, gauze and bandages sponge wand and sterile solution manometer, stopcock and tubing spinal needle
How do you avoid hitting blood vessels on lumbar puncture?
stylet pointing up
What is manometry used for in lumbar puncture?
measure pressure (opening pressure)
Volume of CSF collected and what 3 vials samples?
1ml
culture and gram stain, glucose and protein, cell count
What position is an infant put in for lumbar puncture and what is the disadvantage?
seated
cannot measure pressure accurately
2 reasons for paramedian/lateral approach in lumbar puncture
calcifications from previous lumbar punctures
anatomic abnormalities
Complications of lumbar puncture
headache, apnea, bac pain, nerve trauma, brainstem herniation, bleeding, infection, cyst
Most common complication of lumbar puncture and groups most commonly affected
headache
female, 18-30, low BMI, history of headache
Prevention methods of headache post lumbar puncture
use small diameter needle
pass needle parallel to longitudinal nerve fibres
What does nerve root trauma feel like and how is it investigated+treated
electric shock
CSC, EMG
How would herniation during lumbar puncture present?
altered mental status, cranial nerve abnormalities
How is herniation mid lumbar puncture treated?
remove needle, elevate bed, mannitol and intubate
surgery
What causes an epidermal inclusion cyst
skin driven into spinal space
If lumbar puncture fails what are some alternatives?
image guided
ask colleague eg anaesthetics, neurology
cisterna magna tap
