CSF, Hydrocephalus and Lumbar Puncture Flashcards
What is the main role of cerebrospinal fluid? (CSF) Where is CSF located?
- Shock absorbance
- Located in subarachnoid space (between arachnoid and pia)
What are the main constituents of CSF?
- White blood cells (0-5)
- Protein (300mg/L)
- Glucose (40-80mg/dl)
- Na / Cl
What is the approximate total volume of CSF? How is volume distributed between cranium and spine?
- 150mL
- 50% intracranial, 50% spinal
What is responsible for the secretion and absorption of CSF?
Secretion:
- 80% from choroid plexus in ventricles
- Lining of ventricles (ependyma)
Absorption:
- Arachnoid villi (granulations)
What is the rate of production of CSF? Does it depend on intracranial pressure?
- 0.3-0.5ml/kg/hr (adult - 500ml/day)
- CSF production is independent of ICP
Where is the choroid plexus located?
- Mostly on floors of lateral ventricles
- Some on roof of 3rd ventricle
- Some between 4th ventricle and cerebellum
What are arachnoid granulations? Function?
- They are projections of the arachnoid membrane into the venous dural sinuses
- Function to allow CSF to pass from subarachnoid space to the venous system
Two main functional causes of hydrocephalus?
- Obstructive: blockage of CSF outflow from ventricles
- Communicating: blockage at level of arachnoid granulations
What causes hydrocephalus?
Congenital:
- Chiari malformation / aqueductal stenosis / Dandy-Walker malformation
Acquired:
- Meningitis
- Post-haemorrhagic
- Neoplastic (benign or malignant)
- Cerebellar stroke
- Post trauma / surgery
Symptoms and signs of hydrocephalus in infants?
- Cranial enlargement / splaying of sutures
- Fontanelles bulging / engorged scalp veins
- Abducens (CN VI) palsy
- Perinaud’s syndrome (eyes can’t move up/down)
- Exaggerated reflexes / resp. problems / irritable
Symptoms and signs of hydrocephalus in adults?
- Headaches (worse in morning & on coughing / straining)
- Papilloedema
- Visual disturbances
- Gait abnormality
- Abducens palsy
- Impaired consciousness
- May be asymptomatic
Treatment of hydrocephalus?
Pharmacological:
- Carbonic anhydrase inhibitor (Acetazolamide), reduces CSF production from choroid plexus
Surgical:
- EVD if emergency (external ventricular drain)
- Eliminate obstruction
- Shunting **
Complications of shunting to allow passage of CSF?
- Over drainage (low pressure headache / subdural haematoma)
- Under drainage
- Blockage
- Infection
- Disconnection
- Seizures
What is an ETV?
- Endoscopic 3rd ventriculostomy, treatment for hydrocephalus
- Create a stoma between 3rd ventricle and subarachnoid spaces
What is Normal Pressure Hydrocephalus? Symptoms?
- Hydrocephalus, but CSF pressure measured during lumbar puncture is normal. Can be a reversible cause of dementia
Classic triad of symptoms:
- Dementia
- Gait disturbance
- urinary incontinence
Treatment of normal pressure hydrocephalus?
- Usually improves after shunting
- Can be hard to diagnose though bc of normal pressure
What is idiopathic intracranial hypertension? Who is most at risk? How does it present?
- Raised ICP without obvious cause
- Typical patient is young, obese female
- Present with headaches, visual disturbances and papilloedema
Treatment for idiopathic intracranial hypertension?
- Carbonic anhydrase inhibitor (acetazolomide)
- Shunting
- Weight loss
What are the uses of a lumbar puncture?
- Obtain CSF for analysis (infection / protein etc.)
- Measure pressure (ICP)
- CSF drainage if ICP is high
- Diagnosis of normal pressure hydrocephalus
Things to check pre-Lumbar Puncture?
- Patient is awake and conscious
- No focal neurological deficit (VI nerve palsy)
- CT/MRI to rule out intracranial mass lesion
- Ensure patient not on anticoagulants
What vertebral level is a lumbar puncture taken at?
Between L3/4 or L4/5
Positioning of patient during a lumbar puncture?
- Fetal position: knees up and neck flexed
- Pillow behind the knees (?)
Lumbar puncture technique?
- Get patient to lie on side in fetal position
- Insert needle, angled towards umbilicus
- Feel for “a give” after piercing ligamentum flavum
- Check for CSF, measure pressure etc.
What does cloudy, turbid CSF indicate? What would you expect to see on CSF analysis?
- Meningitis (infection)
On testing CSF:
- High WBC
- High protein (>1g/L)
- Low glucose
