Hydrocephalus Flashcards
What is the passage of CSF?
It is produced by the ependymal cells in the choroid plexus of the lateral ventricles (mainly), it travels from the lateral ventricles to the third ventricle through the interventricular foramen, and then into the 4th ventricle through the cerebral aqueduct. From here, the CSF communicates with the subarachnoid space through the median foramen of Magendie and the 2 lateral foramen of Luschka. CSF is absorbed via the arachnoid granulations (villi) in the superior sagittal sinus.
What is Hydrocephalus?
Abnormal accumulation of CSF in the ventricular system - often due to a blocked cerebral aqueduct.
What is Normal Pressure Hydrocephalus?
Condition of ventricular dilation in the absence of a raised CSF pressure on lumbar puncture. It mainly occurs in elderly patients and is a reversible cause of dementia.
What are the causes of NPH?
1) 50% idiotpathic
2) Abnormal absorption of CSF
3) Build up of toxic metabolites in CSF
4) Abnormal arterial pulsatility compressing the venous vasculature
5) Secondary to SAH, meningitis, tumour, head injury
Clinical presentation of NPH?
1) Triad of urinary incontinence
2) Ataxia/gait abnormalities (Parkinson’s)
3) Dementia, memory loss, bradyphrenia (slowness of thought.
Ddx of NPH?
1) Alzheimer’s
2) Urinary outflow obstruction
3) Parkinsons
Diagnosis of NPH?
1) MRI/CT head will show hydrocephalus with enlarged 4th ventricle
2) LP - CSF pressure normal
Treatment of NPH?
1) Ventriculoperitoneal shunting - CSF surgically shunted to the peritoneum. Complications arise in 10% - catheter breakage, shunt occlusion, CSF hypotensive headaches, infection/seizures/death, cerebral haemorrhage/infarct.
2) In those unsuitable for surgery - control CVS risks of hypertension and hyperlipidaemia.
What is hydrocephalus?
Build up of CSF in cerebral ventricles usually as a result of impaired absorption but also occasionally due to excess secretion. Increased CSF = Increased ICP (in normal hydrocephalus)
What is the aetiology of hydrocephalus?
Communicating/non-obstructive - reduced resorption of CSF:
1) Post-meningitis
2) Trauma
3) Subarachnoid haemorrhage
4) Neoplastic infiltration of subarachnoid space
5) NPH
Non-communicating/obstructive - CSF flow blocked due to obstruction in ventricles:
1) Tumour
2) Trauma
3) SAH
4) Meningeal scarring due to meningitis (TB?)
5) Brain abscess
6) Malformation (congenital) of the brain - e.g. Arnold-Chiari malformation
Clinical presentation of hydrocephalus?
1) Symptoms of raised ICP: progressive headache - worse in morning, straining, can wake patient, relieved by vomitting, drowsiness +/- ALOC, vomitting, papilloedema - swelling of optic disc due to venous return obstruction from the retina due to raised ICP, loss of crisp optic nerve head margin, retinal oedema, can take days to become apparent.
2) Unsteady gait, cognitive deterioration, blurred vision/double vision.
Presentation of hydrocephalus in infants?
1) Since infants have unfused skull structures hydrocephalus will result in an increased head circumference - macrocephaly (will deviate from normal curve on growth charts e.g. 98th percentile for age).
2) Symptoms of raised ICP as well as a failure of upward gaze (sunsetting eyes) due to midbrain compression - in severe hydrocephalus.
Differentia diagnosis of hydrocephalus?
Epilepsy, haemorrhage, abscess, tumours, frontal lobe syndrome.
Diagnosis of hydrocephalus?
1) Lumbar puncture is therapeutic and diagnostic - raised pressure detection and release of fluids (in communicating/non-obstructive only - as the LP pressure change can induce coning in obstructive hydrocephalus - herniation of brain through foramen magnum resulting in brainstem compression and potential death).
2) CT/MRI - shows dilated ventricles and more details about aetiology
Treatment of hydrocephalus?
1) Non-communicating - remove obstruction if possible
2) Ventriculoatrial or ventriculoperitoneal shunting - surgical
3) Diuretics such as furosemide can help inhibit CSF secretion to help defer surgery for short time before damage occurs.
