Hydrocephalus Flashcards
What is hydrocephalus
Group of disorders resulting in excess CSF within the intracranial cavity
Two types of hydrocephalus
Obstructive and communicating
What is primary hydrocephalus
Any disorder where the accumulationof CSF is accompanied by raised ICP
Three main caues of primary hydrocephalus
Obstruction to CSF flow, impaired absorption at arachnoid villi or excess CSF production by choroid plexus
Examples of what can cause primary hydrocephalus
Aqueductal stenosis, herniation, blood clot, inflammatory exudate, colloid cysts or tumours
What is secondary hydrocephalus
Compensatory as an increase in CSF follows loss of brain tissue, so no overall increase in the ICP
Causes of secondary hydrocephalus
Atrophy, infarction
Treatment of hydrocephalus
Inserting a ventricular shunt with one way valve to drain CSF
Where does the flow of CSF flow
2 lateral ventricles -> foramen of munro -> 3rd ventricle -> cerebral aqueduct -> 4th ventricle -> 2 lateral foramen of lushka or foraman Magendie -> spinal CSF space and around brain in subarachnoid space
Causes of obstructive hydrocephalus
Tumour, congenital, post-infectious, or post-haemorrhage
Important causes of obstruction in subarachnoid space
Subarachnoid haemorrhage, infection such as pyegenic meningitis, TB, cryptosporidium and carcinomatous meningitis
Congenital malformations causing obstructive hydrocephalus
aqueductal stenosis, Chiari II, Dandy-Walker syndrome
Which group of hydrocephalus patients should not have an LP
Obstructive
Causes of increased CSF production
Choroid plexus papilloma / carcinoma but this is rare
What do the ventricles look like on a MRI in obstructive hydrocephalus
Ventricle dilation
What happens in impaired absorption of CSF
Increased venous pressure, will cause decreased CSF absorption, and if there are no obstructions in the CSF pathways, it will cause a rise in intracranial pressure without ventricular dilation
Examples of impaired absorption to CSF flow
Idiopathic intracranial hypertension and benign external hydrocephalus
Features of congenital hydrocephalus
Increase in head circumference
Late signs of congenital hydrocephalus
Cracked pot sound on percussion, sunsetting, atrophy of the optic nerves, lethargy, failure to thrive, vomiting, ophisthotonus and coma
Features of adult hydrocephlus
Headache, vomiting, visual impairment, visual obscurations, drowsiness, coma
What is Parinaud’s syndrome
Paralysis of upgaze, dilated pupils - fixed to light, retractile convergence nystagmus, lid retraction
Features of normal pressure hydrocephalus
Triad of gait disturbance, urinary incontinence, and dementia
Which category of patients does normal pressure hydrocephalus occur
Elderly
How to investigate into normal pressure hydrocephalus
Lumbar tap, lumbar infusion test and/or lumbar drain - see if patient improves after removal of CSF
Investigations into hydrocephalus
US through fontanelle, OFC as initial investigations in the neonate, but treatment will require CT and MRI
What type of hydrocephalus should be treated
Only if it is sympatomatic
Options for treatment of hydrocephalus
Remove obstruction, create new intracranial pathway, shunt, external ventricular drain
How to treat hydrocephalus using intracranial pathway
With endoscopic third ventriculostomy (EVT) by making a hole in the floor of the fourth ventricle
What is the preferred shunt to use
Venticle to peritoneal cavity (VP shunt)
When is ETV used
If the obstruction is downstream to the 3rd ventricle and the lateral ventricles are large enough to introduce an endoscope
Complications associated with VP shunts
Fracture, dislodge, disconnect, infection
What is the usual cause of shunt infection
Coagulase negative staph
Symptoms of failed/broken shunt
Raised ICP, blockage and fever, causing rapid decline
