Hydrocephalus Flashcards
define:
• Enlargement of the cerebral ventricular system due to accumulation of CSF.
Causes:
This is either due to too much CSF being produced (rare), blockage in CSF flow or insufficient CSF being re-absorbed.
It can be subdivided into obstructive and non-obstructive
o AKA communicating and non-communicating
Aetiology/risk factors:
Obstructive (Impaired outflow of the CSF from the ventricular system)
Lesions of the 3rd and 4th ventricle or cerebral aqueduct)
• Posterior fossa lesions (e.g. tumour) compressing the 4th ventricle
• Cerebral aqueduct stenosis
Non-obstructive (Impaired CSF reabsorption into the subarachnoid villi)
• Tumours
• Meningitis
• Normal Pressure Hydrocephalus - idiopathic chronic ventricular enlargement. The long white matter tracts are damaged leading to gait and cognitive decline
• Subarachnoid haemorrhage
Epidemiology:
Bimodal distribution
Young = due to congenital abnormalities
Old- due to tumours or strokes
Symptoms of obstructive:
o Acute drop in conscious level
o Diplopia
Symptoms of normal pressure:
- Dementia
- Gait disturbance
- Urinary incontinence
Signs of obstructive:
o Papilloedema
o 6th nerve palsy – results in diplopia
• 6th nerve has the longest intracranial path of all the cranial nerves and so is most susceptible to palsy due to raised ICP
Signs in neonates:
- Increased head circumference
* Sunset sign (downward conjugate deviation of the eyes)
Signs of normal pressure:
o Cognitive impairment (dementia)
o Gait apraxia (shuffling)
o Hyperreflexia
Investigations:
• CT Head
o FIRST-LINE for detecting hydrocephalus
o May also pick up the cause (e.g. tumour)
• CSF
o From ventricular drain or lumbar puncture
o May indicate pathology (e.g. tuberculosis)
o Check MC&S, protein and glucose
• Lumbar Puncture
o IMPORTANT: contraindicated if raised ICP
o Therapeutic in normal pressure hydrocephalus
