Intracranial Pressure Flashcards
What is the normal value for ICP?
5-15 mmHg
Which three components exist in equilibrium in the skull?
Brain
CSF
Blood
How does an increased ICP affect cerebral blood flow (CBF) and cerebral perfusion pressure (CPP)?
Decreases both CBF and CPP
What are the clinical features of raised ICP?
Headache worse on waking, coughing, sneezing Nausea and vomiting Papilloedema Drowsiness Cushing's triad
What is Cushing’s triad?
Increased BP
Decreased HR
Irregular, decreased RR
–> physiological response to raised ICP
What is hydrocephalus?
Excessive accumulation of CSF –> enlargement of ventricles
What are the type different types of hydrocephalus?
Communicating –> no obstruction of flow between ventricles and subarachnoid space
Non-communicating –> obstruction of CSF flow in ventricles
What causes communicating hydrocephalus?
Problem with CSF absorption due to arachnoid granulations
What causes non-communicating hydrocephalus?
Obstruction due to:
- tumour
- colloid cyst
- stenosis of aqueduct
What are the causes of congenital hydrocephalus?
- usually due to aqueductal stenosis
- type 2 Arnold-Chiari malformations
- spina bifida
Which imaging modality is best for hydrocephalus?
MRI
What are the signs and symptoms of hydrocephalus?
Symptoms of raised ICP Diplopia, impaired upgaze, 'setting sun' appearance Dilated scalp veins Increased head circumference Incontinence Gait abnormalities
What is the management for hydrocephalus?
CSF diversion procedure
- -> VP shunt most common
- -> endoscopic 3rd ventriculotomy
What is normal pressure hydrocephalus?
Build up of CSF due to impaired resorption at the arachnoid granulations or overproduction of CSF
BUT normal opening pressure on lumbar puncture
What are the clinical features of normal pressure hydrocephalus?
Progresses gradually, triad of:
- apraxia of gait (shuffling)
- dementia (can be reversible)
- urinary incontinence (due to overactivity of detrusor)
What would you see on MRI of a patient with normal pressure hydrocephalus?
Massively enlarged ventricles
What is the treatment for normal pressure hydrocephalus?
VP shunt
What are Chiari malformations?
congenital or acquired malformations of the hindbrain affecting structural relationships between cerebellum, medulla and upper cervical spinal cord
–> impaired CSF circulation through the foramen magnum
What is idiopathic intracranial hypertension?
Raised ICP in the absence of any SOLs or hydrocephalus
Which patients are more likely to get idiopathic intracranial hypertension?
Women
Obesity
What would you see on CT or MRI of a patient with idiopathic intracranial hypertension?
Normal or reduced (slit-like) ventricles
What are the lifestyle, medical and surgical management options for idiopathic intracranial hypertension?
Weight loss
Diuretics e.g. acetazolamide
CSF diversion with lumbo-peritoneal shunt
