CSF, Hydrocephalus and Lumbar Puncture Flashcards
What is hydrocephalus?
A general condition where there is excess CSF within the intracranial space, specifically the intraventricular spaces within the brain
How is CSF produced?
Majority produced by choroid plexus that pumps sodium into the subarachnoid space with water following from the blood vessels
Describe the pathway of CSF
From the lateral ventricles, CSF travels into the 3rd ventricle then into the cerebral aqueduct and into the fourth ventricle. It then exits the fourth ventricle and flows through the subarachnoid space over and around the brain and spinal cord. It is eventually reabsorbed into the venous system through numerous arachnoid granulations along the dural venous sinuses
What are the two kinds of hydropcephalus?
Communicating/non-obstructive
Non-communicating/obstructive
Describe the pathophysiology of communicating hydrocephalus
In most cases, CSF production is greater than CSF resorption, and so the ventricular system dilates and ICP rises
Rarely, there is overproduction of CSF and communicating hydrocephalus develops
What are the signs and symptoms of communicating hydrocephalus?
In young children, disproportional increase in head circumference compared to the rest of the face and failure to thrive
In those who’s sutures have fused ie older children and up, present with symptoms of increased intracranial pressure: headache, N&V, papilloedema, gait, disturbance, 6th cranial nerve palsy, upgaze difficulty
What are the causes of communicating hydrocephalus?
Infection
Subarachnoid haemorrhage
Post-operative
Head trauma
When does non-communicating hydrocephalus occur?
Whenever there is any physical obstruction to the normal flow of CSF before it leaves the ventricles
What are the causes of non-communicating hydrocephalus?
Aqueductal stenosis Tumours/masses Cysts Infection Haemorrhage/haematoma Congenital malformations
What is the first sign of development of hydrocephalus on MRI?
Dilation of the temporal horns of the lateral ventricles
What signs of hydrocephalus can be seen on MRI?
Dilation of temporal horns of lateral ventricles
Third ventricle becomes ballooned
Lateral ventricle size increases
Peripheral sulci effaced
How is acute hydrocephalus treated?
Surgically- placement of external ventricular drain (EVD- catheter passed into lateral ventricle through scalp)
Some patients may have successful weaning off EVD but many will need a shunt inserted
What is the main complication of EVD?
High infection risk
How is communicating hydrocephalus treated?
Surgical- shunt placement, ventriculo-peritoneal most used
How is non-communicating hydrocephalus treated?
Surgical- shunt may be necessary but can be avoided if obstructing lesion is removed
Third ventriculostomy can also be used, often in conjunction with shunt
What are the symptoms of normal pressure hydrocephalus?
Urinary incontinence
Gait disturbance
Quickly progressive dementia
(wet, wobbly and wacky)
What condition can normal pressure hydrocephalus cause if left untreated?
Dementia
What investigations can be useful in normal pressure hydrocephalus?
Looks like communicating hydrocephalus on CT/MRI
Lumbar puncture- normal opening pressure, symptoms improve with removal of CSF
How is normal pressure hydrocephalus treated?
Surgically- programmable VP shunt placement
What are the indications of lumbar puncture?
To obtain CSF for the diagnosis of: Meningitis Meningoencephalitis Subarachnoid haemorrhage Malignancy Idiopathic intracranial hypertension Infusion of drugs or contrast
What are the contraindications to lumbar puncture?
Unstable patient with cardiovascular or respiratory instability
Localised skin/soft tissue infection over puncture site
Evidence of unstable bleeding disorder
Increased intracranial pressure
Neurologic deterioration can occur if LP done below the level of a complete spinal subarachnoid block
Caution in patient with Chiari malformations
At what vertebral level should a lumbar puncture be done?
L3-L4 or L4-L5
What should the different CSF samples from a lumbar puncture be tested for?
Culture and gram stain
Glucose and protein
Cell count and differential
What are the complications of lumbar puncture?
Headache Apnea Back pain Bleeding or fluid leak around spinal cord Infection, pain, haematoma Subarachnoid epidermal cyst Ocular muscle palsy Nerve trauma Brainstem herniation
What are the risk factors for a spinal headache as a complication of lumbar puncture?
Female Aged 18-30 Lower BMI History of headache Prior spinal headache
How is a spinal headache treated?
Supine position for at least two hours
Hydration
Caffeine either oral or IV
Epidural blood patch
How does brainstem herniation present?
Altered mental status
Cranial nerve abnormalities
Cushing triad
What is Cushing triad?
Bradycardia
Systolic hypertension
Irregular, decreased respirations
What steps can be taken if a lumbar puncture fails and collection of CSF sample is critical?
Have someone else try- anaesthesia, neurology
Bedside ultrasound for difficult LP
Radiographic guided procedure
Cisterna Magna tap
