CSF, Hydrocephalus, Lumbar Puncture Flashcards
Where is CSF found?
Subarachnoid space between arachnoid and pia mater in the brain and spinal cord
Role of CSF
Acts as shock absorber
Fills in gaps between brain and skull
Immunological role
Removal of some waste products
Specific gravity of CSF
1.007
pH of CSF
7.33-7.35
Contents of CSF
0-5 WBC
0 RBC
Protein 300mg/l
Glucose 40-80mg/dl
Total volume of CSF
150ml - 50% spinal, 50% intracranial
Production rate of CSF in adults
0.3-0.5 ml/kg/hour
Where is CSF produced?
Choroid plexus in the ventricles
Where is CSF absorbed?
Arachnoid villi
Components of ventricular system
Lateral ventricles Foramen of Munro (interventricular foramen) Third ventricle Aqueduct of Sylvius Fourth ventricle
Meninges are
the membranous coverings of the brain and spinal cord - dura mater, arachnoid mater and pia mater
Function of meninges
Provide supportive framework for cerebral and cranial vasculature and protect the CNS from mechanical damage
What are the two main dural reflections?
Tentorium cerebelli
Falx cerebri
What do the tentorium cerebelli separate?
The cerebellum and brainstem from the occipital loves of the cerebrum
Where is the falx cerebri located and what does it separate?
Located in the longitudinal cerebral fissure and separates the two cerebral hemispheres
What structures pass through the foramen magnum?
The two vertebral arteries
What structures pass through the optic canals?
Optic nerve
What structures pass through the foramina ovale?
Mandibular branch of trigeminal nerve
What structures pass through the foramina rotunda?
Maxillary branch of trigeminal nerve
What structures pass through the jugular foramina?
Sigmoid sinuses, main venous outflow tracts from brain
What structures pass through cribriform plate?
Olfactory receptor neurones
What structures pass through the superior orbital fissures?
Oculomotor, trochlear, ophthalmic and abducens nerves
What structures pass through the internal auditory meati?
Facial and vestibulocochlear nerves
What structures pass through the stylomastoid foramina?
Facial nerve
What structures pass through carotid canals?
Internal carotid arteries
What structures pass through the foramina spinosa?
Middle meningeal arteries
What is hydrocephalus?
Accumulation of fluid in the brain resulting in the dilatation of the ventricles
Functional classifications of hydrocephalus
Obstructive - blockage outflow from ventricles
Communicating - block at level of arachnoid granulation
Congenital causes of hydrocephalus
Chiari malformation
Aqueductal stenosis
Dandy-Walker malformation
Acquired causes of hydrocephalus
Meningitis Post-haemorrhagic Neoplastic Post-operative Cerebellar stroke Post-traumatic
Symptoms and signs of hydrocephalus in infants
Cranial enlargement Splaying of cranial surfaces Irritability Poor feeding Full and bulging fontanelles Engorged scalp veins Abducens nerve palsy Perinaud's syndrome Exaggerated reflexes Respiratory problems
Symptoms and signs of hydrocephalus in older children and adults
May be asymptomatic Increased ICP Headaches - worse in morning and on coughing/straining Papilloedema Visual disturbances Gaze abnormality Loss of up gaze - abducens nerve palsy Impaired consciousness
Medical treatment of hydrocephalus
Acetazolamide
Surgical treatment of hydrocephalus
External Ventricular Drain
Eliminate obstruction
CSF diversion - third ventriculostomy, shunt insertion
Endoscopic ventriculostomy
Shunts which can be created in the surgical treatment of hydrocephalus
Ventriculo-peritoneal Ventriculo-pleural Ventriculo-atrial Ventriculo-subarachnoid Lumbo-peritoneal Cysto-subarachnoid
What is done in an endoscopic ventriculostomy, and when can it be done?
Create a fistula between third ventricle and subarachnoid cisterns
Can only be done in non-communicating hydrocephalus
Presentation of normal pressure hydrocephalus
Dementia (potentially reversible)
Gait disturbance
Urinary incontinence
Age > 60
Presentation of idiopathic intracranial hypertension
Young obese female
Headaches
Visual disturbances
Papilloedema
Treatment of idiopathic intracranial hypertension
Weight loss
Acetazolamide
CSF diversion
Optic nerve sheath fenestration
What position should a patient be in to undergo a lumbar puncture?
Foetal position - knees up, neck flexed, pillow between the knees
At what vertebral level is a lumbar puncture carried out?
Between L3 and L4
Describe basic technique for lumbar puncture
Aseptic - clean skin with betadine Local anaesthetic Spinal needle angled towards umbilicus Aim for interlaminar space, through the ligamentum flavum Obtain samples and withdraw needle
Indications for lumbar puncture
Need to obtain CSF for analysis
Measurement of ICP
CSF drainage for raised pressure
Diagnostic test for normal pressure hydrocephalus
Pre-lumbar puncture checks
Patient awake and conscious
No focal neurological deficit
CT/MRI to rule out intracranial mass lesion
Ensure patient isn’t on anticoagulation
Risks of lumbar puncture
Bleeding Infection Nerve root injury Retroperitoneal/intra-abdominal injury Brainstem herniation
Post-lumbar puncture care
24 hours bed rest
Warn about low-pressure headaches
Stop LP if patient is developing neurological deficit or becoming unconscious
Contraindications for lumbar puncture
Skin infection near LP site
Suspicion of increased ICP due to cerebral mass lesion
Uncorrected coagulopathy
Acute spinal cord trauma
Describe CSF in meningitis
Cloudy, turbid
Lots of WBC
Protein > 1g/l
Low glucose
Causes of bloody CSF
Traumatic tap
Subarachoid haemorrhage
Causes of yellow CSF
Yellow due to blood breakdown products
Most commonly seen in SAH
