Hydrocephalus Flashcards
What is hydrocephalus?
It is defined as an abnormal increase in the volume of cerebrospinal fluid (CSF) within the ventricular system of the brain
This increase in volume results in increased intracranial pressure within the cranium, which can cause irreversible damage to brain tissue
What are the three classifications of hydrocephalus?
Non-communicating hydrocephalus
Communicating hydrocephalus
Normal pressure hydrocephalus
What is another term for non-communicating hydrocephalus?
Obstructive hydrocephalus
What is non-communicating hydrocephalus?
It is defined as an accumulation of CSF due to an obstruction of CSF outflow
At four locations does non-communicating hydrocephalus tend to occur within the ventricular system?
Interventricular foramen
Cerebral aqueduct
Median apertures of the fourth ventricle
Lateral apertures of the fourth ventricle.
What are the three causes of non-communicating hydrocephalus?
Brain Tumours
Brain Cysts
Congenital Aqueduct Stenosis
What is congenital aqueduct stenosis?
It is narrowing of the cerebral aqueduct in the ventricular system, which usually allows CSF to flow from the third to the fourth ventricle
What brain tumours are most commonly associated with non-communicating hydrocephlaus?
Posterior fossa tumours
What is another term for communicating hydrocephalus?
Non-obstructive hydrocephalus
What is communicating hydrocephalus?
It is defined as an accumulation of CSF due to reduced absorbance into the dural venous sinuses
This is as a result of functional impairment of the arachnoid villi
What are the four causes associated with communicating hydrocephalus?
Infective Meningitis
Subarachnoid Haemorrhages
Spina Bifida
Dandy-Walker Syndrome
What is spina bifida?
It is a condition in which a baby’s spine and spinal cord doesn’t develop properly in the womb, resulting a gap in the spine
What form of spina bifida is most commonly associated with communicating hydrocephalus?
Myelomeningocele
What is myelomeningocele?
It is the most severe type of spina bifida, in which the baby’s spina canal remain open along several vertebrae in the back allowing the spinal cord and protective membranes around it to push out and form a CSF-filled sac
What is Dandy Walker malformation?
It is a condition in which there is atresia of the foramina of Luschka and the foramina of Magendie, which usually allow CSF to escape from the fourth ventricle into the subarachnoid space to be reabsorbed
What is atresia?
It means that a body part that is tubular in nature does not have a normal opening, or lacks the ability to allow material to pass through it
What is normal pressure hydrocephalus (NPH)?
It is defined as an accumulation of CSF due to reduced absorption at the arachnoid villi
Which age group tend to be affected by normal pressure hydrocephalus?
> 60
What are the triad of clinical features associated with normal pressure hydrocephalus?
Urinary incontinence
Dementia
Gait abnormality
Why is it important to differentiate between dementia and normal pressure hydrocephalus?
The clinical features of normal pressure hydrocephalus can be reversed with appropriate treatment
What are the four causes associated with normal pressure hydrocephalus?
Brain Injury
Stroke
Subarachnoid Haemorrhage
Meningitis
How does normal pressure hydrocephalus present on neurogimaging?
Ventriculomegaly in the absence, or out of porportion to, sulcal enlargement
What are the five clinical features of hydrocephalus in infants?
Large Cranial Circumference
Fontanel Development
Dilated Scalp Veins
Sunset Sign
Seizures
What is a fontanel?
It is a bulging or tense soft spot on the top of the head
What is the sunset sign?
It describes the presentation of the patients’ eyes pointing downwards with upper eyelids retracted
What are the six clinical features of hydrocephalus in adults?
Headaches
Diplopia
Nausea & Vomiting
Confusion
Coordination Issues
Urinary Incontinence
What type of headaches are associated with hydrocephalus? Why?
Morning headaches
This is due to a prolonged period of supine lying
What are the four investigations used to diagnose hydrocephalus?
MRI Scan
CT Scan
Ultrasound Scan
Lumbar Puncture
What is the gold standard imaging technique used to diagnose hydrocephalus?
MRI scan
What are the three signs of hydrocephalus on an MRI scan?
Ventricle enlargement
Loss of sulcal gyral pattern
CSF exudation from the ventricles
In what other way can MRI scans be used to investigate hydrocephalus?
They can be used to identify if there are any underlying causes
What are the three signs of hydrocephalus on a CT scan?
Ventricle enlargement
Loss of sulcal gyral pattern
CSF exudation from the ventricles
When are ultrasound scans used to diagnose hydrocephalus?
Antenatally
What are the three signs of hydrocephalus on an ultrasound scan?
Enlarged ventricles
Parenchymal thinning
Dangling choroid sign
What is the dangling choroid sign?
This is when the choroid is seen floating within the ventricle, specifically a separation of more than 3mm between the choroid plexus and the margin of the ventricle is considered abnormal
What is a lumbar puncture?
It involves obtaining a sample of CSF by inserting of a needle into the subarachnoid space of the spinal cord, specifically between L3 and L4 vertebrae
How are lumbar punctures used to investigate hydrocephalus?
They allow the pressure of the CSF sample to be obtained
In addition, they provide symptomatic benefit
What MUST be conducted prior to a lumbar puncture? Why?
CT scan
This is to determine the classification of hydrocephalus that the patient has
This is due to the fact that it lumbar punctures are only deemed as an appropriate investigation in individuals with communicating hydrocephalus and normal pressure hydrocephalus, however contraindicated in non-communicating hydrocephalus
Why are lumbar punctures contraindicated in individuals who have non-communicated hydrocephalus?
This is due to the fact that non-communicating hydrocephalus is associated with a raised intracranial pressure and reduced spinal cord pressure, which means that a lumbar puncture procedure could result in a pressure gradient that could compresses the brain into the foramen magnum
When is pharmacological management of hydrocephalus used?
It is used as a second line treatment option in an acute setting
What is the aim of pharmacological management of hydrocephalus?
To delay surgical intervention
What drug class is used to treat hydrocephalus?
Loop diuretics
What three loop diuretics can be used to treat hydrocephalus?
Furosemide
Acetazolamide
Isosorbide
How do furosemide and acetazolamide treat hydrocephalus?
They decrease the CSF secretion by the choroid plexus
How does isosorbide treat hydrocephalus?
It increases CSF reabsorption
What are the four surgical management options for hydrocephalus?
Lumbar drain
Extraventricular drain
Shunting
Endoscopic third ventriculosotomy
What is a lumbar drain?
It is a procedure that involves removal of CSF from the ventricular system through inserting of a tube into the subarachnoid space of the spinal cord, specifically between L3 and L4 vertebrae
When two classifications of hydrocephalus can be treated with a lumbar drain?
Communicating hydrocephalus
Normal pressure hydrocephalus
What is an external ventricular drain?
It involves the insertion of a catheter into the frontal lobe of the brain where the lateral ventricles are situated, enabling drainage of CSF into an external collecting system
When do we use external ventricular drains to treat hydrocephalus?
It is the first line treatment option of hydrocephalus in an acute setting and is a temporary measure
What is shunting?
It involves the insertion of a valved tube into one of the brain’s ventricles and tunnelling it to another region of the body where the excess fluid can be more easily absorbed
In which two regions of the body do we shunt CSF to?
Abdominal peritoneum
Right atrium
What are the two types of shunts?
VP shunt
VA shunt
What is a VP shunt?
It is a shunt in which CSF circulates from the cerebral ventricles to the peritoneal cavity
What is a VA shunt?
It is a shunt in which CSF circulates from the cerebral ventricles to the right atrium
What is first line a VP or VA shunt?
VP
What are the three complications associated with shunts?
Infections
Intracerebral haemorrhages
Seizures
What is endoscopic third ventriculostomy (ETV)?
It is a procedure that involves the formation of a hole in the bottom of one of the ventricles or between ventricles to enable CSF to flow out of the brain
What classification of hydrocephalus can be treated with ETV?
Non-communicating hydrocephalus
