Hydrocephalus Flashcards
monro kellie hypothesis
signs of hydrocephalus from birth
- large head, thin and shiny scalp withb easily visible veins
- bulging fontanelle
- sunsetting eyes
- poor feeding, irritability, muscle stiffness, vomiting, sleepiness etc
prostitute sign
eyes accomodate but dont react to light
chiari malformation I
displacement of the cerebellar tonsils downthrough the foramen magnum
what can intrauterine hydrocephlaus do to the cerebellar tonsils
cause them to herniate down through FM –> Chiari malformation I
which type of chiari is more common and less severe
I
CF of chiari I
headache (coughing, suboccipital pain, can be brought on by neck extension), downbeat nystagmus, central cord symptoms, ataxic gait
chiari malformation II
caudal displacement of the cerebellum and medulla below foramen magnum with herniation of 4th ventricle
how is chiari associated with spina bifida
spina bifida creates an opening in the spinal cord, CSF is lost, and the brain is pulled down into teh spinal cord (Chiari)
leads to obstructive hydrocephalus
where is a shunt placed
one end into lateral ventricles, drains into abdominal cavity
symptoms of shunt over drainage
- slit like ventricles
- subdural haematoma
- orthostatic headache (relieved when lying down - CSF flows to brain??)
how does shunt over drainage cause subdural haematoma
ventricles collapse, tear blood vessels, haemorrhage, haematoma
what organisms are usually the cause of shunt infection
skin commensals (staph epidermidis most common), or 2y to abdominal infection
how can shunt infection be reduced
impregnate tube with silver or ABx
what symptoms does a blocked shunt cause
hydrocephalus
- headache and vomiting
- sunsetting in kids, lack of upgaze in adults
- stomach pain (drains into abdomen)
- beware of blurred vision! papilloedema precedes blindness but can be rapid
what investigations can be done for shunt malfunction
- tap in extreme cases - send CSF to microbiology
- CT scan to demonstrate hydrocephalus
- surgery to replace shunt
why is there a big risk associated with tapping shunt valve
contamination with skin flora
normal pressure hydrocephalus
accumulation of CSF causes ventricles to become enlarged, with little/no increase in ICP of CSF, despite this there is the potential to respond to CSF diversion
name 2 risk factors for NPH
old age and vascular disease (decreased arterial compliance is thought to be an aspect of the underlying pathology)
classic traid of NPH presentation
ataxia, memory decline and incontinence
also CF of hydrocephalus
what is DD often misdiagnosed as
Parkinsons or Alzheiemrs
which symptom precedes all others in NPH
ataxia - essential to diagnosis
describe the ataxia with NPH
- Inability to walk in standing position, able to make walking movements while lying
- Broad based shuffling gait
- Difficulty rising from chair
- Tendency to fall backwards
- Difficulties initiating gait, slow cautious gait
what drug is the ataxia in NPH unresponsive to
levodopa
presentation of dementia in NPH
Mental slowing (e.g. increased response latency, attention difficulties, impairment of abstract thinking and insight) and memory impairment (e.g. impaired recall)
what is the onset of urinary incontinence like in NPH
generally insidious
imaging of NPH
CT or MRI
May be normal, show evidence of ventricular enlargement or damage to white matter around cerebral ventricles
levodopa challenge in NPH
- Levodopa challenge in all patients with suspected Parkinson’s disease – diagnosis ruled out if ataxia symptoms show no response
further investigations of NPH
- LP to measure ICP - normal/slightly raised
- LP tap test - to determine if there wil be a benefit in shunting and to support diagnosis
- lumbar drainage studies
- infusion studies
outline a LP tap test procedure
- remove 30ml CSF through LP
- assess gait symptoms etc
- if there is an improvement - indication for shunting
what are the expected outcomes after shunting NPH?
tends to have good results for gait problems, poor results incases of pronounced dementia
how long do the benefits of shunting tend to last in NPH
around a year
is the patient with IIH alert or confused?
alert and orientated
clinical features of IIH
increased ICP: headache, papilloedema, constricted visual fields
what is the headache like in IIH
pulsatile, morning, associated nausea
what happens to your visiion in IIH
constricted visual fields (usualy mild at first and not noticed by patients, inferonasal portions of visual field affected first)
enlarged blind spot
precedes loss of visual acuity
what structural damage can IIH go on to cause, and the clinical sign
CNVI palsy - horizontal diplopia
what is the classical patient associated with IIH
female of child bearing age - almost always associated with increased weight
what condition is IIH strongly associated with
sleep apnoea
what causes the onset of IIH
can just happen, often occurs in the setting of weight gain
investigations of IIH
MRI, visual field, optic photography, LP
what is seen on MRI of IIH
negative intracranial pathology, empty sella
what is seen on visual field testing and fundoscopy of IIH
- Visual field testing: enlargement of blind spot and loss of inferonasal portions of visual field
- Fundoscopy: bilateral papilloedema
what is the course of IIH like
can be self limiting or life long chronic
main treatment for IIH
weight loss, low soidum weight reduction programme is recommended
pharmacological management of IIH
- acetazolamide
- loop diuretics
- prednisolone
how does acetazolamide work for IIH
dec the production of CSF by inhibiting CA - causes a reduction in the transport of Na ions across the choroid plexus
surgical management of IIH
LP/VP shunt
what surgical option is available to help with visual problems
optic nerve sheath fenestration - incision in meninges to relieve pressure
subtemporal compression - remove some bone to relieve pressure
what causes spontaenous intracranial hypotension (SIH)
CSF leak
- post surgical, post LP
- idiopathic
- collagen and connective tissue disorders
- trauma
how do collagen and connective tissue disorders predispose one to SIH
predispose pt to dural diverticuli, can rupture
eg marfans, PKD, NF
presentatio of SIH
orthostatic headache
- worse with upright posture, eases off when lying down
- onset is usually gradual
- generalised, throbbing headache
also, neck/interscapular pain, visual field defects, dizziness, muffled hearing etc
investigation of SIH
MRI of head
LP - low CSF pressure
what is a syrinx
fluid filled cavity within the spinal cord
what does syringomyelia mean
cavity within the brainstem
which congenital malformation is syringomyelia v commonly associated with
arnold chiari
describe the disease course/symptom onset of syringomyelia
is a very slow but progressive disease, cavity will expand and lengthen over time
symptoms will likely be long standing and progressive, symptoms can be static for years and suddenly worsen
will syringomyelia go away by itself
no, sponatenous resolution is rare - surgery required
pathology of syringomyelia
The expanding cavity gradually destroys spinothalamic neurons, anterior horn cells and lateral corticospinal tracts. In the medulla (syringobulbia), lower central nerve nuclei are affected.
is syringomyelia more common in male or female
neither
mean age of presentation of syringomyelia
30s
acquired causes of syringomyelia
POST-TRAUMATIC
- Common in traumatic paraplegia victims
- Can occur after spinal trauma
- Intrinsic cord tumours
what is a holocord syrinx
involves the entire spinal cord
key points in history of syringomyelia
recent head or neck trauma
recent meningitis
ARNOLD CHIARI
sensory symptoms of syringomyelia
- damage to ALS tract in the cervical and upper thoracic regions causes loss of pain and temperature sensation in a cape like distribution
- fine touch, vibration and proprioception are preserved (DCML)
what clinical signs reflect the damage to ALS tract
cuts and burns on hands
motor symptoms in syringomyelia
upper limb motor impairement and loss of upper limb reflexes
leads to small muscle wasting in the hands - clawed hands and Charcot’s arthropathy
this can progress to involve arms, shoulders and respiratory muscles
what features indicate syringomyelia has damaged the autonomic nervous system
hyperhidrosis, Horner’s, bladder and bowel dysfunction
what disease are CHiari malformations and syringomyelia associated with
sleep apnoea
