ND - CNS Disorders and Cranial Tumours - Week 9 Flashcards
What is the general prevalence of dementia, and its prevalence >80yoa?
5% increasing to 20-40%
What are the two kinds of dementia causes and percentage of cases.
Degeneration 55%
Infarct 45% of the limbic system
What is the most common form of degeneration type dementia?
Alzhiemers disease
List three causes of dementia in young people. Is it common?
Creutzfeldt-jakob disease (prion)
Picks disease (hereditary)
Alcoholic toxicity
What is the average prognosis for dementia?
From diagnosis to death is ~8 years
What is the limbic system and what does it mediate (3)?
A group of interconnected nuclei that mediates emotions, learning, and memory
What forms neurofibrillary tangles in alzhiemers disease? What do these proteins normally do?
Microtubule protein tau binds tubules in the normal brain
In AD, phosphorylation produces free tau, resulting in tubule breakdown resulting in tangles
Describe how amyloid plaques form in AD. What is it a byproduct of? Where does it accumulate and hat does it result in?
B-amyloid is a byproduct of neural tube breakdown
Accumulates in the ECM, forming plaques
It is neurotoxic, resulting in CNS apoptosis
What ultimately happens with AD?
The brain atrophies
List three CNS effects of limbic system degeneration in AD.
Cortical atrophy
Shrinkage of brain mass
Enlarged ventricles (in the brain)
List a PNS effect of limbal system degeneration in AD and why.
Apoptosis/glaucoma due to decreased bDNF
What is the outcome of limbal system loss in AD (2)?
Dementia (memory/speech)
Visual processing loss ± glaucoma
Are there any ocular signs of AD? Explain (4).
Some research indicates there is
Retinal nerve fibre layer thinning
Resence of B-amyloid plaques in the retina
Retinal vessel calibre changes
Retinal blood flow changes
Where does myelination first begin in the visual system and where does it proceed to and stop?
Starts 5th month gestation in the LGN, proceeds to the eye
Stops at the lamina 6th month
How does a myelinated retina appear (2)? What happens if an individual with a myelinated retina has MS?
Feathery white appearance
Distinct fibres visible
May disappear with MS
What is the primary function of myelin?
To facilitate inter-nodal axonal conduction
List three causes of demyelination and the most common.
Multiple sclerosis (most common)
Toxicity (CO problems)
Inflammation
In what percentage of MS cases is optic neuritis a presenting sign? What percentage of MS cases have optic neuritis?
~20% optic neuritis as the presenting sign
~85% of MS cases have optic neuritis
What are two presentations of optic neuritis?
Visible at the lamina called papillitis
Retrobulbar to orbit called retro-bulbar neuritis
What is an ocular sign of retrobulbar neuritis?
No obvious ophthalmic signs
What can be seen with OCT analysis of retrobulbar neuritis (2)?
Loss of RNFL and optic atrophy
What can form in regions of dense inflammation in retrobulbar neuritis (2)?
Scarring and plaque formations
List 4 eye involvements (symptoms) of retrobulbar neuritis.
Distorted/loss of vision, colour vision
Abnormal visual evoked response
Eye movement anomaly or diplopia
List 5 systemic problems of MS.
Muscle symptoms
Bowel/bladder symptoms
Numbness/tingling/pain
Decreased attention span/poor memory
Fatigue
What is required to identify multiple sclerosis?
Multiple lesions over multiple episodes (MRI)
What is a consequence of expansive disorders?
Raised intracranial pressure
List 5 common diseases associated with raised intracranial pressure.
Uncontrolled systemic hypertension
Cranial mass
Pseudotumour cerebri
Subarachnoid haemorrhage
Intracerebral haemorrhage
Describe the mass effect.
When a space occupying lesion expands in the confines of a fixed volume
What does raised intracranial pressure result in (3)?
Pain (headache)
Axoplasmic stasis
Vascular compromise
List 7 neurologic signs of raised intracranial pressure.
Severe/different CONSTANT headaches
Rigidity about the neck with loss of forward flexion
Gait problems (unsteady)
Projectile vomit with no nausea
Hemi-paresis
Reduced state of alertness
Worstening symptoms ith straining, valsalva, posture change
List 5 ocular signs of raised intracranial pressure.
Photophobia
Short-lived visual disturbance, blur, or loss (5-30 secs)
Diplopia
Pupil abnormality
Papilloedema
What is the cause of ocular signs manifesting with raised intracranial pressure?
Due to transmission of intracranial pressure down the ONH sheath to the lamina cribrosa
What two things would make one highly suspicious of raised intracranial pressure?
Papilloedema ith at least one other neurological sign
How are intracranial pressure abnormalities diagnosed?
Lumbar puncture
Within what timespan of raised intracranial pressure can papilloedema occur? hat is it typically?
Can occur within 24h
Typically 3-7 days
Is spontaneous venous pulsation a reliable rign of raised intracranial pressure?
No
Is papilloedema always bilateral? Explain.
Yes, but often asymmetrical
Describe foster-kennedy syndrome and what it is due to.
Optic atrophy in one eye due to crunch and papilloedema in the other eye due to mass effect
How is papilloedema caused by raised intracranial pressure?
Transmission of intracranial pressure along the sub-arachnoid space
With papilloedema, describe the following:
Pole where it is most marked
Blood vessels at the disc (2)
Vessels in general
Papilla
In addition to this, list three three features you would see.
Most marked at the inferior pole
Disc hyperaemia and buried blood vessels
Venous engorgement
Papilla swelling
Peripapillary haemorrhage
Cotton wool pathes
Retinal or choroidal folds
What are cotton wool spots?
NFL infarcts
How many types of papilloedema can be seen and when do they manifest? What does the type depend on (2)?
Long term (>3 months), 2 types can be seen
Type depends on the level of vascular compromise and shunt development
Describe compensated papilloedema (shunt, venous flow, axoplasmic stasis).
Shunt established, venous flow compromised but axoplasmic stasis still present
What appearance does compensated papilloedema have (2)?
Clean appearance with gross intravitreal swelling of the ON
Describe non-compensated papilloedema (shunt)?
Shunts not established
What appearance does non-compensated papilloedema have (3)?
Very dirty appearance with haemorrhages and cotton wool spots
What is pseudotumour cerebri and who does it typically affect?
False brain tumour, typically affecting premenopausal obese women
What are the signs of pseudotumour cerebri (2)?
Signs as per papilloedema, but all investigations fail to find a cause
What kind of diagnosis is pseudotumour cerebri?
Diagnosis by exclusion
Does pseudotumour cerebri present with many neurological signs?
Few neurological signs
What are the symptoms of pseudotumour cerebri?
As per papillodema
What percentage of patients with pseudotumour cerebri have severe vision loss?
2%%
What cranial nerve involvement and hat ocular problems are common with pseudotumour cerebri?
CN6 involvement and BV problems
Why do aneuryms and subarachnoid haemorrhages often involve vision or visual pathways?
Due to the location of major cerebral blood vessels
What is an aneurysmal rupture considered?
Neurological emergency
When do symptoms of rupture occur before and after rupture (in terms of percentages for each)?
After rupture - 90%
Before rupture due to growth/compression - 10%
What can symptoms of an aneurysm give prodrome for?
Impending aneurysmal rupture
List three typical symptoms of aneurysms.
Severe headaches
Visual disturbances
± neurological symptoms
List 7 symptoms of a subarachnoid haemorrhage.
Recent onset of constant or severe headache that do not comply with recognised patterns (thunderclap/migraine)
Short-lived losses of visiond, blur or visual field
Photophobia
Rigidity about the neck with loss of forward flexion
Papilloedema
Intraorbital haemorrhage
Gradual ON atrophy with/without cupping
Changes in consciousness/alertness
