Multiple sclerosis Flashcards
What is multiple sclerosis?
https://www.youtube.com/watch?v=yzH8ul5PSZ8
MS is a chronic autoimmune T-cell mediated inflammatory disorder of the CNS. Multiple plaques of demyelination occur throughout the brain and spinal cord, occurring sporadically over years (dissemination in space and time which is crucial for diagnosis).
What gender does MS more commonly occur in?
Women
What is the mean age of onset of the disease?
Approximatley 30 years (range 20-40)
What immune cell is impliated in the development of MS?
T-cell mediated autoimmune disease
What parts of the nervous system does MS affect?
CNS
- Brain
- Optic nerve
- Spinal Cord
What neuronal structures are affected by MS?
- Myelin sheaths
- Oligodendrocytes
What are the cardinal pathological features of of MS?
Plaques of demyelination (2-10mm)
Where do plaques most commonly occur in MS?
Can occur anywhere in CNS, but most commonly:
- Optic nerves
- Periventricular region
- Corpus callosum
- Brainstem and cerebellar connections
- Cervical cord (corticospinal and posterior columns)
What does the focal acute inflammation cause in terms of nerve conduction?
Conduction block
What are the pathologial outcomes that can occur from acute demyelinating episodes?
Recovery and remyelination, or permanent axonal destruction
What is the pathological basis for the progression of MS as a disesase?
Progressive axonal damage
What proportion of individuals with relapsing remitting MS develop secondary progressive MS?
>80%
What are the different types of progression of MS?
- Relapsing remitting MS
- Secondary Progressive MS
- Primary Progressive MS
What is relapsing remitting MS?
Symptoms occur in attacks (relapses) with a characteristic time course: onset over days and typically recovery, either partial or complete, over weeks. Patients may accumulate disability over time if relapses do not recover fully.
How often do relapses occur on average in relapsing remitting MS?
On average patients have one relapse per year but occasionally many years may separate relapses (benign MS – 10% of patients).
What is secondary progressive MS?
Late stage of MS consists of gradually worsening disability progressing slowly over years. 80% of those with RRMS progress to this stage by 35 years. Relapses may sometimes occur in this progressive phase (relapsing–progressive MS).
What is primary progressive MS?
Characterized by gradually worsening disability without relapses or remissions. Typically presents later and is associated with fewer inflammatory changes on MRI.
What proportion of those with MS have primary progressive MS?
10-15%
How do those with MS most commonly present?
Wide variety of possible symptoms may occur depending on the anatomical site of lesions. Common ones include:
- Optic neuritis
- Brainstem demyelination
- Spinal cord lesions
What are features of MS affecting the brainstem?
- Diplopia
- Vertigo with nystagmus
- Facial numbness/weakness
- Dysarthria
- Dysphagia
- Pyramidal signs
- Bilateral internuclear opthalmoplegia - Pathognomonic of MS
What is internuclear opthalmoplegia?
Characterised by
- Impaired adduction of the eye on the abnormal side
- Horizontal jerk nystagmus in the opposite eye upon lateral gaze away from the side of the lesion
What is the mechanism behind internuclear opthalmoplegia?
INO is caused by a lesion in the medial longitudinal fasciculus (MLF). The MLF connects the abducens nerve (CNVI) nuclei to the oculomotor nerve (CNIII) nuclei and facilitates conjugate eye movements during lateral gaze by coordinating adduction with abduction.
What are features of spinal cord lesions in MS?
- Paraparesis - developing over days/weeks
- Limb numbness/weakness + tingling
- Lhermitte’s sign positive
- Tight band sensation around chest - thoracic lesion
What is optic neuritis?
A demyelinating inflammation of the optic nerve. It is also known as optic papillitis (when the head of the optic nerve is involved) and retrobulbar neuritis (when the posterior part of the nerve is involved)
What are causes of optic neuritis?
- Idiopathic
- MS
- SLE
- Sarcoidosis
- Sjogren’s syndrome
- Behcets disease
- Syphillis
- Vitamin deficiency
- Diabetes
What are signs of optic neuritis?
- Altered visual acuity - may range from 6/6 to PL
- RAPD
- Lack of red reflex/retina obsured - large haemorrhage
- Red desaturation
- Central scotoma
- Swollen optic disc - if inflamamtion anterior
What are argyle robertson pupils?
https://www.youtube.com/watch?v=IbBYxGk1pUw
Characterised by:
- Miosis (small pupils)
- Absence of the pupillary light response
- Brisk accommodation reaction
- Bilateral involvement.
What is the mechanism behind Argyll-Robertson pupils?
Caused by a pretectal lesion in the dorsal midbrain affecting the fibres of light reflex, which spare the fibres of the accommodation pathway that innervate the Edinger–Westphal nuclei
What criteria are used to diagnose MS?
The Mcdonald Criteria
What might you see on MRI in someone with
-
Demyelinating Plaques - in 85% of clinical presentations
- Multiple plaques are usually present in MS
What would you be looking for on LP in someone with features of MS?
Oligoclonal bands of IgG on electrophoresis
What is visual evoked potential testing?
Detect lesions in visual pathway - The patient has EEG probes on the skull the measure brain response to visual stimuli. They are then given a visual stimulus, and the time between the visual stimulus and the brain response (on EEG) is measured. If the response is delayed this is evidence of some sort of optic nerve lesion.
