Neurology - Multiple sclerosis Flashcards
What is multiple sclerosis
Chronic progressive demyelination of the neurones in the central nervous system
Caused by an inflammatory process involving the activation of immune cells against the myelin.
Pathophysiology of MS in more detail
Typically only the central nervous system (oligodendrocytes)
There is inflammation around the myelin and infiltration of immune cells that damage the myelin
This affects electrical signal transmission and results in symptoms
Lesions vary in their location over time - dissemination in time and space
What is the function of oligodendrocytes?
Produce myelin to wrap around the axons
Causes of MS
Cause of demyelination is unclear but it may be influenced by a combination of:
- Multiple genes
- EBV
- Low vitamin D
- Smoking
- Obesity
Is demyelination in MS permanent?
In early disease, re-myelination can occur and symptoms can resolve.
In the later stages of the disease, re-myelination is incomplete and symptoms gradually become more permanent.
Signs and symptoms of MS - broad
Optic neuritis - most common
Eye movement abnormalities
Focal weakness
Focal sensory symptoms
Ataxia
Depression/labile mood
Speech/swallowing difficulties
Bowel/bladder dysfunction
What is the presentation of optic neuritis?
Unilateral reduced vision over hours to days
Central scotoma (enlarged blind spot)
Pain on eye movement
Impaired colour vision
RAPD
What things other than MS can cause optic neuritis?
Sarcoidosis SLE Diabetes Syphilis Measles Mumps Lyme disease
How is optic neuritis treated?
Steroids
What eye movement abnormalities can occur in MS?
6th nerve lesions can occur - Can cause double vision
Unilateral lesions can cause intranuclear ophthalmoplegia
Lesions can also cause conjugate lateral gaze disorders
What is intranuclear ophthalmoplegia
Internuclear refers to the nerve fibres that connect between the cranial nerve nuclei that control eye movements (3rd, 4th and 6th cranial nerve nuclei). This is an interneuron called the medial longitudinal fasciculus (MLF).
The internuclear nerve fibres are responsible for coordinating the eye movements to ensure the eyes move together.
Ophthalmoplegia means a problem with the muscles around the eye.
INO is a conjugate lateral gaze palsy
What is conjugate lateral gaze palsy?
Inability of both the eyes to look together to the side
In the affected eye the eye will not abduct, whereas the unaffected eye will adduct to the nose
Nystagmus is usually observed with the abduction of the contralateral eye, as it tries to normalise the two discordant images being sent to the brain simultaneously
What focal weakness problems can occur?
Bells Palsy
Horners syndrome
Limb paralysis
Incontinence
What focal sensory symptoms can occur?
Trigeminal neuralgia
Numbness
Paraesthesia (pins and needles)
Lhermitte’s sign
What is Lhermitte’s sign?
An electric shock sensation that travels down the spine and into the limbs when flexing the neck.
It indicates disease in the cervical spinal cord in the dorsal column.
It is caused by stretching the demyelinated dorsal column.