Neurology: Multiple Sclerosis & MND Flashcards
What is multiple sclerosis (MS)?
A chronic and progressive autoimmune condition involving demyelination in the central nervous system.
Pathophysiology of MS?
The immune system attacks the myelin sheath of the myelinated neurones.
Inflammation and immune cell infiltration cause damage to the myelin, affecting the electrical signals moving along the neurones.
What is myelin?
Myelin covers the axons of neurones and helps electrical impulses travel faster.
What produces myelin in the:
a) CNS
b) PNS
a) oligodendrocytes
b) Schwann cells
Does MS typically affect men or women more?
Women (3x)
What age does MS typically affect?
Multiple sclerosis typically presents in young adults (under 50 years)
most commonly diagnosed in people aged 20-40 years
Does MS affect the CNS or the PNS?
The CNS (i.e. the oligodendrocytes)
In which locations is MS more common?
much more common at higher latitudes (5 times more common than in tropics)
What are the 3 subtypes of MS?
1) Relapsing-remitting disease
2) Secondary progressive disease
3) Primary progressive disease
What is the most common type of MS?
Relapsing remitting disease
What happens in relapsing remitting MS?
acute attacks (e.g. last 1-2 months) followed by periods of remission
In early MS, remyelination can occur. What happens here?
symptoms can resolve BUT in the later stages of the disease, re-myelination is incomplete, and the symptoms gradually become more permanent.
What is 2ary progressive MS?
Describes relapsing-remitting patients who have DETERIORATED and have developed neurological signs and symptoms between relapses.
Does relapsing remitting MS always progress to 2ary progressive MS?
Around 65% of patients with relapsing-remitting disease go on to develop secondary progressive disease within 15 years of diagnosis
What is 1ary progressive MS?
- accounts for 10% of patients
- progressive deterioration from onset
- more common in older people
Causes of MS?
The cause of the multiple sclerosis is unclear, but there is growing evidence that it may be influenced by:
- Multiple genes
- Epstein–Barr virus (EBV)
- Low vitamin D
- Smoking
- Obesity
Onset of MS symptoms?
Symptoms usually progress over more than 24 hours. Symptoms tend to last days to weeks at the first presentation and then improve.
How does MS present?
There are many ways MS can present, depending on the location of the lesions.
A characteristic feature of MS is that lesions vary in location, meaning that the affected sites and symptoms change over time. The lesions are described as “disseminated in time and space”.
Potential features of MS?
Non-specific e.g. lethargy (75%)
Visual:
- optic neuritis
- optic atrophy
- Uhthoff’s phenomenon: worsening of vision following rise in body temp
- internuclear ophthalmoplegia
Sensory:
- pins/needles
- numbness
- trigeminal neuralgia
- Lhermitte’s syndrome: paraesthesiae in limbs on neck flexion
Motor:
- spastic weakness: most commonly seen in the legs
Cerebellar:
- ataxia: more often seen during an acute - relapse than as a presenting symptom
tremor
Others:
- urinary incontinence
- sexual dysfunction
- intellectual deterioration
What is Uhthoff’s phenomenon?
Worsening of vision following rise in body temperature
What is the most common presentation of MS?
Optic neuritis (demyelination of the optic nerve)
How does optic neuritis typically present? Features?
Unilateral reduced vision:
- Central scotoma (an enlarged central blind spot)
- Pain with eye movement
- Impaired colour vision
- Relative afferent pupillary defect
Is optic neuritis unilateral or bilateral?
Unilateral
What is a relative afferent pupillary defect?
Where the pupil in the affected eye constricts more when shining a light in the contralateral eye than when shining it in the affected eye.
Describe the:
a) direct pupillary reflex
b) consensual pupillary reflex
in optic neuritis
a) reduced pupil response to shining light in the eye affected by optic neuritis
b) affected eye has a normal pupil response when testing the consensual pupillary reflex
Give some causes of optic neuritis
1) MS
2) Sarcoidosis
3) SLE
4) Syphilis
5) Measles or mumps
6) Neuromyelitis optica
7) Lyme disease
Management of optic neuritis?
1) Urgent ophthalmology input.
2) High dose steroids.
What imaging can help to predict which patients with optic neuritis will go on to develop MS?
MRI
MS can cause eye movement abnormalities.
Give some features of MS causing eye movement abnormalities
1) Diplopia & nystagmus (can lead to oscillopsia): caused by lesions to the oculomotor (CN III), trochlear (CN IV) or abducens (CN VI)
2) Internuclear ophthalmoplegia (characterised by impaired adduction of ipsilateral eye with nystagmus of contralateral abducting eye): caused by lesion to medial longitudinal fasciculus
3) Conjugate lateral gaze disorder: caused by lesion in the abducens (CN VI)
Define oscillopsia
Refers to the visual sensation of the environment moving and being unable to create a stable image.
Lesions affecting what nerves in MS cause diplopia & nystagmus?
Lesions affecting the oculomotor (CN III), trochlear (CN IV) or abducens (CN VI)
What is internuclear ophthalmoplegia in MS caused by?
Caused by a lesion in the medial longitudinal fasciculus
What characterises internuclear ophthalmoplegia?
1) impaired adduction on ipsilateral eye
2) nystagmus in contralateral abducting eye
What does the medial longitudinal fasciculus connect?
The nerve fibres of the medial longitudinal fasciculus connect the cranial nerve nuclei (“internuclear”) that control eye movements (the 3rd, 4th and 6th cranial nerve nuclei).
These fibres are responsible for coordinating the eye movements to ensure the eyes move together.
What is a conjugate lateral gaze disorder?
Conjugate means connected.
Lateral gaze is where both eyes move to look laterally to the left or right.
When looking laterally in the direction of the affected eye, the affected eye will not be able to abduct. For example, in a lesion involving the left eye, when looking to the left, the right eye will adduct (move towards the nose), and the left eye will remain in the middle.
What causes a conjugate lateral gaze disorder in MS?
A lesion in the abducens (CN VI)
Multiple sclerosis may present with focal weakness.
Give some examples of this
1) Incontinence
2) Horner syndrome
3) Facial nerve palsy
4) Limb paralysis
5) Ataxia
Multiple sclerosis may present with focal sensory symptoms.
Give some examples of this
1) Trigeminal neuralgia
2) Numbness
3) Paraesthesia (pins and needles)
4) Lhermitte’s sign