Multiple sclerosis - neurology Flashcards
What is MS?
MS is a chronic autoimmune disease affecting the CNS and is characterised by inflammation, demyelination, gliosis, and neuronal loss
What area of the CNS is affected?
- Affects the entire CNS (rarely the PNS)
- Demyelination in various tracts of mainly white, sometimes grey, matter
Epidemiology of MS
- Most common neurological disorder in young adults
- 9k in Ireland
- Onset between 20 and 40
- 2/3 more common in women than men
- Greater prevalence further north/south from the equator (North America, Canada, Australia, NZ, Scotland, northern Europe)
- Higher prevalence in white people than Black/South Asian people.
- Lower prevalence in some ethnic groups: Sami/Lapps of northern Scandanavia, Inuits in Canada and Maoris of NZ.
- Higher prevalence in Scotland and NI than England and Wales.
Etiology of MS
- Multifactorial: combination of genetic predisposition and environmental factors.
- Emerging research about possible viral triggers - cascade of events in immune system leading to neuronal cell death and nerve demyelination.
Possible environmental factors in MS etiology
viruses, smoking, vitamin deficiency, diet, exposure to UV radiation
Possible viruses that could trigger MS
human herpesvirus 6, varicella-zoster virus, Epstein-Barr virus, human endogenous retrovirus, torque teno virus
Is MS homogenous or heterogenous?
Heterogenous: several etiologies
What is myelin?
The protective sheath of axons of neurons that helps to quickly transmit electrical impulses
Pathogenesis of MS: steps of an inflammatory episode
- The blood-brain barrier protects the brain, allowing only certain molecules and cells through.
- T and B cells require specific surface molecules to enter.
- Once inside, T-cells can be activated (by myelin in MS), altering barrier cells to allow more immune entry.
- MS is a type IV hypersensitivity reaction—activated T-cells release cytokines, widening blood vessels for more immune cells and damaging oligodendrocytes.
- Cytokines attract B-cells and macrophages, which destroy myelin via antibodies and engulfing.
- This forms scar tissue called plaques/sclera.
- Attacks occur in bouts—regulatory T-cells reduce inflammation, allowing remyelination.
- Over time, remyelination stops, damage becomes irreversible, and plaques accumulate
How is MS an autoimmune disease?
The immune system incorrectly destroys myelin sheath of axons, causing communication breakdown between neurons, leading to sensory, motor and cognitive problems.
Prognosis of MS
- Life expectancy is 5-10 years shorter.
- Presentations predict disability and expectancy e.g. better prognosis for RRMS
- Younger age of onset = slower progression
- Black people have faster progression and disabled at younger age - ? social inequality.
- MS itself not fatal: increased risk of life-threatening complications such as severe infection and swallowing problems - pneumonia
Progression of MS
- Most experience 2 stages: RRMS, then gradually enter SPMS.
- If untreated, 50% of RRMS will turn into SPMS within 10 years since onset.
- With treatment approx 10% of PW RRMS will develop SPMS over median 32 years.
- Approx 15% will have PPMS immediately
- Symptoms worsen quicker in progressive types than relapsing types.
Factors affecting MS prognosis
- Treatment: early = better long-term outcomes (DMTs)
- Lifestyle: avoiding smoking and chronic stress, improving diet and physical exercise.
- Biological: negative effects associated with:
- older age
- more relapses early
- increased inflammation and damage in MRI
- obesity - Demographic factors
Early symptoms of MS
- visual loss
- transient diplopia (blurred vision)
- transient parathesias (sensory disturbances like pins and needles)
- mild weakness or clumsiness
- mild vertigo
More severe symptoms of MS
1. Motor Symptoms
* Lack of coordination and balance (ataxia)
* Limb weakness
* Paralysis (in severe cases)
2. Sensory & Visual Symptoms
* Pain
* Nystagmus (involuntary eye movements)
* Blindness (optic nerve involvement)
3. Fatigue
* Extreme fatigue (common and debilitating)
4. Bladder Dysfunction
* Bladder problems (urgency, incontinence, retention)
5. Cognitive & Personality Changes
* Memory issues
* Personality changes
6. Speech & Swallowing Difficulties (Typically in later stages)
* Mixed spastic-ataxic dysarthria (speech disorder)
* Dysphagia (difficulty swallowing
Characteristic features of MS
- optic neuritis: painful visual loss
- internuclear ophthalmoplegia: double vision
- fatigue
- Lhermittes phenomenon: leaning forward can create involuntary powerful jolt/electrical impulse
- Uhthoff’s phenomenon: symptoms worsen with heat due to sensitivity of impoverished nerve
Dysarthria in MS
- Mixed spastic-ataxic most common type - others possible due to variability in damage sites.
- Spastic: hypertonia, uncoordinated, imprecise articulation due to cerebellar involvement.
- Ataxic: excess/equal stress, distorted vowels, decreased coordination in muscles
- Mixed: slow speech, disrupted prosody, hypernasality, strained voice
- Other common features: impaired pitch and volume control, breathiness, and articulation
Sensory involvement in MS
Damage to sensory pathways: dorsal column medial lemniscus, spinothalamus, spinocerebellar
- numbness and tingling
- dyesthesia (burning/elec shock)
- Lhermitte’s Sign
- Loss of vibration and position sense
- Pain
Motor involvement in MS
Damage to motor pathways: corticospinal/pyramidal, extrapyramidal
- muscle weakness
- spasticity
- hyperflexia
- fatigue
- coordination
Subtypes of MS
- Relapsing remitting MS: episodes of attacks with remyelination in between. but decrease in repair over time
- Secondary progressive MS: inititally same as RRMS, but turns into steady progression
- Primary progressive MS: constant and steady progression
- Progressive relapsing MS: one constant attack with relapsing occurring as well - increases progressin even more
(also clinically isolated syndrome: first attack of MS-like symptoms. Can turn into MS or not)
Diagnostic tests for MS
- Objective clinical evidence of 2+ attacks across space and time as well as medical hx, physical exam, MRIs, spinal taps, and blood tests to rule out other diseases.
- MRI: change in appearance of optic nerve and build-up of plaques
- Lumbar puncture/spinal tap: obtains CSF sample, elevated levels of oligoclonal bands (protein) can indicate inflammation - MS?
- Visual evoked potential tests: record electrical signals produced by NS in response to stimuli. Electrodes placed on scalp, flashing checkboard, delay in signal due to damaged optic path.
Treatment options
disease-modifying treatments and symptomatic treatments
Disease-modifying treatments
*Not a cure, but decreases number and severity of relapses and lesions. Mostly for RRMS and SPMS with relapses still occurring.
- Interferon beta and glatiramer acetate (through injections). Reduces relapsed by 1/3
- Tysabri (natalizumab) (through intravenous infusion): reduces relapse rate.
- Mitoxantrone: potent chemotherapeutic agent. Risk of cardio toxicity and leukemia - for aggressiv eprogressive MS
Symptomatic treatments
- Relapses: high dose steroids to improve recovery
- Spasticity: baclofen, tizanidine
- Bladder: meds, self-catheterisation
- Pain: meds, alternative therapies
MDT team for MS
SLT< OT< physion, neurologist, MS specialist nurses, neurorehanbilitation, social services, palliative care
Rating scales for MS
- Functional Systems Score (FSS) and Expanded Disability Status Scale (EDSS)
- MS Functional Composite (MSFC)
- Timed 25-Foot Walk
- 9-Hole Peg Test
- Paced Auditory Serial Addition Test
Impact of MS on cognition and language
- Memory
- Attention
- Executive functioning
- Visual processing
- Word retrieval (WFDs)
- Speed of information processing
SLT Ax of MS
- Swallowing: bedside or instrumental
- Cognitive-linguistic ax: Montreal Cognitive Assessment, Cog-Linguistic Quick Test
- Motor speech ax
- Voice and resonance ax
- Impact: DIP, Fatigue Severity Scale
SLT Intervention for MS
- Communication Partner Training
- Breath support: diaphragmatic breathing, EMST
- Intelligibility and phonation: LSVT
- AAC
- Resonance therapy
- Vocal hygiene
- Dysphagia: EMST, neuroelectrical stimulation, compensatory strategies
- Cognition: compensatory strategies
MS Society of Ireland
- Advocacy and research
- Provide information
- Respite services
- Community services
- Symptom management programmes
- Exercise programmes
