(2) Motor Neurone Disease (ALS) Flashcards
What is a motor neurone disease?
degenerative disorder of upper and lower motor neurones
Where do the pathological changes take place in an MND?
- anterior horn cells of sc
- cranial nerve
- medulla
- corticospinal tract
What is amyotrophy?
muscle wasting
What is lateral sclerosis?
scarring of uppermost pathways of the SC
Where does the scarring happen in lateral sclerosis?
descending upper motor neuron pathways (corticospinal tracts)
What are signs of lateral sclerosis?
- spasticity
- exaggerated reflexes
What is the epidemiology of ALS?
- male > female
- 40-70 years
- life expectancy ~3-10 years
What are the causes of ALS?
- 10-20% dominance one parental gene
- 90% not inherited
- environmental triggers
- defect gene controlling glutamate level in brain
What is primary muscular atrophy?
- primary degeneration in anterior horn cells
-
What is progressive bulbar palsy?
degeneration in cranial nerve nuclei in medulla
What are signs of primary muscular atrophy?
- muscle wasting & fasciculation
- painful muscle cramps
What are signs of progressive bulbar palsy?
paralysis tongue, palate & lower facial muscles
What are signs of ALS?
- UMNL
- spasticity
- weakness usually LL
What are signs of an UMNL (5)?
- slurred speech
- altered emotional control
- spasticity
- brisk reflexes
- decreased dexterity
What are signs of a LMNL (5)?
- weakness
- muscle wasting
- fasciculations
- decreased/absent reflexes
- cramping
What are ‘bulbar’ signs?
- dysphagia
- aspiration
- slurred/loss speech
- breathing problems
- weak cough
What is the course of ALS?
- Insidious onset (bulbar signs)
- 50% motor neurones can be lost before weakness evident
- progressive weakness leads to death ~3-4 years from onset
What are investigations carried out for ALS?
- EMG
- Muscle biopsy
- nerve conduction studies
- blood tests
- lumbar puncture
How can EMG detect a MND?
can identify LMN involvement or denervation prior to muscle wasting
What is a motor unit?
nerve fibre and motor fibres it supplies within the muscle
What is a fibrillation potential?
action potentials that arise from single muscle fibres
What do nerve conduction studies do?
measures speed conduction of electrical impulse through a nerve
What is the El Escorial Criteria?
- Classifies ALS diagnosis as possible, probable, and definite
- requires presence of LMN degeneration
What is definite ALS according to the El Escorial Criteria?
UMN & LMN signs 3 regions
