Motor Neurone Disease Flashcards
What is MND?
A group of progressive neurodegenerative disorders of:
- cortical
- brainstem
- spinal motor neurons
i.e. (lower and upper motor neurons)
causing progressive weakness, and eventuallt death as a result of respiratory failure or aspiration
Are sensory symptoms e.g. parasthesia, tingling or numbness in line with MND?
No
Which conditions make up MND?
- amyotrophic lateral sclerosis (ALS)
- primary lateral sclerosis (PLS)
- progressive bulbar palsy (PBP)
- pseudobulbar palsy
- progressive muscular atrophy (PMA)
- monomelic amyotrophy (MMA)
What are the % incidences of the subtypes of MND?
- ALS - commonest
- Progressive bulbar palsy = less common
- Pseudobulbar palsy = less common
- Progressive muscular atropy = 2nd least common
- Primary lateral sclerosis = 1-2%
What are the risk factors for MND?
cause is still unknown
possible factors implicated:
- environmental
- toxic
- viral
- genetic
Summarise the epidemiology of MND
- RARE
- Incidence: 2/100,000
- 5-10% have a family history with autosomal dominant inheritance
What is ALS?
classic paraneoplastic presentation with UMN and LMN involvement.
- begins in one limb
- progresses to others & trunk muscles
What are the presenting symptoms of ALS?
- progressive focal muscle weakness e.g. one hand
- muscle atrophy
- fasiculations
- cramps (non-specific)
Why do fasiculations occur (UMN sign)?
- surviving axons branch to innervate muscles that have lost their nerve supply
- –> forms abnormally large motor units
- –> spontaneous firing
What are the signs of ALS O/E?
UMN
- Spastic weakness
- Extensor plantar response (Babinski’s sign)
- Hyperreflexia
LMN
- Flaccid weakness
- Muscle wasting
- Fasciculations
- Hyporeflexia
What is progressive bulbar palsy?
- lower motor neuron lesion of CNs IX, X and XII.
- progresses to other lower CNs and their supranuclear connections
presenting symptoms:
- dysarthria
- dysphagia
- nasal regurgitation of fluids
- choking
What is pseudobulbar palsy?
- upper motor neuron lesion of CN IX, X and XII
- cause: commonest = bilateral CVAs affecting internal capsule
clinical features:
- Gag reflex – increased or normal
- Tongue – spastic
- “cannot be protruded, lies on floor of mouth, small & tight”.
- Palatal movement – absent.
- Jaw jerk – increased
- Speech – spastic: “a monotonous, slurred, high-pitched, ‘Donald Duck’ dysarthria” that “sounds as if the patient is trying to squeeze out words from tight lips”.
- Emotions – labile
- Other – bilateral upper motor neuron (long tract) limb signs.
What is progressive musclar atrophy (PMA)?
- pure LMN presentation
- symptoms begin in 1 limb –> spread to adjacent spinal segments
symptoms:
- weakness
- atrophy
- fasiculations
What is primary lateral sclerosis?
What are the primary investigations for ?MND?
- clinically - Hx and examination
- EMG might be useful to confirm denervation of muscle fibres
tests of exclusion:
- CSF testing - to exclude infection
- MRI head - to exclude vascular issues, tumour
