Motor Neuron Disease Flashcards
What is motor neuron disease?
cluster of neurodegenerative disease affect
How common is MND?
6/100,000
What is epid of MND?
- Male more than female (3:2)
- Usually over 40
What is MND characterised by?
loss of neurons in:
- motor cortex
- cranial nerve nuclei
- anterior horn cells
How can you distinguish MND from MS and polyneuropathies?
upper and lower motor neurons can be affected but NO sensory loss or sphincter disturbances: distinguish between MS and polyneuropathies
How can you distinguish between myasthenia gravis and MND?
MND never affects eye movement, so not myasthenia
What are the 4 clinical patterns of MND and their prevelances?
- ALS (amyotrophic lateral sclerosis): 80%
- Progressive bulbar palsy: 10-20%
- Progressive muscular atrophy (<10%)
- Primary lateral sclerosis: rare
Where is the loss of neurons and signs in ALS?
- Loss of motor neurons in motor cortex and anterior horn of cord
- Combined UMN and LMN signs
When does ALS have worse prognosis?
- bulbar onset
- high age
- low Forced vital capacity
What does progressive bulbar palsy affect?
Only affects cranial nerves IX-XII
Where is the loss of neurons and signs in progressive muscular atrophy?
- Anterior horn cell lesion
- LMN signs ONLY
- Affects distal muscle groups before proximal
What is the prognosis of progressive muscular atrophy?
better than ALS
Where is the loss of cells and signs in primary lateral sclerosis?
- Loss of Betz cells in motor cortex
- Mainly UMN cells
- Marked spastic leg weakness and pseudobulbar palsy
- No cognitive decline
What are RF for MND?
- Genetic predispotion
- FHx
- Age
What are symptoms and signs of MND?
- Stumbling spastic gait
- Foot drop ± proximal myopathy
- Weak grip
- Shoulder abduction (hard to hair wash)
- Aspiration pneumonia
- SOB
- Dysphagia
- Progressive muscle weakness
What are UMN signs in MND?
- Spasticity
- Brisk reflexes
- Increased plantars
- Hyper-reflexia
- Clonus
- Positive Babinski’s signs
What are LMN signs in MND?
- Wasting and fasiculation of tongue, abdomen, back, thigh
- Hypotonia
- Hyporeflexia
- Muscle atrophy
What are the bulbar signs of MND?
- speech and swallowing affected
1. Flaccid and fasciulating tongue
2. Jaw jerk is normal or absent
3. Speech is quiet hoarse of nasal
What are possible DDx for MND?
- Cervical spondylosis with myelopathy and radiculopathy
- Multifocal motor neuropathy
- Inclusion body myositis
- Monomelic amyotrophy 5. MG
What criteria is used for ALS?
El Escorial Diagnostic criteria for ALS
What is definite ALS?
UMN and LMN signs in 3 regions
What is probable ALS?
LMN and UMN signs in 2 regions
What is probable ALS with lab support?
LMN and UMN signs in 1 region or UMN signs in more than 1 region and EMG shows acute denervation in 2 or more limb
What is possible ALS?
UMN and LMN signs in 2 regions
What is suspected ALS?
UMN or LMN signs only in 1 or more regions
What investigations may you do in MND and why?
- Brain/cord MRI to exclude structural causes
- LP exclude inflammatory causes
- Neurophysiology can detect subclinical denervation and hep exclude mimicking motor neuropathies
What medication is used in MND to improve survival?
Riluzole 50mg twice daily
How does Riluzole work?
inhibitor of glutamate released and NMDA receptor antagonist: improve survival
When else may you use medication in MND?
do control symptoms
What are examples of other medications used for MND?
- Can use carbocisteine and supportive respiratory management: for excess mucus
- Can used NIPPV: for resp symptoms
- Can used Muscle relaxants: for spasticity
What are possible complications for MND?
- Respiratory failure
- Nutritional deficit
- Aspiration pneumonia
- Riluzole-related hepatotoxicity
- Riluzole-related neutropenia
What can motor neuron disease also be called?
- Amyotrophic lateral sclerosis (ALS)
- Lou Gehrig’s disease
- Charcot’s disease
What is the patho of MND?
- Build up of unbiquinated proteins in cytoplasm
2. Death of corticospinal tracts
How does MND present?
Presents with upper and lower MN symptoms
What is spared in MND?
- oculomotor
- sensory
3, autonomic function
What are areas of wasting in MND?
- tounge base
2. thenar muscles
What does EMG show in MND?
fibrillation and fasiculations
What are fasiculations?
damaged motor units produce spontaneous action potentials, resulting in a visible twitch
What are fibrillations?
spontaneous twitching of individual muscle fibres; recorded during needle electromyography examination
What test is usually positive in MND?
97% of MND patients have ubiquitin inclusions positive for TDP-43
Are there sensory symptoms in MND?
NO - and no autonimic e.g. constipation
