Motor Neurone Disease Flashcards
What is motor neurone disease?
describes a spectrum of heredo-degenerative diseases of the peripheral and central motor nerves
What is the lifetime risk of MND in the USA and Europe?
1/400
What is the gender ratio of MND?
2:1 male to female
What is the mean age of onset of MND for sporadic cases?
50-60 years; rare below age 40
What proportion of cases of MND are sporadic vs familial?
90% of cases sporadic, 10% familial
What are 3 examples of the genes that familial MND can be associated with?
- SOD1
- FUS
- C9ORF72
What is the classification of types of MND based upon?
distinguishing sporadic from familial and division into 4 clinical groups based on distribution of motor neurone involvement
What are the 4 clinical groups of MND?
- Spinal amyotrophic lateral sclerosis
- Bulbar amyotrophic lateral sclerosis
- Progressive muscular atrophy
- Primary lateral sclerosis
What is the most common variant of motor neuron disease?
amyotrophic lateral sclerosis
What is the presentation of amyotrophic lateral sclerosis (ALS)?
mixed clinical picture of upper and lower motor neuron signs
What symptoms are seen with bulbar ALS?
- early tongue and bulbar involvement
- palsy of tongue, muscles of chewing/swallowing and facial muscles due to loss of function of brainstem motor nuclei
What symptoms are seen with progressive muscular atrophy?
only lower motor neuron features; affects distal muscles before proximal
What type of symptoms are seen with primary lateral sclerosis?
only upper motor neurone features
What symptoms are seen with spinal ALS?
the classic MND syndrome - upper and lower motor neuron signs
typically LMN signs in arms and UMN signs in legs
What are 3 features of motor neuron disease which carry poorer prognosis?
- Early bulbar involvement
- Early respiratory muscle involvement
- Older age at onset
What feature of motor neurone disease is associated with more protracted survival?
more prominent lower motor neuron features
Which 2 groups of muscles are usually spared until late in the disease course of MND?
eye and sphincter muscles
What 2 neurological symptoms are not seen in MND ever and should prompt consideration of an alternative diagnosis?
- sensory disturbance
- cerebellar signs
What are 8 aspects of the management of MND?
- Supportive treatment coordinated via MDT approach
- Non-invasive ventilation if T2RF
- Pain relief
- Treatment of spasticity and contractures
- Management of drooling with anticholinergics (including TCAs)
- Supportive feeding via NG/PEG eventually
- only 1 DMT: Riluzole
- Early discussion of advanced care planning
What is the only disease modifying treatment available for MND?
Riluzole
How effective is Riluzole? What effect does it have on prognosis?
results are modest at best; shown to prolong life by 3 months
What is the mechanism of action of Riluzole?
antiglutamatergic drug which dampens motor nerve firing
In which group of MND patients can non-invasive ventilatin be useful?
can prolong survival in patients with type 2 respiratory failure
What are 2 things which can be used to treat spasticity and contractures in MND?
- Baclofen
- Botox injections
What class of drug can be used to treat drooling in MND?
anticholinergics, including TCAs
When may supportive feeding e.g. via NG or PEG be indicated?
as bulbar disease progresses
How is a diagnosis of MND made?
clinical diagnosis
What are 3 investigations which may be performed to aid the diagnosis of MND, although it is a clinical diagnosis?
- Nerve conduction studies
- Electromyography
- MRI
What will nerve conduction studies show in MND?
normal motor conduction, can help exclude neuropathy
What will EMG show in MND?
reduced number of action potentials with increased amplitude
Why might MRI be performed in MND?
usually performed to exclude differential diagnosis of cervicla cord compression and myelopathy
Does MND always fit into a single category?
no, in some patients there is a combination of clinical patterns
What proportion of all patients with MND have ALS?
50%
In familial cases of ALS where does the responsible gene lie and what does the gene code for?
chromosome 21, codes for superoxide dismutase
Which type of MND carries the best prognosis?
progressive muscular atrophy
Which type of MND carries the worst prognosis?
progressive bulbar palsy
Which type of non-invasive ventilation is usually used for respiratory support in MND?
BiPAP
What is the survival benefit of NIV respiratory support in MND?
survival benefit of around 7 months
What is the overall prognosis of MND?
poor - 50% of patients die within 3 years
