Welcome to this Soton Brain Hub rapid review
of motor neurone disease. Motor neurone disease is characterised by a progressive degeneration
of motor neurons most likely due to excitotoxicity from increased levels of the neurotransmitter
glutamate. Motor neurone disease has three main variants
–Amyotrophic lateral sclerosis, which is characterised by upper motor neuron and lower
motor neuron signs. Primary lateral sclerosis which affects only upper motor neurons, and
Progressive muscular atrophy which affects only lower motor neurons.
The onset of motor neurone disease is usually a limb, classically noticed early on as a
clumsy hand with reduced dexterity, but can also begin with brainstem or bulbar signs
and rarely with respiratory depression. The majority of cases are sporadic but there
is also a strong genetic component with the SOD1 and C9NORF72 genes being implicated in
familial amyotrophic lateral sclerosis Life expectancy from symptom onset is around
3-4 years on average, but there is great variation from months to decades – and of course famously
the physicist Professor Stephen Hawking has loved with MND for over 40 years. There are
a number of factors which point towards a poorer prognosis such as later age of onset,
bulbar onset, a short diagnostic interval, and ALS/PMA variant.
In terms of management, Non-invasive ventilation has been shown to improve life expectancy
by up to one year. Typically this is used for greater than 4 hours whilst sleeping.
During the day, respiratory effort by the diaphragm is supplemented by accessory muscle
use which maintains oxygenation. However, when entering REM sleep, we all undergo sleep
paralysis of the majority of muscles, and so the diaphragm has to struggle on its own
but is unable to prevent deoxygenation. We can assist the failing diaphragm with NIV
A good MDT comprised of neurologists, general practitioners, nurses physiotherapists and
other health care professionals can improve outcome by around 6 months, as can the drug
riluzole, which acts to reduce the amount of excitotoxic damage from glutamate. PEG
feeding has no impact on survival but may improve quality of life for some individuals.
So there we have it, hope you have found this rapid review of Motor Neurone Disease useful,
if you have any further questions feel free to ask them in the comments section below.