Motor neurone disease

Motor neurone disease (MND) is a progressive neurodegenerative disease. It tends to affect those in their 60s/70s

There are 3 subtypes of MND: 

1) Amyotrophic lateral sclerosis = Classic motor neurone disease 
  • upper and lower motor neurons affected 
  • commonest form patterns of onset are 
    • limb onset 
      • commonest
      • asymmetrical distal weakness – patients often have difficulty opening bottles/writing if hand is affected, or difficulty going upstairs if a foot is affected 
      • brisk reflexes 
      • muscle wasting 
    • bulbar onset 
      • around 20% of cases start like this 
      • slurring of speech 
      • wasting and fasciculation of tongue 
      • dysphagia 
      • often associated with emotional lability 
    • respiratory onset 
      • rarest form of onset 
      • dyspnoea 
      • orthopnoea 
2) Primary lateral sclerosis 
  • pure upper motor neurone disease 
  • 2% of cases of MND
  • look for upper motor neurone features such as 
    • spasticity 
    • hyperreflexia 
    • extensor plantar response 
3) Progressive muscular atrophy 
  • pure lower motor neurone disease 
  • 4% of cases of MND 
  • look for lower motor neurone features such as 
    • muscle wasting 
    • muscle weakness 
    • fasciculation 
    • absent reflexes 
  • slight male preponderance
  • earlier age of onset 
  • better prognosis than ALS 

Most cases are sporadic although around 5-10% of cases are familial; these tend to have a younger onset 

Diagnosis of MND is usually clinical with supporting electrophysiological evidence and tests to eliminate other possible diagnoses. Investigations may include:
  • Nerve conduction tests 
  • Electromyography 
  • Tests to eliminate other conditions which can present similarly, such as: 
    • Thyroid tests - ? hyperthyroidism 
    • Calcium - ? hyperparathyroidism 
    • B12 
    • Copper 
    • Lyme serology 
    • MRI - ? MS 

Management can include 
  • Riluzole (an inhibitor of glutamate release) - recommended by NICE - prolongs life by around 2 months 
  • NIV if required 
  • NG feeding if required 
  • Symptomatic management 
    • Drooling: Transdermal or sublingual hyoscine, oral atropine, TCA, beta blockers, injection of botulinum toxin to salivary glands, irradiation of parotid gland 
    • Muscle cramps: quinine, diazepam, phenytoin 
    • Spasticity: baclofen, dantrolene, tizanidine 
    • Pain: medications as per pain ladder 
    • Multidisciplinary team approach 

  • most patients die 2 to 3 years after diagnosis 
  • poorer prognosis if 
    • onset with bulbar form of MND 
    • older age at onset 
    • lower than predicted FVC 
    • low BMI <18.5 

Possible differentials include:


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