motor neurone disease

Last reviewed 01/2018

Motor neurone disease most commonly presents with upper or lower motor neurone signs, or a mixture of the two. The disease affects limb muscles or those supplied by cranial nerves.

Motor neurone disease (MND) is a neurodegenerative condition that affects the brain and spinal cord. MND is characterised by the degeneration of primarily motor neurones, leading to muscle weakness.

• disease is of unknown aetiology and results in pathological changes in the anterior horn cells, the motor nuclei of the medulla, and the corticospinal tracts.

• presentation of the disease varies and can be as muscle weakness, wasting, cramps and stiffness of arms and/or legs; problems with speech and/or swallowing or, more rarely, with breathing problems
  • characteristics of lower motor neurone disease include: weakness and wasting, hypotonicity, decreased reflexes, fasciculation
  • characteristics of upper motor neurone disease include: weakness, spasticity, increased tendon reflexes with clonus, extensor plantar response
  • it is important to note that in this condition both upper and lower motor neurone signs can be found in the same limb.
  • as the disease progresses, the pattern of symptoms and signs becomes similar, with increasing muscle weakness in the person's arms and legs, problems swallowing and communicating and weakness of the muscles used for breathing, which ultimately leads to death.
• most people die within 2-3 years of developing symptoms, but 25% are alive at 5 years and 5-10% at 10 years
• most common type of MND is amyotrophic lateral sclerosis (ALS). There are rarer forms of MND such as progressive muscular atrophy or primary lateral sclerosis, which may have a slower rate of progression.

Every person with MND has an individual progression of the disease

• about 10-15% of people with MND will show signs of frontotemporal dementia, which causes cognitive dysfunction and issues in decision-making. A further 35% of people with MND show signs of mild cognitive change, which may affect their ability to make decisions and plan ahead

Poor prognostic factors (1) - when planning care take into account the following prognostic factors, which are associated with shorter survival if they are present at diagnosis:

• speech and swallowing problems (bulbar presentation)
• weight loss
• poor respiratory function
• older age
• lower amyotrophic lateral Sclerosis Functional Rating Scale (ALSFRS or ALSFRS-R) score
• shorter time from first developing symptoms to time of diagnosis

Reference:

• NICE (February 2016).Motor neurone disease