Monday, 13 September 2010

MRCP revision battle 10.2: Motor Neurone Disease

Most people associated motor neurone disease (MND) with Stephen Hawking, that incredible physicist who has lived with MND for over 40 years.  However, in the same way he is not a stereotype for normal intelligence he is also not a stereotype for MND - most people with it die within 5 years.  More stereotypical for the course of the disease was Lou Gehrig, an American baseball player in the 1920s/1930s who was diagnosed with the disease and died within 3 years.  I mention him not just for random interest but also because in America MND is sometimes known as Lou Gehrig disease.  But what is MND?

MND is a group of neurological disorders affecting neurones in motor cortex, CN nuclei and anterior horn cells.

MND affects UMN and LMN but there is no sensory involvement.

As a quick recap, UMN signs include:
  • weakness
  • spasticity
  • brisk reflexes
  • upgoing plantars

LMN signs include:
  • weakness
  • wasting
  • fasciculation
  • depressed reflexes

There are several patterns of MND, including:
  1. Amyotrophic lateral sclerosis
    • presents as UMN signs in legs and LMN signs in arms
    • may be familial - in which case often associated with Ch 21
    • accounts for 50% of cases of MND
    • has an 'intermediate' prognosis
  2. Bulbar palsy
    • accounts for around 25% of cases of MND
    • has the worst prognosis of the presentations
    • more details in the next battle
  3. Progressive muscular atrophy
    • only LMN affected
    • begins distally
    • has a (relatively) good prognosis
  4. Primary lateral sclerosis
    • affects UMN only
10-35% of patients with MND will have fronto-temporal dementia.

Diagnosis of MND is primarily clinical.
EMG will show preserved motor conduction velocities
CSF analysis may show raised protein.

Treatment is with riluzole, which prolongs life by around 3 months and requires monitoring of LFTs.  There is no cure.

As the first paragraph stated, the prognosis is very poor and most patients are dead within 5 years.

So on to battle 10.3, to learn more about bulbar palsy.