Prognosis varies depending on the type of MND and factors such as the age of onset
- PLS progress slowly
- ALS and some forms of spinal muscular atrophy (SMA) are fatal
- ALS is a fatal disease
- median survival is 3 years from clinical onset of weakness (1)
- note though that about 15% of patients with ALS live 5 years after diagnosis, and about 5% survive for more than 10 years
- longer survival is associated with:
- a younger age at onset
- male sex
- limb (rather than bulbar) symptom onset
- slower progession occurs in regionally limited forms of motor neuron disease (ie, brachial biplegia, lumbosacral biplegia, and progressive bulbar palsy [PBP])
- progressive muscular atrophy (PMA), distinct from classic ALS because of lack of upper motor neuron (UMN) findings, progresses at the same rate as classic ALS
- a slower rate of progression is seen in upper motor neuron -predominant ALS
- primary lateral sclerosis (PLS) - survival rate is much longer than ALS (measured in decades)
From the differential prognoses seen in motor neurone disease it seems that the loss of LMNs is a significant prognostic determinant.
Reference:
- Kiernan MC. Motor neurone disease: a Pandora's box. m ed J Aust 2003;178:311-2
- Armon C. Amyotrophic Lateral Sclerosis (ALS), Medscape, May 2014.