Progressive muscular atrophy
(PMA) is a rare subtype of Motor neurone disease
(MND) which affects only the lower motor neurones
. This is in contrast to the most common form of MND, amyotrophic lateral sclerosis
, which affects both the upper
motor neurones. Famous people to suffer from it include Mike Gregory
As a result of lower motor neurone degeneration, the symptoms of PMA include:
However, in contrast to amyotrophic lateral sclerosis
or primary lateral sclerosis
, PMA is distinguished by the absence of:
To be diagnosed with PMA one must have the lower motor neuron
symptoms described above in the absence of upper motor neuron symptoms for a given period of time. Some authors recommend 3 years, others 5 years or even up to 7 years. However it is worth bearing in mind that this illness can progress into typical ALS at any time, even as many as 26 years after the initial diagnosis.
The significance of diagnosing progressive muscular atrophy as opposed to ALS is twofold.
- 1) the prognosis is better. The typical prognosis for ALS is approximately 2-5 years after initial diagnosis. In PMA survival is in the order of 5-10 years.
- 2) Patients with PMA do not suffer from the cognitive change identified in at least a subgroup of patients with ALS.