Just browsing, noticed something that might need tidying up.
I see in the description it says that PMA is a genetic condition, this isn't strictly true. In fact there have been either zero or less than a handful of reported cases of genetically inherited PMA. There are a group of genetically inherited conditions, the spinal muscular atrophies, which are genetically inherited and affect only the lower motor neurones, but these are different to progressive muscular atrophy.
PMA affects only the lower motor neurones and so causes wasting/atrophy and fasciculations but in the absence of UMN signs such as spasticity, brisk reflexes, or the Babinski sign. Patients with PMA survive longer than patients with ALS and in some cases symptoms can be restricted to the arms or legs for a long time before spreading elsewhere in the body. There may be two subtypes, one with a patchy distribution and one with a leg distribution. In the latter case progression is unpredictable, whilst in the latter there is a prolonged latency period between the progression from legs to arms, and then again to the bulbar region. PMA is not rapidly progressive. If it is it's probably not PMA but ALS.
Also it's not true that PMA affects only the lower limbs. All muscles in the body, from head to neck to arms to trunk to legs to toes are ennervated by upper and lower motor neurones. So you can have LMN dysfunction which affects your tongue (atrophy) or UMN dysfunction which affects your ankles (brisk reflexes).
In contrast to patients with ALS, PMA patients are highly unlikely to have a bulbar onset of disease, do not manifest signs of emotional lability / pseudobulbar affect, and so far as I have been able to measure, show no signs of the cognitive abnormalities encounted in a proportion of patients with ALS.
Many PMA patients don't know they have it or don't know the difference from typical ALS. It's hard to diagnose and strictly speaking you need to have had LMN-only symptoms for 4 years or more to be certain, and even then about 50% of LMN-only syndromes progress to ALS (known as "PMA->ALS"), sometimes as much as 26 years later.
When I get the time I'm going to be writing an article on Wikipedia about PMA, please keep your eyes peeled for it soon!
Cheers
Paul Wicks
