- Jul 2, 2008
- Learn about ALS
If you have only lower motor neuron involvement, then you have Spinal Muscular Atrophy, a pure motor neuropathy or some sort of other lmn disease. From what I have been reading these are disabling but not fatal. If you have pure upper motor neuron involvement then you have HSP or PLS and both of these are disabling but not fatal. Now if you have both then it is ALS and it is fatal. My question is why? Why is the sum of two non-fatal diseases fatal? I understand that the decline of respitatory function is what makes ALS fatal, but why wouldn't you have the same result with a pure lmn?