EMG tests in patients who do have PMA usually show denervation (neuron death) in most affected body parts, and in some unaffected parts too.It typically takes longer to be diagnosed with PMA than ALS, an average of 20 months for PMA vs 15 months in ALS. Differential diagnosis
In contrast to amyotrophic lateral sclerosis or primary lateral sclerosis, PMA is distinguished by the absence of:
brisk reflexes
spasticity
Babinskis sign
emotional labilityThe importance of correctly recognizing progressive muscular atrophy as opposed to ALS is important for several reasons. The prognosis is a little better. A recent study found the 5-year survival rate in PMA to be 33% (vs 20% in ALS) and the 10-year survival rate to be 12% (vs 6% in ALS). Patients with PMA do not have the cognitive change identified in certain groups of patients with MND. Because PMA patients do not have UMN signs, they usually do not meet the World Federation of Neurology El Escorial Research Criteria for "Definite" or "Probable" ALS and so are ineligible to participate in the majority of clinical trials conducted in ALS. Because of its rarity (even compared to ALS) and confusion about the condition, some insurance policies or local healthcare policies may not recognize PMA as being the life-changing illness that it is.
In the United States the most common terms are ALS (both specifically for ALS and as a blanket term) or Lou Gehrigs disease. Notable cases
Isaac W. Sprague - Entertainer and sideshow performer, billed as "the living human skeleton". Mike Gregory - Former Great Britain rugby league captain and head coach at Wigan RLFC
Rob Rensenbrink - Former Netherlands and Anderlecht football player

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