What in tarnation is a thenar? The fact you know the answer to that, assuming you're not an MD, tells me you're obsessing and probably googling.I have had tingling and numbness all over my hands. EMG showed the cause was ulnar nerve conduction problem consistent with leaning on my elbows. Explicitly no evidence of neuron damage consistent with ALS. I took it easy on my elbows for 2 months and it got about 95% better.Anyway, also keep in mind that ALS is a disease of weakness, not sensation such as tingling.Best of luck to you!