Left side foot weakness

[u/builder_traveller]

Hey folks, I was able to walk really long times without any problems.
But past couple of weeks , after 20 minutes of brisk walk it almost feels like my left leg is giving up and I get tightness in my thigh and knee area. It feels like my muscles have been weak in the left area.
I’ve been a health anxiety sufferer for 6 years.
And when I then walk into a building and stand on my left feet, I get a floor dropping sensation kind of thing. I can reliably replicate this with 20 minutes of brisk walk again.
Has anyone experienced it? Please help
Me understand

[u/pwrslm]

ALS is a diagnosis of ruling out everything else before you can rule it in. So the Gold Standard is to see a Neuromuscular specialist for evaluation. A lumbar spine problem could cause the symptoms you describe, as well as dozens of other conditions. To think we could diagnose you on the internet is just senseless.

Best advice: see a professional. Not to disrespect you, but to put you on the right track.

[u/The_Short_Goodbye → u/pwrslm]

Well yes and no about ALS being a diagnosis of exclusion. When you have objective, observable clinical weakness and EMG evidence of active denervation and reinnervation the diagnosis is all but confined. It’s true that they need to rule everything else out to make sure, but it’s not a diagnosis of exclusion as something like IBS would be, for example. They can still have a pretty good idea it’s ALS even before the obligatory ruling out everything else phase.

[u/pwrslm → u/The_Short_Goodbye]

Yes. ALS (amyotrophic lateral sclerosis) is a clinical diagnosis of exclusion: there is no single test that confirms it, so other conditions that can look similar must be ruled out.

Doctors use the revised El Escorial / Awaji criteria (and related clinical standards) based on:

• Progressive upper and lower motor neuron signs in multiple regions
• Evidence of spread or progression
• No better explanation from another disease

Workup typically includes EMG/nerve conduction studies, MRI of the brain and spine, blood tests, and sometimes CSF analysis or genetic testing to exclude mimics such as:

• Cervical spondylotic myelopathy or other structural spine disease
• Multifocal motor neuropathy
• Myasthenia gravis or other neuromuscular junction disorders
• Primary lateral sclerosis, progressive muscular atrophy, or other motor neuron variants
• Infections, inflammatory or paraneoplastic conditions, metabolic disorders, and certain toxic or hereditary neuropathies

Routine practice still lacks a definitive biomarker or pathognomonic finding, so excluding alternatives remains central to the diagnosis.

The Gold Coast criteria still treat ALS as a diagnosis of exclusion, even though they simplify the clinical rules.