Info re a “post-GBS syndrome” like “post-polio syndrome”

I’m looking for info re “post-GBS syndrome” — that is, a gradual (over months/years) weakening of muscles, particularly muscles used for walking/standing, that occurs many years after full/near-full recovery from GBS.

I’m 73. Had very severe GBS in 1999 (full paralysis, 4 months on vent), including axonal damage per EMG; recovered 95% (minor foot drop, minor balance issues); have done/still do daily aerobic exercise (elliptical, treadmill, walking). During the last three years, my walking speed very gradually slowed, my standing strength very gradually weakened, and my balance issues very gradually got worse. But, I can still do my daily aerobic exercise and all the “activities-of-daily-living”. During these same three years, I have experienced “stress symptoms” (skipped heart beats, cold hands, tremor) and mild depression. The docs (internist, cardiologist) have no explanation and stress/blood tests are normal.

I’m wondering if I’m experiencing a “post-GBS syndrome” — something like the well-recognized post-polio syndrome in which patients recovered from polio. but many years later developed muscle weakness/fatigue thought to be caused by motor neurons that were damaged by the polio virus, regenerated, and after many years began to wear out due to use/overuse of the regenerated neurons that were not as strong as the original neurons.

There were a few threads in this forum more than a decade ago re post-polio/post-GBS but the threads had no cites to medical literature re “post-GBS syndrome”. Googling “post-GBS” yields little/no useful info. And, in response to my recent inquiry, Foundation staff have no info re “post-GBS syndrome”.

If Forum members have any info re the existence — or, alternatively, the medically-proven non-existence — of “post-GBS syndrome”, I’d appreciate it if they could share it here.

Thanks.