You certainly can try but let me share an example of one of my good tennis friends.
He has been a middle level 4.5 for about 20 years. He has played at sectionals a bunch during that time so his 4.5 rating was secure.
However, over a span of 3 years he had the following medical issues: Heart attack, 1 hip replacement and 3 vertebra fused. He did not play for almost 3 years. When he asked for a medical appeal to 4.0 he was told that these ailments could all be recovered from and his appeal was denied. He was told that if he had waited another 6 months he would have needed to self rate and then appeal his self rating. An appeal of his self rating would likely have been approved.
Getting a medical appeal granted requires very special circumstances indeed.
"You should be playing linebacker, not singles."