Much later, in his fifties, he developed post-polio syndrome, characterized by pain and muscle weakness caused by the chronic over-use of partially paralyzed muscles.
Mult mai târziu, la 50 de ani, el s-a îmbolnavit de sindrom post poliomielitic, caracterizat prin dureri, și slăbiciuni musculare cauzate de suprasolicitarea musculaturii parțial paralizate.