Just noodling here, looking up some famous Senators who died in office.
Hubert Humphrey revealed his cancer in August 1977..He went back to Minnesota for treatment, returned to the Senate in October (Jimmy Carter famously sent Air Force One to bring him back to Washington), made a farewell speech in November and died in January 1978, still in office.
Ted Kennedy suffered a seizure in May 2007. He underwent brain surgery and chemotherapy in June and did not appear in publiic for five weeks. He returned to the Senate, but suffered another seizure in September. In January 2009 he suffered a seizure at Barack Obama’s inauguration luncheon.
The Dope was alive and thriving in those days, and here’s a thread about that event.
Sen. Ted Kennedy and Sen. Byrd collapse at inaugural luncheon
He appeared in the Senate less frequently, at one point going three months without casting a single vote. He was awarded the Presidential Medal of Freedom but could not attend the ceremony and died in August.