Getty, best known for playing Sophia on the 1980s and '90s TV series "The Golden Girls," was 84 when she died at her home in Los Angeles.
"She suffered primarily from dementia -- Lewy Body, which is a form of dementia. In fact, it's sort of a combination of Parkinson's and Alzheimer's. She also had osteoporosis," Gettleman told "Inside Edition." "She had a very strong will to live, and she was fighting until the end. She kept trying to keep (her) eyes open. … Every now and then she'd do a 'Sophia' thing and throw a punch or something."
Gettleman also revealed that his mother had needed 24-hour care.
"Mom had not been ambulatory for a long time. She was wheelchair-bound, she had to be fed and everything," he told the entertainment news program. "She hadn't been lucid for a very long time. … She spoke, but she mainly spoke gibberish."
Gettleman said a funeral was planned for Thursday.
"Mom always worried about this happening and now it's happening. For me it's extremely difficult," he said. "We had a very warm and loving relationship."