My mother, then 83, had emergency surgery for a strangulated hernia when she was stage 4/5. For 11 horrifying days after, she had delirium, tearing at incision, jumping out of bed, calling me screaming that they were murdering her. This passed, but nearly had her turned away from her assisted living placement in the meantime. Delirium is rather common for the elderly, both with and without dementia, and can pass quickly or be permanent. I would be very against any operation in the future.