In an interview with Cosmopolitan, Walsh opened up about how her symptoms progressed, her reaction to the diagnosis, having the benign meningioma removed and her recovery.
"I had been working insane hours, maybe 80 hours a week, and also working out really hard, so I wasn't surprised. I figured okay, I'll change up my workout routine, I'll go back to mellow stuff like hiking. My pilates instructor said 'hey, your right side is dipping', and it didn't feel like I was off, but I looked down and could see it.
In June, the 49-year-old actor went to get a MRI, where she received the diagnosis.
"The words 'brain tumour' were never in my zeitgeist. I went in for the MRI, and you know it's serious when they don't even wait, they're like 'hey, the radiologist wants to see you.' And she starts to say 'well, it looks like you have a very sizable brain tumour', and I just left my body. My assistant had driven me there, and I had to go get her so that she could take notes, because I was gone. It was never anything I would have imagined."
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"I took about nine months off, and when I came back, I hit it hard. I shot a film called "Self", I shot "Girls Trip", I shot "13 Reasons Why", I did a play in New York last year, so it was great, once I was back I was really back.
"Those cliche, existential things do happen when you have a brain tumour, like 'how do I really want to spend my time?' I want to be with my friends and family and work on projects that are hugely important to be, and fun, and that make a cultural contribution. But my health comes first, and I've had to change my lifestyle... I know I absolutely need seven or eight hours of sleep. As basic as that sounds, it was a huge part of my recovery," she said.