"Like two years ago, I had this weird, super rare form of vasculitis, that like knocked out my vision, it knocked out my hearing, it knocked out like all my equilibrium," the That '70s Show alum shared in a preview of his appearance on an upcoming episode of "Running Wild with Bear Grylls." "It took me like a year to build it all back up."
According to the 44-year-old, he's "lucky to be alive" after battling the rare medical condition. "The minute you start seeing your obstacles as things that are made for you, to give you what you need, then life starts to get fun, right?" he told host Bear Grylls. "You start surfing on top of your problems instead of living underneath them."
And while Kutcher shared on Aug. 8 that he's "fully recovered" from his health struggles, his harrowing story shows some of the adverse effects of vasculitis.
Read on for more details about the condition.
Speaking with E! News, Dr. Nazanin Firooz -- a California-based rheumatologist, who has not treated Kutcher -- described vasculitis as "inflammation of the blood vessels" in its lining or walls. "As a result of this inflammation, that blood vessel can become thickened, weakened or narrowed," she explained. "When this happens, it can affect the blood flow to the organ that the blood vessel is supplying."
Though Kutcher did not specify which kind of vasculitis he suffered from, Firooz said there are "many different types" of the condition and each can have varying symptoms--from mild ones such as a skin rashes and muscle pain to major problems with the kidneys and lungs.
"Vasculitis, in general, is not common and there are some vasculitis that are even less common," she said, though noting that the disorder does not discriminately in age and can affect anyone. "Any type of vasculitis can potentially cause systemic problems."
"Yes, people can die from it," Firooz said. "It really depends on which type and how severe that case of vasculitis is." The doctor noted that survival rate also "depends on how quickly appropriate treatment is implemented" and if the condition is affecting major organs, such as the heart, brain or lungs.
Depending on the severity of vasculitis, treatment can range from anti-inflammatory medications for mild cases to stronger immune suppressants for serious ones, according to Firooz. In the case of a severe condition, the doctor said the treatment process can last from months to over a year, as time is required to slowly "wean" the patient off immune suppressants without addition flare-ups and relapses in their recovery.
"If they have relapses, it can take longer," she said. "Some people recover completely, some people have relapses, and some people never complete results."
Long-term damage to the body as a result of vasculitis all depends on if the inflammation was reversed and controlled quickly, Firooz said. If that was the case, "chances are that the blood vessels are OK" and there's minimal to zero impact in the long run. However, she noted, there are some cases where vasculitis "just stays long term" and never resolves itself.
Since symptoms vary widely between each patient and the kind of vasculitis they have, Firooz said it can be difficult to know. Instead, she recommends keeping an eye out for "out of the ordinary" symptoms that are "worsening over time instead of getting better" as an indication to seek medical attention.
"That's always a clue that this needs to be checked out," she said. "For example, let's say you get a rash. You expect something like an allergic reaction or a mosquito bite to get resolved after a few days. But if a rash is not getting better, but it's getting worse and spreading, then it's time to get it checked out. And that's a very simple vasculitis."
For more severe cases like hearing or vision loss, Firooz said it "could be a variety of different things, including vasculitis" and must be taken seriously. "Anything that shouldn't be there should be checked out," she added. "It's not necessarily a symptom of vasculitis, but I think it's symptom of something that needs to be needs to be evaluated."
Unfortunately, there is probably nothing you can do to prevent getting vasculitis, according to Firooz. After all, she explained, there are many causes of vasculitis--including a preexisting condition such as lupus or rheumatoid arthritis, a reaction to a certain drug or the result of a viral or bacterial infection.
"And then a lot of times it's none of the above: We can't find any of these things and it just will be called idiopathic, which means that the causes are unknown," she said. "Maybe you have you have a genetic predisposition plus an environmental factor, which is [how] most autoimmune diseases happen this way."
Still, she emphasized, seeking treatment early improves the chance of recovery without further damage to the body. "We know how to treat these things, so we have usually good outcomes," the rheumatologist noted. "The goal is to prevent damage."