What We Know About Ashton Kutcher's Rare Autoimmune Disorder Diagnosis

In a sneak peek of Ashton Kutcher's appearance on "Running Wild with Bear Grylls: The Challenge," the 44-year-old actor opened up about a recent health scare (via US Weekly). Kutcher revealed that two years ago, he was diagnosed with a very rare kind of vasculitis, an autoimmune condition that left him unable to see, hear, or even stand up.

Vasculitis is inflammation of the blood vessels, from the tiny capillaries to the aorta (via Cleveland Clinic). This inflammation can cause the vessels to weaken and stretch, which can lead to internal bleeding, aneurysms, and a reduction in blood flow. Symptoms can include skin rashes, fatigue, fever, joint pain, abdominal pain, kidney and nerve problems, and shortness of breath.

There are different types of vasculitis depending on which blood vessels are affected, but it's a systemic illness, meaning it can affect multiple organ systems (via Johns Hopkins Vasculitis Center). In fact, it's even referred to as a "hurting disease," since patients can feel sick and in pain when experiencing vasculitis. Depending on the type, vasculitis can affect the skin, joints, lungs, kidneys, eyes, brain, and nerves.

In Kutcher's case, vasculitis affected his ears, eyes, and equilibrium, leaving him bedridden (via US Weekly). He wondered if he would be able to see or hear again, and didn't even know if he'd be able to walk again. He shared that losing these senses and abilities gave him a new appreciation for them. He expressed an optimistic perspective on life, telling Grylls that he began seeing his obstacles as things that were made for him and could give him what he needed. He likened this approach to surfing on top of the problems rather than living underneath them and said this was how life becomes fun.

The cause of vasculitis is often unknown, but is commonly due to a reaction from the immune system, according to the Johns Hopkins Vasculitis Center. In vasculitis, the immune system goes into hyperdrive and attacks the blood cells, causing inflammation. This leads to tissue damage, and it's not clear why this condition develops.

Kutcher said that his severe experience with such a rare form of vasculitis left him feeling happy to be alive (via US Weekly).