Actress Selma Blair, who has been vocal about her struggle with MS, was confused for years by the symptoms she was experiencing. She realized something was seriously wrong when, as she walked the runway during a fashion show, her leg gave out. Blair recalled a similar experience on Instagram: “I have had symptoms for years but was never taken seriously until I fell down in front of [the neurologist] trying to sort out what I thought was a pinched nerve,” she wrote. “Everyone’s experience with MS is different, and these losses may be temporary or long lasting,” says the NMSS, which describes varying symptoms like “numbness, tingling, mood changes, memory problems, pain, fatigue, blindness and/or paralysis.” Some lesser known signs of MS might surprise you, however. Read on to find out about one unexpected red flag to watch for. READ THIS NEXT: You’re 32 Times More Likely to Develop MS If You’ve Had This, Study Says. A chronic disorder, MS occurs when “the immune system attacks the protective sheath (myelin) that covers nerve fibers and causes communication problems between your brain and the rest of your body,” neurologist W. Oliver Tobin wrote in an article for the Mayo Clinic. “Eventually, the disease can cause permanent damage or deterioration of the nerves.” Almost one million people in the United States have the chronic disorder MS. “In general, MS becomes more severe over time [but] there’s no specific timeline that the condition follows,” explains Healthline. “Everyone with MS tends to follow their own timeline.” Healthline notes that there may not be a progression of symptoms in some patients, while others experience increasingly severe symptoms. MS has four stages, defined by the NMSS as clinically isolated syndrome (CIS), relapsing remitting (RRMS), secondary progressive (SPMS), and primary progressive (PPMS). Early symptoms of the disease may include “extreme fatigue, clumsiness, weird prickly sensations, sluggish thinking, [and] wonky vision,” according to WebMD. The NMSS reports that fatigue is “one of the most common symptoms of MS, occurring in about 80 percent of people” and is the leading reason for MS patients to leave the workforce. In some cases, fatigue occurs when other symptoms of MS—such as muscle spasms during the night—cause sleep disruption. The NMSS also notes that “there is another kind of fatigue—referred to as lassitude—that is unique to people with MS” and describes it as a daily fatigue that intensifies throughout the day and is worsened by heat and humidity, among other characteristics.ae0fcc31ae342fd3a1346ebb1f342fcb For more health news sent directly to your inbox, sign up for our daily newsletter. Because the symptoms of MS can vary greatly, with many different signs that can seem like other conditions, there is frequently a delay in diagnosing the disease. “Researchers found that patients with MS had a higher-than-average number of medical appointments, with doctors of various specialties, for up to five years before their diagnosis,” reports WebMD. “MS can look like other things, and other things can look like MS,” neurologist Andrew Solomon told the site. “There’s no question that diagnostic delay is a problem.” One symptom of MS that can be difficult to diagnose, because there are so many other potential causes for it, is an intense feeling of itching. Described by WebMD as a “sudden, intense tingle [that] crops up out of the blue, anywhere on your body,” itching caused by MS is known as dysesthetic itching. Dysesthetic itching isn’t caused by an allergy or irritation of the skin. It is a neurological response, explains Medical News Today: “In MS, the immune system attacks the nerve tissues in the brain and spinal cord,” the site explains. “This can cause changes in the nerves elsewhere in the body.” WebMD advises that other unusual MS symptoms to look out for include PBA (pseudobulbar affect, which presents with laughing or crying uncontrollably) and “banding,” which occurs when muscle spasms happening between the ribs create a tight feeling (“like something’s squeezing you firmly about the chest and won’t let go”). If you think you may have symptoms that indicate MS, see your doctor—and be persistent until you get answers.