Sue thought she had a pinched nerve in her back. The reality was far worse.

Sue loves to run. In fact, it's exactly what she was doing when she realised something was wrong.

"I started to get really sore legs," she told Mamamia.

It got so bad, Sue struggled to get to sleep.

"I would be awake until around two o'clock in the morning with really bad pain. I'd take Panadol, nothing would work, and I would just be sort of pacing the house."

Watch: Celine Dion reveals she has Stiff Person Syndrome. Post continues after video.

Thinking it was a temporary discomfort, Sue travelled overseas with her husband. But things only got worse.

"When I was waking up, my arms and my hands had pins and needles. I just thought I might have had a pinched nerve in my back."

With a six-week trip ahead of them, Sue didn't want to burden her husband, or have them cut the trip short out of concern. So she kept the pain to herself until they returned home, where she visited a doctor.

"I was forgetting a lot of stuff as well, and I was a bit worried about that," Sue said. "So when I saw her, we had an MRI done on my brain, and it showed some lesions."

Immediately, Sue followed up with a neurologist. Her bloods were taken and shipped to the UK, with the test the doctor wanted being unavailable in Australia at the time.

But before an official diagnosis came back, the neurologist predicted the results would show that Sue had Stiff Person Syndrome — a rare neurological disorder, of unclear cause, characterised by progressive muscular rigidity, stiffness, and spasms. 

Six weeks later, the results came back. Sue had tested positive for the GAD65 antibody — a biomarker of autoimmune central nervous system (CNS) disorders and non-neurological autoimmune diseases.

"I was put on some medication to help with nerve pain and Valium to sleep," she told Mamamia. But it wasn't enough. And by 2016, things had progressed.

"I was not getting any better; I was getting a little bit worse," Sue said. "Then I was diagnosed with SPS — PERM."

That is, Stiff Person Syndrome — Progressive Encephalomyelitis with Rigidity and Myoclonus. This is a more severe variant of Stiff Person Syndrome that causes decreased consciousness, ataxia, eye movement issues, and autonomic dysfunction.

"So, I started getting fortnightly infusions in hospital," shared Sue, who added that she will need the treatment for the rest of her life.

Because of SPS-PERM, Sue has experienced severe spasms in her legs, arms, and truncal area, as well as migraine headaches every day.

"If I was to stretch while I was waking up, I would instantaneously get spasms in my feet and my ankle. But it's not just one muscle group. It's all the muscles, it's all contorting, so my toes are going one way, my ankles going another way, and my calf would be doing something by itself."

If Stiff Person Syndrome sounds familiar, it may be because it's the same diagnosis singer Céline Dion has. Her SPS diagnosis brought attention to the rare disease in December 2022, has she shared similar symptoms to Sue, revealing her fingers and hands will get into a position where she cannot unlock them.

Regularly, Dion deals with muscle spasms in her throat and abdominal area. One incident was so strong that the singer broke one of her ribs.

"Unfortunately, these spasms affect every aspect of my daily life… sometimes causing difficulties when I walk and not allowing me to use my vocal cords to sing the way I'm used to," Dion told NBC.

Sue can relate to Dion's walking struggles. When these spasms occur, the mother-of-two will step out of bed as delicately as possible, trying to get her feet to function normally.

The 55-year-old, who is still a shift worker, has also grappled with fatigue.

"If I go to the markets, there's so much stimulation that by the time I'm finished, I start to get a little bit stumbly. We call it my 'drunk walk'. I get a little bit unstable.

"But when I go for a walk for exercise, I don't tend to experience that. What happens is that the brain gets so fatigued that it's not sending the right messages to my legs."

These days, Sue has got her market visits down to a fine art. Just half an hour at the markets, go home for a rest, and then she is alright again.

It does, however, mean that the mother-of-two often has to plan her days down to the minute, and that she sometimes misses out on making memories with loved ones.

"If I've got plans with friends — if I'm at work, for example, and then I've got plans to go for dinner, and then I'm back at work the next morning — sometimes it's too much," she told Mamamia.

"I want to go, but then I get to that point right before I'm going that, realistically, I know that I'm just going to be too tired the next day, and I won't be able to manage."

Along with the physical symptoms, SPS-PERM has taken an emotional toll on Sue, who speaks to a psychologist on occasion.

"I'm about to turn 56, and sometimes you wonder: is this because of my age? Is this a normal thing? Or is this something to do with SPS? I probably over-analyse things because of that reason. So then I find it difficult to get to sleep and stuff like that."

And maintaining a healthy sleep schedule is vital for the shift worker.

"If I get short sleeps, then the next couple of days, I might sleep for 11 or 12 hours, or sometimes more."

Sue's specialist, one who surprisingly had another five patients with the rare condition, often asks the 55-year-old when she is going to slow down.

"I'm the only one of his patients with SPS-PERM that is still working," she said. "He always asks me, 'When are you cutting back hours?' When I'm 60, I'm going to retire."

While she navigates life with the disease, Sue has an invaluable support system in her husband, sister-in-law and daughters.

"My husband and I manage it really well. I couldn't get through each day without him helping, because he manages a lot of stuff at home without me having to do stuff," Sue said.

"I have a sister-in-law who lives not far from me, who's always been very, very supportive. And I have two children, adult children, who assist all the time.

"My daughter's a very good sounding board, because I don't want to load up my husband with everything all the time. And sometimes it's good to get a female's perspective on things. She's been able to sort of say, you're doing a really good job, but why don't you try this instead of this? And she's given me ways to think outside the square on how things could be better."

A few months ago, Sue was put on a new drug — an immunosuppressant called Rituximab — which works by slowing down the process of PERM. It's been a game changer.

"The spasms have decreased, the pain has decreased — but I still have a lot of severe fatigue," Sue said.

Still, she is hopeful the medication will slow progression to the point where she can enjoy her retirement. Already, she can walk more than she has in a decade — an activity which is encouraged for those with SPS.

"They want you to be able to keep moving. If you just sit down and do nothing, it makes things worse. It will just stiff them up even more."

With her body finally responding well to treatment 10 years after her diagnosis, Sue figured there's no better time to walk as much as she can, and make a difference while doing so.

"This is a really good time to actually do something to raise more awareness about SPS. Obviously not celebrating that it's 10 years, but it's a 10-year milestone that I've got through," she said.

With her family, Sue has organised a GoFundMe fundraiser to benefit the Immune Deficiencies Foundation of Australia for Rare Disease Day. The goal is to walk as many steps as possible by February 28.

"Me, my husband, my sister-in-law, and my two children, we were planning to walk 300,000 steps. But we have already done about 157,000, so we've decided that we're just going to try and walk as many steps as we possibly can. Maybe even try and reach one million. Because they call it a one in a million condition, which I don't think is actually really that true anymore. I think there's more people diagnosed with it.

"There are so many people who have rare diseases, and there's not a lot of money that gets put towards them. So we're just trying to do our bit."

You can donate to Sue's fundraiser here.

Feature Image: Supplied.