Rare medical condition tears mum's muscles and sets them solid in response to triggers like noise and distress.
It's the one in a million condition that strikes in minutes - and can prove fatal.
And sufferer Helen Stephens knows all too well how an agonising seizure will leave her body frozen and swollen if she is not treated in time.
For the 50-year-old, of Wednesbury, West Midlands, was diagnosed with the incredibly rare Stiff-Person Syndrome.
Her symptoms first began with spasms and walking problems after a car accident 14 years ago.
Doctors were mystified and she was even branded a hypochondriac as she searched for the answer to her ailments.
The syndrome was finally diagnosed in 2004 by the neurology team at Birmingham's City Hospital. She was put on diazepam to control the stiffness, pain and swelling.
But then came the hammer blow - it was terminal.
More than a decade on, the condition - which tears her muscles and sets them solid in response to triggers like noise and distress - has taken a terrible toll on Helen's body.
When grandmother Helen suffered a major attack earlier this month, her weight shot up by five stone and her neck swelled by four inches.
She compared the attack on her body to the comic book creation, the muscle-bound Incredible Hulk.
"When I have a bad attack I swell up like the Hulk," she told the Mail.
"I look enormous and I even call myself the Hulk, Arnie (Arnold Schwarzenegger) or Rambo. I'm like a bodybuilder.
"My muscles tear at the same time and they increase in mass meaning my weight balloons. If I don't get an injection of diazepam quickly enough my whole body stiffens, leaving me unable to have any treatment because a needle will just snap.
"The symptoms in each person suffering from the condition can differ."
Stiff-Person Syndrome afflicts twice as many women as men and is often misdiagnosed as a range of conditions, including Parkinson's disease and multiple sclerosis.
Recalling her battle for a diagnosis, Helen, a former social worker, said: "I had never heard of this thing.
"But at last I had an answer about what I was suffering from. They believed I had something wrong with me.
"They told me it came in three stages and I was currently in the initial one. But it was terminal. It was devastating."
Over the years, Helen found herself becoming reliant on a wheelchair and the spasms and stiffness began to worsen.
"I had always been a size eight but this has left me at a size 16," she said.
"I can't eat properly and am on soft foods. It's completely ruined my life.
"My body is covered in scar tissues from where the muscles have been torn. I am in constant pain and I have to rely on carers and family to help me.
"I want people out there to know this condition exists because I am constantly met with problems when I am admitted to hospital suffering from an attack.
"Medical staff don't know what to do because it's so rare."
Helen experienced her worst attack yet, on November 6, at City Hospital, in Winson Green, increasing her weight by five stone.
She carries around a letter listing her allergies and explaining what medics should do if she has an attack but she claimed this was ignored.
"I gave the letter to staff but I was left on a bed for two hours without any treatment," she said. "I could have died.
"My condition means I can die if I don't have medication injected into me within minutes.
"My throat shuts down and my rib cage contracts, along with my heart, making it difficult to breathe and for blood to be pumped around my body.
"I explained this numerous times but I was left on a bed screaming in agony as everything in my body was ripping apart.
"They needed to get a canula into me so medication could be given on a regular basis to calm my symptoms.
"This had to be done before my muscles hardened and they only had a matter of minutes to do this.
"But it wasn't until a complaint was made that something was done."
Helen said two carers complained to the patient liaison service, which contacted her former neurologist.
"He called the A&E department and told them exactly what should be done," she said. "But I was as stiff as a rock by the time they put a line inside me.
"I was in unbearable pain and it was by far the worst seizure I have had. I've decided to speak out because I have had enough of medical staff not knowing about my condition," she said.
"I cannot complain about the neurology team that has treated me over the years.
"They have been nothing short of brilliant. I was diagnosed by the City Hospital team and the doctors have saved my life on more than one occasion. But I cannot understand why the staff in the emergency department do not take notice of what I am saying. I want to raise awareness of this condition so people know about it."
A Sandwell and West Birmingham NHS Hospital Trust spokeswoman said: "The Trust is grateful to Ms Stephens for alerting us to her concerns about her care in the Accident and Emergency Unit.
"We are sorry she is not happy with the care she received.
"We understand she will be providing us with details as part of a formal complaint and, until we have completed the subsequent investigation, we are unable to comment further."