Rare 'stiff person syndrome' treated with reconfigured cancer therapy

Stiff person syndrome — a rare, progressive disorder that causes painful muscle spasms — can be treated with a therapy typically used for cancer, a new case report suggests.

In stiff person syndrome (SPS), the immune system attacks a key protein in the nervous system. The condition is rare, affecting fewer than 5,000 people in the U.S., but it recently gained attention when Canadian singer Céline Dion announced she had SPS. 

Those most severely affected by SPS develop progressively worse muscle stiffness, eventually leaving them bedbound, while chest spasms can sometimes hinder their breathing. There is currently no cure for SPS, only treatments to subdue the symptoms — but these don't always help.

Now, a case study published in June in the journal PNAS highlights a potential new treatment for people with SPS. 

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One of the greatest challenges people with SPS deal with is getting a diagnosis, because the disease is rare and its symptoms resemble those of other disorders. In 2014, Dr. Simon Faissner, a neurologist in the St. Josef Hospital at the Ruhr University of Bochum, met the patient featured in the case report. She reported stiffness and pain when moving, but her case notes said that previous physicians thought her symptoms were psychosomatic — brought on by a psychological condition. 

Faissner performed a lumbar puncture test, revealing that the patient's cerebrospinal fluid, which circulates through the spinal cord and the brain, was packed with antibodies against a protein called glutamic acid decarboxylase (GAD). GAD is needed to make GABA, a chemical messenger that helps tamp down neuron activity. Without it, the brain fires off signals at an excessive rate, leading to the muscle cramps and stiffness seen in SPS.