What is Stiff Person Syndrome (SPS)?

Stiff Person Syndrome is a progressive, rare neurological autoimmune disorder affecting 1-2 persons per million.

Updated:   Published

What is Stiff Person Syndrome (SPS)?

In 1956, Mayo Clinic physicians Frederick Moersch and Henry Woltman observed 14 patients with varying levels of muscular rigidity in their torsos, abdomens, and thighs. It must have been a baffling presentation.

Dr. Moersch and Dr. Woltman were first credited with recognizing this condition as a discrete neurologic entity and descriptively coining the term Stiff Man Syndrome. It was later changed to Stiff Person Syndrome (SPS) to include females.

In addition to being a neurologic disorder, SPS also has autoimmune features. Autoimmune disorders occur when the immune system, designed to attack bacteria and viruses, mistakenly also attacks healthy cells, such as insulin-producing cells (Type 1 diabetes), or joints (rheumatoid arthritis), or even pigment-making cells (vitiligo). In SPS, certain central nervous system cells (neurons) that control muscle movement are attacked.

Prevalence

SPS is rare, affecting only one to two individuals per million. By contrast, multiple sclerosis (MS), also a neurological autoimmune disorder, affects about 359 individuals per million. SPS is more common in women than men and affects people in the 20-60 year age range.

Symptoms

When reading about SPS symptoms, the words "spasm,” "pain,” and "stiffness" are repeated over and over in the literature.

Patients literally become stiff and may develop lordosis. Some adopt a hunched-over posture. Mobility and gait are affected, resulting in falls. Some level of disability is usually present.

Muscle spasms are episodic and can range from mild to severe and violent. Muscle spasms can be brief, lasting a few minutes, but according to the SPS Research Foundation, they can last for hours and even days.

There's often an increased sensitivity to noise and light. Sometimes sudden loud noises, such as unexpected loud traffic sounds, can trigger debilitating spasms. Patients may be fearful of crossing a street on a green light or develop other task-specific phobias.

Patients may also experience an increased sensitivity to touch and to stress. Emotional distress can also trigger painful spasms. Not surprisingly, anxiety and depression often accompany SPS. 

Diagnosis

SPS is both underdiagnosed and misdiagnosed. Because it's so rare and has an insidious onset, an accurate diagnosis can take 5 to 7 years. It has been misdiagnosed as fibromyalgia, Parkinson's disease, and multiple sclerosis, as well as anxiety and psychosomatic illness.

There's no one specific test for SPS. Typically a clinical diagnosis is suspected based on the patient's reports and symptoms. Then a definitive diagnosis is arrived at by examining spinal fluid and testing for antibodies.

Blood tests may be ordered to detect antibodies, specifically glutamic acid decarboxylase (GAD) antibodies. It's estimated that 80% of those with SPS have elevated GAD antibodies. These are the antibodies that attack the neurons in the brain. Neurons that control axial and limb muscles.

The provider may also order an electromyography (EMG) to measure abnormal electrical activity characteristic of SPS.

Treatment

There is currently no cure, but there are treatments aimed at symptom management.

They include physical therapy, medications and intravenous immunoglobulin (IVIg). Physical therapy may include aqua therapy and occupational therapy.

Medications  include high-dose diazepam, anti-convulsants (gabapentin), and muscle relaxants (baclofen).

Immunoglobulins are immune-system-produced natural antibodies obtained from healthy donors. IVIg has been shown to be effective at:

  • Reducing noise, stress, and touch and sensitivity
  • Improving balance 
  • Improving gait

Research and clinical trials continue, providing hope for the future. If there's any good to come out of the recent public spotlight on SPS, it's that patients who have suffered without a diagnosis will now get the help they need .

References/Resources

Stiff-person Syndrome and GAD Antibody-spectrum Disorders: GABAergic Neuronal Excitability, Immunopathogenesis and Update on Antibody Therapies  

Stiff Person Syndrome

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Nurse Beth

About Nurse Beth, MSN

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Hi! Nice to meet you! I love helping new nurses in all my various roles. I work in a hospital in Staff Development, and am a blogger and author.

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Specializes in Former NP now Internal medicine PGY-3.

Only saw it once, probably won't again. In a neuro clinic back in medical school. There was an article about it in the news a while back also, I believe it was about it not being diagnosed for years since it is isn't very common, at all, or just under diagnosed…

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Specializes in Tele, ICU, Staff Development.
3 hours ago, Tegridy said:

Only saw it once, probably won't again. In a neuro clinic back in medical school. There was an article about it in the news a while back also, I believe it was about it not being diagnosed for years since it is isn't very common, at all, or just under diagnosed…

It's so tragic for Celine Dion, but maybe the increased attention will help to find a cure.

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Specializes in Former NP now Internal medicine PGY-3.
17 hours ago, Nurse Beth said:

It's so tragic for Celine Dion, but maybe the increased attention will help to find a cure.

It may help, but I surmise it will more likely lead to a lot of people requesting testing for the disease when they almost certainly do not have it. Seems to be the trend when something hits the MSM. 

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Specializes in Tele, ICU, Staff Development.
On 12/24/2022 at 1:15 PM, Tegridy said:

It may help, but I surmise it will more likely lead to a lot of people requesting testing for the disease when they almost certainly do not have it. Seems to be the trend when something hits the MSM. 

Hopefully providers who have never seen it will consider it in a differential diagnosis

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Specializes in Former NP now Internal medicine PGY-3.
22 hours ago, Nurse Beth said:

Hopefully providers who have never seen it will consider it in a differential diagnosis

I agree with this statement. It is very rare and reasonable to consider in the ddx. I couldn’t not imagine behind told that I have severe ancient and fibro then later found to have a rather treatable dx. Though it is difficult to diagnosis rare conditions as false positives are comment when we work up patients for uncommon syndromes. 

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Specializes in Tele, ICU, Staff Development.
5 minutes ago, Tegridy said:

I agree with this statement. It is very rare and reasonable to consider in the ddx. I couldn’t not imagine behind told that I have severe ancient and fibro then later found to have a rather treatable dx. Though it is difficult to diagnosis rare conditions as false positives are comment when we work up patients for uncommon syndromes. 

Right...and my hat goes off to providers who are constrained by 15 minute visits yet expected to get at the root cause of the complaint.

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Specializes in Former NP now Internal medicine PGY-3.
18 minutes ago, Nurse Beth said:

Right...and my hat goes off to providers who are constrained by 15 minute visits yet expected to get at the root cause of the complaint.

It is difficult glad I’m going into a specialty. Primary care is probably one of the hardest specialities due to cognitive load and time constraints. 

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Specializes in Tele, ICU, Staff Development.
3 minutes ago, Tegridy said:

It is difficult glad I’m going into a specialty. Primary care is probably one of the hardest specialities due to cognitive load and time constraints. 

Just curious- what specialty did you choose?

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Specializes in EMS, ED, Trauma, CEN, CPEN, TCRN.
1 minute ago, Tegridy said:

It is difficult glad I’m going into a specialty. Primary care is probably one of the hardest specialities due to cognitive load and time constraints. 

If I recall correctly, in all the charts I have reviewed for patients with SPS, they had their conditions managed by Neuro. Hopefully primary care would see red flags that would trigger a Neuro referral. 

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Specializes in Former NP now Internal medicine PGY-3.
1 hour ago, Lunah said:

If I recall correctly, in all the charts I have reviewed for patients with SPS, they had their conditions managed by Neuro. Hopefully primary care would see red flags that would trigger a Neuro referral. 

Neuro would be the most likely to diagnose it. It's not the first diagnosis on anyone’s radar since it is often picked up on EMGs ordered for other reasons. It is rather difficult though since benzos are first-line for it. Many nonspecific complaints and often coexisting with GAD makes it pretty hard to pick up in the undifferentiated patient.

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Specializes in Former NP now Internal medicine PGY-3.
1 hour ago, Nurse Beth said:

Just curious- what specialty did you choose?

GI, mostly due to good job opportunities, interesting procedures, and the specialty of neuro gastroenterology is pretty interesting. A lot of mystery behind the GI system that I would like to one day understand better (I have a fairly superficial understanding of neuro GI). Had I not done internal medicine, neuro would have been my choice, very interesting and a lot of new treatments coming out. I feel bad for neuro patient’s since the technology is just not there yet. 

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