Stiff person syndrome (SPS)

Also known as: Stiff Man Syndrome

Stiff person syndrome (SPS; sometimes called stiff man syndrome in the medical literature) is a rare neurological disease that affects approximately 1 in 200,000 individuals – both male and female.

In this article

What are the symptoms of stiff person syndrome?

This condition is characterised by progressive stiffness and painful spasms in the back and limbs, which are often triggered by touch, noise or anxiety, and exacerbated by movement.

This is a progressive condition, but only exceptionally does stiffness increase to the extent that the person will require use of a wheelchair.

About 40% of individuals also have type 1 diabetes (see entry Diabetes Mellitus).

Three types of stiff person syndrome have been described:

  • classical person man syndrome – painful spasms and rigidity occur around the back, stomach and sometimes thighs and neck. As the condition progresses, curvature of the lower back can occur. Classical stiff person syndrome is commonly associated with type 1 diabetes
  • stiff limb syndrome – the legs, including the feet, are affected by painful spasms and occasionally fixed rigidity. More rarely, the hands can be affected
  • jerking stiff person syndrome – otherwise known as progressive encephalomyelitis with rigidity – is the rarest form of SPS. It is a more aggressive form of SPS, which involves many of the above symptoms but also may affect the control of the muscles of the head and eyes. It can lead to progressive disability over a number of months or years.

What are the causes of stiff person syndrome?

SPS is an autoimmune condition meaning that the body’s immune system attacks ‘self’, when it should only attack foreign organisms, such as bacteria and viruses.

How is stiff person syndrome diagnosed?

Diagnosis of SPS can often take a long time, simply because it is so rare and the symptoms can baffle doctors. There are two important tests that can be carried out as a means to obtaining a diagnosis. The first test is for autoimmune antibodies. The commonest of these is an antibody to an enzyme called glutamic acid decarboxylase (GAD) involved in the generation of an inhibitory chemical messenger. Individuals with classic type 1 diabetes may show a similar antibody, although generally in much weaker concentrations. Other antibodies may also be found in the SPS, especially in the variant called jerking stiff person syndrome or progressive encephalomyelitis with rigidity. Here, antibodies include two to the receptors for two other chemical messengers – NMDA and glycine. The second test is an electromyogram (EMG), which is a muscle recording study.

How is stiff person syndrome treated?

While treatments do not lead to a cure, they can control symptoms in the majority of individuals. Some individuals are more responsive to certain treatments than others. The most effective drug treatments are diazepam and baclofen, which help reduce stiffness. Some patients with more severe symptoms need therapies that manipulate their immune systems. The commonest of these treatments is intravenous infusions of immunoglobulins.

Inheritance patterns and prenatal diagnosis

Inheritance patterns
SPS is not inherited, although there may be a family predisposition to other autoimmune diseases like diabetes mellitus and thyroid disorders.

Prenatal diagnosis
None available.

Is there support for people diagnosed with stiff person syndrome and their families?

If your child is affected by a medical condition or disability, we can help. Call our freephone helpline on 0808 808 3555 to get information, support and advice. We also offer emotional support for parents via our Listening Ear service.

We have a range of parent guides on aspects of caring for a disabled child in our resource library. You may also find our Early Years Support useful, which contains links to parent carer workshops and help for families going through the diagnosis process.

We’ve listed a support group below and you can also meet other parents online in our closed Facebook group.

Stiff Person Syndrome Support Group

Tel: 01482 868 881
Email: [email protected]

The Group is a Registered Charity in England and Wales No. 1099206. It provides support, information and linking for affected individuals and their families in the UK and the Republic of Ireland. The Group raises awareness of the condition, assists with research and is happy to hear from medical professionals and anyone else with an interest in this condition. 

Group details last updated October 2019.


Last updated September 2019 by Professor P Brown, Professor of Experimental Neurology, Department of Clinical Neurology, University of Oxford, Oxford, UK.

Although great care has been taken in the compilation and preparation of all entries to ensure accuracy, we cannot accept responsibility for any errors or omissions. Any medical information provided is for education/information purposes and is not designed to replace medical advice by a qualified medical professional.

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