What to Know About Stiff Person Syndrome (SPS)

What is Stiff Person Syndrome (SPS)?

Stiff person syndrome (SPS), also known as Moersch-Woltman syndrome, is a progressive neurological condition that causes muscle rigidity and painful spasms. First diagnosed in 1954, SPS was originally known as a stiff-man syndrome until further studies found that women were at higher risk of developing SPS. It generally affects people between the age of 20 to 50 and is much rarer in children. However, it is a very rare condition, affecting only one in every one million people.

The main symptoms of SPS are stiff muscles in the trunk (or torso), arms, and legs, as well as heightened sensitivity to various stimuli, including bright lights and even stress. These can occur gradually or rapidly, sometimes without any warning. The painful spasms a person may infrequently (or often) experience can lead to a higher risk of a fall and, if not treated promptly, can lead to even more serious health complications.

Is it an Autoimmune Condition?

SPS exhibits features that make it seem like an autoimmune condition. While the exact cause is still not well understood, it is believed that the immune system mistakenly attacks a protein called glutamic acid decarboxylase (GAD). GAD is important as it creates a substance called gamma-aminobutyric acid (GABA), which is important in regulating muscle movement by decreasing motor neuron activity. The deficiency of GABA is theorised to be the cause behind SPS, but further research is still needed.

The First Signs of SPS

Signs of SPS can sometimes present themselves very early, and it can be easy to mistake it for something else. One SPS survivor recounts her first experience of SPS signs in 2013: “painful muscle knots” in her “upper back, shoulder blade and neck areas.” Over the next few years, her symptoms began to progress until they began to interfere with her work and daily life. It was only in mid-to-late 2019 that she was diagnosed with SPS and underwent immediate treatment.

For most people, muscle rigidity first occurs in the trunk, or torso, which can cause major discomfort or significant pain. It can potentially “spread” to affect other parts of the body, especially the limbs. It can either remain unchanged or it may fluctuate irregularly for long periods of time. After some time, it can become a constant stiffness that makes it difficult – or even impossible – to move the affected limb.

Muscle spasms may also occur, either affecting a single area or the entire body. The worrying aspect of these spasms is how unexpectedly they can occur. For some people, being startled by bright lights or sudden loud sounds can trigger these spasms – and some spasms can last for hours. Survivors recall how these spasms often left them in tears due to the pain they experience.

Both the stiffness and unexpected spasms can make it that much easier for a person to fall. Because no one knows that it is SPS, an unsupervised person can either fall when the leg suddenly cramps up and becomes rigid or when an involuntary muscle spasm occurs due to a trigger. It makes it that much harder for someone to walk properly, let alone stand straight.

It has also been noted that SPS is frequently associated with other types of autoimmune conditions such as “type-I diabetes, thyroiditis, vitiligo, and pernicious anaemia.” One survivor recalls suddenly being diagnosed with diabetes before their SPS diagnosis; no explanation could be given for why it occurred.

Diagnosing SPS

Because of the rarity of SPS, it might take an average of five to seven years to diagnose it in a person. The difficulty in identifying it early is primarily because of that rarity, but also because not a lot of doctors might be able to identify the signs. Your best bet would be to see a neurologist in order to get a clear diagnosis of whether it is SPS or otherwise.

The first step is to get a thorough physical examination and a look at your medical history. The physical examination might allow the doctor to ascertain the severity of muscle rigidity in the limbs. These methods may help with making a more accurate diagnosis before a lab test is ordered to determine if SPS is suspected. A variety of tests may be needed to confirm the diagnosis.

A neurological exam may also be performed if needed.

Treating SPS

As there is still no cure for SPS, treatment plans focus on mitigating the symptoms of SPS while improving mobility and reducing pain. Depending on the severity of symptoms and the effects of medication in treating your condition, your care plan will be tailored to meet your personal recovery needs.

Medications

Medications may be prescribed to help manage the pain from rigid muscles or muscle spasms. Some prescriptions include:

• Benzodiazepines: These help relieve anxiety (owing to how triggers can happen at any time) and muscle tension. On higher doses, it may be used to treat muscle spasms. Diazepam is most commonly prescribed for treating SPS.
• Muscle relaxants: Baclofen may be prescribed to treat muscle spasms, as it can help to relieve muscle stiffness.
• Anti-inflammatory/seizure medications: These may be prescribed only when needed to relieve pain.

Immunotherapy

Currently, intravenous immunoglobulin (IVIG) is considered the most effective method to treat SPS symptoms. Studies have found that persons with SPS are less sensitive to triggers, experience fewer episodes of stiffness or pain, and can go about their lives relatively normally with regular treatment. IVIG contains purified immunoglobulins, which are antibodies produced by the immune system, derived from many healthy donors.

There are other forms of immunotherapy for treating SPS, but all of these methods do come with side effects that could impact your recovery. Doctors will need to carefully consider all options before deciding if immunotherapy is the best course of action for your treatment.

Physical Therapy

Massages and acupuncture may, or may not, help with alleviating muscle stiffness and relieving pain, while also improving a person’s mental well-being. All forms of physical therapy are usually introduced primarily to manage symptoms as best as possible or to promote better posture and greater independence. Some SPS survivors find that it helps, while others recall feeling no improvement in their condition.

Supporting People with SPS

It is estimated that the life expectancy of people with SPS ranges between 6 to 28 years “from the onset of the condition.” This is still an estimation as various factors may have an impact on a person’s overall life expectancy. There are instances where persons with SPS report having a “reduced quality of life due to physical and social limitations” caused by their condition. It is entirely possible for life expectancy to shrink in such scenarios.

Given how rare SPS is and how it can permanently impact a person’s life, getting the necessary support for someone with SPS is crucial. Of particular concern is how it is often misdiagnosed as a “range of non-neurological conditions,” which only delays early treatment when it is most needed. Survivors have reported instances where doctors dismissed their complaints about their health, stating that it is merely “psychosomatic” in nature, or that it will go away on its own after some time. With how triggers can happen at any time, those with SPS will find it so much harder to live a normal life without feeling anxious about possible triggers.

More research is being undertaken to understand the causes of SPS and what can be done to mitigate its impacts on people further if a cure is still unattainable for now. Clinical trials are one such avenue that you can participate in to find new ways of treating SPS. Some trials may be funded by the Ministry of Health, while others may be by private hospitals or other organisations involved in medical research. Any information gained from these trials can significantly help improve our understanding of SPS, which in turn may lead to newer breakthroughs in its treatment.

Beyond just clinical care, you should also take care of yourself as best as possible to help combat the emotional or mental toll of SPS.