Stiff Person Syndrome (SPS) is a rare neurological disorder that affects about one in one million people. It is characterized by muscle stiffness and spasms, which can be severe and affect much of the body.

SPS is a progressive disorder, which means that it can get worse over time. It is also associated with other conditions, such as type 1 and type 2 diabetes and autoimmune disorders. SPS typically appears in adulthood and varies from person to person. They often progress in severity over time.

What is SPS?

The cause of stiff person syndrome or SPS is not well understood, but it is thought to be related to an autoimmune process in which the body's immune system mistakenly attacks healthy cells in the central nervous system.

The central nervous system is the part of the nervous system that controls voluntary muscle movement, and damage to these cells can lead to the various symptoms associated with SPS. These symptoms include stiffness in the trunk and limbs, difficulty moving, and problems with posture, which will be discussed at length in this article.

medical document showing "stiff person syndrome" as the diagnosis


Muscle stiffness and spasms

Muscle spasms and stiffness are the primary symptoms of stiff person syndrome. These effects often target the trunk and limbs and can make it difficult for a person to move and maintain their posture, among many other issues.

The severity of the stiffness and spasms can vary from person to person and may fluctuate over time. In some cases, they can be so severe that a person with SPS may need assistance to move and perform daily activities.

woman experiencing leg muscle spasm



Pain is a common symptom of stiff person syndrome, most often caused by spasms, which can range from mild to severe. The pain may be localized to the muscles that are experiencing spasms, or it may be more widespread throughout the body. The type of pain can be dull and chronic or sharp and acute.

Pain management is an important part of treating SPS.

older woman experiencing back muscle pain



Fatigue is more than just exhaustion. It usually is not relieved by sleeping, and it's a common symptom of stiff person syndrome. Spasms can cause tiredness and weakness, which can make it difficult for a person to go about their day-to-day life. The regular jerking of the muscles, the tension of trying to prevent the spasms, and the stress and anxiety of having limited movement can all contribute to this symptom.

The fatigue may be constant, or it may come and go, and physical activity or stress can make it worse. Some people find they also develop difficulty concentrating and irritability.

older woman feeling fatigue due to muscle soreness


Anxiety and depression

SPS can be a stressful and isolating disorder. The spasms people with the condition experience can be unpredictable and may occur without warning. People with SPS may worry about when the next spasm will come and how severe it will be, and this can cause anxiety and fear of being out in public or around friends and family. The anxiety may also be related to other symptoms of SPS, such as pain and difficulty moving.

If a person with SPS limits their social interactions because of their symptoms, they may also experience depression. This symptom can come from isolation, as well as feelings of helplessness as they begin to require assistance with daily tasks.

man experiencing symptoms of depression from muscle pain


Difficulty walking

The stiffness and spasms associated with SPS can make walking difficult. People with the condition may have trouble maintaining their balance and could fall often, which increases the risk of other injuries.

woman with difficulty walking using a walker being helped by doctor


Difficulty swallowing

The muscle stiffness and spasms associated with SPS can also affect the muscles used for swallowing. This can make it difficult to eat and drink and can lead to choking and aspiration in some cases.

woman having difficulty swallowing water


Difficulty speaking

As with swallowing, spasms and tense muscles can also affect the muscles used for speaking. This can make it difficult to produce clear speech and can lead to communication challenges.

woman depressed and upset because of medical symptoms


Sensitivity to noise and touch

Some individuals with SPS experience heightened sensitivity to noise and touch. This can be distressing and can interfere with daily activities. The symptom can also lead to increased anxiety and depression symptoms.

man covering his ears from pain of noise


Difficulty with fine motor skills

The muscles used for fine motor tasks such as writing or buttoning a shirt will often also be affected by the primary symptoms. As these tasks become more challenging for a person with SPS, they can start to lose their independence.

nurse helping woman with walker get her coat on


Bowel and bladder problems

Other muscles affected by stiffness and spasm include those used for bowel and bladder control. This can lead to constipation, incontinence, and other problems that may result in secondary conditions and require the help of a caregiver.

woman with abdominal pain bladder control problems


Diagnosis of SPS

Diagnosing SPS can be difficult because the symptoms are similar to those of other neurological disorders, such as Parkinson's disease and multiple sclerosis. To diagnose SPS, a doctor will conduct a physical examination and review the person's medical history. They may also order tests, such as imaging studies and blood tests, to rule out other conditions.

doctor explaining diagnosis to a patient


Treating SPS

There is no cure for SPS, so treatment seeks to control symptoms with a combination of medications and physical therapy. Medications used to treat SPS may include muscle relaxants, anti-seizure drugs, and immunosuppressants.

Physical therapy can help improve muscle strength and flexibility. In severe cases, surgery can address any underlying conditions contributing to muscle stiffness and spasms.

Though people who develop SPS will always have it, with proper treatment, they can lead relatively normal lives.

physical therapist working with a patient to walk


Living With SPS

Living with SPS can be challenging, but support groups and organizations can provide valuable information and support for both people with the condition and their loved ones and caregivers. One such organization is the Stiff Person Syndrome Foundation.

Living with SPS can be challenging, but there are resources available to help. Support groups can provide a valuable source of information and support for people with SPS and their loved ones. In addition, there are organizations that provide information and support for people with rare disorders, such as the Stiff Person Syndrome Foundation.

smiling woman walking with a cane with her caregiver


Popular Now on Facty Health


This site offers information designed for educational purposes only. You should not rely on any information on this site as a substitute for professional medical advice, diagnosis, treatment, or as a substitute for, professional counseling care, advice, diagnosis, or treatment. If you have any concerns or questions about your health, you should always consult with a physician or other healthcare professional.