What is Stiff Person Syndrome: Causes, Symptoms, Treatment, Prognosis

Stiff Person Syndrome is an extremely rare neurological condition which affects the nervous system of the body.¹ Stiff Person Syndrome affects mainly the spinal cord and the lower parts of the body. It is basically an autoimmune disorder that is characterized by extreme muscle rigidity. Any sort of emotional stress sparks off this condition. An individual with Stiff Person Syndrome will experience muscles spasms with severe pain stimulated normally by noise, touch, and most commonly emotional stress.

Individuals with Stiff Person Syndrome will have a hunched or a stiff posture due to muscle rigidity. Stiff Person Syndrome makes it difficult for the individual to move or walk fluidly as a normal person does. Stiff Person Syndrome can be triggered by small things like a horn of a car or being stuck in traffic resulting in severe muscle pain and spasm due to Stiff Person Syndrome. This condition is more common in females than in males and is associated with other medical conditions like diabetes, thyroid disorder, and anemia.

Stiff person syndrome is a rare neurological disorder also known as the stiff-man syndrome. So far there has been no evidence to support the cause of this disease. Stiff person syndrome predominantly affects the truncal muscles, superimposed by spasm and causes postural deformities. It primarily affects the brain and the spinal cord. The common symptoms associated with Stiff Person Syndrome are muscle stiffness, rigidity, and spasms in the trunk and limbs. Eventually, it causes hindrance to mobility and movement. Patients with stiff person syndrome have heightened sensitivity to noise, sudden movements, and emotional distress. Persistent symptoms lead to the abnormal posturing of the spine and hunched back. Stiff person syndrome is a rare condition, affecting one in a million people and is commonly found in middle-aged people. It is said to have an autoimmune component and is frequently associated with diabetes, vitiligo, thyroiditis and various other autoimmune diseases.¹ The muscle stiffness initially fluctuates, sometimes for days or weeks, but eventually begins to impair mobility consistently. Factors such as cold weather, stress, and infections lead to an increase in the symptoms, whereas, a deep sleep cycle reduces the symptoms considerably.

Stiff person syndrome is characterized by recurring muscle stiffness, rigidity and painful spasms in the trunk and limbs. The time of occurrence of the symptoms varies from person to person. Most people start experiencing it between 30 and 60 years of age. In some cases, prolonged spasms can even lead to bone fracture. Patients having Stiff person syndrome are prone to frequent falls during walking.

As the disease progresses, the condition starts deteriorating, and causes abnormal posturing of the spine and hunched back. It also creates hindrance in performing routine activities such as getting up from the bed, taking a bath, dressing, etc. Apart from leading to physical inabilities it also takes a toll on the patient’s mental health, as they become increasingly anxious and depressed due to their difficulties. The patient’s self-esteem also drops down because of the lack of social connections.

Coming to the causes of Stiff Person Syndrome, researchers have still not been able to come up with a clear cut cause for this disorder but most researchers are of the belief that Stiff Person Syndrome occurs because of some abnormalities in the immune system of the body, especially in the brain and spinal cord.¹ Since Stiff Person Syndrome is an extremely rare condition hence it is more often than not misdiagnosed as Parkinson’s disease, multiple sclerosis, fibromyalgia or anxiety.

People with stiff person syndrome have antibodies that attack glutamic acid decarboxylase (GAD). GAD is a protein which is present within some of the neurons. The function of GAD is to produce Gamma-Aminobutyric acid (GABA). GABA is responsible for regulating the movement of muscles. In patients with stiff person syndrome, the symptoms begin when the immune system accidentally attacks the neurons producing GAD. This leads to inadequate production of GABA.

In some cases, patients have antibodies that attack amphiphysin. Amphiphysin is a protein which is responsible for transmitting signals from one neuron to another. In such patients, the chances of acquiring lung cancer, breast cancer, and colon cancer are very high.

Stiff Person Syndrome is mainly characterized by extreme muscle rigidity with painful muscle spasms.¹ Other than that an individual with Stiff Person Syndrome will always have a stiff upright posture which may cause back pain. Individuals with Stiff Person Syndrome also find it difficult to sleep due to the continued stiffness. The symptoms of pain and spasms become more significant with triggers like extreme anger, stress, and fright. The stiffness in Stiff Person Syndrome in its initial stages may be limited to the extreme lower parts of the body but as the disease process advances this may spread all over the body. In severe forms of Stiff Person Syndrome, there may also be deformities which may be visible. With time as the disease process advances, an individual with Stiff Person Syndrome will become totally disabled and completely unable to move.

Inheritance of Stiff Person Syndrome

Though there have been cases of multiple persons from the same family suffering from stiff person syndrome, there is no evidence to support the involvement of genetic factors in the occurrence of the same. Most cases appear in an isolated manner.

The diagnosis of Stiff Person Syndrome is quite complex and difficult as the disease is quite rare and the symptoms mimic other disease conditions like Parkinson disease or fibromyalgia and this is the reason for this condition being misdiagnosed, although with specific blood tests a confirmed diagnosis of Stiff Person Syndrome can be made. Specifically, the level of Glutamic Acid Decarboxylase pinpoints towards a diagnosis of Stiff Person Syndrome. In an individual with Stiff Person Syndrome, the levels of GAD will be higher than normal. Other than this, EMG is also an important test which can diagnose Stiff Person Syndrome. In an individual with Stiff Person Syndrome, the low frequency and motor unit activity of the agonist and antagonist muscles will clearly confirm the diagnosis of Stiff Person Syndrome. Apart from this, the physical features and the symptoms experienced by the patient also gives a decisive hint towards a diagnosis of Stiff Person Syndrome.

Various other tests are used to detect the presence of other diseases which are associated with stiff person syndrome. A hemoglobin A1C test is used to detect the presence of diabetes mellitus. A complete blood count is done to rule out pernicious anemia, a thyroid stimulating hormone (TSH) test to rule out thyroiditis and a lumbar puncture to look for oligoclonal bands. These bands indicate the inflammation in the central nervous system.

Though there is no permanent cure devised for stiff person syndrome as of now, there are various kinds of medicines which attempts to control the symptoms and improve mobility to an extent. The way in which the patients respond to the procedure differs from person to person. Some people maintain a considerable amount of physical activity while others tend to become more sedentary and less active. Also, the method of treatment is planned and customized according to the severity of Stiff person syndrome condition.

Benzodiazepines, diazepam, or baclofen can be used in the treatment of muscle stiffness and spasms. Anti-seizure medications and pain medications may also be useful for some people. Recent studies have shown that intravenous immunoglobulin (IVIG) or plasmapheresis may be helpful in improving some of the symptoms of stiff person syndrome.

Physical therapy and occupational therapy help in maintaining the muscle strength and prevents the condition from getting worsened. One of the significant advantages is that it is devoid of any side effects which are a natural consequence of drugs.

At present, there is no definite cure for Stiff Person Syndrome, although with the advancement that medical science has made over the decades the progression of the disease can be slowed down and the symptoms can be significantly controlled. Studies suggest that use of IVIG or intravenous immunoglobulin has shown quite a lot of effectiveness in controlling the symptoms of Stiff Person Syndrome by reducing the sensitivity to noise, touch, and stress among many patients diagnosed with Stiff Person Syndrome. Anxiolytics, muscle relaxants, and anticonvulsants are also quite helpful in controlling the symptoms of Stiff Person Syndrome. Pain medications may also be given for pain relief to an individual with Stiff Person Syndrome.

The prognosis of persons affected by stiff person syndrome differs from person to person. In the case of some patients, the problems can be resolved to an extent with the help of the treatment. On the other hand, for individual patients, the symptoms might continue to occur. The affected area also differs from person to person. In some instances, the progression of Stiff person syndrome might even affect the muscles of the patient’s face.

Progression of Stiff person syndrome symptoms leads to fatigue, excruciating pains and frequent falls, which can be very dangerous for the patients. Stiff person syndrome patients who do not get any improvement with the current treatment options face great difficulties physically as well as mentally because they always worry about their health and the future which leads them to anxiety and depression.

Stiff Person Syndrome patient will always have some muscle pain and stiffness despite treatment as the treatments are aimed at controlling the symptoms and they are not a cure for the condition. The patient will always be at risk for frequent falls due to muscle rigidity and stiffness and difficulty moving the lower extremities. Also, the individual will be at risk for frequent injuries due to fall and other risk factors due to Stiff Person Syndrome.

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