Stiff Person Syndrome is a rare autoimmune movement disorder that affects the central nervous system (brain or spinal cord). The specific symptoms of the syndrome include stiffness of the axial muscles such as the back and abdominal muscles, which gradually leads to rigidity in the legs and other body muscles, including respiratory and facial muscles.
What You Need to Know About Stiff Person Syndrome
What is Stiff Person Syndrome?
Stiff Person Syndrome was first fully described by Moersch and Woltman in 1956, and is also known as Moersch-Woltman Syndrome. Muscle stiffness may occur spontaneously or in response to sudden triggers such as noise, psychological stress, movement, or touch. Over time, the stiffness in the muscles may lead to changes in gait, spinal deformities such as kyphosis or lordosis, and can even result in the patient becoming unable to walk.
Stiff Person Syndrome is an extremely rare neurological disorder, occurring at a rate of 1 in 1,000,000, with a prevalence in females that is twice that of males. The syndrome can occur at any age but is most commonly seen in individuals aged 30 to 60. Conditions often associated with Stiff Person Syndrome include:
- Type I Diabetes
- Autoimmune Thyroiditis
- Vitiligo
- Pernicious Anemia
- Certain cancers such as lung, breast, kidney, thyroid cancer, or Hodgkin’s disease
Causes of Stiff Person Syndrome
Researchers currently do not know the exact cause of Stiff Person Syndrome. It is believed to have an autoimmune origin, meaning that the body of the affected individual produces antibodies against the enzyme glutamic acid decarboxylase (GAD). GAD plays a role in the production of the neurotransmitter GABA, which controls muscle movement. Consequently, the presence of anti-GAD antibodies reduces GABA levels at the nerve synapses and is thought to be the cause of muscle stiffness. However, the true role of anti-GAD antibodies in Stiff Person Syndrome is not yet fully understood.
Singer Celine Dion diagnosed with Stiff Person Syndrome.
In practice, there are individuals with Stiff Person Syndrome who do not have detectable anti-GAD antibodies, or conversely, patients with anti-GAD antibodies in their blood but who do not exhibit symptoms of the syndrome.
Symptoms of Stiff Person Syndrome
The symptoms of this syndrome may occur quietly, gradually progressing over a few months to several years. Initially, the axial muscles and abdominal muscles may stiffen, sometimes in episodes, causing pain or discomfort for the patient. Gradually, the leg muscles, neck and shoulder muscles, or even facial muscles may also become stiff. This prolonged muscle stiffness can lead to conditions such as kyphosis or lordosis. Stiffness in the leg muscles can make it difficult for patients to walk, potentially requiring the use of a wheelchair.
Along with muscle stiffness, muscle spasms can cause pain. These spasms may appear suddenly or in response to triggering factors such as noise, movement of limbs, touch, or emotional factors. Patients may experience symptoms such as frequent startle reactions or leg jerking, which may lead to falls. Muscle spasms can last for seconds, minutes, or even hours, and sometimes the intensity of the spasms can be strong enough to cause fractures.
Stiff Person Syndrome can manifest in several different clinical forms.
- Classic Stiff Person Syndrome (Classic SPS): Initial symptoms typically include pain, discomfort, and muscle stiffness in the lower back. As the disease progresses, leg stiffness often occurs on one side, or stiffness in the neck and shoulder muscles may develop. Patients may experience painful muscle spasms that occur spontaneously or in response to sudden stimuli such as knocking, voices, or touch, or during psychological stress. The frequency of spasms decreases when the patient sleeps. Due to difficulties in mobility or fear of falling, individuals with Stiff Person Syndrome often experience anxiety, panic disorders, or depression. When respiratory muscles become stiff, patients may experience difficulty breathing or even respiratory failure. There have been reports of patients experiencing paroxysmal autonomic nervous system disorders, causing fever, rapid heart rate, rapid breathing, high blood pressure, and profuse sweating.
- Focal Stiff Person Syndrome (Focal SPS): Also known as Stiff-limb syndrome. Muscle stiffness accompanied by spasms is similar to the classic form but is localized to one limb, typically a leg. Gradually, the stiffness may spread to the other leg and cause difficulties in walking for the patient.
- Jerking Stiff Person Syndrome (Jerking SPS): Muscle stiffness and spasms typically occur in both legs. Additionally, patients may also exhibit brainstem symptoms, characterized by myoclonus (sudden muscle jerks).
- Progressive Encephalomyelitis with Rigidity and Myoclonus (PERM): PERM is characterized by stiffness and muscle pain similar to the classic form. However, it has a faster onset and progression, usually within weeks, along with symptoms such as dizziness, loss of balance, difficulty speaking, swallowing difficulties, or oculomotor paralysis.
- Paraneoplastic Stiff Person Syndrome: This is a very rare form associated with cancer, particularly lung or breast cancer. Symptoms of stiffness and spasms may appear many years before the cancer is detected.
Diagnosis of Stiff Person Syndrome
Stiff Person Syndrome is diagnosed based on the criteria established by Dalakas, which includes clinical symptoms, blood tests, electromyography, and response to medication.
- Blood Tests: Approximately 60-80% of patients with Stiff Person Syndrome have the presence of anti-GAD antibodies in their blood. Additionally, anti-amphiphysin or anti-gephyrin antibodies may also be found.
- Electromyography: Signs of muscle contraction can be observed in both agonist and antagonist muscles simultaneously. This muscle contraction diminishes or disappears with high doses of Benzodiazepine medications.
- Cerebrospinal Fluid: Anti-amphiphysin antibodies may be detected and other causes should be ruled out.
Treatment of Stiff Person Syndrome
The goal of treating Stiff Person Syndrome is to alleviate symptoms and improve mobility.
Medications used may include:
- Benzodiazepines such as diazepam or clonazepam.
- Muscle relaxants such as baclofen.
- Anticonvulsants such as Depakine, Neurontin, etc.
- Steroids.
- Other methods such as intravenous immunoglobulin therapy, plasma exchange, or Rituximab.
Combined with physiotherapy and massage. - If cancer is detected, in addition to symptomatic treatment, cancer treatment must also be combined.
Complications of Stiff Person Syndrome
Stiff Person Syndrome causes muscle stiffness and painful spasms. Therefore, complications such as fractures, falls, depression, difficulty breathing, or excessive sweating may occur.
Prognosis for Patients with Stiff Person Syndrome
The prognosis depends on the symptoms of each patient. Generally, over time, patients may find it increasingly difficult to walk and perform daily activities. Different treatment methods may alleviate symptoms in some patients. Patients and their families should be aware of the risk of falls and fractures. Some patients may require assistance when walking or may even need to use a wheelchair.
