What is Stiff person’s syndrome?

In December last year via her Instagram page, singer Celine Dion, 54, told her fans she had been diagnosed with a rare neurological condition called Stiff person syndrome (SPS).  

"I have been diagnosed with a rare neurological condition called stiff-person syndrome which affects something like one in a million people. While we are still learning about this rare condition, we now know that this is what has been causing all of the spasms that I have been suffering," she said.

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Since the disease is rare, sometimes, people are misdiagnosed. Mwesigwa’s mother, who is in her early 60’s had been diagnosed with Parkinson’s disease and for about two months, she was on treatment but without any improvement. 

She was sensitive to noise, had spasms in her hands and legs and according to Mwesigwa, her joints became deformed over time, making it difficult for her to walk. She also go a hunched back.

“Each day, my mother’s health deteriorated even when she was on treatment. We had been in hospital for about two months but she was just getting worse. Her back was more hunched, she suffered uncontrolled spasms and could only move with the aid of a wheelchair since it was difficult to walk,” he says.

With his mother deteriorating every day, Mwesigwa sought help from another hospital where a neurologist diagnosed his mother with Stiff Person Syndrome. 

“The doctor prescribed medicine that my mother was supposed to take for one week but after just one day, the spasms stopped,” he says.

What is SPS?
SPS is a rare, chronic condition that causes continuous muscle activity despite relaxation. It affects the nervous system, specifically the brain and spinal cord, causing spasms. 

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According to Dr Robert Sebunya, a neurologist at Nsambya Hospital in Kampala, a person suffering from SPS often has heightened sensitivity to noise, sudden movements and emotional distress, which can cause muscle spasms. 

“Patients with this condition are generally prone to injuries, which reduces their lifespan by a considerable amount of time. However, if symptoms are treated, one is likely to get relief,” he says.

Types
SPS is categorised according to the signs and symptoms. The traditional type of SPS involves stiffness, spasms and rigidity in the lower back, legs and hands. This is the commonest type of SPS affecting about 70 percent of the people. The spasms vary in intensity and walking, bending and turning. 

“With time, it may be hard for a person with this type of SPS to balance so they often fall accidentally and may develop orthopedic problems such as joint deformities, abnormal posturing and lumbar lordosis (an exaggerated inward curve of the spine affecting the lower back). The person may also have task-specific phobias, fear of open spaces, depression and anxiety,” Dr Sebunya says.

The variant type of SPS involves stiffness and jerking that is limited to one side of the body such as the leg or arm. If it is the leg that is affected, walking may become difficult and may sometimes be mistaken for dystonia (a movement disorder that causes muscles to contract involuntarily). 

Sebunya remarks that the most severe type of SPS is the catastrophic SPS (progressive encephalomyelitis with Rigidity and Myoclonus (PERM), which involves rigidity of the entire body, including the head and spinal cord. 

“This type of SPS may present with jerky muscle contractions (myoclonus), difficulty swallowing, abnormal eye and eyelid movements causing insomnia, seizures, cognitive and behavioural changes as well as problems regulating the heart rate and blood pressure,” he says.

Causes
Many neurologists do not know the cause of SPS. It is, however, said to be an autoimmune disease where a person’s immune system malfunctions and produces antibodies against its own tissues.

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According to Dr Sebunya, for most of the patients with this autoimmune condition, the body produces antibodies against the glutamic acid decarboxylase (GAD), an enzyme responsible for the formation of a specific neurotransmitter called gamma-aminobutyric acid (GABA) in the central nervous system. The amino acid once inhibited causes continuous stimulation of muscles by motor neurons, resulting in muscle rigidity.

Elderly women suffering from breast cancer, especially the adenocarcinoma type cannot form antibodies against the brain and spinal cord, leading to SPS.

The syndrome affects twice as many women as men, especially those above the age of 50. It also occurs in children younger than three years. 

It is important to note that a big number of people with this condition usually have other autoimmune conditions such as vitiligo, hyperthyroidism or diabetes. They may also suffer from neuropsychiatric comorbidities such as anxiety and phobia.  

Signs 
Symptoms may include extreme muscle stiffness, rigidity and painful spasms in the trunk and limbs, severely impairing mobility. One may also have heightened sensitivity to noise, touch, and emotional distress, which can set off muscle spasms. People with SPS may also have abnormal posture, such as being hunched. 

Other symptoms may include anxiety, lack of sleep and rapid eye movement due to pain, back pain and stiffness, Lordosis (curved lower back) and deformed joints in the body, stiff-legged walk, severe muscle spasms in the arms and legs when the person is startled, touched, upset, or anxious and limited chest expansion, leading to difficulty breathing, among others. 

Management
There is no cure for Stiff Person Syndrome but treatment of the symptoms will provide relief and improve the person's quality of life. Treatment options depend on the symptoms and severity of the disease. Dr Sebunya says management involves the use of anti-seizure medications and drugs that enhance the GABA effect. 

“Benzodiazepines are the best initial therapy for SPS because they slow down the nervous system and may relieve muscle spasms and anxiety. For some people who fail to respond to Benzodiazepines, Baclofen, a muscle relaxant, can be added to their regimen,” he adds.

People with severe symptoms of SPS may not get relief with benzodiazepines and baclofen. The next option can include immune-modulating therapies such as intravenous immunoglobulin (IVIg) therapy, and plasmapheresis (plasma exchange).

Physiotherapy and occupational therapy play an essential part in the management of the disease, especially in severe cases. It is helpful in improving mobility and function as well as controlling the symptoms. Part of the physiotherapy can include myofascial release, massage therapy, yoga, and meditation.

He warns that, “Since it is an autoimmune disease, prevention is not possible and, therefore, one has genetic susceptibility. However, it is important that you seek medical attention once you notice the symptoms and signs. Early treatment prevents further damage to the brain and the spinal cord,” Dr Sebunya advises.

Diagnosing SPS
Since both children and adults with SPS may be misdiagnosed, Dr Robert Sebunya, a neurologist at Nsambya Hospital in Kampala, emphasises the importance of ruling out other disease conditions such as dystonia, hereditary spastic paraplegia or hyperekplexia whose symptoms are similar to those of SPS. 

“A proper diagnosis of SPS is made based on patient history, a thorough study of the signs and symptoms and a clinical evaluation. Additional tests such as blood tests that measure the level of glutamic acid decarboxylase (GAD) antibodies can be used to support a diagnosis and to rule out other conditions,” he says, adding that people with SPS have higher levels of GAD antibodies up to 10 times above normal levels.