Singer Celine Dion, 54, took to this week to tell fans that she had been diagnosed with a rare neurological condition called stiff-person syndrome.
"I've been dealing with problems with my health for a long time, and it's been really difficult for me to face these challenges and to talk about everything that I've been going through," said Dion. "It hurts me to tell you that I won't be ready to restart my tour in Europe in February."
"Recently, I've been diagnosed with a very rare neurological condition called stiff-person syndrome, which affects something like one in a million people," she continued. "While we're still learning about this rare condition, we now know that this is what has been causing all of the spasms that I've been having."
"Unfortunately, these spasms affect every aspect of my daily life, sometimes causing difficulties when I walk and not allowing me to use my vocal cords to sing the way I'm used to," Dion added. "I'm working hard with my sports medicine therapist every day to build back my strength and my ability to perform again. But I have to admit, it's been a struggle."
What Is Stiff-Person Syndrome?
According to the , "stiff-person syndrome (SPS) is a rare, progressive neurological disorder. Symptoms may include stiff muscles in the trunk, arms, and legs; and greater sensitivity to noise, touch, and emotional distress, which can set off muscle spasms."
It was by Frederick Moersch, MD, and Henry Woltman, MD, based on a case series of 14 patients with progressive fluctuating tightness of the spinal, abdominal, and thigh muscles.
SPS affects . It is two to three times more common in women than men and typically occurs between the ages of 20 and 50 years old. Because of its rarity, it is not often recognized by medical providers. It can take, on average, 5 to 7 years to diagnose.
SPS is often misdiagnosed as Parkinson's disease, multiple sclerosis, fibromyalgia, psychosomatic illness, or anxiety and phobia.
SPS is considered an autoimmune disease associated with high titers of autoantibodies to a variety of components of inhibitory synapses. The autoantibodies cause impaired function due to low levels of gamma-aminobutyric acid on pre- or post-synaptic neuronal junctions. This leads to hyperexcitability of the motor cortex and impairment of muscle relaxation.
Symptoms
Symptoms are dependent on the type of SPS, of which there are several forms.
Classic SPS
is the most common form, occurring in 70% to 80% of patients. Symptoms include muscle rigidity, stiffness, and spasms in muscles of the trunk, especially the back, and limbs. Muscle spasms vary in intensity and duration and typically become worse over time (months to years).
Patients may complain of difficulty bending or turning and may describe their walking as like a "tin-man." Stiffness and rigidity may eventually lead to chronic orthopedic problems such as lumbar lordosis, joint deformities, and abnormal posturing. Gait is often affected and can result in multiple falls.
Painful muscle spasms and exaggerated startle responses are also prominent symptoms and may be precipitated or exacerbated by unexpected tactile, visual, or acoustic stimuli, as well as strong emotions. The frequency and duration of muscle spasms can vary widely, and in some cases can last for hours ("status spasticus").
Involvement of the distal extremities and face are later developments. In rare cases, the respiratory muscles may be involved.
Psychological comorbidities are not uncommon and include depression, task-specific phobias, fear of open spaces, and anticipatory anxiety.
Partial (or Focal) SPS Variants
SPS can present with isolated limb involvement, mostly in one leg. Muscle stiffness, spasm, and jerking may be present. Walking becomes increasingly difficult. Abnormal posturing may resemble dystonia. Later, truncal muscles may become involved. Stiff trunk syndrome involves spasms in the axial musculature only, sparing the extremities.
Progressive Encephalomyelitis with Rigidity and Myoclonus (PERM)
This is a more severe form of SPS and is usually associated with rapid deterioration. The brain and spinal cord are also involved. This form of SPS may include jerky muscle contractions (myoclonus), abnormal eye and eyelid movements, seizures, cognitive and behavioral changes, and difficulty swallowing, along with problems regulating blood pressure, heart rate, and body temperature.
Paraneoplastic Stiff-Person Syndrome
This is a very rare disorder in which the autoimmune antibodies are associated with tumors that may or may not be cancerous. The most common tumors associated with this form of SPS include those of the thymus, colon, lung, breast, and ovary.
Diagnosis
The diagnosis of SPS depends on multiple factors including history, physical examination, bloodwork, and other possible tests.
One particularly useful test looks for antibodies to glutamic acid decarboxylase (GAD), of which approximately 80% of people with SPS have, although their absence does not rule SPS out. Extremely high levels of GAD antibodies (>10,000 IU/mL) support a diagnosis of SPS.
Although nerve conduction studies in SPS are usually normal, needle electromyography shows continuous involuntary motor activity, even at rest. This continuous motor activity, as well as co-activation of agonist-antagonist muscles, are key diagnostic features, especially when seen in trunk muscles.
Treatment
There is currently no curative treatment for SPS. Treatment instead focuses on relief of symptoms with the use of muscle relaxants, anti-seizure medications, physical therapy, myofascial release, massage therapy, acupuncture, acupressure, yoga, meditation, and aqua therapy.
As anxiety and depression often accompany SPS, mental health treatment is also important for these patients, including cognitive behavioral therapy and selective serotonin reuptake inhibitors. Serotonin and norepinephrine reuptake inhibitors should be avoided as they can exacerbate symptoms.
Immunotherapy in SPS
Immunotherapy can be used to reduce or remove autoantibodies. First-line immunotherapies include intravenous immunoglobulins, subcutaneous immunoglobulin typically delivered with a pump system, and intravenous methylprednisolone. Second-line immunotherapies target B or T cells and include rituximab (Rituxan), cyclophosphamide, mycophenolate mofetil (Cellcept), and azathioprine (Imuran).
Michele R. Berman, MD, is a pediatrician-turned-medical journalist. She trained at Johns Hopkins, Washington University in St. Louis, and St. Louis Children's Hospital. Her mission is both journalistic and educational: to report on common diseases affecting uncommon people and summarize the evidence-based medicine behind the headlines.