What is Stiff-Person Syndrome?

August 26th, 2011

One very rare and unusual condition associated with diabetes is Stiff-Person syndrome, also referred to as Myotonic Dystrophy. Stiff-Person syndrome (SPS) is a central nervous system disorder characterized by severe muscle stiffness that moves from place to place in the trunk, arms and legs. SPS affects about 1 in 1 million Americans, and about 1 in 10,000 diabetics.

Someone with SPS is exceedingly hypersensitive to normal stimuli such as sound, touch and emotional stress. A sudden noise, tap or worry can trigger muscle spasms that distort the body into hunched over stiff postures. People with SPS suffer from frequent falls when spasms are triggered by commonplace noises like a door slamming or a car horn. Because people with SPS lack normal protective reflexes, spasms and falls can result in serious injuries, including fractures, muscle tears and joint dislocations.

SPS is also referred to as "Stiff Man Syndrome", although - like many autoimmune conditions - it is much more common in women than in men. SPS usually strikes between the ages of 30 and 50, but the syndrome can also occur as Stiff Baby Syndrome in children under three. Commonly, SPS begins with an exaggerated upright posture due to muscle stiffness in the lower back, and then moves into the legs. As the disease progresses the patient must move very slowly, as rapid movements can trigger severe spasms.

The unusual and unfortunate symptoms of SPS can be confused with those of fibromyalgia, Parkinson's disease or multiple sclerosis. Sufferers may also be misdiagnosed as having an anxiety or psychosomatic disorder. A diagnosis of SPS is aided by the detection of elevated levels of the antibody glutamic acid decarboxylase (GAD), which is present in the cerebral spinal fluid of about 80% of SPS cases.

GAD antibodies tests are also an important diagnosis tool for diabetes mellitus. GAD tests are used to differentiate between types of diabetes, to predict the risk and track the progression of the disease, and to predict the need for insulin therapy in type 2 diabetics. GAD reduces the brain's main inhibitory transmitter, GABA. It's theorized that this reduction of GABA interferes with the modulation of spinal cord reflexes, resulting in the hyperactivity and hyperexcitabity that characterizes SPS.

SPS can be treated, but not cured. Symptoms can be eased with a combination of anti-anxiety medications, anti-convulsants, muscle relaxers and pain medication. A recent study proved intravenous immunoglobulin treatment (a therapy for autoimmune diseases and immune deficiencies) effective in reducing stiffness and hypersensitivity in patients with Stiff-Person syndrome. Another study using the arthritis drug rituximab led to disappointing results.

The cause of SPS remains a mystery, but it appears to be an out of kilter autoimmune response in the brain and spinal cord. SPS is associated with other autoimmune diseases such as diabetes, pernicious anemia, thyroiditis, and the skin disease vitiligo. The National Institute of Neurological Disorders and Stroke is continuing to both conduct and support research into SPS, focusing on uncovering the cause of this rare and curious condition.