June 9, 2009 by Vonda Sines

Have You Heard of Stiff-person Syndrome?

He was a well-respected physician, still in his forties, when it started. As he examined patients, his body stiffened, often bending him backward so that he was frozen into position, staring at an imaginary sky.

Stiff-person syndrome is a very rare disease of the nervous system that claims features of an autoimmune malfunction. The National Institutes of Health (NIH) page on the condition suggests that abnormal postures such as being hunched over and stiffened are typical. Some patients with SPS are unable to walk or even move. Others are afraid to leave their homes because street noises such as a horn blowing can trigger spasms and cause them to fall.

The rigidity of muscles in the trunk and limbs fluctuates in SPS patients. They appear to possess an acute sensitivity to outside influences like noise, touch and emotional reactions. These stimuli frequently set off painful muscle spasms.

The onset of SPS is usually in the patient's forties. Many individuals suffer from other autoimmune disorders.

Information from Johns Hopkins Medicine indicates that perhaps fewer than one person in a million develops stiff-person syndrome. It's twice as prevalent in women than in men and so far remains unlinked to any race or ethnic group. Researchers have established no tendency for SPS to run in families, so genetic testing is not used for the condition.

Around half of SPS patients have diabetes or will contract it. SPS is also associated with autoimmune conditions such as thyroid disease and vitiligo. Researchers note an increased incidence of epilepsy. An unusual, variant form has been connected to breast and lung cancer but can be clearly differentiated under the microscope as different from typical SPS.

There are several ways to approach diagnosing stiff-person syndrome. Physicians always perform an exam and take a neurological history because laboratory tests by themselves aren't definitive as far as making a diagnosis. Patients typically report symptoms such as stiffness, rigidity or painful spasms. These movements usually involve the legs or lumbar spine but can also affect the face, neck, abdomen or arms. The next step is to rule out other causes of the symptoms such as dystonia, transverse myelitis, vascular malformation or Parkinson's disease.

In conjunction with a physical exam, patients need antibody testing. High levels of glutamic acid decarboxylase (GAD) antibodies can confirm a diagnosis of stiff-person syndrome in the majority of sufferers. GAD antibodies are also associated with diabetes.

Electromyography (EMG) is a standard tool for diagnosing SPS. It should be performed by a physician who is familiar with SPS. Certain low-frequency motor unit activity in certain muscles is an indicator of the condition.

Although patients can suffer severely from the contortions of their bodies, they have a number of current treatment options that usually control the symptoms. Physicians commonly treat them with intravenous immune-globulin (IVIg) immunotherapy. They might also prescribe high doses of the drug diazepam and several anti-convulsants. Pain relievers and anti-anxiety medications can help relieve the symptoms but won't cure stiff-person syndrome.

The NIH information page for stiff-person syndrome contains links to the agency's clinical trials as well as others available worldwide.