Moersch-Woltman Condition

December 31, 2014

Overview

Moersch-Woltman Condition/Syndrome has also been refered to as: Stiff-Person-Syndrome or Stiff-Man Syndrome (SMS). Stiff-man Syndrome is a rare disease of severe progressive muscle stiffness of the spine and lower extremities with superimposed muscle spasms triggered by external stimuli or emotional stress. Typically symptoms begin between the age of 30 and 50 and respond to benzodiazepines. EMG shows a characteristic abnormality and anti-GAD (glutamic acid decarboxylase) antibodies, which are very specific, are present in 60% of people with the disease.

SMS is very rare. The prevalence has not been reported however it may be as rare as 1 per 1,000,000 persons. There is no clear racial or ethnic predisposition although the disease may be more common in women than in men. Patients with SMS often have other autoimmune disease. A related disorder has been found in association with lung or breast cancer and is distinguished by the production of anti-amphiphysin antibodies.

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Symptoms

progressive stiffening of back or a limb which may worsen under stress/pressure (i.e. crossing a busy street, etc.)
sensation of aching or stiffness
stiffness, rigidity, hypertonia, or increased tone
spasms of involved muscles that are severe, tremendous, intense, and painful
proneness to unprotected falls (i.e. falling over like a tin soldier)
When in spasm the muscles are hard to palpation and may produce abnormal joint position: extension or contraction
Spasms may be triggered by sudden noise, touch, electrical shock, passive or volitional movement and are typically relieved by sleep
An increase in the normal curvature of the lumbar spine or hyperlordosis is common
strong association with other autoimmune diseases such as diabetes, hyperthyroidism, hypothyroidism, pernicious anemia and vitiligo
before correct diagnosis, symptoms might be considered psychosomatic and often people are considered for psychiatric evaluation because symptoms wax and wane over time and are apparently worsened by heightened emotional states
Patients with SMS have been described at fearful, afraid and depressed; it is important to consider the impact of the symptoms of SMS on the patientís overall well-being

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Causes

Genetics

The disease has not been described in members of the same family and there is no known genetic predisposition. An association with human leukocyte antigen (HLA) type has been described.

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Diagnosis

Antibody testing

While the absence of antibodies in the serum does not rule out SMS, the presence of anti-GAD autoantibodies strongly supports that diagnosis (99% specific by immunocytochemistry). There are several ways to measure anti-GAD antibodies: immunocytochemistry and Western blotting were the first methods used. Immunocytochemistry allows the detection of antigens in tissue section whereas Western blotting visualizes protein antigens which have been separated by size. ELISA and radioimmunoassay (RIA) use antigen specific binding to attach enzyme linked or radioactively labeled substrates to the antibodies in serum. Developed more recently ELISA and RIA have the advantage of quantitatively assessing the amount of anti-GAD antibody a patient has produced.

Physical exam

Central to evaluation for SMS is a detailed history and neurological exam. The cardinal symptoms are essential to the diagnosis of this disease and isolated laboratory results do not stand alone. The symptoms of stiffness, rigidity or increased tone, spasm or pain are identified by the patient and physician together. The areas of involvement may include the face, neck, abdomen or arms but more typically the legs or lumbar spine are involved. The response to medications is important in discriminating other causes of stiffness e.g. Parkinsonís disease and spasticity. Evaluation may include tests to rule out other causes of stiffness such as multiple sclerosis or transverse myelitis.

Electromyography

Electromyography (EMG) is an important diagnostic tool in evaluating patients for SMS. The typical pattern of continuous low frequency firing of normal motor units or continuous motor unit activity (CMUA) is found simultaneously in agonist and antagonist muscles of the affected region. This abnormal firing pattern is abolished by centrally and peripherally acting agents (general anesthesia, intravenous diazepam, neuromuscular blockade). The EMG findings of SMS may be subtle in patients who are fully treated for the symptoms of SMS.

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Treatment

There are several important features specific to the treatment of this disease. Although there seems to be a strong autoimmune link, immunomodulating therapies have yet to produce consistent results. Anecdotal reports of response to prednisone, immunoglobulin or plasmapheresis have appeared. The most consistently effective therapy is benzodiazepines. These drugs produce symptomatic relief and discontinuation often leads to reemergence of symptoms. Other drugs which modulate the function of GABAergic neurons are employed with variable efficacy. Physical therapy may exacerbate spasms in some patients and should be used carefully in those for whom passive motion may be a trigger of spasm. The course of the disease is variable; there are reports of patients with SMS who respond well to medication and are able to exercise vigorously. Abrupt withdrawal of therapy may be harmful.

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