LAUSR

Background Stiff Person Syndrome (SPS) an encephalomyelitis, is an immune-mediated disorder characterized by rigidity of the axial and proximal limb muscles with painful spasThis rare disease responds to immunotherapies and is frequently associated with other autoimmune diseases. More than 80% of SPS patients have autoantibodies to GAD65 and up to 15% have antibodies to glycinereceptor. Neurophysiological studies can help in the diagnosis by demonstrating the presence of continuous motor unit activity at rest, that the patient cannot voluntarily suppress. Material and methods We present a male patient 28 y/o with a history of weight loss, abdominal pain, ortostathic hypotension, ptosis and babinski sign, whith stiffness and painful spasms in both cuadriceps, tibialis anterior, gastronemius, rectus abdominis, thoracic and lumbar paraspinal muscles. Results EMG showed continuous, involuntary activity of normal motor unit potentials. Painful spasms of involuntary muscle activity, were also detected. No other abnormal spontaneus activity such as fibrilations, positive waves, miokimias, high frequency nor myotonic or neuromyotonic discharges were recorded. The SSR was absent en both hands. The Silent period was normal. ENG and SFEMG were normal. Antibodies to glycinereceptors were positive. After treatment with IvIg and plasma exchange the patient had moderate improvement and at present he is on baclofen, diazepam, methylprednisone and levetirazetam, with persistence of fluctuating stiffness and spas. Conclusions The neurophysiological studies play an important role in the differential diagnosis of the diseases associated with excess motor unit activity, leading in this patient to the diagnosis of encephalomyelitis with rigidity, variant of SPS.