|Note|| Stiff-person syndrome is a rare neurological disorder
characterized by stiffness of skeletal muscles with superimposed
spasms. The syndrome is a putative autoimmune disease occurring
as an idiopathic or paraneoplastic condition. It is often
associated with antibodies to glutamic acid decarboxylase (GAD)
or, less commonly, to the 128 kD synaptic protein later
amphiphysin (AMPH) and few other autoantigens.| |Phenotype and
clinics|| Diagnosis of GAD-antibody associated stiff-person
syndrome is made according to the following criteria: Prodrome
of stiffness and rigidity in axial muscles | Progression to
include stiffness of limbs, making walking difficult Increased
lumbar lordosis Presence of superimposed painful spasm, often
precipitated by external stimuli (auditory stimulation like hand
clapping) Normal sensation, no paresis An EMG finding of
continuous motor unit activity (CMUA) at rest Response to
benzodiazepines including clinical response and reduction on
CMUA High levels of GAD antibodies Other fe