The stiff man syndrome is a rare disorder of the CNS, which is characterised clinically by fluctuating and progressive muscle rigidity and spasms. It was recognised as a distinct entity in 1956 by Moersch and Woltman.1 2 The diagnosis relies also on the presence of continuous motor unit activity, without evidence of neuromyotonia, extrapyramidal or pyramidal dysfunction, or focal lesions of the spinal cord. Rigidity and spasms may dominate in the axial muscles, or in one or more distal limbs at clinical examination.

In 1986, the acute onset of diabetic ketoacidosis in a patient affected by stiff man syndrome, prompted us to investigate further the potential pathogenetic association of the two entities.3-5 …