Stiff person syndrome: An unusual paraneoplastic neurological phenomenon in Carcinoid tumour

ABSTRACT

@#Stiff person syndrome is a rare neurologic disorder characterised by rigidity of the truncal and proximal limb muscles with intermittent superimposed spasms. It’s unique because it lacks similarity to any other neurologic disorder. Possibly tetanus is the closest related condition with both inhibiting central gamma-aminobutyric (GABA) systems. Stiff person syndrome is extremely rare with less than 20 cases reported from South Asia which has a population of nearly 2 billion. In its classic form, it is associated with the presence of high titres of glutamic acid decarboxylase (GAD) antibodies. Paraneoplastic stiff person syndrome comprising of around 5% of the patients has been reported with malignancies of the breast, colon, lung, thymus and Hodgkin’s lymphoma. Antibodies against amphiphysin and gephyrin are detected in paraneoplastic stiff person syndrome. We report a 58 year old Sri Lankan male with stiff person syndrome with a high GAD antibody titre and classical electromyographic changes, who was found to have an underlying carcinoid tumour. We postulate that stiff person syndrome was a paraneoplastic phenomenon secondary to the carcinoid in this case. Although neurological syndromes such as sensory neuropathy, limbic encephalitis and, myelopathy have been described as paraneoplastic features in carcinoid, we believe this is the first report of stiff person syndrome associated with carcinoid tumour.