3580 Bulbar onset motor neuron disease (MND) as a paraneoplastic phenomenon associated with anti-SOX1 antibodies

Background Motor neuron disease (MND) is a progressive neurodegenerative disease that is universally fatal. Rare cases of paraneoplastic MND have been described in the literature. Anti-Sry-like high mobility group box (SOX) 1 antibodies (anti-SOX1 antibodies) are strongly associated with cancer, in particular non-small cell lung cancer (NSCLC). Anti-SOX1 antibodies have been associated with a number of neurological conditions, most commonly Lambert-Eaton myasthenic syndrome (LEMS) and paraneoplastic cerebellar degeneration (PCD).Cases The present case describes an 83 year old male who presented with a 6 month history of progressive dysarthria, dysphagia, dyspnoea and weight loss. Anti-SOX1 antibodies were positive in the serum, though not detected in cerebrospinal fluid (CSF). CT chest/abdomen/pelvis did not reveal an obvious malignancy, in particular no lesions suggestive of lung cancer. EMG demonstrated widespread complex fasciculations. Physical examination revealed a wasted and weak tongue, with fasciculations present. He was dysarthric and limb examination revealed globally brisk reflexes, with spread of reflexes noted in the lower limbs.Ultimately this patient was diagnosed with bulbar onset MND and chose not to pursue further investigation for possible malignancy.Conclusion/Discussion Paraneoplastic MND is a rare phenomenon that has been rarely described in literature, and this case appears to be the second case of anti-SOX1 associated MND described.