Hyponatraemia presenting as reversible cerebellar ataxia in Addison's disease.

Addison's disease is a common endocrinopathy often diagnosed in patients presenting with hyponatraemia. Cerebellar ataxia as a presentation of hyponatraemia is extremely rare. A 42-year-old man presented with vomiting, fever, ataxic gait and scanning type of dysarthria. Clinical examination revealed signs suggestive of isolated cerebellar involvement. Patient was found to have severe hyponatraemia and serum cortisol was found to be extremely low while MRI brain was found to be normal. Corticosteroid therapy was initiated and cerebellar ataxia was resolved following normalisation of sodium levels.