Hashimoto’s encephalopathy is an autoimmune encephalopathy that came to be regarded as a new clinical entity distinct from myxo-oedema encephalopathy, associated with Hashimoto’s thyroiditis.^1,2

Hashimoto’s encephalopathy has a wide clinical spectrum with various neuropsychiatric features. The detection of antithyroid antibodies in patient sera is helpful but not sufficient for the diagnosis of Hashimoto’s encephalopathy because of the high prevalence of antibodies in the normal population.

Recently, we reported serum autoantibodies against the amino (NH₂) terminal region of α enolase (NAE) as a useful diagnostic marker of Hashimoto’s encephalopathy.³

We describe here a patient with Hashimoto’s encephalopathy, who presented with progressive cerebellar ataxia with mild abnormality on electroencephalography (EEG) and showed marked improvement after steroid administration. The patient was diagnosed as having Hashimoto’s encephalopathy owing to the presence of the anti-NAE antibodies as well as antithyroid antibodies in the serum.

A 41-year-old woman, who had a normal dietary history, became aware of a slight unsteadiness while walking and mild dysarthria in December 2003. She had no familial history of neurological disorders or episodes of seizures. The symptoms gradually worsened, and she was admitted to the University of Fukui hospital in September 2004 because she could not stand or walk without support.

Neurological examinations showed severe gait ataxia, slurred speech and dysmetria on finger-to-nose and heel-to-knee manoeuvres. Cognitive functions and intellectual performance were normal. Ocular …