[Autoimmune encephalopathy in Hashimoto's thyroiditis. A differential diagnosis in progressive dementia syndrome].

HISTORY AND CLINICAL FINDINGS

A 58-year-old woman, known for 10 years to have Hashimoto's thyroiditis, was admitted from another hospital where, after an initial period of unconsciousness, she had developed progressive severe dementia, abnormal arousal and generalized myoclonia. Jakob-Creutzfeldt disease (JCD) was suspected.

INVESTIGATIONS

The electroencephalogram (EEG) showed marked slowing of the basic activity and episodes of triphasic waves. The titres of thyroid antibodies (TPO 764 kU/l, TgAk 398 kU/l) and of the antinuclear antibodies (ANA 1:1280) were raised, as was the erythrocyte sedimentation rate (80/120 mm and the cerebrospinal fluid albumin concentration (1 g/l).

TREATMENT AND COURSE

The history and findings suggested autoimmune encephalitis (AIE) and treatment with prednisolone, 2 mg/kg body weight daily, was initiated, achieving lasting improvement of arousal within two days. 6 weeks later the EEG merely showed mild alteration of basic activity. The thyroid antibody titres were now within normal limits and the signs of inflammation were regressing.

CONCLUSION

In case of rapidly progressive dementia autoimmune antibodies should be looked for in the differential diagnosis, because autoimmune disease may be the treatable cause.