Steroid-Responsive Epilepsia Partialis Continua with Anti-Thyroid Antibodies: A Spectrum of Hashimoto's Encephalopathy?

Abstract

Background: When a neuropsychiatric symptom due to encephalopathy develops in a patient with anti-thyroid antibodies, especially when the symptom is steroid-responsive, Hashimoto's encephalopathy (HE) needs to be included in the differential diagnosis of the patient. Although HE is an elusive disease, it is thought to cause various clinical presentations including seizures, myoclonus, and epilepsia partialis continua (EPC).

Case report: We present the case of a 33-year-old Japanese woman who acutely developed EPC in the right hand as an isolated manifestation. A thyroid ultrasound showed an enlarged hypoechogenic gland, and a thyroid status assessment showed euthyroid with high titers of thyroid antibodies. A brain MRI revealed a nodular lesion in the left precentral gyrus. Corticosteroid treatment resulted in a cessation of the symptom.

Conclusions: A precentral nodular lesion can be responsible for steroid-responsive EPC in a patient with anti-thyroid antibodies and may be caused by HE. The serial MRI findings of our case suggest the presence of primary demyelination, with ischemia possibly due to vasculitis around the demyelinating lesion.

Keywords: Demyelination; Epilepsia partialis continua; Hashimoto's disease; Hashimoto's encephalopathy; MRI; Vasculitis.

Fig. 1

Brain MRIs of a patient with HE presenting with a unilateral frontal nodular lesion. The initial brain MRI on day 10 revealed a nodular lesion in the left precentral gyrus on FLAIR images (a), DWI (b), and an ADC map (c). MRIs conducted on day 22 showed an enlargement of the lesion on FLAIR images (d), hyperintensities in the central part of the lesion on DWI (e), and an increased value on an ADC map (f). A FLAIR MRI sequence revealed a remarkable reduction in the size of the lesion following steroid treatment as compared with that before treatment (not shown).