Background/Purpose: Steroid-responsive encephalopathy and associated autoimmune thyroiditis (SREAT) is characterized by encephalopathy and the presence of antithyroid antibodies. We describe the clinical presentation, outcome and treatments for SREAT by a systematic review of the literature. 

Methods:  MEDLINE via PubMed, Web of Science and the Cochrane Library were searched for articles published until 2015. Inclusion criteria were unexplained encephalopathy with antithyroid antibodies.

Results: We found reports of 251 patients (median age 52 years [range 18–86], 73% females, 80 [32%] with preexisting thyroiditis). Patients presented encephalitis signs with convulsions (n=117; 47%), confusion (n=115, 46%), speech disorder (n=91, 37%), memory impairment (n=107, 43%), gait disturbance (n= 67, 27%) and persecutory delusions (n=61, 25%). 28 patients (11%) presented progressive memory impairment and 26 (10%) isolated psychiatric disorders. In serum, 34% of patients were positive for anti-thyroid peroxidase (TPO) antibodies, 7% for anti-thyroglobulin (TG) antibodies, and 69% both. Thyroid-stimulating hormone levels were usually normal, at 2 UI/ml [0.001–205]. Cerebrospinal fluid analysis showed mild to moderate hyperproteinorachia in 107/131 patients (82%), with median level 0.71 g/l [0.13–7.65]. Cerebrospinal fluid from 10/53 patients (19%) was positive for anti-TPO antibodies, 2/53 (4%) anti-TG antibodies and 28 (53%) both. Electroencephalography findings were abnormal for 82% of patients, showing diffuse slowing consistent with encephalopathy (70%) or epileptic activity (14%). The first-line treatment was steroids in 193 patients and other immunosuppressive drugs in 10 (intravenous immunoglobulin (n=4), azathioprine (n=2), plasma exchange (n=2), rituximab (n=1) or hydroxychloroquine (n=1). Among 146 patients evaluated within a median delay of 5 days [1-20], 134/146 (92%) showed neurological response. At a median final follow-up of 12 months [range 0.2–110], 91% of patients showed complete or partial neurological response, with anti-TPO and -TG antibody titers at 347 UI/ml [0–825000] and 110 UI/ml 0–50892], respectively. During follow-up, 40 patients (16%) experienced at least one relapse. Relapse was more frequent in patients with initial coma (26% vs 13%, p=0.08).

Conclusion:

SREAT is a rare syndrome with various clinical presentations that should be considered in any patient with acute or subacute encephalopathy without obvious etiology but also with progressive cognitive impairment and psychiatric signs, to quickly start corticosteroid treatment. The benefit of other immunosuppressive drugs remains to be determined. Table 1:

Table 1. General characteristics of 251 patients with steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT).

Data are no. (%) unless indicated.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/steroid-responsive-encephalopathy-associated-with-autoimmune-thyroiditis-characteristics-treatment-and-outcome-in-251-cases-from-the-literature/