Steroid responsive encephalopathy associated with autoimmune thyroiditis
Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT), also known as Hashimoto encephalopathy, is a rare and well-recognized neurological complication of autoimmune thyroid disease and occurs independently of the thyroid status. Patients exhibit neurological symptoms in the presence of serologic evidence of autoimmune thyroid disease, usually, in the majority of cases, with a normal MRI scan.
It is a rare condition with a few case reports in the medical literature.
Symptoms are non-specific and usually manifest in a relapsing and remitting pattern; they can include seizures, stroke-like signs (transient focal neurologic deficits), psychosis, dementia and coma 1,3.
It is not common to have thyroid dysfunction at the time of neurologic presentation 2.
- no evidence of bacterial or viral infection
- positive for a high serum concentration of antithyroid microsomal, antithyroid peroxidase, or antithyroglobulin antibodies
The pathogenesis of SREAT is not well understood, it is believed to represent a cross-reaction between autoimmune antithyroid antibodies and neurons resulting in a diffuse CNS inflammation 1,2.
MRI studies are frequently normal (around 60%). When abnormalities are present they are non-specific, such as 2:
- T2/FLAIR: subcortical white matter high signal intensities
- T1 C+ (Gd): contrast enhancement of the meninges can occur
Treatment and prognosis
Most patients respond to glucocorticoid therapy 4, however a minority of patients require other immunosuppressants or therapies such as intravenous immunoglobulin or plasmapharesis. Patients may require life-long therapy in order to avoid relapses 4.
History and etymology
Hashimoto thyroiditis was first described in 1912 by Hakaru Hashimoto, Japanese physician (1881-1934) whilst working in Germany 5,6.
- 1. Mahad DJ, Staugaitis S, Ruggieri P et-al. Steroid-responsive encephalopathy associated with autoimmune thyroiditis and primary CNS demyelination. J. Neurol. Sci. 2005;228 (1): 3-5. doi:10.1016/j.jns.2004.08.015 - Pubmed citation
- 2. Degnan AJ, Levy LM. Neuroimaging of rapidly progressive dementias, part 2: prion, inflammatory, neoplastic, and other etiologies. AJNR Am J Neuroradiol. 2014;35 (3): 424-31. doi:10.3174/ajnr.A3455 - Pubmed citation
- 3. Reorganized text. JAMA Otolaryngol Head Neck Surg. 2003;141 (2): 428. doi:10.1001/archneur.60.2.164 - Pubmed citation
- 4. Endres D, Perlov E, Stich O, van Elst LT. Steroid responsive encephalopathy associated with autoimmune thyroiditis (SREAT) presenting as major depression. (2016) BMC Psychiatry. 16 (1): 184. doi:10.1186/s12888-016-0897-3 - Pubmed
- 5. H. Hashimoto: Zur Kenntnis der lymphomatösen Veränderung der Schilddrüse (Struma lymphomatosa). Archiv für klinische Chirurgie, Berlin, 1912, 97: 219−248.
- 6. Sawin CT. The heritage of Dr. Hakaru Hashimoto (1881-1934). (2002) Endocrine journal. 49 (4): 399-403. Pubmed