Hashimoto Encephalopathy

CLINICAL COMMUNICATION TO THE EDITOR

Hashimoto Encephalopathy: A Case Report To the Editor: An 89-year-old woman presented to our emergency department with a 3-day history of loss of appetite and altered mental status. She had underlying type 2 diabetes mellitus and adenomatous goiter of thyroid. Her family reported a 3-day history of agitation before admission. On admission she reported no fever, abdominal pain, constipation, or diarrhea. On physical examination she was in acute distress, with a body temperature of 36.6 C, heart rate of 111 beats per minute, blood pressure of 186/88 mm Hg, respiratory rate of 24 per minute, and an oxygen saturation of 98% on room air. On admission her Glasgow coma scale score fluctuated between E1V1M1 and E4V4M6. Results from all motor and sensory examinations were normal. The laboratory findings were as follows: white blood cell count, 11,200/mL; serum sodium, 108 mEq/L; serum potassium, 3.6 mEq/L; and serum chloride, 74 mEq/L. Her blood glucose level was 122 mg/dL. The serum osmolarity was 231 mOsm/L. Her serum thyroid-stimulating hormone level was 0.68 mIU/mL, with a free T4 level of 1.24 ng/dL. Her cerebrospinal fluid (CSF) appeared clear with no signs of xanthochromia. The CSF cell count was 1/mm3 with 1 lymphocyte, and the CSF glucose concentration was 173 mg/dL. Despite treatment of hyponatremia with hydration, myoclonus and progressive altered mental status developed during her admission. We decided to perform magnetic resonance imaging (MRI) of the brain and electroencephalography (EEG). Findings on MRI were normal. The EEG demonstrated nonspecific slow waves without spikes. Because of her previous history of adenomatous goiter of thyroid, Hashimoto encephalopathy was suspected. Thus, we conducted further blood tests, including anti-TPOAb and anti-TgAb titrers, which were found to be 137.1IU/mL and 60.7IU/mL, respectively. Anti-NH2-terminal of a-enolase (NAE) antibody was negative. A diagnosis of Hashimoto encephalopathy was established according to the criteria of Peschen-Rosin et al.1 After the diagnosis was established on the 14th day of admission, we initially administered

prednisolone (30 mg/d). However, the dose of prednisolone was subsequently increased to 50 mg/d because her altered mental status remained unchanged. After increasing the dosage, her mental status drastically improved and completely resolved. The patient received 50 mg prednisolone for 7 days before the dosage was gradually decreased. Upon discharge, her altered mental status had resolved completely without any long-term complications, while she continued to receive 25 mg prednisolone. Hashimoto encephalopathy is a rare syndrome associated with autoimmune thyroiditis, as first reported by Brain et al in 1966.2 Peschen-Rosin et al1 described the criteria for the diagnosis of Hashimoto encephalopathy as unexplained episodes of relapsing various neurologic symptoms and at least 3 of the following: abnormal EEG; positive antiTPOAb; elevated CSF protein; excellent response to steroids; and normal head MRI findings. Anti-NAE antibody has utility as a biomarker of Hashimoto encephalopathy, with a sensitivity and specificity of 50% and 91%, respectively.3 Because 5%-15% of men and 10%-25% of women in Japan are believed to have anti-TPOAb antibodies,3 the number of unrecognized patients with Hashimoto encephalopathy may be higher in Japanese populations than in Western populations. Patients with Hashimoto encephalopathy may demonstrate various symptoms, with normal thyroid function in the majority of cases that may be elevated or depressed. Accordingly, Hashimoto encephalopathy is often misdiagnosed. However, this disease represents a treatable form of dementia that physicians must be aware of. For these reasons, Hashimoto encephalopathy is an extremely important, though rare, diagnosis. Hashimoto encephalopathy should be suspected and screened for in patients with encephalopathy due to unknown causes because responses to treatment are typically excellent. Ryota Sato, MD Tadaaki Takada, MD Michitaka Nasu, MD Department of Emergency and Critical Care Medicine Urasoe General Hospital Okinawa, Japan

http://dx.doi.org/10.1016/j.amjmed.2016.04.021

References Funding: None. Conflict of Interest: None. Authorship: All authors had access to the data and played a role in writing the manuscript. Requests for reprints should be addressed to Ryota Sato, MD, Urasoe General Hospital, 4-16-1, Iso, Urasoe-city, Okinawa 901-2131, Japan. E-mail address: [email protected] 0002-9343/$ -see front matter Ó 2016 Elsevier Inc. All rights reserved.

1. Peschen-Rosin R, Schabet M, Dischgans J. Manifestation of Hashimoto’s encephalopathy years before onset of thyroid disease. Eur Neurol. 1999;41(2):79-84. 2. Brain L, Jellinek EH, Ball K. Hashimoto’s disease and encephalopathy. Lancet. 1966;2(7462):512-514. 3. Yoneda M. Hashimoto encephalopathy and autoantibodies. Brain Nerve. 2013;65(4):365-376.