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Table of Contents    
Year : 2020  |  Volume : 68  |  Issue : 3  |  Page : 681-683

Sudden-onset Encephalopathy: Do not ignore the Possibility of Hashimoto's Encephalopathy

King Fahd Hospital, Department of Neurology, Imam Abdulrahman Binfaisal University, Dammam, Saudi Arabia

Date of Web Publication6-Jul-2020

Correspondence Address:
Dr. Erum Mubbashir Shariff
King Fahd Hospital of University, Imam Abdulrahman Binfaisal University, Dammam
Saudi Arabia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0028-3886.289015

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 » Abstract 

Hashimoto's encephalopathy (HE) is an uncommon neurological disorder of unknown etiology, found in association with thyroid autoimmunity, mostly uncommon in males. The disease occurs primarily in the fifth decade of life and may occur in two forms; a sudden vasculitic type or a progressive subacute type associated with cognitive dysfunction, confusion, and memory loss. We report a case of a 51-year-old Sri Lankan gentleman with no comorbidities who was presented with one episode of the generalized tonic- clonic seizure (GTCs) followed by prolonged agitation and disorientation. His EEG showed generalized slowing while CT scan and MRI brain were unremarkable. CSF examination showed high protein level with normal cell count and glucose. Routine serologic examination showed very high thyroid-stimulating hormone (TSH) level, with significantly high antithyroid antibodies. He was diagnosed as a case of Hashimoto's encephalopathy and treated with a high dose of steroid and showed remarkable improvement.

Keywords: Autoimmune, Hashimoto encephalopathy, hypothyroidism
Key Messages: HE should always be considered in cases of persistent agitation and disorientation after a single seizure, despite the control of seizures and treatment for possible central nervous system (CNS) infection.

How to cite this article:
Shariff EM. Sudden-onset Encephalopathy: Do not ignore the Possibility of Hashimoto's Encephalopathy. Neurol India 2020;68:681-3

How to cite this URL:
Shariff EM. Sudden-onset Encephalopathy: Do not ignore the Possibility of Hashimoto's Encephalopathy. Neurol India [serial online] 2020 [cited 2023 Mar 21];68:681-3. Available from: https://www.neurologyindia.com/text.asp?2020/68/3/681/289015

Hashimoto's encephalopathy (HE) is a complex disorder that is characterized by a heterogeneous clinical clustering of seizures, stroke-like episodes, cognitive and behavioral changes, and neurological features such as myoclonus. A diagnosis is usually made by having a high index of suspicion for the disorder, considering other causes of encephalopathy and detecting high titres of antithyroid antibodies. HE is a rare disease with an estimated prevalence of 2 per 100,000 people.[1] Approximately more than 100 scientific articles on Hashimoto's encephalopathy have been reported and published between 2000 and 2013.[1] Steroids remain the first-line treatment for this condition after the exploration of effective therapies. We report a case of HE, who presented acute generalized tonic-clonic seizure (GTCs) and delirium and who had been diagnosed as HE and treated with steroid, further showing remarkable recovery.

 » Case History Top

We report a case of a 51-year-old man diagnosed with Hashimoto's encephalopathy, who presented with one episode of GTCs followed by disorientation and agitation. He was healthy in the past and had worked as a chef in a private house. According to his employer, he was perfectly well earlier. On admission, he was severely agitated and disoriented, and was unable to follow commands. His vital signs were stable except body temperature of 38°C; he was moving all four limbs equally, with + 3 deep tendon reflexes, and flexor planters bilaterally. There were no signs of meningeal irritation found. Complete blood count, serum electrolyte, blood urea nitrogen, creatinine, and liver function tests were all normal. His EEG showed generalized slowing, CT scan, and MRI brain were unremarkable and cerebrospinal fluid (CSF) showed protein of 126 (21–41), with normal cell count and negative HSV PCR. TSH was performed as a routine test which came out to be very high 33.23 (0.35–4.94). Repeat TSH test was also high, fT4 was low 0.63 (0.70–1.48 while fT3 was normal 1.84 (1.71–3.71). Antithyroid antibodies titres were significantly high, including antithyroid peroxidase (anti-TPO) level of 83.0 (<5.6) and antithyroglobulin (ATA) level 26 (<4.11). The patient was initially treated with acyclovir but showed no improvement. After all the investigation results were reported, the diagnosis of HE was established. The patient was started on high dose intravenous steroid with remarkable improvement. Steroids were tapered off gradually and later he was started on levothyroxine.

 » Discussion Top

Hashimoto's encephalopathy is a term used to describe an encephalopathy of presumed autoimmune origin characterized by high titres of antithyroid peroxidase antibodies. It was initially described in 1966.[2] Since HE is a treatable disorder, it should be considered in cases of unexplained encephalopathy. Our patient showed hypothyroidism; however, previous studies revealed cases presented with euthyroidism or even hyperthyroidism.[2],[3] Therefore, normal or slightly abnormal thyroid function tests (TFTs) do not exclude the diagnosis.

The clinical presentation may involve a relapsing and remitting course and include seizures, stroke-like episodes, cognitive decline, neuropsychiatric symptoms, and myoclonus. Systemic symptoms such as malaise, myalgia, and fatigue can occur in Hashimoto's encephalopathy, although, fever is rarely described. The mean age of symptoms' onset ranges from 45 to 55 years. The condition is more frequently found in females than in males, with a ratio of ~ 5:1.[4],[5]

Thyroid function is usually clinically and biochemically normal. Diagnosis is made in the first instance by excluding other toxic, metabolic, and infectious causes of encephalopathy with neuroimaging and CSF examination. Neuroimaging findings are often not helpful in clarifying the diagnosis. Although most of the described cases showed neural symptoms for months before the acute onset, in this case, we acknowledged a dramatic acute onset. Thus, neurologic complications can begin either abruptly, in the form of seizures or agitation, with or without other neurologic complaints, or they can develop gradually, in a relapsing-remitting manner, including, among others, cognitive deterioration and psychiatric illness.

Most cases of Hashimoto's encephalopathy are either clinically euthyroid or subclinically (low thyroid hormone levels without clinical signs) hypothyroid (>60%). CSF is usually examined in cases of encephalopathy. In Hashimoto's encephalopathy, elevated CSF protein was found in 80% of cases.[2],[3] Initially thought to be a diagnostic marker for Creutzfeldt-Jakob disease (CJD), 14-3-3 protein is now known to be a nonspecific marker of diffuse neuronal injury.[6],[7] Elevated 14-3-3 has been reported in a few patients with Hashimoto's encephalopathy and is not of specific diagnostic significance. EEG findings are nonspecific. The most frequently reported abnormalities are slow-wave abnormalities associated with any encephalopathic process.[8] Although abnormalities in computed tomography (CT) scans of the brain have been reported in as many as 50% of cases [9] findings are generally nonspecific. Initially, both CNS and systemic causes of encephalopathy need to be considered. Systemic disorders such as sepsis, hepatic failure, and renal failure may produce an encephalopathic picture but can be readily excluded on clinical grounds and routine investigations. Infectious CNS causes such as meningitis or encephalitis can be excluded by appropriate CSF analysis; the vascular and neoplastic disease is usually detected with structural or functional neuroimaging techniques; seizure disorders can usually be excluded by single EEG or prolonged EEG monitoring; thyroid hormone studies are not helpful but may identify subclinical thyroid dysfunction. Detection of antithyroid (anti-TPO) antibodies further confirms the diagnosis.[10] Despite the link to autoimmune thyroid disease, the etiology of Hashimoto's encephalopathy is unknown. It is likely that antithyroid antibodies are not pathogenic but titres can be a marker of treatment response. Pathological findings can suggest an inflammatory process but features of a severe vasculitis are often absent. The links between the clinical pictures, thyroid disease, auto-antibody pattern, and brain pathology await further clarification through research. It may be that Hashimoto's encephalopathy will be subsumed into a group of nonvasculitic autoimmune inflammatory meningoencephalopathies. This group may include disorders such as limbic encephalitis associated with voltage-gated potassium channel antibodies. Some authors have suggested abandoning any link to Hashimoto and renaming the condition as “steroid-responsive encephalopathy associated with autoimmune thyroiditis” to better reflect current, if limited, understanding of this condition.

HE is a rare but very serious illness. The incidence is probably underestimated because of the low overall awareness about the disease. [11,12]

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.


The author would like to thank the patient and administration for the contribution.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

 » References Top

Zhu Y, Yang H, Xiao F. Hashimoto's encephalopathy: A report of three cases and relevant literature reviews. Int J Clin Exp Med 2015; 8:16817-26.  Back to cited text no. 1
Chong JY, Rowland LP, Utiger RD. Hashimoto encephalopathy: Syndrome or myth? Arch Neurol 2003; 60:164-71.  Back to cited text no. 2
Sawka AM, Fatourechi V, Boeve BF, Mokri B. Rarity of encephalopathy associated with autoimmune thyroiditis: A case series from Mayo Clinic from 1950 to 1996. Thyroid 2002;12:393-8.  Back to cited text no. 3
Payer J, Petrovic T, Baqi L, Lisy L, Langer P. Hashimoto's encephalopathy and rare cases of hyperthyroidism (review and case report). Endocr Regul 2009;43:169-78.  Back to cited text no. 4
Oide T, Tokuda T, Yazaki M, Watarai M, Mitsuhashi S, Kaneko K, et al. Anti-neuronal autoantibody in Hashimoto's encephalopathy: Neuropathological, immunohistochemical, and biochemical analysis of two patients. J Neurol Sci 2004;217:7-12.  Back to cited text no. 5
Shiga Y, Wakabayashi H, Miyazawa K, Kido H, Itoyama Y. 14-3-3 protein levels and isoform patterns in the cerebrospinal fluid of Creutzfeldt-Jakob disease patients in the progressive and terminal stages. J Clin Neurosci 2006; 13:661-5.  Back to cited text no. 6
Vander T, Hallevy C, Alsaed I, Valdman S, Ifergan G, Wirquin I. 14-3-3 protein in the CSF of a patient with Hashimoto's encephalopathy. J Neurol 2004;251:1273-4.  Back to cited text no. 7
Schauble B, Castillo PR, Boeve BF, Westmoreland BF. EEG findings in hypophysitis treated with intravenous glucocorticoid therapy. Steroid-responsive encephalopathy associated with autoimmune thyroiditis. Clin Neurophysiol 2003;114:32-7.  Back to cited text no. 8
Chaudhuri A, Behan PO. The clinical spectrum, diagnosis, pathogenesis and treatment of Hashimoto's encephalopathy (recurrent acute disseminated encephalomyelitis). Curr Med Chem 2003;10:1945-53.  Back to cited text no. 9
Kothbauer-Margreiter I, Sturzenegger M, Komor J, Baumqartner R, Hess CW. Encephalopathy associated with Hashimoto thyroiditis: Diagnosis and treatment. J Neurol 1996;243:585-93.  Back to cited text no. 10
Pradhan S, Das A, Mani VE. Immunotherapy in autoimmune encephalitis - A need for “presumptive” diagnosis and treatment. Neurol India 2018;66:1584-9.  Back to cited text no. 11
[PUBMED]  [Full text]  
Harzheim M, Feucht J, Pauleit D, Pöhlau D. Hashimoto's encephalopathy and motor neuron disease: a common autoimmune pathogenesis? Neurol India 2006;54:301-3.  Back to cited text no. 12
[PUBMED]  [Full text]  

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[Pubmed] | [DOI]


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