Thyroid Research and Practice

CASE REPORT
Year
: 2018  |  Volume : 15  |  Issue : 1  |  Page : 52--55

Steroid-responsive encephalopathy in autoimmune thyroiditis: A diagnostic enigma?


Balram Sharma, Vijay Kumar Bhavi, Hardeva Ram Nehra, Anshul Goyal, Sanjay Saran, Sandeep Kumar Mathur 
 Department of Endocrinology, SMS Medical College, Jaipur, Rajasthan, India

Correspondence Address:
Dr. Balram Sharma
Department of Endocrinology, SMS Medical College, JLN Road, Jaipur - 302 015, Rajasthan
India

Abstract

Hashimoto's encephalopathy or steroid-responsive encephalopathy associated with autoimmune thyroiditis is a neuroendocrine disorder of unknown cause associated with thyroid autoimmunity. We report case of a 61-year-old male, previously healthy, who developed a subacute onset of declining higher mental functions. Serologic studies demonstrated the high levels of antithyroid antibodies. Electroencephalographic, cerebrospinal fluid, and magnetic resonance image findings were normal, consistent with Hashimoto's encephalopathy. It is a diagnosis of exclusion once the detailed neurology evaluations were done. This unusual disorder is often underrecognized because of the multiple and protracted neurocognitive manifestations; therefore, it is important to be aware of this clinical manifestations to make a correct diagnosis and favorable outcome.



How to cite this article:
Sharma B, Bhavi VK, Nehra HR, Goyal A, Saran S, Mathur SK. Steroid-responsive encephalopathy in autoimmune thyroiditis: A diagnostic enigma?.Thyroid Res Pract 2018;15:52-55


How to cite this URL:
Sharma B, Bhavi VK, Nehra HR, Goyal A, Saran S, Mathur SK. Steroid-responsive encephalopathy in autoimmune thyroiditis: A diagnostic enigma?. Thyroid Res Pract [serial online] 2018 [cited 2021 Jul 28 ];15:52-55
Available from: https://www.thetrp.net/text.asp?2018/15/1/52/228381


Full Text



 Introduction



Hashimoto's encephalopathy is a poorly understood syndrome consisting of heterogeneous neurological symptoms and high-serum antithyroid antibody titers, typically responding to steroids. After 38 years and reports of more than 100 cases of Hashimoto's encephalopathy, it is still debatable whether this is a specific syndrome seen in patients with Hashimoto's thyroiditis or the coincidence of a rare neurologic condition with a common endocrine disease. Only a few of these cases have been reported in the endocrinology literature, and endocrinologists are still less familiar with this clinical entity and terminology more frequently seen and used by neurologists, respectively.

 Case Report



A 61-year-old male known hypertensive presented with a history of mild grade fever which followed by tremulousness in the upper limbs and incoordination in bilateral lower limbs associated with history of walking like a drunken person for the past1 year. The patient also had formed visual hallucinations along with. There are no complaints of weakness in the upper limbs/slurring of speech/any bowel, bladder and bulbar involvement, altered consciousness, and headache/nausea/vomiting. This was associated with the history of forgetfulness and behavior abnormalities in the form of increased agitation. History of occasional myoclonic jerks affecting the truncal area was also present while riding as a pillion on a bike. On examination, general physical examination was normal. Systemic examination including central nervous system (CNS) was normal. Mini-mental score examination score was 27/30. The patient was conscious, oriented, following verbal commands. Motor system was normal except increased tone in all four limbs. Cranial nerves, sensory system, and cerebellar examination were normal. The antithyroid peroxidase (TPO) antibody was markedly raised [Table 1]. Magnetic resonance imaging (MRI) brain and Normal magnetic resonance angiography of circle of Willis. was normal [Figure 1]a and [Figure 1]b. Electroencephalograph (EEG) was normal [Figure 1]c. Electroencephalograph (EEG) was normal. Cerebrospinal fluid (CSF) investigation was also normal. The patient was given oral steroids (prednisolone 60 mg orally) keeping the clinical possibility of Hashimoto encephalitis once the other neurologic disorders were ruled out, and the patient showed marked improvement with therapy in his above mentioned clinical features and than the steroid doses were tapered off to a bare minimum of 5 mg every alternate day in few weeks. The patient did not reported again till he had relapse of symptoms after few months when he discontinued treatment. He was again stated on steroids and showed improvement as he did previously.{Table 1}{Figure 1}

 Discussion



Hashimoto's encephalopathy, also known as steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT), is a neurological condition characterized by relapsing encephalopathy, thyroid autoimmunity, and good clinical response to steroids. It is associated with Hashimoto's thyroiditis. It was first described in 1966.[1] It is sometimes referred to as a neuroendocrine disorder. The literature shows no proven association between thyroid disease and the neurologic process. Although the association of a common endocrinology condition and a rare neurologic disease may occur by chance, this type of encephalopathy probably has an autoimmune nature and thus is more likely to occur in the background of another autoimmune condition such as autoimmune thyroid.[2] Despite the link to autoimmune thyroid disease, the exact etiology of Hashimoto's encephalopathy is still unknown. In some reported cases of Hashimoto's encephalopathy, an association with other autoimmune conditions is found.

It is likely that antithyroid antibodies are not pathogenic. Pathological findings can suggest an inflammatory process, but features of severe vacuities are often absent. Consistent with this hypothesis, autoantibodies to alpha-enolase have been found to be associated with Hashimoto's encephalopathy.[3] Since enolase is the penultimate step in glycolysis, if it were inhibited one would expect decreased energy production by each cell, leading to resulting atrophy of the affected organ. This would occur most likely through each cell shrinking in size in response to the energy deficit. This may occur as a result of not being enough ATP to maintain cellular functions. Two subtypes of Hashimoto encephalopathy were proposed: a vasculitic type with stroke-like episodes and a diffuse, progressive type with insidious onset but progressive deterioration of mental functions. Onset is often gradual and may go unnoticed by the patient and close associates to the patients. It may involve a relapsing and remitting course and may include seizures, stroke-like episodes, cognitive decline, neuropsychiatric symptoms, and myoclonus. The patients described in the original article on Hashimoto's encephalitis had neurological symptoms of myoclonus, dementia, cerebellar ataxia suggestive of a neurodegenerative disorder.

Common differential diagnoses when these conditions are excluded are Creutzfeldt-Jakob disease, rapidly progressive dementias, and paraneoplastic and non-paraneoplastic limbic encephalitis.

Diagnosis must be considered in cases of “investigation negative encephalopathy.” When neurologists are faced with a patient with a possible diagnosis of acute or subacute encephalopathy and no other specific cause is found, an autoimmune process is considered in the differential diagnosis. When direct involvement of the CNS by a well-defined systemic autoimmune disease is excluded, and anti-thyroid antibodies are positive, and the condition responds to corticosteroid therapy, a diagnosis of Hashimoto's encephalopathy is made.[4] The first set of diagnostic criteria for HE was put forward by Peschen-Rosin et al., in 1999, which encompassed the unexplained episodes of relapsing myoclonic, generalized seizures, focal neurological deficits, or psychiatric disorders, and at least 3 of the following: abnormal EEG, elevated thyroid antibodies, elevated CSF protein and/or oligoclonal bands, excellent response to steroids, and unrevealing cerebral MRI.[5] It is made in the first instance by excluding other toxic, metabolic, and infectious causes of encephalopathy with neuroimaging and CSF examination. Thyroid hormone abnormalities are common (>70% cases): subclinical hypothyroidism (35% cases), overt hypothyroidism (20% cases), hyperthyroidism (5% cases), and euthyroid (30% cases).

Thyroid antibodies – both anti-TPO antibodies (anti-TPO antithyroid microsomal antibodies, anti-M) and antithyroglobulin antibodies (anti-Tg) – in the disease are elevated, but their levels do not correlate with the severity. Because most patients respond to steroids or immunosuppressant treatment, this condition is now also referred to as SREAT. Initial treatment is usually with oral prednisone (50–150 mg/day) or high-dose intravenous methylprednisolone (1 g/day) for 3–7 days. Thyroid hormone treatment is also included if required. Failure of some patients to respond to this first-line treatment has produced a variety of alternative treatments including azathioprine, cyclophosphamide, chloroquine, methotrexate, periodic intravenous immunoglobulin, and plasma exchange. There have been no controlled trials, so the optimal treatment is not known. Seizures, if present, are controlled with typical antiepileptic agents. More recent studies, which suggest that relapse commonly, occurs after initial high-dose steroid treatment.[6] If left untreated, this condition can result in coma and death. Endocrinologists should be familiar with the nosology used in the literature. However, they should manage thyroid dysfunction no differently than they would in the absence of encephalopathy. Thyroxine suppressive therapy does not lower antibody levels or suppresses autoimmunity in thyroid patients.

 Conclusion



This case report has shown the existence of this rare but still very important neuroendocrine clinical entity, which is still clinically debatable. Only a handful case report is available in literature. This is basically diagnosis of exclusion but, if this clinical entity is considered in a proper clinical scenario that outcomes are remarkable with carefully selected therapy.

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.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

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2Castillo P, Woodruff B, Caselli R, Vernino S, Lucchinetti C, Swanson J, et al. Steroid-responsive encephalopathy associated with autoimmune thyroiditis. Arch Neurol 2006;63:197-202.
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