Steroid-responsive encephalopathy associated with thyroiditis: A diagnostic challenge

Aamir Shahzad; Phool Iqbal; Muhammad Bilal Jamshaid; Rubab Fatima Malik; Muhammad Tayyeb; Abdulaziz Zafar

doi:10.4103/LJMS.LJMS_86_20

CASE REPORT

Year : 2021 | Volume : 5 | Issue : 1 | Page : 36-38

Steroid-responsive encephalopathy associated with thyroiditis: A diagnostic challenge

Aamir Shahzad¹, Phool Iqbal¹, Muhammad Bilal Jamshaid¹, Rubab Fatima Malik¹, Muhammad Tayyeb², Abdulaziz Zafar¹
¹ Department of Medicine, Hamad General Hospital, Doha, Qatar
² Department of Medicine, Mayo Hospital, King Edward Medical University, Lahore, Pakistan

Date of Submission	03-Oct-2020
Date of Acceptance	16-Mar-2021
Date of Web Publication	10-Apr-2021

Correspondence Address:
Dr. Muhammad Bilal Jamshaid
Hamad General Hospital, Appartement #332, Area #38, Building #29,AlSADD, Doha
Qatar

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/LJMS.LJMS_86_20

Abstract

steroid responsive encephalopathy associated with autoimmune thyroiditis (SREAT) is an autoimmune entity with a strong association with elevated antithyroid antibodies. It is a rare cause of encephalopathy and is usually a diagnosis of exclusion. Responsive to corticosteroids is required to make the diagnosis. Herein, we report a male patient presented with recurrent convulsive episodes not controlled well by anticonvulsant drugs and had drops in Glasgow coma scale (GCS). After unremarkable of extensive investigations, Hashimoto's encephalitis was suspected and antithyroid peroxidase antibodies test turned out to be positive, while thyroid function tests were normal and the diagnosis of steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT) was made. He received a course of intravenous methylprednisolone for 5 days and responded very well to therapy, with an improvement of his GCS to 15/15.

Keywords: Encephalopathy, thyroiditis, tremors

How to cite this article:
Shahzad A, Iqbal P, Jamshaid MB, Malik RF, Tayyeb M, Zafar A. Steroid-responsive encephalopathy associated with thyroiditis: A diagnostic challenge. Libyan J Med Sci 2021;5:36-8

How to cite this URL:
Shahzad A, Iqbal P, Jamshaid MB, Malik RF, Tayyeb M, Zafar A. Steroid-responsive encephalopathy associated with thyroiditis: A diagnostic challenge. Libyan J Med Sci [serial online] 2021 [cited 2023 Mar 30];5:36-8. Available from: https://www.ljmsonline.com/text.asp?2021/5/1/36/313528

Introduction

Steroid-responsive encephalopathy associated with thyroiditis (SREAT) is an autoimmune entity with a strong association with elevated antithyroid antibodies.^[1] It is a rare cause of encephalopathy and is usually a diagnosis of exclusion. Responsive to corticosteroids is required to make the diagnosis. It has varied presentations ranging from seizures, psychosis, stroke-like episodes, and encephalopathy.^[2] Due to its nonspecific presentation and low clinical suspicion by the physicians, it is often underreported. The purpose of presenting this case is to highlight SREAT as a rare cause of encephalopathy, which should be kept in mind when dealing with a patient with unexplained neurological symptoms.

Case Report

A 57-year-old man with no significant medical history presented to the emergency room (ER) with recurrent convulsive episodes in the past month. On the first visit to ER patient came with complain of symmetrical bilateral upper limb tremors, he was labelled with diagnosis of essential tremor and discharged on propranolol 40mg twice a day. Then, during the second admission, he presented with an accidental fall and developed generalized tonic–clonic seizures while being in ER, aborted by lorazepam. In addition to his propranolol, he was started on phenytoin 100 mg three times a day. His electroencephalogram (EEG) was normal. Magnetic resonance imaging (MRI) of the head was unremarkable apart from nonspecific atrophic changes [Figure 1]. Then, during the third admission, the complaint progressed to involve both upper limbs with jerky movements. Phenytoin was stopped and he was started on levetiracetam 500 mg twice a day.

Figure 1: Magnetic resonance imaging of the brain: Remarkable for atrophic nonspecific changes

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In this admission, he presented with dizziness, generalized weakness, but no loss of consciousness. In the ER, he had an episode of acute involuntary jerky movements in both upper limbs and received diazepam 5 mg to abort it. He was admitted for further workup of recurrent seizures. Initial workup including a complete metabolic panel was normal. The toxicology screen was negative. Computed tomography scan of the brain and perfusion studies of the brain were unremarkable. Psychiatric assessment was done which ruled out any psychological issues.

There were intermittent episodes of involuntary jerky movements in both upper limbs. His levetiracetam dose was increased to 1000 mg twice a day and lacosamide 100 mg twice a day was added as well. After a few days, he had a drop in his Glasgow coma scale (GCS) from 15/15 to 6/15. He was intubated and remained under medical intensive care unit care. His repeat MRI of the brain did not show any new change. Lumbar puncture was performed, and cerebrospinal fluid (CSF) analysis was remarkable for only high protein. CSF polymerase chain reaction for viral infections such as enteroviruses, Epstein–Barr virus, cytomegalovirus, herpes simplex 1 and 2, varicella zoster, and mumps was negative. EEG did not reveal any epileptic waveforms but showed diffused slowing. Autoimmune workup including antinuclear antibodies and anti-N-methyl D-aspartate antibodies in the CSF were negative. Anti-thyroid peroxidase (anti-TPO) antibodies for suspected Hashimoto's encephalitis, send. It turns out to be positive, while thyroid functions were normal. He received intravenous (IV) methylprednisolone 500 mg for 5 days and responded very well to therapy with an improvement of GCS to 15/15. The patient improved and was kept on oral steroids with follow-up of physical therapists to help him mobilize. He did not deteriorate further throughout the management.

Discussion

SREAT was first described by Brain et al. in 1966,^[3] and it is a neuropsychiatric illness that is characterized by various nonspecific clinical features including encephalopathy, seizures, stroke-like episodes, and psycho-affective symptoms that are not explained by conventional laboratory testing, CSF analysis, EEG, and neuroimaging.^[2] It is also known as Hashimoto's encephalopathy or nonvasculitic autoimmune meningoencephalitis and is recognized as a rare disease by the National Institution of Health Genetic and Rare Diseases Information Center, with an estimated prevalence of 2.1/100,000 populations.^[4] The exact mechanism of this disorder is unknown, but the evidence mostly suggests it to be of autoimmune nature.^[5] It can present with unexplained encephalopathy, abnormal body movements such as myoclonus or tremors, seizures, stroke-like episodes, depression, and psychosis.^[2] It is considered to be an autoimmune entity that has a strong association with elevated anti-TPO antibodies and anti-thyroglobulin (anti-TG) antibodies.^[1] Due to its nonspecific presentation and low clinical suspicion by the physicians, it is often underreported. Diagnosis of Hashimoto's encephalopathy can be made when all six of the following criteria have been met.^[5]

Encephalopathy with seizures, myoclonus, hallucinations, or stroke-like episodes
Subclinical or mild thyroid disease (usually hypothyroidism)
Unremarkable brain MRI or with nonspecific abnormalities
Presence of serum thyroid (thyroid peroxidase, TG) antibodies
Absence of well-characterized neuronal antibodies in the serum and CSF
Reasonable exclusion of alternative causes.

CSF analysis showed elevated protein in 75% of cases and lymphocytic pleocytosis in 10%–25% of patients,^[6] as seen in our case. EEG usually demonstrated nonspecific slowing. Neuroimaging are usually normal but might show cerebral atrophy or nonspecific T2 signal in the subcortical white matter.^[3] Our patient had a very nonspecific initial presentation with bilateral hand tremors. His thyroid function tests were normal, and he was treated with propranolol as a case of essential tremor, but his symptoms did not improve. Instead, he had a rapidly evolving presentation with myoclonic jerks and slurring of speech culminating in encephalopathy. Stroke, infections, autoimmune workup, and toxic causes such as ethanol were ruled out. EEG showed diffuse slowing, MRI head showed atrophic changes relative for age, and CSF analysis showed elevated protein with high anti-TPO and anti-TG antibodies, which were are seen in cases of SREAT and also correlated in our patient, as shown in [Table 1]. Our patient was treated with 5 days of IV steroids, and his condition returned to baseline. Then, he was discharged on oral prednisolone for 6 weeks with gradual tapering and was followed with no further complications.

Table 1: Relevant laboratory investigations

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Conclusions

SREAT can have many different presentations, and clinicians should have SREAT in differential diagnosis whenever dealing with unexplained neuropsychiatric symptoms in a patient. It can be diagnosed after the exclusion of more common etiologies, including infectious, autoimmune, toxic, and neoplastic causes. Responsiveness to steroids and elevated antithyroid antibodies are the hallmarks of this disorder.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

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