Thyroid Research and Practice

CASE REPORT
Year
: 2017  |  Volume : 14  |  Issue : 1  |  Page : 38--40

Encephalopathy associated with autoimmune thyroid disease in an 11-year-old girl, a rare clinical presentation


Meenakshi Cheripady Nayanar, Shakil Vadalivala, Tabrez Noorani, Hiral Shah 
 Department of Paediatrics, Smt. NHL Municipal Medical College, V. S. General Hospital, Ahmedabad, Gujarat, India

Correspondence Address:
Meenakshi Cheripady Nayanar
Room No 56, Girls' Hostel, V. S. General Hospital, Ellisbridge, Ahmedabad - 380 006, Gujarat
India

Abstract

Encephalopathy associated with autoimmune thyroid disease (EAATD) is a rare clinical presentation in pediatric age group whose exact prevalence has not been precisely elucidated. EAATD is characterized by neurological and psychiatric symptoms, high levels of antithyroid antibodies, increased cerebrospinal fluid (CSF) protein concentration, nonspecific electroencephalogram abnormalities, and responsiveness to the corticosteroid treatment. We present a case of an 11-year-old female patient who presented with acute history of fever, irritability, double vision, altered behavior, and unsteady gait which progressed to altered sensorium with drowsiness, tremors, and ataxia. The child had exophthalmos which was long standing in view of which thyroid profile was sent. Preliminary work-up, CSF analysis, and neuroimaging with magnetic resonance imaging of the brain proved normal. Thyroid profile was high with positive thyroperoxidase antibody. Thus, we came to the diagnosis of EAATD. EAATD still requires a better definition of its pathophysiology, the diagnostic criteria, and the most appropriate management including the long-term follow-up of patients.



How to cite this article:
Nayanar MC, Vadalivala S, Noorani T, Shah H. Encephalopathy associated with autoimmune thyroid disease in an 11-year-old girl, a rare clinical presentation.Thyroid Res Pract 2017;14:38-40


How to cite this URL:
Nayanar MC, Vadalivala S, Noorani T, Shah H. Encephalopathy associated with autoimmune thyroid disease in an 11-year-old girl, a rare clinical presentation. Thyroid Res Pract [serial online] 2017 [cited 2022 Dec 8 ];14:38-40
Available from: https://www.thetrp.net/text.asp?2017/14/1/38/200560


Full Text

 Introduction



Encephalopathy associated with autoimmune thyroid disease (EAATD), also called Hashimoto's encephalopathy, is a rare condition that may occur in patients with clinical or subclinical autoimmune thyroid disease (ATD). It is characterized by unspecific and protean neurological and/or psychiatric symptoms often associated with high serum and/or cerebrospinal fluid (CSF) levels of antithyroid antibodies (Abs), increased CSF protein concentration, nonspecific diffuse electroencephalogram (EEG) abnormalities, and responsiveness to the treatment with corticosteroids.[1],[2],[3],[4] The diagnosis of EAATD is still based mostly on exclusion criteria, which might affect the accurate estimation of its genuine prevalence.

The clinical manifestations range from stroke-like focal signs to generalized symptoms, either with dramatic or blunted presentation. Seizures, loss of consciousness, cognitive alterations, hallucinations and psychiatric disorders, behavioral changes, myoclonus, involuntary movements including tremors, ataxia, language impairment, sensory deficits, headache, and inflammatory signs of encephalitis and/or meningitis have been frequently reported.[2],[4],[5],[6]

Several mechanisms, such as cerebral autoimmune vasculitis with focal or global brain hypoperfusion, cerebral tissue-specific autoimmunity with or without demyelination, and neuronal dysfunction secondary to brain edema, have been thought to be involved in the pathogenesis.[1],[2],[5],[6],[7],[8],[9],[10],[11],[12] In general, EAATD occurs in patients with normal, or slightly abnormal, thyroid hormone levels and seems to be unrelated to the thyroid function.[2],[4],[10] Anti-thyroperoxidase (TPO) and antithyroglobulin Abs have been often detected in the CSF of EAATD patients, but their possible role in the pathogenesis has been not defined.[2]

Novel antigens, such as α-enolase and 36-kDa protein present in a soluble fraction from the cerebral cortex, have been recently identified in EAATD patients, but their involvement in the pathogenesis has been not documented enough.[11],[12] Converging evidence support the hypothesis of EAATD as a cerebral autoimmune vasculitis with or without immune complex deposition.[3],[8]

The onset of EAATD may be acute or subacute and the following trend progressive or relapsing. By definition, EAATD symptoms are steroid-responsive, but spontaneous remission or lack of responsiveness to corticosteroids rarely occurs. The prognosis appears depending on the responsiveness to the corticosteroid treatment, but the evolution of the disease in the long-term is unpredictable.

 Case Report



An 11-year-old female patient presented to our pediatric ward with complaints of moderate grade fever, headache, and blurred vision for 2 days. Subsequently, she developed altered sensorium and inability to stand and sit due to excessive tremors for next 12 h. Medical history was unremarkable, and she was not on any medication. Family history and birth history were unremarkable. The patient was taking regular family diet, and she was developmentally appropriate for age.

On general examination after admission, she had altered sensorium, pulse-128 with temperature of 100.4 and respiratory rate - 24/min. The child was severely undernourished. The local neck examination was supple, but she had exophthalmos which was since long, and parents have not noticed it. On neurological examination, she was confused, disoriented, stuporous having blurring of vision with normal hearing, slurred speech, tremors, ataxia, and brisk tendon reflexes without any focal deficit. All other systems were normal on clinical examination.

Routine blood tests including complete blood count, serum electrolytes, blood glucose, liver function tests, kidney function tests, and urine microscopic examination were within normal limits. Her CSF showed elevated protein levels (75 mg/dl) with normal cells.

Assuming meningoencephalitis of viral origin, magnetic resonance imaging was done which was unremarkable, and the patient was started on acyclovir and ceftriaxone, still no clinical improvement was seen for 2 days.

On the 3rd day, thyroid functions test, serum free triiodothyronine, free thyroxine, and thyroid-stimulating hormone were done. Serum anti-TPO Abs were also sent. Values observed are mentioned in [Table 1].{Table 1}

Thus, it was concluded that patients were having hyperthyroidism with ATD.

Considering encephalopathy, EEG was planned, and the patient was started on beta-blockers. EEG showed nonspecific slow waved patterns confirming encephalopathy. Thus, the patient was diagnosed as having hyperthyroid EAATD. The patient was referred to the endocrinologist for consideration for further therapy. On the 6th day of admission, the patient was conscious, oriented, was able to sit and walk without tremors, and there is still persistent exophthalmos. The patient was discharged successfully and was asked for follow-up.

 Discussion



EAATD is a rare clinical entity that is reported to have a prevalence of 2.6/lakh adult population. Moreover, incidence in pediatric age group is not elucidated. Hence, it is a clinical entity demanding more research and development of standard diagnostic approach and management. As per one study [13] done in adult patients, hormonal changes are irrelevant in regard to the occurrence of EAATD that can develop independently from high, normal, or low thyroid hormone levels. Antithyroid autoimmunity was active in all patients in other studies. Still in adult studies, the nature of the auto-Abs involved in the pathogenesis of EAATD, and the mechanisms that cross antithyroid autoimmunity and encephalopathy are still undefined. As seen in this case, the morphological analysis of the brain by the conventional radiological methods does not provide any specific finding but strongly contributes to the diagnosis because of the exclusion of other possible causes of the neurological or psychiatric symptoms. Imaging methods that study the vascular function of the brain, such as magnetic resonance angiography and single-photon emission computed tomography, can be useful tools for the diagnosis of EAATD as done in some studies, but due to unavailability, it could not be useful in this case. The EEG patterns recorded in EAATD patients are unspecific, but a diffuse slowness of the background rhythm is the most common, and characteristic report seen in most adult patients studies also.

As the diagnostic criteria have not yet been clearly defined, in our patient, after excluding all other possible causes including meningoencephalitis, cerebrovascular accidents, encephalopathy of hepatic and renal cause, and even psychiatric diseases, we confirmed the entity. Due to early diagnosis and timely intervention, our patient responded well though the chances of recurrence are common in this kind of entity, so she was asked for regular follow-up and endocrinal evaluations. Due to the rarity of disorder and lack of guidelines, optimal treatment modalities and doses have not been clearly defined in children and adolescents.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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