Introduction

Hashimoto’s encephalopathy is associated with Hashimoto’s disease and was first described in 1966. This disease is believed to be an immunologically mediated disorder that affects the central nervous system independently from low thyroid hormone levels [1]. Its exact pathophysiology is unknown, but most evidence points to an autoimmune vasculitis or other inflammatory processes, possibly associated with immune complex deposition and alteration of the cerebral microvasculature. Like most autoimmune diseases, it is more frequent in women with a ratio of four to one [1], and it can be concomitant with other autoimmune pathologies in up to 30% of patients [2].

Hashimoto’s encephalopathy has been seen to occur independently of Hashimoto’s disease. As it is linked to an increase in autoimmune antibodies related to thyroid pathology beyond the antithyroid peroxidase antibody, some propose a different eponym: steroid-sensitive encephalopathy associated with autoimmune thyroiditis [3].

Its clinical presentation is characterized by neuropsychiatric symptoms of varying intensity that, in some cases, may end in a coma. Neurological symptoms include stroke-like episodes, seizures, dementia, myoclonus, and myelopathies compatible with nonspecific encephalopathies [3]. Among the psychiatric symptoms, the most frequent are sensory-perceptual disturbances but behavioral and thought disturbances may also be present [4]. Finding at least one frankly elevated antithyroid antibody is a fundamental criterion. The literature indicates that the antithyroid peroxidase antibody should be greater than 200 mili-international units per milliliter (more than five times the average value). Some authors even place a cut-off point of 500 mili-international units per milliliter [5]. The first line of treatment is corticosteroids at high doses for 3 to 5 days, associated with drugs for disease complications and most patients show complete improvement after management with corticosteroids [2]. We present the clinical case of a female patient who presented with Hashimoto’s encephalopathy with a psychotic episode as a debut.

Case report

For the report of this case, informed consent and institutional authorization were requested.

This is the case of a 42-year-old woman of mixed race, cohabitant, and housewife with no relevant family or medical history. Four months before her admission, she presented with constant headaches that partially resolved with outpatient analgesics. In September 2021, she had an emergency consultation at the medical service of Goyeneche Hospital with a sudden episoide of confusion, psychomotor agitation, and sensory-perceptual disturbances (auditory and visual hallucinations). Clonazepam and mannitol were administered, suspecting a cerebral vascular accident. Since there was no favorable response, hospitalization was decided.

Physical examination showed normal vital signs with no other particularities. The mental examination showed a confused patient, disoriented in time and space and partially in person, with incoherent language and thoughts, the presence of nihilistic delusions ("My son is dead", "My mother is dead", "They have taken all my blood"), delusions of persecution ("The police are looking for me"), bizarre delusions ("How they are going to glue the mouse skin on me? They have scraped my whole body and put blond wool on me, I am a brunette", "My head is empty, light, flat, they have put much garbage in me, they have put glass in me"), pejorative auditory hallucinations, cenesthetic hallucinations ("I have excrement behind my head, clean it"), affective incontinence, hypoprosexia, dyscalculia, and null judgment and introspection.

In the neurological examination, anosmia was found without alteration of cranial pairs, and the rest of the neurological examination was normal. Paraclinical examinations were requested (Table 1) to rule out infection or electrolyte alteration, with results within normal parameters. A lumbar puncture was performed to rule out a neurological compromise, and resulted in normal cerebrospinal fluid (Table 2). The electroencephalogram showed no particularities, and the computed axial tomography showed a normal brain. Magnetic resonance imaging of the brain showed bilateral focal subcortical lesions with a nonspecific demyelinating aspect (Figure 1), so serological, immunological, and biochemical tests were requested. Tumor markers were negative, thyroid-stimulating hormone (TSH), thyroxine (T4), and thyroglobulins were normal. The antithyroid peroxidase antibody was elevated (600 U/ml) (Table 3). Even though the patient was clinically euthyroid, these findings supported the diagnosis of Hashimoto’s encephalopathy.

Figure 1

Axial view of magnetic resonance imaging of the brain, with bilateral focal subcortical lesions of nonspecific demyelinating appearance.

Source: Prepared by the authors of this study.

Full size

With a presumed diagnosis of Hashimoto encephalopathy, the patient started treatment with prednisone 50 milligrams per day for seven days, followed by methylprednisolone one gram per day for three days. During hospitalization, remission of neuropsychiatric symptoms was observed, so the patient was discharged with outpatient follow-ups, which she did not attend.

Discussion

Hashimoto’s encephalopathy is a clinical entity that may present with multiple neuropsychiatric manifestations and represents a challenge for diagnosis and treatment. The age of presentation of the present case is similar to findings from a systematic review that analyzed 46 cases of Hashimoto’s encephalopathy, finding an age range of presentation at 50 years [6]. The clinical presentation, acute onset, and debut with profound atypical psychiatric manifestations (nihilistic delirium, delirium of persecution, bizarre delirium), associated with anomia, are not very frequent in the reported literature [7,8]. Chang, Jan Shun, and colleagues report three cases in which there is a predominance of visual and auditory hallucinations and, in one of them, persecution delusions associated with frank alterations of the thyroid profile and subsequent evident clinical manifestations [9]. Likewise, Amamou et al. report a case of a 39-year-old male patient who presented hypochondriac delirium and depressive symptoms [8]. Churilov L et al. reported 17 cases of Hashimoto’s encephalopathy in patients with schizophrenia, in whom phobias and sleep disorders were identified in up to 52% and hallucinations in 18% of the series of cases studied [7]. Case reports with similar demographic characteristics highlight the history of previous thyroid or psychiatric pathologies associated with this entity [10,11]. Our report highlights the onset of encephalopathy with no previous medical history.

An elevated level of antithyroglobulin antibodies, in addition to cerebrospinal fluid studies, electroencephalogram, and imaging studies without significant alterations, are criteria that corroborate our clinical suspicion [7]. Finally, the recommended treatment guidelines were applied [2,10], obtaining a clinical improvement in the patient.

One of the limitations of our study is that we do not have a long-term follow-up of the presented case and lack of exclusion of other autoimmune pathologies.

We highlight the importance of comprehensively evaluating patients with atypical psychiatric symptomatology and deepen the differential diagnoses.

Conclusions

We recommend having special attention to sudden onset psychosis in patients without premorbid mental pathology. We also emphasize the importance of taking a detailed clinical history that will provide valuable information about the origin of psychosis since organic etiology should always be present in a differential diagnosis of psychiatric pathology and to reach a timely diagnosis and treatment.