Presentations

Abstract

Introduction:

Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT) may be characterized by neuropsychiatric symptoms such as confusion, altered level of consciousness, seizures, mania, and psychosis. Corticosteroids are the first-line treatment, with immunosuppressants as additional therapy. Thyrotoxicosis is an excess of thyroid hormone with symptoms including tachycardia, weight loss, tremors, depression, and emotional lability. Treatment includes antithyroid agents and beta-blockers. We present a young woman with a second episode of psychotic symptoms in the setting of thyroid disease, suspected to have SREAT.

Case Information: 

Our patient, a 31-year-old woman with a past medical history of hyperthyroidism and depression, was seen by this team during two admissions in the same year. We were asked to evaluate this patient after she presented to the emergency department (ED) for a motor vehicle accident and was found to be hypothyroid. During an earlier admission, months prior to our evaluation, the patient was agitated with delusions and auditory hallucinations. Physical examination at that time was remarkable for trismus and tonic-clonic movements. The patient denied alcohol and substance use and her blood alcohol level and urine drug screen were negative, as was a pregnancy test. Lab results included an elevated prolactin level of 72.4 ng/mL (consistent with seizure activity), elevated TSH (15.9 mcU/mL), low free T4 (<0.1 ng/dL), low free T3 (1.1 pg/mL), and elevated cerebrospinal fluid (CSF) 14-3-3 protein with negative real-time quaking-induced conversion. An electroencephalogram (EEG) was normal, with 9 Hz frequencies and no epileptic discharges. Magnetic resonance imaging (MRI) revealed a prominent ventricular system and areas of white matter change. She was started on levetiracetam, hydrocortisone, and levothyroxine. One week after admission and treatment with several antipsychotics, her psychiatric symptoms resolved and she was discharged. During the patient's current admission, she presented to the ED for bizarre behavior, including elevated mood and grandiosity. She was severely hyperthyroid and behaviorally similar to her prior admission. Lab results included low TSH (<0.01 mcU/mL), high free T4 (2.3ng/dL), and high free T3 (7.4 pg/mL). Physical examination was remarkable for hypertension and tachycardia. A repeat MRI demonstrated cerebral white matter lesions that appeared increased. Despite our suspicions for SREAT, the patient was started on methimazole, propranolol, and olanzapine. Three days after admission, her mania/psychosis resolved although she was discharged before informed consent for this case report could be obtained.

Discussion:

SREAT is a rare disease, affecting approximately 2.1 out of every 100,000 people. The exact pathogenesis is believed to be immune-mediated and most patients present with anti-thyroperoxidase or anti-thyroglobulin antibodies. Hyperthyroidism is much more common, affecting 1.3% of the United States population. Thyrotoxicosis and SREAT clinically overlap in many ways, presenting with thyroid hormone abnormalities and neuropsychiatric manifestations. However, treatment differs such that treating SREAT as a primary thyroid disorder may lead to poor response and relapse. Psychotic symptoms occur in SREAT in up to 36% of patients, while psychosis secondary to hyperthyroidism only occurs in 1% of patients. The presentation of our patient during her first admission was suggestive of myxedema psychosis, however she also presented with seizure activity which is more common in SREAT, with 47% of patients presenting with convulsions. Further work-up revealing abnormal MRI findings and positive CSF 14-3-3 protein raised suspicion for SREAT. Her second admission for psychosis in the setting of hyperthyroidism and with a history of seizure activity, abnormal labs, and imaging, is most suggestive of SREAT.

Conclusion:

We believe this case emphasizes the importance for clinicians (1) to consider SREAT for these patients, especially females presenting as thyrotoxicosis with a second episode of psychosis and history of seizure activity, and (2) to understand and be able to identify the differences between SREAT and thyrotoxicosis.