Case Presentation: Hashimoto encephalopathy is a poorly understood and rare complication of Hashimoto thyroiditis. Patients can present with seizures, movement disorders, or cognitive decline that improves with steroid therapy. The disease is a diagnosis of exclusion, but delay in recognition and treatment can lead to increased morbidity and mortality.
A twenty-one year old white female with a history of Hashimoto thyroiditis was transferred to our university hospital after she was found unresponsive by her friends. Recent history included breaking up with her significant other, generalized fatigue, and weakness. Empty bottles of naproxen and omeprazole were found near the patient, which initially prompted suspicion for a suicide attempt. She was intubated for airway protection and transferred to our institution’s medical intensive care unit. Physical exam revealed an intubated and sedated female with an enlarged, warm thyroid gland. CBC, CMP, blood cultures, urine analysis, urine toxicology screen, TSH, T4, synthetic marijuana screen, and MRI/MRA of the head/neck revealed no abnormalities. C-reactive protein was 13. 8 mg/dl, and anti-thyroid peroxidase antibody was elevated at 558 IU/mL. The patient was weaned off sedation and extubated. She did not recall preceding events but responded appropriately to questioning. A few hours after extubation, the patient became unresponsive with limb and postural flaccidity. Gag reflex remained intact but sternal rub and nailbed pressure did not elicit a response. The differential was narrowed to infectious encephalitis, non-convulsive seizure, Hashimoto encephalopathy, versus a less likely somatization disorder. Psychiatry, endocrinology, and neurology were all consulted. 24 hour EEG did not reveal seizure or generalized slowing. CSF analysis did not reveal an infection and cell counts were within normal limits. Given the patient’s elevated anti-thyroid peroxidase antibody levels and lack of evidence for other etiology of encephalopathy, the patient was started on methylprednisolone 1000mg per day for presumed Hashimoto encephalopathy. After receiving steroids, the patient’s responsiveness improved within hours. She was discharged on a steroid taper and her symptoms completely resolved.

Discussion: Hashimoto encephalopathy is a clinical diagnosis without a clear consensus on diagnostic criteria. This case illustrates the importance of early recognition and treatment of Hashimoto encephalopathy by ruling out other etiologies of disease. This presentation was atypical, as the majority of patients have abnormalities on EEG and elevated protein in their CSF. After rapid recognition of unresponsiveness by ICU nursing staff, consultation with appropriate specialties, and testing to rule out other causes of encephalopathy, we were able to diagnose Hashimoto encephalopathy and start treatment for this patient within two days after transfer to our institution.

Conclusions: By promptly recognizing an atypical presentation of Hashimoto encephalopathy, we likely reduced the time period to recovery and risk of permanent cognitive impairment, which are complications seen with delayed treatment of this disease.