Episodic Hemiparesis, Cognitive Decline, and Seizures in a Woman With Pernicious Anemia

Abstract

A 46-year-old woman with a history of pernicious anemia, sought care for intermittent episodes of weakness in her right upper extremity and speech difficulties followed by a headache. It was initially thought that she had migraine headaches. Blood tests showed increased thyrotropin and low free thyroxine levels, and she was diagnosed with Hashimoto thyroiditis. She initiated treatment with levothyroxine. One month later, the patient had a confusional episode and over the course of the following 2 months, the cognitive difficulties progressed. She was brought to the emergency department after a generalized tonic-clonic seizure. On examination, she was profoundly encephalopathic. Formal bedside cognitive testing could not be obtained. Findings of magnetic resonance imaging of the brain were normal. Electroencephalography revealed diffuse slowing. Cerebrospinal fluid analysis showed increased protein concentration and lymphocytic pleocytosis. Thyroid peroxidase antibody value was markedly increased. Thyroglobulin antibody value was also increased. Consistent with her history of pernicious anemia, she was positive for gastric parietal cell antibodies. The clinical presentation was compatible with steroid-responsive encephalopathy associated with autoimmune thyroiditis, also known as Hashimoto encephalopathy. The patient started levetiracetam therapy and had no further seizures. She received intravenous methylprednisolone. At the completion of treatment, her confusion rapidly and substantially improved. She was discharged home on oral prednisone. She also started pantoprazole, calcium, and vitamin D supplementation and Pneumocystis jirovecii prophylaxis. For long-term immunotherapy, she initiated methotrexate. Three months later, the patient and her family reported 90% improvement in her cognitive functioning and resolution of the episodes of hemiparesis. The patient continued tapering prednisone. It was recommended that she continue methotrexate for 5 years before discontinuing. Steroid-responsive encephalopathy associated with autoimmune thyroiditis, also known as Hashimoto encephalopathy, was initially described as strokelike episodes and subacute encephalopathy months after the onset of autoimmune (Hashimoto) thyroiditis.