Hashimoto Encephalopathy or Neurosarcoidosis? A Case Report

Hashimoto encephalopathy (HE) is a rare autoimmune disease characterized by symptoms of acute or subacute encephalopathy associated with increased antithyroid antibody levels. Neurosarcoidosis is also a rare entity that occurs in less than 5% of patients with systemic sarcoidosis. Neurosarcoidosis usually presents with cranial neuropathies, myelopathy, or new-onset seizure. We report a case of a 49-year-old caucasian woman, previously healthy, who initially presented for a workup of a new-onset seizure. She had a gradually progressive course with neurocognitive decline and recurrent partial seizures refractory to conventional anti-epileptic drugs. Her seizures responded well to a course of intravenous immunoglobulin. She was subsequently diagnosed with HE and pulmonary sarcoidosis based on serological and pathological studies. She improved neurologically once the seizures were controlled. Hashimoto encephalopathy is a rare condition that is potentially treatable and presents with various neuropsychiatric manifestations. It is a diagnosis of exclusion that requires a strong clinical suspicion and is often underrecognized.