title: A follow-up ¹⁸F-FDG brain PET study in a case of Hashimoto's encephalopathy causing drug-resistant status epilepticus treated with plasmapheresis.
abstract: Hashimoto's encephalopathy (HE) is a rare neuropsychiatric syndrome associated with antithyroid antibodies. It may have an acute onset (episodes of cerebral ischemia, seizure, and psychosis) or it may present as an indolent form (depression, cognitive decline, myoclonus, tremors, and fluctuations in level of consciousness). We here describe a case of encephalopathy presenting as non-convulsive status epilepticus associated with Hashimoto's thyroiditis (HT), unresponsive to corticosteroid therapy, with improvement after plasma exchange treatment. A previously healthy 19-year-old woman, presented generalized tonic-clonic seizures. About a month later, she manifested a speech disorder characterized by difficulties in the production and comprehension of language. Within a few days she also developed confusion and difficulties in recognizing familiar places, with gradual worsening over time. EEG revealed a non-convulsive status epilepticus (NCSE). CSF examination showed slightly elevated cell count and four oligoclonal bands. MRI was unremarkable, and (18)F-FDG brain PET showed widespread hypometabolism, mostly in posterior regions bilaterally. Laboratory and ultrasound findings showed signs of HT. Treatment with steroid was introduced without any improvement. After five sessions of plasma exchange there was a decrease of antithyroid antibodies, as well as EEG and clinical improvement. Three months after discharge (18)F-FDG brain PET showed a complete normalization of the picture, and the patient was asymptomatic. This report emphasizes the successful treatment of HE with plasma exchange in a patient who presented with NCSE. Based on the actual evidence, the term "Encephalopathy associated with Hashimoto's thyroiditis" may be the most proper. Furthermore, to our knowledge, this is the first case of an adult patient studied twice with an (18)F-FDG brain PET: prior to treatment with plasma exchange, and at 3 months follow-up when the patient was clinically completely asymptomatic. Studies in more patients are needed to clarify the relevance of (18)F-FDG brain PET as a possible diagnostic tool for HE.
authors.affiliation: Neurology Department, University Hospital "Spedali Civili", Brescia, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Pari
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Rinaldi
authors.forename: Enrico
authors.initials: E
authors.lastname: Premi
authors.forename: Maria
authors.initials: M
authors.lastname: Codella
authors.forename: Renata
authors.initials: R
authors.lastname: Rao
authors.forename: Barbara
authors.initials: B
authors.lastname: Paghera
authors.forename: Maria Beatrice
authors.initials: MB
authors.lastname: Panarotto
authors.forename: Giovanni
authors.initials: G
authors.lastname: De Maria
authors.forename: Alessandro
authors.initials: A
authors.lastname: Padovani
mesh_terms: D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000927:Anticonvulsants / Q000627:therapeutic use; D001927:Brain Diseases / Q000150:complications / Q000000981:diagnostic imaging*; D004351:Drug Resistance; D004569:Electroencephalography; D004660:Encephalitis; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D050031:Hashimoto Disease / Q000150:complications / Q000000981:diagnostic imaging*; D006801:Humans; D009460:Neurologic Examination; D010956:Plasmapheresis; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D013226:Status Epilepticus / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000209:etiology; D055815:Young Adult
chemical_list: D000305:Adrenal Cortex Hormones; D000927:Anticonvulsants; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18