Late-onset seizures and epilepsy: Electroclinical features suggestive of autoimmune etiology

Alessandra Morano; Emanuele Cerulli Irelli; Enrico Michele Salamone; Biagio Orlando; Martina Fanella; Emanuele Tinelli; Gabriele Ruffolo; Luigi Zuliani; Jinane Fattouch; Mario Manfredi; Anna Teresa Giallonardo; Carlo Di Bonaventura

doi:10.3389/fneur.2022.924859

Late-onset seizures and epilepsy: Electroclinical features suggestive of autoimmune etiology

Front Neurol. 2022 Aug 12:13:924859. doi: 10.3389/fneur.2022.924859. eCollection 2022.

Affiliations

¹ Department of Human Neurosciences, Epilepsy Centre, "Sapienza" University of Rome, Rome, Italy.
² Neurology Unit, Ospedale "Fabrizio Spaziani", Frosinone, Italy.
³ Unit of Neuroradiology, Department of Medical and Surgical Sciences, "Magna Graecia" University, Catanzaro, Italy.
⁴ Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, "Sapienza" University of Rome, Rome, Italy.
⁵ Istituto di ricerca e cura a carattere scientifico (IRCCS) San Raffaele Roma, Rome, Italy.
⁶ Neurology Unit, AULSS8 Berica, Vicenza, Italy.

Abstract

Introduction: Late-onset epilepsy (LOE) has recently become a topic of intense research. Besides stroke, tumors, and dementia, autoimmune encephalitis (AE) has emerged as another possible cause of recurrent seizures in the elderly, and may account for a proportion of cases of LOE of unknown origin (LOEUO). This 24-h ambulatory electroencephalography (AEEG)-based study compared patients with LOEUO and AE to identify features suggestive of immune-mediated seizures in the elderly.

Materials and methods: We retrospectively reviewed 232 AEEG examinations performed in patients over 55 years with ≥6-month follow-up, and selected 21 subjects with AE and 25 subjects with LOEUO. Clinical charts and AEEG recordings were carefully analyzed.

Results: Twenty-five patients with LOEUO (12 women, mean age at onset 67.9 years) and 21 AE subjects (8 women, mean age at onset 65.7 years) were enrolled. High-frequency seizures were reported in 20/21 AE and 7/25 LOEUO cases (p < 0.00001). Focal aware seizures were more common in AE (14/21 vs. 6/25, p = 0.00058), whereas "isolated" focal-to-bilateral tonic-clonic seizures occurred in 5/25 patients with LOEUO only (p = 0.053). AE subjects reported ictal autonomic manifestations more frequently (p = 0.0033). Three-hundred-seventy and 24 seizures were recorded in 13/21 patients with AE and 3/25 patients with LOEUO, respectively (p = 0.0006). Interictal epileptiform discharges were observed in 70% of both groups, but their sleep activation was more common in AE (p = 0.06).

Conclusion: Our study shows that high-frequency focal seizures with autonomic manifestations should raise the suspicion of AE in the elderly with new-onset seizures. It also highlights the relevant contribution of AEEG, which might reduce the diagnostic delay and provide useful clues to recognize AE.

Keywords: ambulatory EEG; autoimmune encephalitis; elderly; late-onset epilepsy; late-onset seizures; piloerection; sleep; temporal lobe.