{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,2]],"date-time":"2026-09-02T11:26:58Z","timestamp":1788348418624,"version":"build-2803163510"},"reference-count":12,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[2024,1,3]],"date-time":"2024-01-03T00:00:00Z","timestamp":1704240000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Epileptic Disorders"],"published-print":{"date-parts":[[2024,2]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Objective<\/jats:title><jats:p>Within the spectrum of developmental and epileptic encephalopathy (DEE), there are a group of infants with features that are distinct from the well\u2010recognized syndromes of early infantile developmental and epileptic encephalopathy (EIDEE), infantile epileptic spasm syndrome (IESS), and Lennox\u2013Gastaut syndrome (LGS). We refer to this condition as late infantile epileptic encephalopathy (LIEE). Our objective was to highlight the characteristics of this group by analyzing patients who exhibit prototypical features.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>From July 2022 to May 2023, we searched for LIEE features in pediatric patients who underwent epilepsy follow\u2010up at the University of Chicago Comer Children's Hospital.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Out of 850 patients evaluated, thirty patients (3.5%) were identified with LIEE based on electroclinical characteristics. These patients had an average onset of epilepsy at 6.8\u2009months and an average onset of LIEE features at 18.1\u2009months. The epilepsy etiology was most commonly genetic and metabolic (50%), followed by congenital cortical malformations (23%), acquired structural abnormalities (20%), and unknown (7%). The predominant seizure types were myoclonic\u2013tonic (70%), spasm\u2013tonic (50%), epileptic spasms (47%), tonic (43%), and myoclonic (43%) seizures. All patients reported a history of either spasm\u2013tonic or myoclonic\u2013tonic seizures in addition to other types. All patients had EEGs showing discontinuity, electrodecrements, or both along with diffuse slowing, background voltages between 100 and 300\u2009\u03bcV, and superimposed multifocal, diffuse epileptiform discharges. Every patient, except one, fulfilled the definition of drug\u2010resistant epilepsy, and all reported either moderate\u2010to\u2010severe or severe developmental delay.<\/jats:p><\/jats:sec><jats:sec><jats:title>Significance<\/jats:title><jats:p>Late infantile epileptic encephalopathy (LIEE) is characterized by several unique clinical and electrographic features. Typically, LIEE manifests in patients during the second year of life and occurs before two years of age, hence late infantile onset. The condition is commonly observed in infants with symptomatic epilepsy. Myoclonic\u2013tonic and spasm\u2013tonic seizures are the quintessential seizure types. The inter\u2010ictal EEG exhibits more organization and lower voltages than seen with hypsarrhythmia and lacks the defining EEG characteristics of EIDEE, IESS, or LGS. We propose that LIEE is a distinct electroclinical syndrome within the spectrum of developmental and epileptic encephalopathies.<\/jats:p><\/jats:sec>","DOI":"10.1002\/epd2.20185","type":"journal-article","created":{"date-parts":[[2023,12,15]],"date-time":"2023-12-15T18:54:20Z","timestamp":1702666460000},"page":"98-108","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Late infantile epileptic encephalopathy: A distinct developmental and epileptic encephalopathy syndrome"],"prefix":"10.1002","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8761-6419","authenticated-orcid":false,"given":"Shawn","family":"Kacker","sequence":"first","affiliation":[{"name":"The University of Chicago The University of Chicago Medical Center  Chicago Illinois USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chalongchai","family":"Phitsanuwong","sequence":"additional","affiliation":[{"name":"The University of Chicago The University of Chicago Medical Center  Chicago Illinois USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Audrey","family":"Oetomo","sequence":"additional","affiliation":[{"name":"The University of Chicago The University of Chicago Medical Center  Chicago Illinois USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"suffix":"Jr","given":"Douglas R.","family":"Nordli","sequence":"additional","affiliation":[{"name":"The University of Chicago The University of Chicago Medical Center  Chicago Illinois USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2024,1,3]]},"reference":[{"key":"e_1_2_9_2_1","doi-asserted-by":"publisher","DOI":"10.1111\/epi.17239"},{"key":"e_1_2_9_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ejpn.2019.12.023"},{"key":"e_1_2_9_4_1","volume-title":"Epileptic encephalopathies of infancy","author":"Ohtahara S","year":"2007"},{"key":"e_1_2_9_5_1","doi-asserted-by":"publisher","DOI":"10.1097\/WNP.0b013e31826bd961"},{"key":"e_1_2_9_6_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1528-1167.2006.00518.x"},{"key":"e_1_2_9_7_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1528\u20101167.2010.02534.x"},{"key":"e_1_2_9_8_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1528\u20101167.2007.00978_2.x"},{"key":"e_1_2_9_9_1","doi-asserted-by":"publisher","DOI":"10.1007\/BF00442097"},{"key":"e_1_2_9_10_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0022\u20103476(95)70294\u20106"},{"key":"e_1_2_9_11_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1528\u20101167.2009.02397.x"},{"key":"e_1_2_9_12_1","doi-asserted-by":"publisher","DOI":"10.1542\/peds.13.1.66"},{"key":"e_1_2_9_13_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1528-1157.1993.tb00445.x"}],"container-title":["Epileptic Disorders"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/epd2.20185","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,3,18]],"date-time":"2024-03-18T16:40:31Z","timestamp":1710780031000},"score":1,"resource":{"primary":{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/10.1002\/epd2.20185"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,1,3]]},"references-count":12,"journal-issue":{"issue":"1","published-print":{"date-parts":[[2024,2]]}},"alternative-id":["10.1002\/epd2.20185"],"URL":"https:\/\/doi.org\/10.1002\/epd2.20185","archive":["Portico"],"relation":{},"ISSN":["1294-9361","1950-6945"],"issn-type":[{"value":"1294-9361","type":"print"},{"value":"1950-6945","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,1,3]]},"assertion":[{"value":"2023-06-29","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2023-11-24","order":1,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2024-01-03","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}