Original articleUncovered primary seizure foci in Lennox–Gastaut syndrome after corpus callosotomy
Introduction
Lennox–Gastaut syndrome (LGS) is described as an epileptic syndrome with intractable, multiple seizure types including tonic, atonic, myoclonic and atypical absence seizures. Its interictal electroencephalography (EEG) pattern is characterized by generalized slow sharp wave discharges (GSSW) and generalized paroxysmal fast activities (GPFA) [1], [2]. Sometimes, LGS has shown symptomatic generalized epileptic encephalopathy with primary seizure foci in which it would be possible to do potential resection by the multimodal approach [1], [2], [3], [4], [5].
Corpus callosotomy (CC) is a palliative surgical procedure used to control intractable seizure, especially atonic, tonic, or generalized tonic–clonic seizure and also improves the quality of life [6], [7], [8]. CC disrupts the pathway that connects homologous cortical areas of cerebral hemisphere and disconnects epileptogenic discharges that propagate from one hemisphere to the other. It not only interrupts the generalization of focal epileptogenic discharges and suppresses the duration, frequency and amplitude of seizure, but also allows patients to decrease intake of antiepileptic drugs [9], [10], [11], [12]. Some authors have observed gratifying results, such that generalized bilaterally synchronous spikes in interictal EEG might change into unilateral or asymmetric focal discharges after the procedure [13], [14], [15], [16].
Section snippets
Methods
39 patients with LGS had undergone CC to control the seizures as palliative goals from January 2004 to December 2008. All patients had suffered from medically-intractable seizures. Prior to CC, EEG showed GSSW or GPFA and no conclusive evidence of unilateral seizure foci was obtained following the phase-I assessment including EEG or neuroimaging. Fortunately, all patients had no serious surgical complication although two patients showed a transient ataxia for about 1 month and another one
Results
Among 39 patients who had undergone CC, seven patients were able to undergo the second operation for the control of seizures because of being identified primary seizure foci after CC. Four patients were classified as having cryptogenic infantile spasms and three patients as symptomatic infantile spasms had normal development prior to seizure onset. All patients progressed to develop LGS which represented various type of seizure. Two patients had pathologic handedness associated with the primary
Discussion
Our observations found that callosotomy sometimes happened to make EEG convert to focal evidence of epileptic discharges in some patients with secondary epileptic encephalopathy who had primary epileptogenic foci. These finding could support the fact that corpus callosum might play a role in interhemispheric spread and generation of cortical discharges and contribute to pathway for bilateral synchrony [21], [22]. Callosotomy could not only disrupt bilateral synchrony of generalization and
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Cited by (29)
Corpus Callosotomy in the Modern Era: Origins, Efficacy, Technical Variations, Complications, and Indications
2022, World NeurosurgeryCitation Excerpt :After corpus callosotomy, 17.4% and 8.7% of patients were seizure free at 1 year and 5 years follow-up, respectively; the greatest improvement in seizure frequency was seen for tonic, tonic-clonic, and atypical absence seizures and the least improvement for myoclonic seizures.103 Corpus callosotomy may offer an additional benefit for this syndrome by altering the preoperative EEG or fluorodeoxyglucose-PET imaging patterns and uncovering underlying focal lesions that can subsequently be removed, leading to seizure freedom.104 Although ≤25% of the LGS population may show focal abnormalities on EEG, an even higher percentage might be considered for potentially curative focal resections after corpus callosotomy.105
Epilepsy Surgery is a Viable Treatment for Lennox Gastaut Syndrome
2021, Seminars in Pediatric NeurologyChallenges in managing epilepsy associated with focal cortical dysplasia in children
2018, Epilepsy ResearchPredictive role of brain connectivity for resective surgery in Lennox–Gastaut syndrome
2016, Clinical NeurophysiologyCitation Excerpt :Therefore, these discharges may provide a clue of the underlying brain pathologies, such as cortical dysplasia. Corpus callosotomy reveals PEAs by disrupting GSWs, and it can induce changes in electrical activity, blood flow, and metabolism in the lesion (Ono et al., 2009; Lin and Kwan, 2012; Hur et al., 2011). A previous study suggested that bilateral cortical epileptogenesis could exist with asymmetrical susceptibility, although callosal compound action potentials exhibited no difference in conduction time between an altered and an unaltered group after corpus callosotomy (Ono et al., 2002).
The causal epileptic network identifies the primary epileptogenic zone in Lennox-Gastaut syndrome
2015, SeizureCitation Excerpt :Lennox–Gastaut syndrome (LGS) is one of the most intractable epilepsies and is characterized by multiple types of seizures, electroencephalographic (EEG) characteristics, such as generalized slow sharp and wave discharges and generalized paroxysmal fast activities, and progressive mental retardation. Generalized sharp and wave discharges (GSW) with bilateral synchronization in a secondary generalized epileptic encephalopathy, such as LGS, can originate from the primary epileptogenic zone through the transcallosal pathway [1–3]. Although resective surgery of the primary epileptogenic zone results in a seizure-free surgical outcome in 59.2% of patients, the GSW often fail to reveal the primary epileptogenic zone if they are not accompanied by the types of focal EEG features that have been described in previous studies [2,3].
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These authors contributed equally to this work.