Original article
Pediatric Epilepsy Surgery in Focal Lesions and Generalized Electroencephalogram Abnormalities

https://doi.org/10.1016/j.pediatrneurol.2007.03.004Get rights and content

Generalized abnormalities on scalp electroencephalograms (EEG) are not uncommon in children with partial epilepsy in whom a dominant focus of interictal and ictal abnormalities concordant to the brain lesion usually clarifies surgical candidacy. Children with exclusively generalized or multiregional EEG abnormalities and mental retardation are usually not considered surgical candidates, even when brain lesions are seen on imaging. Of 176 pediatric epilepsy surgeries at our center, we describe 10 children with exclusively generalized and multiregional interictal and ictal EEG abnormalities who had resection of a focal lesion seen on brain MRI. Surgical decisions were strengthened by clinical data. Surgery was offered as a last resort because of catastrophic epilepsy and treatment failures. At 26 months’ mean postoperative follow-up, eight had no seizures, and two had infrequent seizures. Six months after surgery, generalized electroencephalographic abnormalities had resolved in all. We conclude that generalized and multiregional EEG abnormalities in the absence of dominant focus may not preclude epilepsy surgery in children with a congenital or acquired lesion seen on MRI. Generalized EEG abnormalities are likely secondary phenomena that resolve after surgery. Maladaptive neural plasticity and secondary epileptogenesis are potential mechanisms that mask an epileptogenic lesion with generalized EEG abnormalities.

Introduction

During evaluation for epilepsy surgery, patients with exclusively generalized and bilaterally multiregional interictal and ictal scalp electroencephalogram (EEG) epileptiform abnormalities and cognitive delay are not usually considered surgical candidates, because such findings are presumed to suggest generalized epilepsy. However, this paradigm does not hold true in infants with generalized scalp EEG patterns such as hypsarrhythmia, and in infantile spasms where seizure freedom has been obtained after resection of the cortical lesion that was apparent on the brain magnetic resonance imaging (MRI) or positron emission tomography [1], [2], [3].

It is not clear if some children beyond infancy who have exclusively generalized and multiregional EEG abnormalities in the presence of a focal brain lesion could benefit from epilepsy surgery. In this case series, we report on 10 such children with catastrophic epilepsy who became seizure-free or who significantly improved after surgery. We also discuss the potential mechanisms of generalized EEG abnormalities and the masking of focal epileptiform abnormalities on scalp EEG.

Section snippets

Materials and Methods

Of 176 children (less than 16 years of age) who underwent epilepsy surgery at the Cleveland Clinic during 2001-2003, we identified 10 children, aged 3-16 (mean age, 8.5) years, who under went surgical resection of a focal lesion apparent on brain MRI and fluorodeoxy glucose-positron emission tomography, despite the presence of generalized and multiregional scalp EEG abnormalities and a lack of a predominant EEG focus. All children were desperately sick, and had catastrophic epilepsy. Six

Demographic and Seizure Data

In 10 children (6 females), the age of seizure onset was 1 day to 4 years (mean, 22 months; median, 18 months; for a summary of data, see Table 1). The range of ages at surgery was 3-16 (mean, 8.5) years. The interval between seizure onset and surgery was 3-16 (mean, 6.75) years. All patients were previously rejected as epilepsy surgery candidates after one (five patients) or two (five patients) presurgical evaluations at our center and other centers. At the time of their final presurgical

Epilepsy Surgery Despite Generalized EEG Findings

Our surgical series indicates that even in older children with surgically remediable epilepsy, interictal and ictal scalp EEGs may reveal generalized and multiregional abnormalities with no dominant EEG focus. In these patients, freedom from seizures, or significant improvement after complete resection of a lesion seen on MRI, suggests that the localized epileptogenic process was preoperatively masked by generalized EEG abnormalities. In addition to the evidence of a focal lesion (presumed to

Conclusions

The exclusively generalized expression of EEG abnormalities in the presence of a focal cortical lesion (congenital or acquired during infancy) may occur beyond infancy. Freedom from seizures is possible in some older children after resection of a brain lesion seen on MRI, despite the presence of generalized scalp EEG abnormalities and the absence of dominant or concordant focal EEG abnormalities. When present, focal motor deficits such as hemiparesis, carefully observed focal features of

References (23)

  • H.G. Wieser et al.

    ILAE commission reportProposal for a new classification of outcome with respect to epileptic seizures following epilepsy surgery

    Epilepsia

    (2001)
  • Cited by (62)

    • Generalized seizures presurgically in a cohort of children with hemispherectomy: Predictors and a potential link to surgical outcome?

      2018, Seizure
      Citation Excerpt :

      Studies showed that age was one of the important factors that affected the semiology of epilepsy, and young children were prone to experience generalized seizures [17]. Because synchronous neuronal activity easily occurs in the immature brain structural and functional networks of young children, they display extensive cortical excitability [18]. However, no statistically significant difference in generalized seizures was found between different age subgroups in this study.

    • Seizure outcomes in children with epilepsy after resective brain surgery

      2015, European Journal of Paediatric Neurology
      Citation Excerpt :

      Overall, 76% of children with seizures and resective brain surgery were seizure free on long term follow up. It is difficult to directly compare outcomes from other studies because of differences in patient selection (most studies report on children with refractory seizures only), some include specific aetiologies only (eg focal cortical dysplasia), duration of follow up (often shorter), inclusion of patients with invasive and non-invasive EEG monitoring in presurgery evaluation, use of ECoG to tailor resections.3,6–28 However, despite these limitations, our results do compare favourably with published studies.

    View all citing articles on Scopus
    View full text