Trevor Resnick

Over the last two decades the surgical treatment of epilepsies has become a commonly used and effective method for the treatment of intractable epilepsy. However, because of its wide use in various types of centers throughout the world the methodology involved varies significantly throughout the centers. With this article we propose the bases from which a multi-disciplinary team of numerous centers can eventually develop aneffective and acceptable international protocol for the surgical treatment of the epilepsies and the classifications of the centers [REV NEUROL 1998; 27: 305-8].

We describe the clinical, radiologic, and EEG features of 3 children who had dysplastic gangliocytomas of the cerebral hemispheres and drug resistant partial seizures that began in infancy. Following cortical resection, 2 are seizure-free and the third almost seizure-free. The dysplastic gangliocytoma may be an important and surgically remediable cause of very early malignant partial seizures.

We present a modified EEG montage that detects small interchannel time differences and assists in localizing the epileptogenic focus. Regions with apparently synchronous epileptic discharges are displayed simultaneously in referential and subtraction derivations. The subtraction derivation is a bipolar configuration of two regions of interest that are not necessarily adjacent. The referential derivation reveals the polarity, voltage, and morphology of the two discharges, and the subtraction derivation detects asynchrony; the combined reference-subtraction derivation thus indicates the region that is activated first.

Children with well-localized medically resistant seizures are often referred for surgical therapy. In young children, at least three maturational issues play a significant role in the selection process and long-term outcome. First, the early years are a time of exceptionally rapid brain development leading to dynamic changes in the electroencephalogram and the clinical expression of seizures. Many early-onset seizure presentations are also associated with catastrophic outcomes, developmental arrest, or regression. Second, the immature limbic system may be vulnerable to stresses operating in early life, although the consequences may not become apparent for many years. Third, in comparison to the adult, the child's nervous system typically exhibits superior functional recovery after lesioning, but the process of sparing and recovery is often incomplete. An understanding of how these neurobiologic factors influence developmental outcome will ultimately lead to greater selectivity of candidates for early surgery and to improved long-term prognosis.

Surgical resection for localization-related epilepsy has recently become a generally accepted treatment in children. Evidence of the poor outcome in natural history studies of temporal lobe epilepsy in childhood initiated consideration of surgical intervention. Subsequent favorable outcome following surgery was encouraging. A number of variables differentiate adults with focal seizures from children. Evolving biologic factors modify the clinical and electroencephalographic expression of seizures in childhood. The pathologic substrate is different, and there is a higher incidence of extratemporal epilepsy. Chronic seizures beginning under age 2 years rarely remit, especially when associated with a demonstrable structural lesion. Behavioral consequences of chronic seizures are significant and become a major problem by adolescence if seizures are not controlled. Early surgery results in superior functional outcome, although subtle deficits persist postoperatively. Surgical outcome is as favorable as in adults with improvements in behavioral status and socialization. Abundant data exist to more adequately assess the benefits and risks of surgery in children so that intervention is not deferred longer than it needs to be.

The relation between hyperventilation (HV)-induced high-amplitude rhythmical slowing (HIHARS) and altered responsiveness without generalized spike and wave activity has not been clearly defined. To test whether altered responsiveness is a nonspecific physiologic response rather than a symptom of generalized epilepsy, we assessed verbal recall ability and motor response testing in 12 healthy nonepileptic children (mean age 9.6 years). Both tasks were administered as a baseline before HV, during HV but before onset of EEG slowing, and during HIHARS. Verbal recall and motor responsiveness remained unchanged during baseline and HV before onset of slowing. During HIHARS, all children exhibited impaired verbal recall (p < 0.005) and 8 of 12 failed to respond to repeated auditory clicks (p < 0.005). Our findings indicate that in a normal setting, responsiveness may be impaired during HV in healthy nonepileptic children.

During the course of a seizure, subdural recordings often show secondary areas which develop independent electrographic sequences that may outlast the primary seizure sequence. We reviewed the subdural data on 8 patients with intraictal secondarily activated foci (ISF). In 6 patients, ISFs were documented to be capable of generating independent seizures; ISF seizures occurred during the initial subdural monitoring period in 3, but became ictal generators only after excision of the primary focus in the other 3. Prominent interictal abnormalities were observed at the ISFs in 5 of 8 patients. The ISF in 1 patient correlated with the structural lesion on magnetic resonance imaging (MRI) scan. We believe that ISFs have significant epileptogenicity and should be resected when possible.

Temporal lobe epilepsy (TLE) in early life is often a catastrophic disorder with pharmacoresistant seizures and secondary neurological deterioration. there is little data available regarding epilepsy surgery performed in infants and young children and no prior study has focused on tle. We analyzed the results of temporal resection for epilepsy as the primary indication in children less than age 5 years who had at least 2 years of follow-up. 20 children (14 males) were identified with a mean age at surgery of 26 months and a mean age at seizure onset of 12 months. Clinical presentation was diverse. Typical psychomotor seizures (n = 4; mean age at surgery 37 months) were followed by prominent motor changes (n = 7; 30 months) and were occasionally isolated (n = 3; 23 months). Epileptic spasms were noted in six patients and were frequently associated with lateralizing features. The interictal EEG was lateralizing in 15 patients and the ictal EEG was lateralizing in 18 patients. Brain MRI provided localizing value in 16 patients, ictal SPECT was concordant in 4/8 cases. Invasive EEG was employed in six cases. At mean follow-up of 5.5 years, 65% of the children were seizure-free and 15% had >90% seizure reduction. Morbidity included infection and hydrocephalus in one case and stroke-related hemiparesis in two cases. Cortical dysplasia was identified in eight children, tumors in eight including two DNET, two ganglioglioma, and four malignant tumors. Hippocampal sclerosis was present in four cases, always as dual pathology. TLE presents in early life with varied and severe manifestations. Excisional procedures in this age group are associated with favorable seizure reduction similar to older children and in adults.

A 32-month-old child presented in status epilepticus (SE) involving the left side of the body. Fast spin-echo magnetic resonance imaging (FSE-MRI) with hippocampal volumetry performed < or = 24 h after the seizure showed increased T2 signal of the right hippocampus, but no atrophy. Complex partial seizures (CPS) appeared at age 33 months, and three more episodes of SE occurred between 33 and 37 months of age. Follow-up FSE-MRI at 34 and at 45 months of age demonstrated progressive hippocampal atrophy with resolution of the increased T2 signal. Her CPS became intractable and, at age 51 months, she underwent right temporal lobectomy. In the ensuing 5 months, she has had only one major motor seizure. This case demonstrates that acute increased hippocampal T2 signal intensity can occur soon after SE and hippocampal sclerosis (HS) may become evident within months in the setting of recurrent early childhood SE. This observation may support the hypothesis that early childhood SE can lead to HS. Furthermore, this case suggests that years of temporal lobe CPS may not be necessary for development of HS.