Biomedical subjects

P Jayakar

Publications and source records attributed to P Jayakar.

At least 19 recordsLinked to original sources

PubMed2000

Predictors of outcome in pediatric epilepsy surgery.

OBJECTIVE: To determine the correlation between pre- and perioperative variables on the outcome of children undergoing focal resections for medically intractable partial epilepsy. METHODS: Retrospective analysis of pre- and perioperative variables in a cohort of 75 patients younger than 12 years of age who underwent excisional surgery and had at least 1 year of follow-up. Outcome, measured by postoperative seizure frequency, was analyzed as a function of age at seizure onset, duration of epilepsy, presence of cognitive impairment, lobe of seizure origin, presence of a lesion, histopathology, and completeness of resection. Completeness of resection was defined on the basis of excising both the entire structural lesion if present and the region revealing prominent interictal and ictal abnormalities on intracranial EEG. RESULTS: Seventy-seven percent of patients had good outcomes (class 1 or 2), and 59% were seizure-free. Lesional status, site of resection, and pathologic diagnoses were not significant predictors of outcome except for in multilobar resection, for which overall outcome was relatively poor (44% class 3 or 4; 22% seizure-free). Completeness of resection was the only significant predictor of good outcome (p < 0.001), with 92% of patients who underwent complete resection of the epileptogenic zone achieving good outcome compared with 50% of patients who had incomplete resections. CONCLUSION: In this series of pediatric patients, complete resection of the lesion and the electrographically abnormal region was the main determinant of outcome after focal resections. Except for multilobar resections, other factors examined in this study did not significantly influence postoperative seizure prognosis and should not influence candidate selection for the surgical process.

Child↗

PubMed2000

Neurophysiological evaluation of children with traumatic radiculopathy, plexopathy, and peripheral neuropathy.

Neurophysiological evaluation of children with traumatic peripheral nervous system injury is accomplished with electromyography, motor and sensory nerve conduction studies, and somatosensory and motor-evoked potentials. Preoperative neurophysiological tests are performed if motor deficits persist for more than 3 months. Evidence of reinnervation on these neurophysiological tests predates clinical recovery by weeks, hence they help determine the site of the lesion and provide objective measures for selecting candidates for surgical exploration. Intraoperative neurophysiological tests help to identify and confirm the integrity of nerves and to develop the optimal surgical strategy. Postoperative evaluations every 3 to 6 months may determine efficacy of treatment.

Brachial Plexus Neuropathies↗

PubMed1999

Invasive EEG monitoring in children: when, where, and what?

With rapid advances in noninvasive technology, the need for chronic intracranial monitoring to define the epileptogenic region has diminished significantly. Its role in presurgical evaluation has come under scrutiny particularly in adults with lesional epilepsy. With the shift in surgical candidacy toward the younger age groups, however, invasive monitoring has regained its utility especially in children with normal imaging studies and cortical dysplasia. This review critically evaluates its continuing role, attempting to assess cost-benefit under specific clinical scenarios and proposes how the findings can be incorporated into the challenging task of surgical planning in intractable childhood epilepsy.

Child, Preschool↗

PubMed1998

Epilepsy surgery in the first three years of life.

PURPOSE: Partial seizures in early postnatal life may be catastrophic and associated with poor long-term outcome. Epilepsy surgery can alleviate partial seizures in older children and adults, but there is little experience with surgical therapy in infancy apart from hemispheric epilepsy syndromes. METHODS: We analyzed the results of cortical resection to treat medically refractory partial epilepsy in 31 children (16 boys, 15 girls) aged <3 years (mean, 18.3 months). Subjects were included only if seizure relief was the primary indication for surgery. RESULTS: Follow-up of at least 1 year (mean, 4.6 years) in 26 patients revealed that 16 were seizure-free, 4 had >90% seizure reduction, and 6 had <90% reduction. There was no significant difference in seizure outcome between hemispherectomy/multilobar resections and lobar resections or temporal versus extratemporal resection. Seizure outcome was independent of the amount of cortex removed in nonlesional patients. Only the presence of a discrete lesion on preoperative neuroimaging correlated with a favorable outcome. Family perceptions of accelerated development in seizure-free patients were not confirmed on developmental assessment. CONCLUSIONS: We conclude that cortical resection often benefits very young children with catastrophic partial seizures, but does not guarantee enhanced neurological development. The location and extent of the excised cortex may not be critical as long as the entire epileptogenic region and lesion are removed.

Adult↗

PubMed1998

[Epilepsy centers: classification and basic requirements].

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 multidisciplinary team of numerous centers can eventually develop an effective and acceptable international protocol for the surgical treatment of the epilepsies and the classifications of the centers.

Epilepsy↗

PubMed1997

Results and complications after reoperation for failed epilepsy surgery in children.

The seizure outcome and neurological outcome in children who undergo reoperation for failed epilepsy surgery have not been well documented. This retrospective study evaluated 20 children who underwent a second resective surgery for recurrent seizures. Four categories of patients were identified: (1) extension of the initial resection was performed in 8 patients; (2) 5 patients underwent lobectomy or corticectomy in a region remote from the original surgical site; (3) multilobar resection which may have included further resection of the initial procedure was accomplished in 4 patients; (4) hemispherectomy was performed in 3 patients. Patients with reoperation in the same lobe as the first procedure (group 1) had a 62% seizure-free rate, while 44% of patients in groups 2 and 3 were free from seizures at follow-up evaluation. Patients undergoing hemispherectomy had a 67% seizure-free rate. Significant unexpected neurological deficits occurred in 3 patients who underwent multilobar resection at reoperation. Complications included motor and language deficits. Reoperation for intractable partial epilepsy is beneficial in selected children. Patients who require multilobar resections may have higher risk of postoperative neurological deficit than those patients with reoperation in one lobe. These factors may be useful in counseling parents of children considering reoperation for recurrent epilepsy.

Adolescent↗

PubMed1997

[Neuropathology of refractory epilepsy in children].

INTRODUCTION AND OBJECTIVES: The pathological findings in surgical material from children with refractory epilepsy has not offered yet a clear understanding of its role in this condition. The objective of this paper is to report our findings to further expand our knowledge about refractory epilepsy in children. MATERIAL AND METHODS: Results of microscopic examination of the surgical specimen obtained from 80 children, ages 12 or younger, who had surgery for intractable epilepsy at Miami Children's Hospital between 1990 and 1996 were reviewed. RESULTS: Examination was normal only in one. The rest revealed ectopic neurons (1), dysplastic cells with ectopic neurons (2), dyslamination with large neurons (7), dyslamination with ectopic neurons (18), dyslamination with dysplastic cells (10), pachygyria (2), encephalomalacia (9), gliosis with ectopic neurons (10), gliosis without ectopic neurons (3), developmental ectodermal tumor (6), ganglioglioma (2), tumors (3), and Rasmussen encephalitis (4). Lesions were located to the temporal lobe in 34 children. CONCLUSIONS. Extratemporal lesions are more frequent than temporal one, including hyppocampal sclerosis. Ectopic neurons, the most frequent pathological findings, rather than a cause of seizure may be a marker other highly epileptogenic cortical malformations.

Brain↗

PubMed1996

Language cortex representation: effects of developmental versus acquired pathology.

Relatively little is known about language cortex representation in patients with developmental pathology and epilepsy. We report the results of mapping language by electrical stimulation of chronically implanted subdural electrodes in 34 patients (mean age, 12.2 years) evaluated for epilepsy surgery, 28 of whom had magnetic resonance imaging or histological evidence of developmental tumors or cortical dysplasia. Language cortex was identified in the temporal or frontal lobe of 19 patients (left hemisphere in 17, right hemisphere in 2), and overlapped or bordered the epileptogenic region in 12. Language cortex was not found in the frontal or temporal lobe of 15 patients (left hemisphere in 4, right hemisphere in 11) and was presumed to be contralateral to grid placement. Three patients with left-hemisphere perinatal or postnatal cerebral insults before the age of 5 years had no language in the left hemisphere, while 3 patients with insults between the ages of 6 and 16 years had preserved left-hemisphere language. Developmental lesions and early-onset seizures do not displace language cortex from prenatally determined sites, whereas lesions acquired before the age of 5 years may cause language to relocate to the opposite hemisphere, but only when language cortex is destroyed.

Adolescent↗

PubMed1996

Hemifacial seizures and cerebellar ganglioglioma: an epilepsy syndrome of infancy with seizures of cerebellar origin.

We investigated a 6-month-old infant with daily episodes of left hemifacial contraction, head and eye deviation to the right, nystagmoid jerks to the right, autonomic dysfunction, and retained consciousness. The episodes began on day 1 of life and were unresponsive to antiepileptic medication. Interictal and ictal scalp electroencephalographic (EEG) recordings were unremarkable. Magnetic resonance imaging revealed a mass in the left cerebellar hemisphere and peduncle. Ictal single-photon emission computed tomography revealed focal hyperperfusion in the region of the cerebellar mass. Ictal EEG recordings with implanted cerebellar electrodes demonstrated focal seizure discharges in the region of the mass. Resection of the mass resulted in remission of seizures and histopathology revealed ganglioglioma. Six previously reported infants with similar semiology (described as "hemifacial spasm"), imaging findings, and histopathology are reviewed. We believe the previously reported infants and our patient constitute a rare but important clinicopathological syndrome of infancy characterized by epileptic seizures of cerebellar origin.

Age of Onset↗

PubMed1996

Detection of seizures from small samples using nonlinear dynamic system theory.

The electroencephalogram (EEG), like many other biological phenomena, is quite likely governed by nonlinear dynamics. Certain characteristics of the underlying dynamics have recently been quantified by computing the correlation dimensions (D2) of EEG time series data. In this paper, D2 of the unbiased autocovariance function of the scalp EEG data was used to detect electrographic seizure activity. Digital EEG data were acquired at a sampling rate of 200 Hz per channel and organized in continuous frames (duration 2.56 s, 512 data points). To increase the reliability of D2 computations with short duration data, raw EEG data were initially simplified using unbiased autocovariance analysis to highlight the periodic activity that is present during seizures. The D2 computation was then performed from the unbiased autocovariance function of each channel using the Grassberger-Procaccia method with Theiler's box-assisted correlation algorithm. Even with short duration data, this preprocessing proved to be computationally robust and displayed no significant sensitivity to implementation details such as the choices of embedding dimension and box size. The system successfully identified various types of seizures in clinical studies.

Algorithms↗

PubMed1996

Preoperative clinical, EEG, and imaging findings do not predict seizure outcome following temporal lobectomy in childhood.

Although certain clinical, electroencephalographic (EEG), magnetic resonance imaging (MRI), and pathologic findings in adults with intractable temporal lobe epilepsy predict seizure outcome following temporal lobectomy, predictors of seizure outcome have not been studied systematically in pediatric temporal lobectomy series. We retrospectively analyzed preoperative clinical, EEG, and neuroimaging findings with reference to seizure outcome (seizure free or non-seizure free) in 33 children (mean age, 9.3 years) who underwent tailored temporal lobe resections for intractable temporal lobe epilepsy. Trends were apparent with (1) younger age at seizure onset, younger age at surgery, shorter duration of epilepsy, localized unilateral temporal lesions on MRI, and right-sided surgery more frequently associated with a seizure-free outcome, and (2) significant prior history, daily preoperative seizures, generalized motor seizures, mental retardation, and localized unilateral temporal epileptiform EEG activity more frequently associated with a non-seizure-free outcome. However, none of these findings, alone or in combination, correlated with postoperative seizure status at a statistically significant level. Submitting the four variables generally considered to be most predictive of favorable outcome (ie, normal intelligence, unilateral ictal and interictal EEG discharges, and focal temporal MRI lesion) to a multiple-cutoff procedure did not predict seizure freedom. Our data indicate that predictors of outcome of temporal lobectomy in adults may not apply in children, perhaps due to inherent neurobiologic differences in the etiology and expression of temporal lobe epilepsy, and should therefore not be used as sole determinants of surgical candidacy in children.

Adolescent↗

PubMed1996

[Results of surgery treatment of epilepsy].

The recent advances in the surgical treatment of epilepsy have resulted in great improvement in the overall outcome of these patients. The pediatric group has probably benefited the most as patients who previously were not candidate for this form of treatment are now able to undergo epilepsy surgery with results which are as good as those of adults. In fact, children may now benefit the most, as the control of their epilepsy and our ability to stop their anticonvulsants may allow them to better develop from a psychosocial aspect. Also, because of their plasticity, young children may tolerate surgery involving loss of eloquent cortex without subsequent permanent deficits. The most recent reported results from different centers indicate that 68-90% of patients undergoing temporal lobectomy remain seizure free while the percentage of patients remaining seizure free after extratemporal resections is approximately 50-66%. However, one of the problems with these results is that they vary significantly from one center to another because of the methodology used to evaluate results and the selection of patients depending on the strength of the centers. At present we do not have an optimal method to evaluate results of epilepsy surgery that takes in consideration not only seizure control but also psychosocial outcome. It is our goal to develop such method which will ultimately help us identify the best surgical candidates and predict their outcome.

Age Factors↗

PubMed1995

Electroclinical significance of rolandic spikes and dipoles in neurodevelopmentally normal children.

"Centrotemporal" (rolandic) spikes are elemental to the diagnosis of benign rolandic epilepsy (BRE) and may reveal a characteristic dipole distribution. Yet, not all children with rolandic spikes present with clinical seizures. Using additional scalp coverage according to the 10-10 electrode system, we attempted to correlate 2 specific spike features: (a) dipole fields, and (b) exact location of maximum negativity, with the presence or absence of clinical seizures in 42 neurodevelopmentally normal children with rolandic (central) spikes. Thirty-three (79%) presented with seizures. Seventeen of 21 children revealing dipoles (81%) and 16 of 21 patients without dipoles (74%) had seizures. Children with high central (C3/C4) foci were just as likely to present with seizures (10 of 15, 67%) as were those with low central (C5/C6) foci (23 of 27, 85%) (P > 0.10). The majority of our study subjects (27 of 42, 64%) revealed maximum negativity in the low central region (C5/C6), and the dipole feature was as likely to be associated with high central foci (7 of 15, 47%) as with low central foci (14 of 27, 52%). Although rolandic spikes are a reliable indicator of potential epileptogenicity, neither their exact location nor dipolar distribution help to further define the population with clinical seizures.

Brain↗

PubMed1995

Cuban embargo.

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Commerce↗

PubMed1994

Posterior temporal epilepsy: electroclinical features.

In the course of evaluating children with posterior temporal lobe epilepsy with subdural electrodes, we observed that their seizures commonly arose from basal rather than convexity foci and that they followed a stereotyped clinical sequence. Seizures characteristically began with behavioral arrest that coincided with basal temporal seizure discharges and progressed to motor signs as the seizure activity spread to the ipsilateral cortical convexity. Behavioral automatisms were observed in approximately half the patients, but were never the first or most prominent ictal manifestation. Focal lesions were identified preoperatively in 7 patients. We performed tailored temporal lobe resections in 14 patients, 10 (71%) of whom were seizure free (N = 9) or had occasional auras (N = 1) at a mean follow-up of 2 years. These findings suggest that in childhood, posterior temporal seizures frequently arise from basal cortex and have a consistent and recognizable ictal and electrographic semiology. In medically refractory patients, tailored temporal resection is an effective therapy.

Adolescent↗

PubMed1994

Medical intractability in children evaluated for epilepsy surgery.

We assessed the value of therapeutic reevaluation and additional pharmacotherapy in medically intractable children referred for epilepsy surgery. In 21 children with antiepileptic drug treatment omissions, correcting the omission was ineffective in 19 (90%). Two children (10%), both of whom had structural lesions, achieved significant seizure control with high-dose carbamazepine monotherapy. Therapeutic reevaluation is indicated in all medically intractable children prior to epilepsy surgery.

Adolescent↗

PubMed1994

Early surgery for epilepsy: redefining candidacy.

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.

Adolescent↗

PubMed1994

Neurobiologic considerations in early surgery for epilepsy.

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.

Animals↗