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Biomedical subjects

M Duchowny

Publications and source records attributed to M Duchowny.

At least 37 records · Page 2Linked to original sources
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

Pediatric epilepsy syndromes: an update and critical review.

Epilepsy syndromes occupy an important position in the current nosology of the epilepsies, describing and classifying seizure disorders with shared clinical and EEG features. Increasingly, this schema is being refined as new information becomes available and our understanding of etiology and presentation of each syndrome widens. Advances in neuroimaging and neurogenetics have been particularly important and are likely to fundamentally change our concepts of syndrome classification. At present, the International League Against Epilepsy classification of epilepsy syndromes according to presumed localization (partial, generalized, undetermined) and etiology (idiopathic, cryptogenic, symptomatic). In clinical practice, it is often useful to conceptualize epilepsy syndromes according to their usual age at presentation, which greatly facilitates syndrome identification in new patients and recognizes the age-related expression of many childhood epilepsies. Definitional problems exist for many pediatric epilepsy syndromes, particularly the epileptic encephalopathies of early infancy, the benign epilepsies of infancy and childhood, the myoclonic epilepsies of infancy and early childhood, and the idiopathic generalized epilepsies of childhood and adolescence. It is likely that further input from the fields of molecular genetics and neuroimaging will enable the classification of epilepsies to become more etiologically oriented and disease specific.

Adolescent↗
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↗
PubMed1995

Reversible dementia and apparent brain atrophy during valproate therapy.

Two children developed severe cognitive and behavioral deterioration suggestive of a degenerative disease while being treated with sodium valproate for idiopathic, localization-related epilepsy with centrotemporal spikes. Magnetic resonance imaging revealed marked central and generalized cortical and cerebellar atrophy. In both patients, clinical symptoms and signs cleared in a few weeks following valproate withdrawal. The magnetic resonance imaging appearance improved within 3 months in 1 of the patients and normalized in both after 6 and 12 months. No metabolic changes were associated with the clinical or imaging abnormalities. Although the mechanism of this rare idiosyncratic complication of valproate therapy is unknown, we advocate discontinuing valproate therapy in all epileptic patients with neuromental deterioration or brain atrophy of unknown etiology.

Atrophy↗
PubMed1995

Epilepsy surgery in children.

The practice of operating on children with chronic epilepsy is rapidly gaining acceptance as an important therapeutic modality. This review summarizes some of the recent advances in pediatric epilepsy surgery in relation to the natural history of chronic childhood seizures, surgical treatment, and outcome. Candidate selection has been greatly facilitated by new information bearing on the natural history of medically resistant seizures and the greater than expected incidence of early hippocampal sclerosis. Because the majority of children suffer from extratemporal epilepsy, ictal single photon emission computed tomography and subdural electroencephalogram recording are becoming increasingly important for both seizure and functional localization in the child, and have been shown to be well tolerated, even in very young patients. Furthermore, the outcome of both excisional and commissural procedures in early life with respect to seizure control is similar to that reported for adults, irrespective of age. More information about the long-term effects of epilepsy surgery in children is urgently needed, but the available data confirms surgical therapy as an effective intervention with low morbidity.

Child↗
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↗
PubMed1994

Subdural monitoring in the evaluation of children for epilepsy surgery.

Noninvasive assessment of children with chronic epilepsy is often imprecise and localization of seizure foci requires intracranial electroencephalographic monitoring. Subdural electrodes provide coverage of large areas of neocortex and are ideally suited for evaluating children with intractable epilepsy and to functionally map critical cortex. This report discusses the role of subdural electroencephalography in the evaluation of childhood epilepsy.

Brain Mapping↗
PubMed1993

Carbamazepine toxicity resulting from generic substitution.

Generic substitution is practiced widely in both hospital and community settings. There have been several reports of reduced serum concentrations and seizure exacerbation following generic substitution of Tegretol. We describe the first 2 cases of carbamazepine toxicity resulting from the substitution of Tegretol with Epitol. Two 6-year-old children experienced increases in the maximum serum carbamazepine concentration, one of 22% and one of 41%. Both became asymptomatic when their serum concentrations were lowered and had no residual effects.

Carbamazepine↗
PubMed1992

The syndrome of partial seizures in infancy.

Partial seizures, the most frequent type of epilepsy at all ages, remain a distinct yet relatively understudied disorder in early life. Their true incidence has not been defined, despite an extremely unfavorable long-term prognosis. They differ from partial seizures presenting later in life in several important aspects and are prone to misdiagnosis because of the difficulties inherent in recognizing subtle seizure manifestations and in assessing level of consciousness in very young patients. Most seizures are symptomatic of assorted prenatally acquired hemispheric insults; perinatal damage and tumors are less common. Video-electroencephalographic studies indicate that the majority of ictal events consist of behavioral arrest, stereotyped automatisms, and motor phenomena. Oroalimentary and gross motor automatisms are frequent, whereas highly organized gestural and behavioral sequences are extremely rare. Lateralized or asymmetric tonic, clonic, and occasional myoclonic motor manifestations characterize the majority of episodes. Pure behavioral arrest is much less common. These seizure patterns imply immaturity of systems responsible for inhibiting access to motor pathways and for organizing motor expression. Ictal and interictal epileptiform discharges are often focal or lateralized but lack age-specific features. Although as a rule partial seizures persist, some individuals display generalized or mixed seizure disorders in later life.

Brain↗
PubMed1992

Ictal head deviation: lateralizing significance of the pattern of head movement.

To resolve the controversy surrounding the lateralizing value of ictal head deviation, we analyzed head-turning movements in relation to the actions of the two divisions of the sternocleidomastoid muscle. In 12 (75%) of 16 patients with surgically confirmed lateralized seizure foci, the face rotated upward and contraversive to the hemisphere of seizure origin, consistent with activation of the ipsilateral sternomastoid muscle. One patient showed a sustained, downward ipsiversive head tilt consistent with the action of the ipsilateral cleidomastoid muscle, and three patients had a combined ipsiversive head tilt and contraversive face rotation. No patient exhibited ipsiversive upward face rotation or contraversive head tilting, as would be expected if the contralateral sternocleidomastoid were activated. Our findings indicate that hemispheric seizure foci activate one or both divisions of the ipsilateral sternocleidomastoid muscle. Accurate lateralization of the seizure focus is possible only when ictal head deviation is assessed in the context of the different actions of the sternomastoid and cleidomastoid muscle divisions.

Adolescent↗
PubMed1991

Childhood obsessive-compulsive disorder and cingulate epilepsy.

There are no reports of an association between obsessive-compulsive disorder and cingulate epilepsy in childhood. We report the behavioral, cognitive, and EEG findings in a young girl with medically resistant seizures and severe obsessive-compulsive symptomatology. Her scalp EEG and neuropsychological test scores suggested right frontal lobe dysfunction. The intractability of her seizures and progressive intellectual and psychosocial deterioration prompted evaluation for excisional surgery. Intracranial EEG recording demonstrated a focal seizure origin in the right anterior cingulate gyrus. Cingulotomy resulted in freedom from seizures and significant improvement in her obsessive-compulsive symptoms.

Brain Mapping↗
PubMed1991

Localization of seizure foci: pitfalls and caveats.

The pitfalls and difficulties in accurately localizing seizure foci are reviewed. Basic issues regarding modeling, volume conduction, inhomogeneities, and corticocortical propagation are discussed, and the limitations of scalp and intracranial recordings are outlined. The ambiguities in interpreting patterns and their significance are highlighted with a concluding commentary on pitfalls in defining the epileptogenic region.

Brain↗