Evidence that temporal lobe is a default area in absence epilepsy.

Correctly classifying seizures is essential for appropriate epilepsy management. Focal and generalized epilepsy rarely occur independently in the same patient. Cases of focal ictal evolution during seizures that are generalized in onset have been reported though these have included a small heterogeneous series of patients with generalized epilepsy and features on the EEG. We wish to report two patients with absence epilepsy that were noted on video-EEG monitoring to manifest a focal temporal electroclinical transformation from a typical absence seizure. Defining the electroclinical spectrum of absence seizures could add to our understanding of the selective cortical and subcortical networks that are involved in patients with "prototypic" generalized and focal seizures.

Thalamofrontal neurodevelopment in new-onset pediatric idiopathic generalized epilepsy.

BACKGROUND: Quantitative MRI techniques have demonstrated thalamocortical abnormalities in idiopathic generalized epilepsy (IGE). However, there are few studies examining IGE early in its course and the neurodevelopmental course of this region is not adequately defined. OBJECTIVE: We examined the 2-year developmental course of the thalamus and frontal lobes in pediatric new-onset IGE (i.e., within 12 months of diagnosis). METHODS: We performed whole-brain MRI in 22 patients with new-onset IGE and 36 age-matched healthy controls. MRI was repeated 24 months after baseline MRI. Quantitative volumetrics were used to examine thalamic and frontal lobe volumes. RESULTS: The IGE group showed significant differences in thalamic volume within 1 year of seizure onset (baseline) and went on to show thalamic volume loss at a significantly faster rate than healthy control children over the 2-year interval. The control group also showed a significantly greater increase in frontal white matter expansion than the IGE group. In contrast, frontal lobe gray matter volume differences were moderate at baseline and persisted over time, indicating similar developmental trajectories with differences early in the disease process that are maintained. CONCLUSIONS: Brain tissue abnormalities in thalamic and frontal regions can be identified very early in the course of IGE and an abnormal trajectory of growth continues over a 2-year interval.

Practice parameter: evaluation of the child with global developmental delay: report of the Quality Standards Subcommittee of the American Academy of Neurology and The Practice Committee of the Child Neurology Society.

OBJECTIVE: To make evidence-based recommendations concerning the evaluation of the child with a nonprogressive global developmental delay. METHODS: Relevant literature was reviewed, abstracted, and classified. Recommendations were based on a four-tiered scheme of evidence classification. RESULTS: Global developmental delay is common and affects 1% to 3% of children. Given yields of about 1%, routine metabolic screening is not indicated in the initial evaluation of a child with global developmental delay. Because of the higher yield (3.5% to 10%), even in the absence of dysmorphic features or features suggestive of a specific syndrome, routine cytogenetic studies and molecular testing for the fragile X mutation are recommended. The diagnosis of Rett syndrome should be considered in girls with unexplained moderate to severe developmental delay. Additional genetic studies (e.g., subtelomeric chromosomal rearrangements) may also be considered in selected children. Evaluation of serum lead levels should be restricted to those children with identifiable risk factors for excessive lead exposure. Thyroid studies need not be undertaken (unless clinically indicated) if the child underwent newborn screening. An EEG is not recommended as part of the initial evaluation unless there are historical features suggestive of epilepsy or a specific epileptic syndrome. Routine neuroimaging, with MRI preferred to CT, is recommended particularly if abnormalities are found on physical examination. Because of the increased incidence of visual and auditory impairments, children with global developmental delay may undergo appropriate visual and audiometric assessment at the time of diagnosis. CONCLUSIONS: A specific etiology can be determined in the majority of children with global developmental delay. Certain routine screening tests are indicated and depending on history and examination findings, additional specific testing may be performed.

Successful use of Tesio catheters in pediatric patients receiving chronic hemodialysis.

Semipermanent venous catheters remain the most commonly used access for chronic hemodialysis (HD) in pediatric patients. The recent availability of Tesio catheters in 7 and 10 F has expanded available HD catheter options for children and adolescents. We report our experience with Tesio catheter survival, complications, and effect on dialysis adequacy in comparison to standard dual-lumen (DL) catheters in our pediatric HD patients. Demographic data were similar between the two groups. Overall actuarial survival was significantly longer for Tesio versus DL catheters (46% versus 0% at 1 year; P = 0.003). A comparison of smaller catheters (7 F Tesio catheter, 8 or 10 F DL catheter) showed that smaller Tesio catheters had a significantly longer survival (median survival, 244 versus 13 catheter-days; P < 0.01). Tesio 10 F catheters also survived significantly longer than the larger 11.5 and 12 F DL catheters (P < 0.02). Catheter sepsis occurred less frequently with Tesio catheters (one episode/20 catheter-months) than DL catheters (one episode/5 catheter-months) despite the longer duration of Tesio catheters. Adequate dialysis (single-pool Kt/V > 1.2) was delivered with the same frequency, but for a longer duration with Tesio catheters (76% +/- 32% over 100 monthly measurements versus DL catheter, 57% +/- 45% over 54 monthly measurements). Our clinical practice was to replace cuffed catheters when adequate dialysis could not be delivered. We conclude that Tesio catheters provide superior performance compared with DL catheters in terms of catheter survival, infection rates, and duration of adequate performance.

Pediatric epilepsy surgery: neuroimaging, neuropsychology, and anticonvulsants.

Neuroimaging and the neuropsychological evaluation are important components of the presurgical evaluation for epilepsy surgery. Advances in neuroimaging over the last decade, to a large part, underlie improvements in pediatric epilepsy surgery outcomes. The neuropsychological evaluation plays an important role in the evaluation of the older child and adolescent, particularly in the evaluation of mesial temporal sclerosis. However, its role in the young child being considered for surgery remains to be defined. This section reviews the definition of medical intractability, issues related to medication withdrawal during video-EEG monitoring, recent neuroimaging advances, and the neuropsychological evaluation.

Intractable pediatric epilepsy: presurgical evaluation.

Epilepsy surgery in children requires a multidisciplinary approach. This section examines the role of scalp EEG, video-EEG monitoring, and intracranial EEG in the presurgical evaluation. Concepts central to understanding the basis for surgical treatment, such as the epileptogenic zone, the irritative zone, and the epileptogenic lesion, are discussed. An illustrative case then demonstrates application of the process in clinical practice. Neuroimaging and neuropsychological issues are not discussed herein; rather they are addressed elsewhere in this issue.

Vascular C3 deposits on renal biopsy in pediatric patients with hematuria.

Isolated deposition of the third component of complement (C3) in the renal arterioles has been noted on biopsy specimens in patients with hematuria. This entity is of little known significance and reports of this finding in pediatric patients with hematuria are rare. We reviewed the clinical histories and biopsies of 17 children with hematuria and vascular C3 deposition on biopsy at Texas Children's Hospital over an 14-year period. The mean age of presentation was 10.8 (range 4.5-16.6) years with a male preponderance (71%). Family history for hematuria was positive in 6 of 17 patients (35%). Light microscopy was normal or showed only minor abnormalities. Immunofluorescence was negative for IgA and IgG in all patients. Seven patients (41.1%) were noted to have diffuse or focally thin basement membranes on electron microscopy in addition to positive C3 immunofluorescence. The mean follow-up time was 23.8 months, during which 2 of 17 patients (12%) developed worsening proteinuria. The etiopathogenesis of this condition remains unclear, but an underlying immunological process cannot be ruled out. It is possible that this condition represents a stage of an acute glomerulonephritis. Clinical follow-up of these patients is warranted, as the long-term prognosis remains unclear.

Status epilepticus associated with cefepime.

Cefepime is a fourth-generation cephalosporin widely used for gram-negative sepsis. The authors report two patients in whom nonconvulsive status epilepticus developed while they were on treatment with cefepime for Pseudomonas aeruginosa infection. The status epilepticus resolved completely once the drug was withdrawn. Cefepime therapy can result in status epilepticus, especially if given in higher doses than required.

Gelastic seizures of neocortical origin confirmed by resective surgery.

Ictal laughter is a relatively unusual phenomenon that appears to arise from within hypothalamic hamartomas. Gelastic seizures of neocortical origin are rare and when reported typically originate from temporofrontal regions in proximity to the hypothalamus, raising the possibility of a subtle lesion in the hypothalamus. A girl with gelastic seizures originating in a dysembryoblastic neuroepithelial tumor at the cranial vertex had resolution of her seizures following surgical resection. Electrical propagation of seizures via the cingulate gyrus appears to be an alternative mechanism underlying gelastic seizures.

Acute spinal cord infarction: vascular steal in arteriovenous malformation.

Central nervous system arteriovenous malformations typically present with chronic neurologic impairment. An 8-year-old boy presented with acute spinal cord infarction associated with a spinal arteriovenous malformation. Vascular steal phenomenon suggested by spinal angiography happens to underly the pathogenic mechanism.

Neonatal suck reflex pattern does not predict apnea.

Respiration and suck are gestational age-dependent reflexes modulated in the brain stem. To determine if the suck reflex pattern could be used to predict apnea, the relationship between the two was examined in 28 neonates. The suck reflex was quantified with respect to burst-pause rhythm, amplitude of negative suck pressure, and synchrony of the negative-positive pressure. Apneas were counted 5 days prior to and following measurement of the suck reflex pattern. Increasing gestational age correlated with a lower frequency of apnea (P < .01) and higher suck scores (P < .01). A mature suck reflex pattern, however, failed to predict the occurrence of apnea.

Persistent occipital electrographic status epilepticus.

A 13-year-old girl of normal intellect had clinically silent occipital electrographic status epilepticus that persisted for more than 3 years. Neurologic examination and cranial magnetic resonance imaging were entirely normal. [18F]Fluorodeoxyglucose positron emission tomography demonstrated a hypermetabolic focus in the right occipital lobe. Electrographic status lasting years can be seen in epilepsia partialis continua. However, the absence of focal clinical seizures, nonprogressive course, and normal magnetic resonance imaging study seen in this patient are not features characteristic of epilepsia partialis continua.

Infantile botulism: pitfalls in electrodiagnosis.

Botulism in infants, unless recognized early, is associated with high mortality and morbidity. The diagnosis is suspected when infants present with sudden onset of weakness, respiratory failure, and constipation and is confirmed by demonstration of botulinum toxin in stool several weeks later. Electrodiagnosis allows quick and reliable confirmation of botulism. Low-amplitude compound muscle action potentials, tetanic or post-tetanic facilitation, and the absence of post-tetanic exhaustion support the diagnosis. Two infants with confirmed botulism did not exhibit the characteristic electrodiagnostic features, demonstrating the pitfalls in electrodiagnosis of infantile botulism.

Electroencephalogram confirmatory rate in neonatal seizures.

The electroencephalogram (EEG) is confirmatory in 70% of children and adults with seizures, although gestation- and etiology-specific EEG confirmatory rates in neonates have not been well defined. All neonates treated for seizures and who underwent EEG were identified from 4,575 neonates admitted between 1985 and 1996 to a neonatal intensive care unit. The relationship between EEG findings (epileptiform discharges and background abnormalities) and gestation, mortality rate, and seizure etiology was examined using the Student t test. One hundred eighty-three neonates treated for seizures underwent a total of 352 EEGs: 144 of these neonates (79%) had an abnormal EEG (epileptiform discharges in 113 (60%) and nonepileptiform background abnormalities in 31). The EEG confirmatory rate increased with gestation (63% at 28 weeks vs 77% at term, P < 0.02). Etiology for seizures also influenced the EEG confirmatory rate: central nervous system (CNS) infection 95% (P < 0.05), hypoxic-ischemic encephalopathy 80% (P < 0.05), germinal matrix-intraventricular hemorrhage 65%, and CNS malformations 65%. The EEG confirmatory rate was predictive of neonatal mortality (19% vs 6%, P < 0.03). The EEG was directly confirmatory (epileptiform discharges) in 60% and supportive (nonepileptiform background abnormalities) in a further 17% of neonates with seizures. Gestation and etiology influence the EEG confirmatory rate in neonatal seizures.

Vigabatrin: a novel therapy for seizure disorders.

OBJECTIVE: To review the pharmacology, pharmacokinetics, efficacy, and adverse effects of vigabatrin and its role in the management of seizure disorders. METHODS: A MEDLINE search of English-language literature from January 1993 through January 1999 was conducted using vigabatrin as a search term to identify pertinent studies and review articles. Additional studies were identified from the bibliographies of reviewed literature. The manufacturer provided postmarketing surveillance data. Priority was given to randomized, double-blind, placebo-controlled studies. FINDINGS: Vigabatrin is a selective and irreversible inhibitor of gamma-aminobutyric acid transaminase. In controlled clinical trials of vigabatrin add-on therapy in patients with uncontrolled partial seizures, 24-67% of patients achieved a < or =50% reduction in seizure frequency. Data from two comparative trials with carbamazepine monotherapy indicate that vigabatrin monotherapy reduces the frequency of partial seizures in patients with newly diagnosed epilepsy. Vigabatrin also controls infantile spasms, particularly those associated with tuberous sclerosis. Vigabatrin is more effective in patients with partial seizures than in those with generalized seizures. The drug is generally well tolerated. Headache and drowsiness were the most common adverse effects observed in controlled clinical trials; visual field defects, psychiatric reactions, and hyperactivity also have been reported. There are no known clinically significant drug interactions. CONCLUSIONS: Vigabatrin improves seizure control as add-on therapy for refractory partial seizures and may produce therapeutic benefits in the treatment of infantile spasms. Vigabatrin is generally well tolerated, with a convenient administration schedule, a lack of known significant drug interactions, and no need for routine monitoring of plasma concentrations.

Neonatal seizures: incidence, onset, and etiology by gestational age.

OBJECTIVE: To examine the influence of gestational age on seizures in the neonatal intensive care unit. STUDY DESIGN: A cohort of 4165 neonates admitted to a university intensive care unit between 1986 and 1995. The incidence, time of onset, and etiology of neonatal seizures in the cohort were distributed by gestational age. Logistic regression and t test were used to examine the relationship between gestational age and seizures in the neonatal intensive care unit. RESULTS: Seizures occurred in 356 (8.6%) infants. The seizure rate was parabolically related to gestational age, such that infants at 30 to 36 weeks' gestation had a 4.8% rate compared with 11.9% and 14.1% rates for infants < 30 and > 36 weeks, respectively (p < 0.001). Seizures manifested earlier in infants < 30 weeks (2.3 +/- 5.6 days of life) and > 36 weeks (3.7 +/- 8.7 days) gestational age compared with neonates 30 to 36 weeks (10.4 +/- 14.5 days) (p < 0.001). Intraventricular hemorrhage was the principal etiology underlying the higher seizure rate for infants < 30 weeks (p < 0.001). Hypoxic-ischemic encephalopathy and congenital malformations were primary factors for infants > 36 weeks (p < 0.01). Nervous system infections were evenly distributed across gestational age. CONCLUSION: Gestational age exerts a considerable influence on the incidence, onset, and etiology of neonatal seizures.

Basilar artery occlusion and the dense artery sign in the newborn.

A child with basilar artery occlusion in the neonatal period is reported. The occlusion was documented by unenhanced computed tomography performed in the neonatal period demonstrating a "dense" artery at the tip of the basilar artery. The pattern of cerebral damage on MRI scan at 10 years of age confirmed the site of the vascular occlusion. The evidence suggests that embolization was the operating pathogenic mechanism of cerebral vascular occlusion. Neonatal arterial thrombosis involving the carotid circulation has been well documented and may be due to many pathological factors including direct trauma to the carotid artery and embolization from remote sites. Thrombosis of the vertebral artery in the neonate is only rarely reported and only in association with significant cervical trauma. A second child with a similar pattern of cerebral injury demonstrated on neuroimaging is described suggesting that this event may be more common than recognized. The clinical features of basilar artery occlusion as seen in the adult are not apparent in the neonate. Recognition of the neuroimaging characteristics seen in this condition may help to provide the clinician with a reasonable pathogenetic explanation for unexplained cerebral injury.