PubMed Health⌕ Search

Biomedical subjects

W G Mitchell

Publications and source records attributed to W G Mitchell.

At least 37 records · Page 2Linked to original sources

Usefulness of [18F]fluorodeoxyglucose positron emission tomography in pediatric epilepsy surgery.

We sought to analyze our experience with pediatric epilepsy surgery patients to determine the place of [18F]fluorodeoxyglucose (FDG) positron emission tomography (FDG-PET) in the preoperative evaluation of such children relative to chronic invasive intracranial monitoring. Fifty-six children who received an interictal FDG-PET as part of a phase 1 epilepsy surgery evaluation were compared with 44 children who did not have this study in a retrospective analysis of 100 patients accrued over a 4-year period. There was no significant difference between the two groups of children in terms of age or follow-up or was there a significant difference between the FDG-PET group and the no-FDG-PET group in regard to the numbers of children who had surgery, the type of procedure done, whether chronic invasive intracranial monitoring was performed, or outcome. The hypometabolic area demonstrated on interictal FDG-PET was concordant with that of the epileptogenic zone as mapped out with ictal recordings from subdural electrodes in 2 of 13 patients in whom a complete data set was available for comparison. In the other 11 children there was either poor agreement between interictal FDG-PET and ictal electrocorticographic data or the interictal FDG-PET was normal in the face of an epileptogenic focus which was successfully mapped by invasive electrophysiologic techniques and excised. We conclude that one cannot exclude a child with intractable partial seizures from surgical consideration because the interictal FDG-PET is normal; nor is there sufficient correlation between the interictal hypometabolic area on FDG-PET and the epileptogenic zone in terms of anatomic location and size to justify forgoing chronic invasive intracranial monitoring in children with intractable partial seizures being evaluated for epilepsy surgery unless there is absolute concordance between all neuroimaging, clinical, and video-electroencephalographic data.

Adolescent↗

Status epilepticus and acute repetitive seizures in children, adolescents, and young adults: etiology, outcome, and treatment.

Status epilepticus (SE) is one of the most common neurologic emergencies in children, adolescents, and young adults. SE may be due to acute neurologic conditions such as meningitis, encephalitis, or stroke, complicated febrile seizures, intractable epilepsy, degenerative diseases, intoxication, or may be the first manifestation of epilepsy. Initial treatment of convulsive SE is usually with an intravenous benzodiazepine (BZD) [lorazepam (LZP) or diazepam (DZP)], phenobarbital (PB), or phenytoin (PHT). LZP is less likely to cause respiratory depression than DZP and is therefore preferred. Sequelae and risk for recurrence of SE are primarily related to the underlying cause. Refractory SE (RSE) is most often symptomatic of an acute neurologic condition or neurodegenerative disease. Treatment for RSE is difficult, usually requiring intensive support of vital functions. Reported treatments for RSE include very high dose PB, continuous infusions of pentobarbital or BZDs (DZP, midazolam), lidocaine, inhalation anesthesia, and propofol. Outcome is related to underlying cause. Nonconvulsive SE may present as confusion or may mimic psychiatric illness. Response to BZDs is usually rapid but may not be sustained. Rapid initiation of oral or rectal valproate may be useful. Epilepsia partialis continua (EPC) is almost always due to an acute or chronic destructive lesion. Surgical treatment may be the only effective modality in some children with EPC. Acute treatment of breakthrough seizures and clusters of seizures at home with rectal BZDs (usually DZP, 0.2-0.5 mg/kg) may prevent progression to SE in some children and adolescents and reduce the need for visits to emergency facilities.

Adolescent↗

High-dose corticotropin (ACTH) versus prednisone for infantile spasms: a prospective, randomized, blinded study.

OBJECTIVE: To compare the efficacy of corticotropin (ACTH) (150 U/m2/day) and prednosone (2 mg/kg/day) given for 2 weeks, in suppressing clinical spasms and hypsarrhythmic electroencephalogram (EEG) in infantile spasms (IS). AACTH and prednisone are standard treatments for IS. ACTH at high doses causes severe dose- and duration-dependent side effects, but may be superior to prednisone, based on retrospective or uncontrolled studies. Blinded prospecive studies have shown equal efficacy of prednisone and low-dose ACTH, and low versus high-dose ACTH. DESIGN: A prospective, randomized, single-blinded study. SUBJECTS AND METHODS: Patient population consisted of consecutive infants fulfilling entry criteria, including the presence of clinical spasms, hypsarrhythmia (or variants) during a full sleep cycle video-EEG, and no prior steroid/ACTH treatment. Response required both cessation of spasms and elimination of hypsarrhythmia by the end of the 2-week treatment period, as determined by an investigator "blinded" to treatment. Treatment of responders was tapered off over 12 days; those failing one hormone were crossed-over to the other. RESULTS: OF 34 eligible infants, 29 were enrolled. Median age of patients was 6 months. Twenty-two infants were "symptomatic" with known or suspected cause, and seven were cryptogenic (two normal). Of 15 infants randomized to ACTH, 13 responded by EEG and clinical criteria (86.6%); Seizures stopped in an additional infant, but EEG remained hypsarrhythmic (considered a failure). Four of the 14 patients given prednisone responded (28.6%,, with complete clinical-EEG correlation), significantly less than with ACTH, (chi2 test). CONCLUSIONS: Using a prospective, randomized approach, a 2-week course of high-dose ACTH is superior to 2 weeks of prednsone for treatment of IS, as assessed by both clinical and EEG criteria.

Adrenocorticotropic Hormone↗

Inhibition of pituitary-adrenal secretion by a corticotropin releasing hormone antagonist in humans.

Corticotropin releasing hormone (CRH) is the primary modulator of ACTH release from the pituitary, and a neuromodulator in limbic and autonomic brain regions. Dysfunction of CRH-mediated neurotransmission is emerging as a critical mechanism in several disorders. Therefore, modulation of CRH availability at receptor sites is a potentially powerful therapeutic tool. Inhibitory analogues of CRH have been tested in rodents and primates, but their safety and hormonal effects in humans are unknown. We administered a CRH-antagonist, alpha-helical-CRH-(9-41) to six individuals. Each received two intravenous infusions: 50 micrograms kg-1 on day 1, and 100 micrograms kg-1 on the following morning. These doses block both endocrine and central effects of CRH in experimental animals. ACTH, cortisol, electrolytes, glucose and autonomic parameters were monitored in comparison with control values. Infusion of CRH antagonist did not alter heart rate, blood pressure, temperature or plasma electrolytes and glucose. Pre-infusion plasma ACTH levels averaged 26.8 +/- 6.7 pg ml-1 on day 1, and 29.0 +/- 5.8 pg ml-1 on day 2. Post-infusion values were 11.8 +/- 2 and 11.5 +/- 2.4 pg ml-1, significantly lower than pre-infusion levels. Plasma cortisol levels, which averaged 21.4 +/- 4 micrograms dl-1 on the first morning and 22.9 +/- 4.2 on the second, also decreased significantly after CRH antagonist infusions (to 14.0 +/- 2.9 micrograms dl-1 on day 1, and 13.9 +/- 3.0 micrograms dl-1 on day 2). Hormonal changes were transient, and circadian rhythm was not affected. Though not measured formally, euphoria, anxiety or somnolence were not observed. In conclusion, CRH antagonist administration to adults reduces hormonal secretion by pituitary corticotrophs, with resulting decrease in plasma ACTH and cortisol.

Adrenocorticotropic Hormone↗

Clinical utility of video-EEG monitoring.

This study investigated the efficiency of simultaneous video-electroencephalography (EEG) monitoring in documenting paroxysmal events, the value in clinical diagnosis, and the effect on treatment. In this retrospective review, 230 children underwent this procedure between January, 1990 and December, 1992. The data demonstrated that video-EEG monitoring can be used as a daytime procedure with a high success rate (80%) in detecting and differentiating the nature of recurrent paroxysmal behaviors that have occurred on a daily basis. Video-EEG monitoring has a high diagnostic rate in differentiating seizure versus nonseizure events (70%), in classifying seizure types (88%), and in evaluating the candidacy for epilepsy surgery (64%). Video-EEG diagnosis resulted in an alteration of clinical management in 45% of patients. Continuous video-EEG monitoring is an efficient and valuable procedure in the diagnosis and management of paroxysmal disorders in children.

Anticonvulsants↗

Cerebrospinal fluid corticotropin and cortisol are reduced in infantile spasms.

Infantile spasms respond to ACTH, and levels of the hormone in cerebrospinal fluid of untreated infants with this disorder were found to be lower than in age-matched controls. In this study we analyzed cerebrospinal fluid cortisol and ACTH using improved immunoassays in a larger cohort of infants with infantile spasms. Analysis of 20 patients and 15 age-matched controls revealed significantly lower levels of both ACTH and cortisol in the cerebrospinal fluid. These data, combined with the efficacy of ACTH and glucocorticoids for infantile spasms, support an involvement of the brain-adrenal-axis in this disorder.

Adrenocorticotropic Hormone↗

Long-term prognosis for children with epilepsy.

In discussions of prognosis that are based primarily on epidemiologic data, it is important to emphasize two issues: first, statistical rates of recurrence or remission apply to groups, not individuals. Whereas important and useful information is obtained from examining the epidemiology of epilepsy, it is the individual child who is the concern of the physician, family, and community. That individual child may do well despite indicators that suggest a risk of poor outcome, or may do poorly, experiencing recurrent seizures or adverse effects of treatment, despite apparent "low risk." It is unimportant to a parent that "90% of children with this type of epilepsy do well" if his or her child is doing poorly. All treatment decisions, including the decision to withdraw anticonvulsants after prolonged seizure-free periods, must be made individually. An adolescent or young adult, seizure-free on treatment, may be unwilling to risk even a 10% to 25% risk of recurrence if it means giving up driving privileges or risking a seizure in school or on the job. In addition, although it is appropriate to reassure most parents of children with newly-diagnosed epilepsy that seizures do not cause cognitive or behavioral deficits, problems do occur frequently and must be addressed. Comprehensive treatment programs for children with epilepsy must include evaluation and treatment of coexisting learning, cognitive, and behavior problems, as well as family education to prevent excessive parental anxiety and overprotection.

Adolescent↗

Psychosocial, behavioral, and medical outcomes in children with epilepsy: a developmental risk factor model using longitudinal data.

OBJECTIVE: We studied factors predicting the risk of adverse long-term psychosocial, behavioral, and medical outcomes in children with epilepsy. METHODS: Children (N = 157, 4.5 to 13 years) were enrolled in a prospective longitudinal study when first seen. Potential subjects were excluded if they were moderately or severely mentally retarded, had motor or sensory handicaps interfering with testing, or did not speak either English or Spanish. MEASURES: To develop risk predictors, we collected information regarding the child's medical and seizure history, cognitive functioning, and behavior problems, and family functioning. Children and their families were followed for a minimum of 18 months, then underwent reassessment of medical status, parent's attitudes toward epilepsy, and the child's behavioral and cognitive functioning. Data were analyzed by confirmatory factor analysis to develop baseline factors (Sociocultural Risk, Seizure Risk, and Behavior Problems) and outcome factors (Medical/Seizure Problems, Parent's Negative Attitudes Toward Epilepsy, and Behavior Problems), followed by structural equation modeling to determine across-time causal effects. Eighty-eight subjects completed all baseline and outcome measures. RESULTS: Among significant across-time effects, Medical Outcome was predicted by Seizure Risk. An increased number of stressful life events predicted better Medical Outcome. Low acculturation increased Parent's Negative Attitudes and was associated with increased Behavior Problems at baseline. Behavior Problems were stable across time. It is interesting that IQ did not affect any of the outcomes, although its effect may have been mediated through other baseline measures. CONCLUSIONS: Seizure history was the best predictor of ongoing medical difficulties, whereas the most important causes of ongoing parental anxiety and negative attitudes toward epilepsy were sociocultural. Variation in medical or attitudinal outcomes was not influenced by either the child's IQ or reported behavioral problems. These findings suggest that to alter attitudes toward epilepsy, programs should be tailored to the sociocultural background of the family. Studies of quality of life of children with epilepsy should include appropriate sociocultural measures.

Acculturation↗

Effects of human immunodeficiency virus and immune status on magnetic resonance imaging of the brain in hemophilic subjects: results from the hemophilia growth and development study.

To determine the effects of hemophilia and human immunodeficiency virus (HIV) infection on the nervous system, the authors examined the relationship of brain magnetic resonance imaging (MRI) findings to immunologic function and neurologic examination findings. Baseline examinations included physical and neurologic examination, immunologic and virologic testing, and MRI of the brain. On neurologic examination, muscle atrophy was considered to be related to hemophilia if adjacent joints had arthropathy due to bleeding. Muscle atrophy was considered non-hemophilia-related if unrelated to arthropathy or if muscle atrophy was diffuse. Subjects were boys aged 6 to 19 years, enrolled in a multicenter study of the effects of hemophilia and HIV infection on growth and development, all with congenital coagulopathies requiring factor infusions. Three hundred ten subjects had complete data including neurologic examination, T-cell subsets, HIV antibodies, and MRI. Subjects with HIV infection whose CD4+ counts were < 200/microL were compared with subjects with HIV infection and CD4+ counts > or = 200/microL and with HIV-negative subjects, all of whom had CD4+ counts > 200/microL. MRI studies were normal in 230. Abnormal MRI studies were more frequent in HIV-positive subjects with CD4+ counts < 200 (29.4% abnormal compared with 17% in HIV-positive subjects with CD4+ counts > or = 200 and 15.3% in HIV-negative subjects). Diffuse atrophy accounted for most of the excess abnormalities in HIV-positive subjects with CD4+ counts < 200 (77.3% of abnormal scans). Diffuse atrophy on MRI was associated with decreased muscle bulk on neurologic examination, but not with abnormal tendon reflexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Effects of antiepileptic drugs on reaction time, attention, and impulsivity in children.

Simple, choice, and complex reaction times, attention (variability of responses and omission errors), and impulsivity (commission and wrong-hand errors on choice and complex reaction time) were repeatedly measured in 111 epileptic children, aged 5 to 13 years, tested a total of 232 times. Antiepileptic drugs (AEDs) were started, stopped, and adjusted throughout the study period, for a variety of clinical indications, and AED serum levels were monitored. The relationship of performance to AED serum level was examined. Overall the nonspecific effect of AEDs was minimal: higher total serum levels of AEDs correlated with more impulsive errors on complex reaction time testing only. In contrast, in 54 children receiving carbamazepine monotherapy, we found a dose-related beneficial effect upon reaction time, with higher serum levels associated with faster responses and fewer omission errors, particularly on complex reaction time. Phenobarbital caused minimal dose-related effects: only variability and impulsive errors increased with increasing serum levels, and only on one segment of the test (73 subjects).

Adolescent↗

Brain abnormalities in male children and adolescents with hemophilia: detection with MR imaging. The Hemophilia Growth and Development Study Group.

Cranial magnetic resonance (MR) imaging was performed in 124 male patients (aged 7-19 years), from 14 institutions, in whom a diagnosis of moderate to severe hemophilia was made. Blood tests in all subjects were negative for human immunodeficiency virus. Findings in MR studies were abnormal in 25 (20.2%) subjects. Six lesions in five subjects were classified as congenital. The most commonly identified congenital lesion was a posterior fossa collection of cerebrospinal fluid (five cases). Twenty-two subjects had acquired lesions that were probably related to the hemophilia or its treatment. The most commonly acquired lesions were single- or multifocal areas of high signal intensity within the white matter on T2-weighted images noted in 14 (11.3%) subjects. Two subjects had large focal areas of brain atrophy, and six had some degree of diffuse cerebral cortical atrophy. Three subjects (2.4%) had hemorrhagic lesions. To the authors' knowledge, the unexpected finding of small, focal, nonhemorrhagic white matter lesions has not previously been reported.

Adolescent↗

Brain-adrenal axis hormones are altered in the CSF of infants with massive infantile spasms.

Massive infantile spasms (MIS), a seizure disorder unique to infants, is considered an age-dependent response of the immature brain to various insults and stressors. The seizures improve with ACTH and glucocorticoids, both major components of the brain-adrenal axis. We hypothesized that CNS levels of these hormones are abnormal in infants with MIS and studied CSF from 14 infants with MIS and 13 age-matched controls by analysis for corticotropin-releasing hormone (CRH), ACTH, cortisol, and interleukin-1-beta. ACTH levels in CSF of patients were significantly lower than those of controls, but differences in cortisol levels between patients and controls were not statistically significant. CRH levels in both groups were similar and fluctuated diurnally. These results indicate an alteration of specific CNS components of the brain-adrenal axis in MIS.

Adrenocorticotropic Hormone↗

Academic underachievement in children with epilepsy.

Academic achievement was studied in 78 children with epilepsy, ages 5 to 13 years, to determine how seizures, treatment of seizures, and sociocultural factors influence academic achievement. Cognitive abilities were assessed with either the McCarthy Scales of Children's Abilities or the Wechsler Intelligence Scale for Children--Revised. Achievement was measured with the Peabody Individual Achievement Tests. Achievement scores were corrected for cognitive ability (IQ), and underachievement was defined as achievement score 1/2 standard deviation or more below IQ. Information regarding seizure history (severity, duration) and treatment with anticonvulsant drugs was obtained. In addition, the family was extensively interviewed regarding the child's environment, behavior, and demographic background. The Home Observation for Measurement of the Environment (HOME) scale was completed on a home visit. Underachievement was frequent, ranging from 16% (Reading Recognition) to 50% (General Knowledge), but there was no relationship between severity or duration of seizure disorder or total exposure to anticonvulsant medications and achievement. Major determinants of achievement included subscales of the HOME scale, age (older children more likely to be underachieving), and parental education. An equal proportion of newly diagnosed and/or untreated subjects were underachieving compared to those with longstanding epilepsy and anticonvulsant drug treatment.

Adolescent↗

Stroke as a late sequela of cranial irradiation for childhood brain tumors.

Cerebrovascular disease involving large and medium-size vessels is thought to be an uncommon sequela of treatment of childhood brain tumors. We reviewed 11 children who developed cerebrovascular disease manifested by strokes or transient ischemic attacks 6 months to 4 years after treatment of brain tumors, while their tumors were in remission. All had received radiation therapy, and seven had received chemotherapy. One child died of acute bilateral cerebral infarctions due to carotid occlusion on one side and marked stenosis on the other 2 years after receiving radiation therapy for an incompletely resected craniopharyngioma. Pathologically, there was marked subendothelial fibrosis of the vessels of the circle of Willis, with inflammatory changes surrounding some of the vessels. In addition to the widely recognized small-vessel damage caused by radiation and chemotherapy in children (mineralizing microangiopathy), damage to medium and large intracranial vessels may result in late sequelae, manifested by stroke or transient ischemic attacks.

Adolescent↗

Opsoclonus-ataxia due to childhood neural crest tumors: a chronic neurologic syndrome.

Five children with subacute or acute onset of cerebellar ataxia and opsoclonus are described. Two had cerebrospinal fluid pleocytosis at the onset of ataxia and were initially thought to have acute parainfectious cerebellar ataxia of childhood. All were found to have tumors of neural crest origin (two neuroblastomas, three ganglioneuroblastomas). Tumors were small and only found by computed tomographic techniques. Urinary catecholamine metabolites were elevated in only two of the patients. Four of the five failed to improve neurologically with resection of the tumor. All four have had a steroid-sensitive chronic ataxic syndrome that worsens with acute nonspecific illnesses and has resulted in long-term deficits, particularly in speech and gross motor function. This is a metabolic encephalopathy associated with permanent residual neurologic deficits but without visible lesions on neuroimaging studies. We stress the frequency of cerebrospinal fluid pleocytosis in patients with tumor-associated opsoclonus and the clinical difficulty in separating tumor-associated cases from those due to other causes [corrected].

Abdominal Neoplasms↗

Reaction time, impulsivity, and attention in hyperactive children and controls: a video game technique.

Maturation of sustained attention was studied in a group of 52 hyperactive elementary school children and 152 controls using a microcomputer-based test formatted to resemble a video game. In nonhyperactive children, both simple and complex reaction time decreased with age, as did variability of response time. Omission errors were extremely infrequent on simple reaction time and decreased with age on the more complex tasks. Commission errors had an inconsistent relationship with age. Hyperactive children were slower, more variable, and made more errors on all segments of the game than did controls. Both motor speed and calculated mental speed were slower in hyperactive children, with greater discrepancy for responses directed to the nondominant hand, suggesting that a selective right hemisphere deficit may be present in hyperactives. A summary score (number of individual game scores above the 95th percentile) of 4 or more detected 60% of hyperactive subjects with a false positive rate of 5%. Agreement with the Matching Familiar Figures Test was 75% in the hyperactive group.

Attention↗