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Biomedical subjects

E B Fennell

Publications and source records attributed to E B Fennell.

At least 19 recordsLinked to original sources
PubMed1999

Cognition, behavior, and development in Joubert syndrome.

This article reports on a series of studies of children with Joubert syndrome who were examined in three investigations from 1994 through 1998. Neuropsychologic screening of 10 of 40 children showed a variety of deficits in cognition, verbal memory, visuomotor, motor, and language-related tasks. Parent report of developmental attainments revealed only 3 of 40 children functioning in the borderline range, with the rest scoring in the severely impaired range. Parent reports of behaviors revealed problems in temperament, hyperactivity, aggressiveness, and dependency, as well as problems in physical development and care that were felt to be related to their neurologic handicaps. Future directions of research with this rare disorder are suggested.

Adolescent↗
PubMed1997

"Joubert syndrome" revisited: key ocular motor signs with magnetic resonance imaging correlation.

Joubert syndrome is characterized by episodic hyperpnea and apnea, developmental delay, hypotonia, truncal ataxia, ophthalmologic abnormalities, and vermian dysgenesis. We studied 15 patients with the diagnosis of Joubert syndrome to (1) more fully define the syndrome's clinical features, and (2) correlate the clinical features with magnetic resonance imaging (MRI) findings. Eight of 15 patients had a history of episodic hyperpnea and apnea. All patients had developmental delay and hypotonia. Of the 13 patients receiving detailed neuro-ophthalmologic evaluations, three had optic nerve dysplasia, pendular nystagmus, and gaze-holding nystagmus. All 13 patients had a normal vestibulo-ocular reflex based on head thrust, but had absent to poor ability to cancel the vestibulo-ocular reflex horizontally and vertically. Twelve of 13 patients had impaired smooth pursuit. Twelve of 13 patients had defects in initiation of saccades and quick phases. Two of the most consistent radiologic features were absent or hypoplastic posterior cerebellar vermis, and deformed midbrain and pontomesencephalic junction, which based on ocular motor physiology correlate with the vestibulo-ocular reflex cancellation/ pursuit defect and saccade initiation defect, respectively. As a result of midbrain, vermian, and superior cerebellar peduncle abnormalities, axial neuroimaging showed a unique "molar tooth" appearance of these structures. These results indicate that Joubert syndrome results from maldevelopment of the midbrain and cerebellar vermis, producing a pathognomonic sign on MRI.

Adolescent↗
PubMed1996

Pars triangularis asymmetry and language dominance.

The pars triangular is a portion of Broca's area. The convolutions that form the inferior and caudal extent of the pars triangularis include the anterior horizontal and anterior ascending rami of the sylvian fissure, respectively. To learn if there are anatomic asymmetries of the pars triangularis, these convolutions were measured on volumetric magnetic resonance imaging scans of 11 patients who had undergone selective hemispheric anesthesia (Wada testing) to determine hemispheric speech and language lateralization. Of the 10 patients with language lateralized to the left hemisphere, 9 had a leftward asymmetry of the pars triangularis. The 1 patient with language lateralized to the right hemisphere had a significant rightward asymmetry of the pars triangularis. Our data suggest that asymmetries of the pars triangularis may be related to speech-language lateralization.

Adolescent↗
PubMed1996

Altered cognitive functioning in children with idiopathic epilepsy receiving valproate monotherapy.

Once a child is diagnosed with epilepsy, a primary concern is whether or not the child's behavior and cognitive abilities will be affected by the disease, by the drug prescribed for seizure control, or both. Direct cognitive effects by the epileptic condition have been described. On the other hand, cognitive effects in epilepsy have been attributed to antiepileptic drug therapy. Valproate is an antiepileptic drug of choice in managing the commonest childhood epilepsy syndromes. Although frequently prescribed in pediatric neurology practice, there have been relatively few studies investigating the cognitive effects of valproate therapy in children. Cognitive effects of valproate reported in normal adult volunteers and in adults with epilepsy cannot be generalized to the pediatric population. The results of investigations on children are less conclusive. Guidelines for antiepileptic drug trials in children have recently been formulated. Carefully designed studies are required in determining the cognitive effects of valproate in the pediatric population. Neuropsychological measures that are likely to assess subtle changes in higher brain functions crucial to learning in children should be employed. We propose a test battery to assess for cognitive changes associated with anticonvulsant therapy in children.

Anticonvulsants↗
PubMed1995

Dissociation of anosognosia for hemiplegia and aphasia during left-hemisphere anesthesia.

The stroke literature indicates that the explicit denial of hemiplegia, a form of anosognosia, is associated more commonly with right- than left-hemisphere lesions. Some investigators have suggested that this asymmetry may be an artifact and that the aphasia that often accompanies left-hemisphere dysfunction may mask some instances of anosognosia. Mechanisms suggested for anosognosia have been either "global" or "modular" in nature. Mechanisms posited in global explanations include psychological denial and general mental deterioration; modular explanations include feedback and feedforward theories. Videotapes of 54 patients with medically intractable seizures who had selective barbiturate anesthesia (Wada test) as part of their evaluation for seizure surgery were assessed for anosognosia of hemiplegia and aphasia after hemispheric anesthesia had worn off. The results suggest that, although aphasia may confound the reported rate of anosognosia for hemiplegia following left-hemisphere dysfunction, the frequency of anosognosia for hemiplegia is still higher with right- than left-side dysfunction. Anosognosia for hemiplegia and aphasia were dissociable, providing support for the postulate that awareness of dysfunction is mediated by a modular system.

Adult↗
PubMed1995

Anosognosia during intracarotid barbiturate anesthesia: unawareness or amnesia for weakness.

Previous studies have demonstrated asymmetric hemispheric contributions to deficit awareness during hemisphere inactivation with intracarotid barbiturate infusion (Wada studies). These observations provide insight into the neuropsychological basis of anosognosia for hemiparesis (AHP), arguing against earlier explanations based upon psychological denial, global cognitive disturbance, or emotional indifference. Although prior Wada studies equated AHP after the procedure with AHP during the period of deficit, a selective memory failure could also account for these findings. We, therefore, assessed the occurrence of AHP during and after right-hemisphere inactivation in a group of epilepsy patients undergoing preoperative Wada testing. Because aphasia obscures assessment of deficit awareness during left carotid studies, we compared the frequency of AHP between right- and left-hemisphere inactivation only after recovery. As noted in earlier reports, AHP was present significantly more often after right- than left-hemisphere inactivation. The proportions of subjects with AHP during right-hemisphere anesthesia compared with the proportion of subjects with AHP after the procedure were statistically equivalent, suggesting that the AHP observed after right-hemisphere anesthesia results from true failure of deficit awareness rather than inability to recall the deficit.

Amnesia↗
PubMed1995

Apraxia during Wada testing.

Apraxia is the loss of the ability to perform learned skilled movements correctly. In right-handers, apraxia and aphasia are most frequently associated with left-hemisphere lesions. When they are dissociated, however, aphasia is more common in the absence of apraxia than vice versa. There are two hypotheses that can account for this discrepancy: (1) in right-handers, praxis is more likely than language to be mediated by the right hemisphere, or (2) the left-hemisphere network that mediates language is either more widely distributed than the network that mediates praxis or is more likely to be in the middle cerebral artery distribution. We studied apraxia in a group of right-handers undergoing selective hemispheric anesthesia, or Wada testing. All nine subjects had language lateralized to the left hemisphere, and seven of the nine had praxis lateralized to the left hemisphere. Two of the subjects had praxis bilaterally represented. Although our data suggest that speech and praxis functions tend to be lateralized to the left hemisphere in most right-handers, praxis appears to be more distributed between the hemispheres than speech-language functions. Furthermore, an analysis of the types of errors made during praxis testing suggests differential roles of the hemispheres in praxis functions.

Adolescent↗
PubMed1993

Assessing neurobehavioral changes in HIV+ infants and children. A methodological approach.

The rationale and development of a developmental approach to assessing neurobehavioral changes in infants and children exposed to or infected with the HIV-1 virus is presented. Methodological problems in earlier approaches to assessment are reviewed. Among these are measures employed, impact of different treatments on measures of outcome, multicultural differences between samples, and analytic approaches to developmental data. The assessment protocol developed by the Pediatric Neurobehavioral Study Group of NIMH/NICHD/NIAID is described.

Adolescent↗
PubMed1993

Brainstem glioma: I. Pathology, clinical features, and therapy.

Gliomas that arise in the brain stem have been associated with a poor prognosis. Diagnostic neuroimaging readily identifies the tumor as it extends between normal brainstem structures. Histologic sampling of tumor with stereotactic methods is notoriously unreliable in establishing a definitive prognosis. Clinical trials that incorporate high-dose chemotherapy, autologous bone marrow rescue, and irradiation hold promise of better tumor control by overcoming the inaccessibility of the central nervous system to standard doses of chemotherapy. We review the pathology, clinical features, neuroimaging features, and current therapeutic concepts relative to brainstem glioma. The pediatric neurologist has a pivotal role in identifying and monitoring children with this malignancy.

Biopsy↗
PubMed1990

A longitudinal study of the cognitive function of children with renal failure.

Fifty-six children with chronic renal failure who either received a kidney transplant, were hemodialyzed or peritoneally dialyzed, or who were being medically managed were given a series of neuropsychological tests every 6 months for a total of four testing sessions. Each child was matched by age, sex, and race to healthy children who received the same sequence of tests. The performance of each treatment group was compared with their controls longitudinally, using a repeated measure analysis of variance. In general, renal subjects performed at lower levels than their controls on tasks of verbal ability, visual perception, memory and visual motor skills. Visual motor performance was the most clinically affected. When compared with controls, the renal subjects did not improve as much or actually deteriorated on some measures of memory and learning skills.

Adolescent↗
PubMed1990

Association between renal function and cognition in childhood chronic renal failure.

Forty-five children with renal failure who were either being medically managed, receiving dialysis (hemodialysis or continuous ambulatory peritoneal dialysis) therapy or who had received successful kidney transplants were longitudinally examined on multiple neuropsychological measures. A variety of medical parameters was also obtained at each time of testing. The neuropsychological variables were correlated with the medical variables using the repeated measures regression analysis method. There were associations between levels of renal function, short-term memory and list learning. Other neuropsychological variables did not in general correlate with the medical parameters consistently for all ages at the time of initial testing. Verbal performance decreased with increasing duration of renal failure in 6- to 11-year-olds and immediate recall decreased with increasing percentile rank of systolic blood pressure in 16- to 18-year-olds.

Adolescent↗
PubMed1990

Correlations between performance on neuropsychological tests in children with chronic renal failure.

A series of neuropsychological tests were given every 6 months to children with renal failure for up to 4 testing periods. Controls matched to the renal failure children were also given the same series. Associations between various neuropsychological variables for both the renal and control subjects were estimated and compared by a generalized growth curve procedure. Measures of vigilance and immediate recall were significantly related to more complicated measures of memory; vigilance and reaction time were significantly related to speed of decision making. Where differences occurred, the renal subjects more often exhibited correlations between neuropsychological variables than the controls, suggesting that renal failure has an impact on both generalized arousal and on other higher order complex brain functions.

Adolescent↗
PubMed1984

Effects of kidney transplantation on cognitive performance in a pediatric population.

The cognitive functioning of 20 children and adolescents with end-stage renal disease was assessed 1 to 3 weeks prior to the onset of hemodialysis, and at 1 month and 1 year after successful kidney transplantation, and results were compared with those of a matched control group. A battery of intelligence, achievement, problem solving, learning, memory, and attention tasks were administered. Both groups had significantly improved scores over time on most measures. The group with renal disease exhibited significantly greater improvement than the control group from initial testing to 1 month after transplantation on the performance IQ and full-scale IQ as well as in mathematics achievement. This significant difference was not maintained, however, at 1 year after transplantation. Cognitive performance was less impaired the later the onset of renal failure or the fewer the years in end-stage renal disease. BUN nitrogen, serum creatinine levels, and BP did not consistently correlate with any of the cognitive or academic achievement measures.

Achievement↗
PubMed1983

The development of handedness and dichotic ear listening asymmetries in relation to school achievement: a longitudinal study.

To assess the development of dichotic ear asymmetries and handedness, 208 male school children were evaluated in kindergarten and at Grades 2 and 5 (ages 66, 92, and 130 months of age, respectively) with a dichotic listening task and a hand preference test. The Wide Range Achievement Test (WRAT) also was administered at each of the three grade levels. There was significant variability in handedness scores over time only for those subjects whose scores at initial testing, that is, in kindergarten, identified them as non-right-handers. Both right and left handers had a significant increase in dichotic listening scores over time; however, only right handers had a significant right ear advantage at each evaluation. Regression analyses showed that combined hand preference scores and ear recall scores at each probe when combined accounted for almost 44% of the variance in WRAT achievement scores at Grade 5. Ear asymmetry scores, however, were not predictive of school achievement.

Achievement↗
PubMed1982

Problems associated with establishing a clinic for the elderly.

Actual use of a newly established geriatric clinic in a low-cost housing unit was appreciably below projected numbers, even though cost and transportation were removed as barriers to care. In a survey of building occupants, 20% were unaware of the clinic's existence. More than 90% of the occupants did not know clinic hours but a third could identify clinic staff. About half of the occupants had used the clinic, often for minor services. The major reason for lack of use of the clinic was an established pattern of receiving medical care which occupants were reluctant to risk or abandon. Needs must be appropriately assessed before service programs are designed for the elderly. Assumptions may at times be incorrect. A thorough understanding of needs and existing methods of meeting them leads to more appropriately designed programs.

Aged↗