Biomedical subjects

J Willemse

Publications and source records attributed to J Willemse.

At least 19 recordsLinked to original sources

PubMed1995

Non-invasive ICP monitoring in infants: the Rotterdam Teletransducer revisited.

Measurement of intracranial pressure (ICP) is important in patients at risk of raised ICP, as in hydrocephalus. Ideally, it should be non-invasive, thus avoiding the risk of infection and other complications: Such is provided by measurement of ICP through the anterior fontanelle. There are several methods of measuring anterior fontanelle pressure (AFP); those most frequently used are based on the applanation principle. An evaluation of AFP measurement devices resulted in the choice of the Rotterdam Teletransducer (RTT) to be used in our study of children with hydrocephalus. The literature contains little information on the accuracy or validation of the AFP measurements using the RTT. Therefore, the physical qualities of the RTT were reassessed, using a specially developed calibration device. The results of this study demonstrate that membrane temperature does not have any effect on the measured pressure. The thermal stabilization time of the RTT was found to be 3 h after switching on. Insufficient thermal stabilization results in a pressure underestimation of up to 3 mmHg. Furthermore, a maximum inaccuracy of 2.6 mmHg, after calibration and readjustment of the transducer, was calculated. Validation of the equipment was achieved by simultaneous AFP/ICP measurements in hydrocephalic patients showing high correlations (r = 0.96-0.98). The discussion suggests a measurement protocol as a means of increasing the reliability of RTT measurements.

Calibration↗

PubMed1995

Monitoring intracranial dynamics by transcranial Doppler--a new Doppler index: trans systolic time.

Since the introduction of transcranial Doppler sonography (TCD) several investigators have described the relationship between raised intracranial pressure (ICP) and Doppler waveform. This waveform has been expressed by several indices, such as the pulsatility index (PI) and the resistance index (RI). These indices are used to demonstrate the presence of raised ICP. In childhood hydrocephalus this information can be used to indicate the need for shunt implantation. However, PI and RI do prove to have certain disadvantages as both are strongly influenced by the heart rate. Moreover, both indices have a broad range of reference values, especially in children. Therefore, they are not very reliable for detecting insidious changes in the ICP. These drawbacks are due to the fact that these indices are composed of blood flow velocity measurements and do not embody the slope of the TCD waveform itself. An ideal TCD waveform analysis should be performed concerning the time-related changes of the velocities. We present a hydrodynamic model, with its electrical analogue, which shows the effects of raised ICP on the intracranial hemodynamic system. Based on these physical findings we define a new Doppler index, the Trans Systolic Time, reflecting specific changes in the TCD waveform induced by changes in the mean ICP. The applicability of this index, compared with PI and RI, is illustrated by consecutive simultaneous TCD and AFP measurements in three children with hydrocephalus.

Blood Flow Velocity↗

PubMed1993

Unruptured intracranial arteriovenous malformations with hereditary haemorrhagic telangiectasia. Neurosurgical treatment or not?

Clinical decision analysis is applied to treatment decisions for three patients with unruptured familial intracranial arteriovenous malformations (AVMs) in association with hereditary haemorrhagic telangiectasia (HHT). The grades of the AVMs--according to Spetzler--were 1-0-0 (two patients aged 12 and 14) and 2-0-1 (one patient aged 43). The AVM in one patient (graded 1-0-0) was operated on without sequelae. In the decision analysis, life expectancy is used as an outcome measure, with and without quality of life adjustment and discounting for time preference. It is concluded that neurosurgical treatment is the optimal strategy for all three patients. Because no conclusive data are available concerning the natural history and neurosurgical treatment of unruptured AVMs, we recommend the prospective application and testing of AVM grading systems. General treatment guidelines balancing the lifetime risk of haemorrhage, risk of incomplete extirpation and surgical mortality and morbidity are given. The analysis suggests that patients with low-graded AVMs which have not bled should be treated surgically, unless they are older than 60 years and have an increased risk of incomplete extirpation.

Adolescent↗

PubMed1992

Sequential EEG mapping may differentiate "epileptic" from "non-epileptic" rolandic spikes.

Sequential topographic mapping was performed to differentiate "epileptic" from "non-epileptic" rolandic spikes. Twenty-four children without any indication of organic brain lesion were divided into a group with epilepsy and a group without epilepsy. The group with epilepsy was subdivided into "classical BECT" (benign focal epilepsy of childhood with centro-temporal spikes) and "non-classical BECT." Sequential mapping of the rolandic spikes revealed two different topographic patterns: a pattern of stationary potential fields and a pattern of non-stationary potential fields. The topographic pattern of stationary potential fields was morphologically represented by a single spike-and-wave complex whereas that of non-stationary potential fields was morphologically represented by a "double" spike-and-wave complex. Among the non-stationary topographic patterns represented by a "double" spike, one specific sequence of changes of potential fields was found. This sequence started with a dipolar field, with the negative pole in the frontal region and the positive pole in the centro-temporal region, morphologically represented by the small first spike of the "double" spike-and-wave complex. This dipolar field, changes to a unipolar or dipolar field, with a negative potential field in the centro-temporal region and, sometimes, a simultaneous positive potential field in the frontal region, morphologically represented by the prominent rolandic spike. This characteristic pattern was found to be significantly related to classical BECT.

Adolescent↗

PubMed1992

Rolandic spikes in the inter-ictal EEG of children: contribution to diagnosis, classification and prognosis of epilepsy.

The clinical correlates of Rolandic spikes were studied in 47 children to determine the significance of this EEG finding to the diagnosis and classification of epilepsy. The children were classified into 'functional' and 'organic' groups, with and without epilepsy. Children with epilepsy were further subdivided into those with Rulandic and those with non-Rulandic seizures. In children without neurological abnormalities, the EEG finding of Rolandic spikes plays a decisive role in the diagnosis of an epileptic syndrome as benign focal epilepsy of childhood with centro-temporal spikes (BECT), a diagnosis with an excellent prognosis. Neurological and neuroradiological examinations of the 'functional' group revealed that the Rolandic spike may occur as a true 'functional' spike. The frequency of a family history of epilepsy among neurologically normal children with Rolandic spikes suggests, in addition to the inheritance of BECT and the EEG trait, the existence of a hereditary susceptibility to epilepsy.

Adolescent↗

PubMed1992

The prevalence of cerebral visual disturbance in children with cerebral palsy.

Assessment of visual acuity using the visual acuity card procedure in 164 children with cerebral palsy revealed low visual acuity in 71 per cent. Results of ophthalmological examination were available for 74 of these patients, but could not explain adequately the low visual acuity of 36 of the 43 patients (84 per cent) assessed by both the acuity card procedure and other techniques. There is a high probability that cerebral visual disturbance is present in these patients. Awareness of visual disability when compiling a programme of visual and neurodevelopmental stimulation for children with cerebral palsy is essential.

Adolescent↗

PubMed1992

Grating-acuity in children. Normal values of visual acuity in children up to 13 years as assessed by the acuity card procedure.

The acuity card procedure proved to be a useful method for assessing visual acuity in children. Normal values of visual acuity measured by this method had already been assessed in children up to four years. To enable application of the test in older children this study obtained values in a group of 396 normal children, aged three months to 13 years. The mean curve as well as the 10th centile was calculated in different age groups. A considerable variation of acuity values causing a 'dip' in the 10th centile was found in the ages 18 to 24 months. A smaller 'dip' was found in the ages 48 to 52 months. This has to be attributed to behavioural properties connected with age. The results obtained in the group of children under four years of age corresponded fairly well with other studies. In schoolchildren a fair agreement could also be found between the data obtained using the acuity card procedure and the data obtained with the Landolt-C rings. Obtaining normal values for the acuity card procedure in children covering a wide age range facilitates recognition of visual handicap in children who are difficult to assess.

Adolescent↗

PubMed1991

Visuomotor performance of normal and clumsy children. II: Arm-tracking with and without visual feedback.

Tracking performance was investigated in normal and clumsy children in two age-groups, six to seven and 10 to 11 years. Target signals moving unpredictably along a straight line had to be tracked, both with and without visual feedback. Performance was described in three ways: (1) performance in the low-frequency range (LF); (2) the delay between target signal and tracking movement (DL); and (3) a measure of tracking quality or over-all similarity in the shape of target signal and tracking movement (Q). Clumsy children in both age-groups had a lower tracking quality (Q) and longer delay (DL) than the normal children. Disturbances in the regulation of attention seemed to affect tracking performance, particularly of the six- to seven-year-old clumsy children. There was no significant difference between normal and clumsy children in the effect of visual feedback on tracking performance. This suggests that clumsiness is not linked to disturbance of integration of visual feedback information and motor processes.

Attention↗

PubMed1991

Visuomotor performance of normal and clumsy children. I: Fast goal-directed arm-movements with and without visual feedback.

The mechanisms underlying accuracy in fast goal-directed arm-movements were investigated in normal and clumsy children in two age-groups, six to seven and 10 to 11 years. Clumsy children in both age-groups had a longer movement time than normal children; this difference increased slightly when there was visual feedback. For both normal and clumsy children, the relative variability of the total distance moved was smaller than that of the distance moved during acceleration, indicating a variability reduction mechanism in the course of a movement. In the six- to seven-year-old group, the relative variability of the distance moved during acceleration and of the total distance was larger for clumsy than for normal children; this did not reach significance in the 10- to 11-year-old group. It is suggested that motor difficulties are linked to inaccuracy in open-loop control processes and to less efficient use of visual feedback.

Age Factors↗

PubMed1991

Myelination as an expression of the functional maturity of the brain.

A prospective cross-sectional study was performed on hydrocephalic infants and children. MRI was used to assess the state of myelination and to quantify the intracranial cerebrospinal fluid (CSF) volume repeatedly in all children. At the same time, neurodevelopmental testing was performed. A positive correlation was found between the progress of myelination and psychomotor development, but there were no significant correlations between CSF volume and myelination or between CSF volume and psychomotor development. This study provides strong evidence in favour of Flechsig's thesis that myelination expresses the functional maturity of the brain. The interdependency of neuronal maturation and progress of myelination are discussed.

Brain↗

PubMed1990

On-line detection of transient neuropsychological disturbances during EEG discharges in children with epilepsy.

Short-term memory tasks (visual-spatial and verbal) were devised to identify the influence of transient EEG discharges, without clinically manifest disturbances, on neuropsychological performance. 53 children with subclinical focal and generalized EEG discharges were tested 72 times and 16-channel telemetered EEG and video-recordings were made. 36 per cent of test sessions showed a significant preponderance of errors when discharges were recorded. Children with right-sided discharges had impaired performance in 50 per cent of their test sessions, with performance on the visual-spatial task most affected: left-sided discharges appeared to exert greater influence on the verbal task. These tests can easily be used to monitor six- to 15-year-old children.

Adolescent↗

PubMed1989

Ischaemic stroke in the basal ganglia and internal capsule in childhood.

Ischaemic stroke in childhood is rare. In particular, there have only been a few reports of lacunar infarcts in children. In this study, four children with true lacunar infarcts and four with larger subcortical infarcts are described. We compare the clinical features and the possible pathogenesis of ischaemic strokes in the basal ganglia and internal capsule in childhood with those in adults, and discuss diagnostic and therapeutic management.

Basal Ganglia↗

PubMed1989

Macrocephalies--a differentiated approach.

We present a clinical study of 43 macrocephalic children with a normal rate of headgrowth. The aims of the study were an evaluation of the usual criteria of macrocephaly and the drafting of a differentiated approach to the investigation of macrocephalics. Firstly, the value of head measurement in evaluating intracranial volume was assessed. As a golden standard for the intracranial volume the volume obtained by means of a CT-scan technique was used. It appeared that only about 30% of the variance of the intracranial volume was determined by the occipito-frontal circumference (OFC). A better estimation of the intracranial volume of the macrocephalic children was obtained by means of the "Utrecht Head Measure", the product of OFC-squared and the head height. Based on length measurements taken from CT-scans, the macrocephalic children were divided into three subgroups: megalencephaly (n = 15), extraventricular obstructive hydrocephalus (n = 5) and communicating hydrocephalus (n = 23). The clinical pictures of the megalencephalic and hydrocephalic children appeared to differ substantially. The megalencephalic subgroup had less neurological symptoms and physical abnormalities and showed a higher intelligence or a more advanced development or both. On the basis of our experience and theoretical considerations guidelines were developed for the assessment of patients with macrocephaly and a normal rate of head growth with a differentiated approach for megalencephalic and hydrocephalic patients.

Brain↗

PubMed1988

The diagnostic management of newborns with congenital contractures: a nosologic study of 75 cases.

A prospective clinical study is presented of 75 patients with multiple congenital contractures. With the data from medical history, child neurologic examinations, laboratory tests including chromosome and dermatoglyphic analysis, and neuropathology in 23 cases with perinatal death, a nosological or syndromal diagnosis was made in 61 cases. These cases were classified by localization of causal pathology in the categories "cerebral dysgenesis", spinal cord defects, neuromuscular disorders and miscellaneous disorders without muscle weakness. Following this concept, the various modes of inheritance of specific disorders presenting with congenital contractures, as well as possibilities for prenatal diagnosis by ultrasonography are discussed. A guideline for the child neurologic evaluation of infants with congenital contractures is proposed. It is concluded that: 1) specification of the causal lesion and proper classification of disorders with congenital contractures is crucial for genetic counseling, (prenatal) diagnosis and management; 2) the analysis of dermatoglyphics in differential diagnosis of congenital contractures should be restudied; and 3) more study and experience is required in the observation of abnormal or decreased fetal movements by ultrasonography.

Brain↗

PubMed1988

The value of estimating pressure-volume index in childhood macrocephaly. The relationship between pressure-volume index and the volumes of intracranial structures.

In this study on cerebrospinal fluid (CSF) dynamics in childhood macrocephaly, we investigated the relationship between the pressure volume index (PVI) and the volume of various brain structures. The most important variables of CSF dynamics are the outflow resistance (Ro) and the PVI. We applied a constant CSF infusion rate to measure the PVI. The volumes of intracranial structures were calculated by means of computed tomography. Our study revealed no significant correlation between PVI and CSF volume or between PVI and the intracranial volume, as suggested by earlier studies. We did, however, find a significant correlation between PVI and ventricle volume. These results indicate that in order to estimate PVI for clinical purposes, the ventricle volume rather than CSF volume or head circumference should be used.

Brain↗

PubMed1988

Megalencephaly: definition and classification.

The various definitions and classifications of megalencephaly are reviewed, and numerous diseases and syndromes associated with megalencephaly are listed. A new definition of megalencephaly based on quantitative radiographic features is proposed. We define megalencephaly as a brain volume which exceeds the mean by more than twice the standard deviation. Furthermore, a modified etiopathogenic classification of megalencephaly results in three main groups, viz anatomic, metabolic and dynamic megalencephaly. The clinical pictures in these main groups of megalencephaly, and the largest subgroup of anatomic megalencephaly, familial anatomic megalencephaly, appear to be quite different.

Brain↗

PubMed1988

Neuro-imaging of cerebral visual disturbances in children.

The present study comprises the neuroradiological examination (computertomography++, magnetic resonance imaging) of 26 children--9 of them were premature, 16 were full-term and in one patient, no details of the pregnancy were known--all suffering from: a) visual disturbance, not caused by ocular disease or afflictions of the optic nerve b) infantile encephalopathy The examination revealed characteristic lesions of the retrochiasmatic part of the visual system. These consisted of white matter abnormalities located periventricularly and just below the striate area, and of grey matter abnormalities of the striate cortex. The demonstration of these abnormalities may advance the diagnosis of the visual handicap and may facilitate early adjustment of developmental stimulation.

Adolescent↗

PubMed1988

Intracranial spaces in childhood macrocephaly: comparison of length measurements and volume calculations.

CT scanning was done to calculate the volume of intracranial spaces in children with the purpose of developing a reliable method of differentiating the various causes of macrocephaly. The technique has been applied to the CT scans of 60 apparently normal children, and the resulting graphs show the normal relationship between intracranial volumes and age from birth to 15 years. The measurements for 25 children with macrocephaly and normal rate of growth of head circumference were then compared with the reference values. It was possible to make accurate differentiations between megalencephaly, extraventricular hydrocephalus and communicating hydrocephalus. The advantage of this technique in relation to length measurements on CT scans is discussed. The authors advocate the estimation of the product of head circumference and head height as a much more reliable indication of normal and deviant head-size than head circumference alone.

Brain↗