PubMed Health⌕ Search

Biomedical subjects

F Cowan

Publications and source records attributed to F Cowan.

At least 37 records · Page 2Linked to original sources
PubMed2001

Combined use of electroencephalogram and magnetic resonance imaging in full-term neonates with acute encephalopathy.

OBJECTIVE: The electroencephalogram (EEG) is widely used in full-term infants with acute neonatal encephalopathy, and its prognostic value has been confirmed by several studies. Magnetic resonance imaging (MRI) of the brain has also been applied in these patients, and increasing numbers of reports affirm its prognostic reliability. The aim of this study has been to investigate the correlation between an early EEG and MRI findings in infants with acute neonatal encephalopathy and to assess the prognostic value of a combination of EEG and MRI findings. PARTICIPANTS AND METHODS: Twenty-five full-term infants had an EEG recorded within the first 72 hours after birth and a neonatal brain MRI scan after the end of the first week. RESULTS: Both EEG and MRI were predictive of outcome. A normal MRI was always associated with normal EEG background activity and normal outcome and severe abnormalities on MRI with marked EEG abnormalities and an abnormal outcome. When the MRI showed moderate abnormalities, the EEG in all cases but one identified patients with normal and abnormal outcome.EEG, MRI, HIE, neurodevelopment.

Brain↗
PubMed2001

Comparison of findings on cranial ultrasound and magnetic resonance imaging in preterm infants.

OBJECTIVE: To compare findings on hard copies of cranial ultrasound (US) and magnetic resonance imaging (MRI) obtained between birth and term in a group of preterm infants. PARTICIPANTS AND METHODS: Infants born at or below a gestational age of 30 weeks who underwent cranial US scan and MRI on the same day were eligible for this study. Infants underwent, whenever possible, 3 scans between birth and term. We calculated the predictive probability (PP) of US findings as a predictor of findings on MRI. RESULTS: Sixty-two paired MRI and US studies were performed between birth and term in 32 infants born at a median gestational age of 27 (range: 23-30) weeks and a median birth weight of 918 (530-1710) grams. US predicted some MRI findings accurately: germinal layer hemorrhage (GLH) on US had a PP of 0.8 with a 95% confidence interval of (0.70-0.90) for the presence of GLH on MRI, intraventricular hemorrhage (IVH) on US had a PP of 0.85 (0.76-0.94) for the presence of IVH on MRI, and severe white matter (WM) echogenicity on US had a PP of 0.96 (0.92-1.0) for the presence of WM hemorrhagic parenchymal infarction on MRI. Other MRI changes were less well-predicted: mild or no WM echogenicity on US had a PP of 0.54 (0.41-0.66) for the presence of normal WM signal intensity on MRI, and moderate or severe WM echogenicity on US had a PP of 0.54 (0.42-0.66) for the presence of small petechial WM hemorrhage and/or diffuse excessive high-signal intensity (DEHSI) in the WM on T2-weighted images on MRI. However, mild/moderate or severe WM echogenicity on US scans performed at >/=7 days after birth had a PP of 0.72 (0.58-0.87) for the presence of WM hemorrhage and/or DEHSI on MRI. There were no cases of cystic periventricular leukomalacia. CONCLUSION: US accurately predicted the presence of GLH, IVH, and hemorrhagic parenchymal infarction on MRI. However, its ability to predict the presence of DEHSI and small petechial hemorrhages in the WM on T2 weighted images is not as good, but improves on scans performed at >/=7 days after birth. In addition, normal WM echogenicity on US is not a good predictor of normal WM signal intensity on MRI.

Brain↗
PubMed2001

Prothrombotic disorders and abnormal neurodevelopmental outcome in infants with neonatal cerebral infarction.

BACKGROUND AND PURPOSE: The aim of this study was to evaluate the occurrence of prothrombotic disorders in a well-characterized cohort of infants with neonatal stroke and to document any association of prothrombotic disorders with the type of infarct seen on magnetic resonance imaging (MRI) and clinical outcome. METHODS: Twenty-four infants with perinatal cerebral infarction confirmed by neonatal MRI were enrolled in the study. All the infants and, when possible, both parents were tested to identify inherited and acquired prothrombotic disorders. RESULTS: None of the infants had a significant bleeding diathesis, but 10 (42%) had at least 1 prothrombotic risk factor. Five children showed heterozygosity for factor V Leiden, and 6 had high factor VIIIc concentrations. There was a striking association between the occurrence of these abnormalities and both the presence of cerebral hemorrhage on MRI and poor neurologic outcome. Eight of the 11 patients (73%) with hemiplegia or global developmental delay had factor V Leiden and/or raised factor VIIIc, whereas only 1 of the 13 patients (8%) with normal outcome had any prothrombotic risk factors. In particular, all 5 infants with factor V Leiden had hemiplegia, compared with only 4 of the 19 infants without factor V Leiden (21%). CONCLUSIONS: These data suggest that the presence of prothrombotic risk factors and, in particular, of the factor V Leiden mutation, is significantly associated with poor outcome after perinatal cerebral infarction.

Activated Protein C Resistance↗
PubMed2000

Automated assay for nicotinamide adenine dinucleotide (NAD+).

Sulfur mustard (HD), a vesicating chemical warfare compound, has been shown to deplete the nicotinamide adenine dinucleotide (NAD+) content in several cell systems and tissues. This NAD+ depletion has been proposed as an indicator of HD exposure and can be used to evaluate potential antivesicant compounds. To examine NAD+ levels, an automated method based on the alcohol dehydrogenase cycling assay of Jacobson and Jacobson and utilizing a Cobas FARA clinical analyzer has been developed. Automation of this assay led to smaller sample volumes and more efficient use of personnel and resources. The usefulness of this automated method was tested by evaluating the protection, if any, by the topical application of vitamin D or betamethasone against HD-induced NAD+ depletion in skin punches from the hairless guinea pig. The results showed that the samples exposed to HD exhibited significant decreases in NAD+ levels when compared with controls. However, neither vitamin D nor betamethasone demonstrated protection against HD-induced NAD+ depletion. In fact, betamethasone exacerbated the NAD+ depletion when compared with the HD exposed group. This assay appears to be useful for testing potential antivesicant compounds using both in vivo and in vitro exposure systems.

Animals↗
PubMed2000

Occipital sawtooth: a physiological EEG pattern in very premature infants.

OBJECTIVE: To evaluate EEG maturational features in preterm infants below 27 weeks postmenstrual age. METHODS: EEGs recorded from 5 preterm infants (postmenstrual age 24-26 weeks) were examined and selected maturational features were scored and quantified. The five infants also had serial cranial ultrasound scans (US) and magnetic resonance images of the brain within the first weeks after birth. RESULTS: Background activity was markedly discontinuous in all patients and very variable. Temporal sawtooths occurred but less frequently than in older preterm infants. All 5 infants also showed a particular novel feature, characterized by rhythmic, regularly shaped, medium-high amplitude 4-7 Hz activities, lasting 0.5-3 s and located in the occipital regions. This pattern was symmetrical but sometimes asynchronous. CONCLUSIONS: Occipital sawtooth, so called because it shares shape and frequency with temporal sawtooth but has an occipital localisation, constitutes a physiological EEG pattern characteristic of premature infants between 24 and 26 weeks of postmenstrual age.

Electroencephalography↗
PubMed2000

Brain magnetic resonance imaging abnormalities in merosin-positive congenital muscular dystrophy.

We report the brain magnetic resonance imaging (MRI) findings in 23 patients with merosin-positive congenital muscular dystrophy (CMD). Twelve patients had normal scans. Eight other children had essentially normal scans but showed mild non-specific periventricular white matter changes. Three children had structural abnormalities on imaging. The first patient, a 15-month-old boy with hypotonia, muscle weakness and global development delay, had moderate cerebellar atrophy and mild dilatation of the lateral ventricles. The second child, a 3-year-old ambulant girl with subtle learning problems, had mild cerebellar hypoplasia and a large subarachnoid space when scanned at 16 months. The third patient, a 15-year-old ambulant male with normal intelligence and complex partial seizures, had polymicrogyria of both temporoparietal lobes on brain MRI. The clinical features and motor ability of children with merosin-positive CMD are variable, although usually milder than merosin-deficient CMD. Our findings confirm that central nervous system involvement can occur in some merosin-positive cases. We suggest performing brain MRI in children with merosin-positive CMD, as this may help in our understanding of this very heterogeneous disease.

Atrophy↗
PubMed2000

Outcome after intrapartum asphyxia in term infants.

Investigatory techniques, particularly magnetic resonance (MR) imaging and spectroscopy, performed in the early neonatal period on infants suspected of intrapartum asphyxia i.e. abnormal fetal heart recording, poor cord gases, low Apgar scores and the need for resuscitation, or with neonatal encephalopathy or seizures, have allowed a much better understanding of the patterns of brain injury and the biochemical processes that follow these events. It is usually possible to distinguish these patterns from those seen in other, often confounding, diagnoses. This has allowed far more precision about the timing of insults and in the prediction of particularly motor, feeding and visual outcome and to some extent intellectual outcome. Long-term neurological and psychometric follow-up of infants in whom detailed perinatal clinical histories and examination, haematological and biochemical investigation and MR brain scans are obtained will allow even more accurate prediction of outcome in the future. Such studies also help to validate standardized neonatal and infant clinical neurological examinations, making them useful tools to predict outcome.

Asphyxia Neonatorum↗
PubMed2000

Cranial ultrasound abnormalities in full term infants in a postnatal ward: outcome at 12 and 18 months.

OBJECTIVE: To investigate whether cranial ultrasound abnormalities found in low risk full term infants had any influence on neurodevelopmental outcome. METHODS: For 103 infants who had a neurological assessment, a cranial ultrasound examination, and for whom antenatal and perinatal data were collected within 48 hours of delivery, neurodevelopmental status was evaluated at 12 and 18 months. The results of a scored neurological examination and the Griffiths mental developmental scale were correlated with the presence and type of ultrasound abnormality found in the neonatal period. RESULTS: None of the infants with ultrasound abnormalities showed any signs of cerebral palsy or severe developmental delay. There was also no significant difference between the overall neurological and neurodevelopmental scores of the infants with normal and abnormal ultrasound findings. However, when the individual subscales of the Griffiths test were analysed, all infants with bulky choroid or intraventricular haemorrhage had normal scores in all subscales, four of eight with periventricular white matter lesions had low scores on the locomotor subscale, and three of five with asymmetrical ventricles had low scores on the performance subscale. The presence of adverse antenatal and perinatal factors did not affect the outcome in this group. CONCLUSION: Incidental ultrasound abnormality in full term neonates, in particular intraventricular haemorrhage, although common, appear to have a good prognosis. Longer follow up studies are needed to see whether some of these infants, in particular those with white matter lesions, develop dyspraxia or other minor neurological impairments at school age.

Brain↗
PubMed2000

An evaluation of near patient tests for detecting herpes simplex virus type-2 antibody.

OBJECTIVES: To examine the "in use" test characteristics of the POCkit "near patient" HSV-2 rapid test for the detection of HSV-2 IgG antibodies for use in the clinic. This test relies on a visual interpretation of the result. METHODS: 2093 serum samples, 229 from UK and 919 from Italian genitourinary medicine clinic patients and 945 from obstetric and gynaecology clinic patients in Italy were tested. Tests were carried out according to manufacturers' protocol in the United Kingdom and Italy. Three readers independently recorded a score for each test carried out and the results were compared. RESULTS: In the UK study, the three readers disagreed on the result on 5.2% of tests. In the Italian study, there was disagreement in 10.2% of tests. CONCLUSIONS: This study has demonstrated a problem in the subjective nature of the interpretation of the POCkit HSV-2 test. It highlights the need for adequate training of clinic staff and the need for clinics to adopt policies of quality assurance and ongoing monitoring which will ensure the validity and accuracy of this clinic based test.

Antibodies, Viral↗
PubMed1999

Optimality score for the neurologic examination of the infant at 12 and 18 months of age.

The aim of this study was to develop and validate a simple, quantifiable, neurologic examination for infants between 2 and 24 months of age. The assessment consists of 37 items, divided into 3 sections. The first section includes 26 items assessing cranial nerve function, posture, movements, tone, and reflexes; the second section of 8 items documents the development of motor function, and the third section of 3 items evaluates the state of behavior. We applied this assessment to a cohort of ninety-two 12-month-old infants and forty-three 18-month-old infants, with no known perinatal risk factors. The proforma presented has been designed according to the frequency distribution of the neurologic findings in this cohort. Each item is scored individually, and a global score is the sum of all individual scores. The quantitative score enhances the value of this examination, both in clinical practice and in research settings.

Behavior↗
PubMed1999

Magnetic resonance imaging of the brain in a cohort of extremely preterm infants.

To define magnetic resonance imaging (MRI) appearances of the brain in extremely preterm infants between birth and term, a sequential cohort of infants born at a gestational age <30 weeks was studied with a dedicated neonatal magnetic resonance scanner. Images of infants (n = 41) with a median gestational age of 27 weeks (range 23 to 29 weeks) were initially obtained at a median age of 2 days (range 1 to 20 days) and then repeatedly studied; 29 (71%) infants had MRI at a median gestational age of 43 weeks (range 38 to 52 weeks) (term MRI). On the initial MRI scan 28 of 41 infants had abnormalities: either intraventricular hemorrhage, germinal layer hemorrhage, ventricular dilatation, or diffuse and excessive high signal intensity in the white matter on T(2)-weighted images. When magnetic resonance images for preterm infants at term gestation were compared with those of infants in the control group born at term, 22 of 29 infants had dilatation of the lateral ventricles, 24 of 29 had squaring of the anterior or posterior horns of the lateral ventricles, 11 of 29 had a widened interhemispheric fissure or extracerebral space, and 22 of 29 had diffuse and excessive high signal intensity in the white matter. There were no cases of cystic periventricular leukomalacia. We conclude that MRI abnormalities are commonly seen in the brain of preterm infants on whom images are obtained within 48 hours of birth and that further abnormalities develop between birth and term. A characteristic appearance of diffuse and excessive high signal intensity in the white matter on T(2)-weighted images is associated with the development of cerebral atrophy and may be a sign of white matter disease. These MRI appearances may help account for the high incidence of neurodevelopmental impairment in extremely preterm infants.

Age Factors↗
PubMed1999

Prediction of neurological outcome after birth asphyxia from early continuous two-channel electroencephalography.

OBJECTIVE: To determine whether two-channel continuous electroencephalography (EEG) applied within 12 h of birth can predict the severity of neurological complications and neurodevelopmental outcome following birth asphyxia. METHODS: A continuous two-channel EEG was performed within 12 h of birth in 22 infants suspected of having suffered birth asphyxia and 11 healthy control infants (22 infants at a general and 11 at a specialist paediatric unit). Criteria to categorise normal and abnormal EEG records were defined and compared with the severity of hypoxic/ischaemic encephalopathy (HIE) and with neurodevelopmental outcome, assessed at or after 12 months of age. RESULTS: EEG recordings were commenced at a median (range) of 2 h 50 min (1 h 45 min to 12 h) after birth. Technically satisfactory recordings were obtained in all but one infant. All control infants remained asymptomatic and had a normal EEG with discernible sleep/awake periods. 12 h after birth the EEG was normal in all 12 infants suspected of asphyxia who remained well or developed grade 1 HIE and was abnormal in six of nine infants with grade II or III HIE. Fifteen of 16 infants suspected of asphyxia with a normal neurodevelopmental outcome had a normal EEG at 12 h; transient abnormalities lasting not more than 8 h had been detected in three of these infants. All five infants who died or developed neurodevelopmental abnormalities had an abnormal EEG. At 12 h of age the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and likelihood ratio for predicting severe (grade II or III) HIE were: 67, 100, 100, 80% and infinity and for subsequent death or neurodevelopmental impairments: 100, 94, 83, 100 and 16%, respectively. Assessment of the EEG before 12 h of age altered prognostic accuracy: 4 h after birth the sensitivity, specificity, positive and negative predictive values and the likelihood ratio for poor neurodevelopmental outcome were 100, 71, 33%, 100 and 3.7%, respectively (16 infants). CONCLUSION: Continuous two-channel EEG is an accurate tool for assessing the severity of neurological insult soon after birth asphyxia.

Asphyxia Neonatorum↗
PubMed1999

Merosin-deficient congenital muscular dystrophy: the spectrum of brain involvement on magnetic resonance imaging.

Children with merosin-deficient congenital muscular dystrophy (CMD) have striking white matter changes on T-2 weighted brain magnetic resonance imaging (MRI). There have been occasional cases with structural abnormalities, mainly involving the occipital cortex. We report our brain imaging findings in 14 children with merosin-deficient CMD. Ten cases had a severe reduction or absence of merosin on immunocytochemistry and four cases had partial reduction. All 14 cases had white matter changes, which appeared after the first 6 months of life and persisted with time. The changes were diffuse and the oldest child scanned (14 years) also showed involvement of the U fibres. Five children with total absence of merosin also had structural abnormalities. One child had moderate mental retardation and epilepsy, mainly characterised by complex partial seizures, with atypical absences, which had been difficult to treat. Brain MRI showed marked occipital agyria and pontocerebellar hypoplasia. The gyral pattern of the rest of the brain looked normal. The four other cases, all with normal intelligence, also had cerebellar hypoplasia with variable involvement of the pons. They did not, however, have neuronal migration defects. It is recognised that several forms of congenital muscular dystrophy, namely Fukuyama CMD, muscle-eye-brain disease and Walker-Warburg syndrome, have structural brain abnormalities and associated severe mental retardation. Our cases demonstrate that a range of structural malformations can also be found in a significant number of children with merosin-deficient CMD.

Adolescent↗
PubMed1999

Neonatal neurological examination in infants with hypoxic ischaemic encephalopathy: correlation with MRI findings.

Neurological examination and magnetic resonance imaging were performed in the neonatal period in 58 full-term infants who presented with hypoxic-ischaemic encephalopathy. The aim of this study was to evaluate the patterns of neurological abnormalities and their correlation to brain lesions on MRI. The prognostic value of the neurological examination performed at different times in the neonatal period was also evaluated. Our results showed that specific clinical patterns can be observed in infants with HIE and these can be related to the pattern of lesion on brain MRI. In particular, while infants with normal MRI or minimal changes tend to show only minor tone abnormalities after the first week of life, infants with more severe lesions such as basal ganglia lesions show persistent and diffuse neurological abnormalities. Infants with white matter changes but intact basal ganglia show a different clinical pattern with improved sucking reflex and behaviour and less severe tone abnormalities. Our results also suggested that the neurological examination performed after the second week of life is a reliable indicator of outcome in these infants.

Asphyxia Neonatorum↗
PubMed1999

Clinical spectrum and diagnostic difficulties of infantile ponto-cerebellar hypoplasia type 1.

We present the clinical and histopathological features and the diagnostic difficulties encountered in five children affected by a motor neuron disorder other than spinal muscular atrophy. Investigations performed suggested the diagnosis of ponto-cerebellar hypoplasia type 1 (PCH-1). Severe respiratory difficulty was present at birth in two of these children; hypotonia, arthrogryposis, microcephaly and nystagmus were present in all. Early and progressive bulbar involvement with swallowing difficulties and stridor was also a common feature in these infants. Severe cognitive delay was invariably present. Brain magnetic resonance imaging showed ponto-cerebellar hypoplasia in four children while striking atrophy of the cerebellar vermis and cerebellar hemispheres were present in the fifth child. Electrophysiological and pathological investigations of proximal muscles performed at presentation in all these children were not conclusive, while the post-mortem studies, or the study of distal muscles during life, showed a clear neurogenic picture. Genetic studies excluded involvement of the SMN gene, or of other genes located on chromosome 5q, confirming that ponto-cerebellar hypoplasia type 1 is a different entity from typical proximal spinal muscular atrophy.

Abnormalities, Multiple↗
PubMed1999

Visual function in term infants with hypoxic-ischaemic insults: correlation with neurodevelopment at 2 years of age.

AIMS: To determine if there is any association between the findings of visual assessment performed at the age of 5 months and neurodevelopmental outcome at the age of 2 years in children who have sustained hypoxic-ischaemic insults. METHODS: Twenty nine term infants with hypoxic-ischaemic encephalopathy and/or brain lesions on neonatal magnetic resonance imaging (MRI) were prospectively evaluated. At 5 months of age all the infants had their visual function assessed using the Atkinson Battery of Child Development for Examining Functional Vision, which includes the assessments of optokinetic nystagmus (OKN), acuity, visual fields, fixation shift and phase and orientation reversal visual evoked potentials. At 2 years of age the children had a structured neurological evaluation and a Griffiths developmental assessment. RESULTS: There was good correlation between the extent of the early detected visual impairment and both neuromotor and global development. Children with more than three out of five abnormal visual tests at 5 months of age tended to have abnormal neurological examination results and abnormal developmental quotients. Children with three or fewer abnormalities tended to have developmental quotients in the normal range; the level of their performance, however, was still related to the number of visual tests passed. CONCLUSIONS: Individual visual tests can provide important prognostic information. While abnormal OKN and acuity were always associated with abnormal outcome, normal results on visual evoked potentials and fixation shift tended to be associated with normal outcome.

Brain↗
PubMed1999

Early prognostic indicators of outcome in infants with neonatal cerebral infarction: a clinical, electroencephalogram, and magnetic resonance imaging study.

OBJECTIVE: The aim of this study was to identify prognostic factors in newborns with cerebral infarction. DESIGN: Antenatal and perinatal factors and early clinical, electroencephalogram (EEG), and magnetic resonance imaging (MRI) findings were compared with neurodevelopmental outcome in 24 children with evidence of cerebral infarction on neonatal MRI. RESULTS: Out of 24 infants, 19 had an infarction in the territory of a major cerebral vessel and 5 in the borderzone between cerebral arteries. Neuromotor outcome was normal in 17 and abnormal in 7 infants. Of these 7 infants, 5 infants showed a definite hemiplegia, whereas the other 2 showed some asymmetry of tone or function but no definite hemiplegia. None of the adverse antenatal or perinatal factors was significantly associated with abnormal outcome. Neonatal clinical examination was also not always predictive of the outcome. The extent of the lesion on MRI was a better predictor. In particular, it was the concomitant involvement of hemisphere, internal capsule and basal ganglia that was always associated with an abnormal outcome whereas the involvement of only one or two of the three tended to be associated with a normal outcome. EEG was also very helpful. Abnormal background activity either unilateral or bilateral was found in 6 infants and 5 out of 6 developed hemiplegia. In contrast, the presence of seizure activity in presence of a normal background was not related to abnormal outcome. CONCLUSIONS: Early MRI and EEG can help to identify the infants with cerebral infarction who are likely to develop hemiplegia.

Cerebral Infarction↗