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Biomedical subjects

J Pennock

Publications and source records attributed to J Pennock.

At least 19 recordsLinked to original sources
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↗
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

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↗
PubMed1997

Visual function in full-term infants with hypoxic-ischaemic encephalopathy.

Thirty-one full term infants with hypoxic-ischaemic encephalopathy (HIE) were studied with a battery of tests designed to evaluate visual function in infancy and with serial MRI. Their age ranged between 5 and 31 months. The aim of the study was to evaluate whether the degree of HIE or the site and size of lesions on MRI could predict visual outcome. Twenty of the 31 infants studied showed abnormal results on at least one of the visual tests used. While visual function was generally normal in grade I HIE and severely impaired in grade III, visual outcome was variable in grade II. MRI findings were better predictors of visual impairment than the degree of HIE. Normal scans tended to be associated with normal visual function, irrespective of the severity of HIE. All but one of the infants with diffuse hemispheric involvement also showed multiple visual abnormalities. The concomitant involvement of basal ganglia was always associated with more severe visual outcome. These results suggest that infants with generalised lesions secondary to global insults are at high risk of severe visual impairment even in presence of normal acuity and require early assessment of various aspects of visual function.

Basal Ganglia↗
PubMed1997

Basal ganglia damage and impaired visual function in the newborn infant.

AIM: To examine the effects of early lesions in the visual pathway on visual function; and to identify early prognostic indicators of visual abnormalities. METHODS: The visual function of 37 infants with perinatal brain lesions on magnetic resonance imaging was assessed using behavioural and electrophysiological variables. RESULTS: Normal visual behaviour was observed in most infants with large bilateral occipital lesions, but all the infants with associated basal ganglia involvement had abnormal visual function. Visual abnormalities were also present in six infants with isolated basal ganglia lesions. CONCLUSIONS: These observations suggest that basal ganglia may have an integral role in human visual development and that their presence on neonatal MRI could be an early marker of abnormal visual function.

Basal Ganglia↗
PubMed1996

Sequential study of central and peripheral nervous system involvement in an infant with merosin-deficient congenital muscular dystrophy.

Diffuse white matter changes on brain imaging and peripheral neuropathy are associated features of merosin-deficient congenital muscular dystrophy (CMD). In this report we describe the early manifestation and evolution of brain changes, and the involvement of the peripheral nervous system in a female infant with merosin-deficient CMD diagnosed in the neonatal period who had sequential clinical, neurophysiological and magnetic resonance imaging (MRI) assessment. Both MRI and nerve conduction velocity in the first week of life failed to demonstrate any abnormality. By 6 months of age both nerve conduction and MRI were abnormal. White matter changes became more evident on a further scan at 1 yr of age and this pattern remained unchanged on the following scan performed at 17 months of age. Our findings suggest a failure in the physiological maturation process of myelination of both the central and peripheral nervous system.

Central Nervous System Diseases↗
PubMed1996

Evaluation of the corpus callosum in clumsy children born prematurely: a functional and morphological study.

The aim of this study was to evaluate the incidence of functional and neuroradiological abnormalities of the corpus callosum in a group of 21 prematurely born children (GA < 34 weeks) who were found to be "clumsy" on the Movement Assessment Battery for Children at 6 years of age. All children underwent functional and morphological assessment of the corpus callosum. The functional assessment included tests of somesthesis, diadochokinesis and repetitive finger tapping. The morphology of the corpus callosum was evaluated on midsagittal MRI. Thirteen of the 21 clumsy children showed morphological abnormalities which were significantly associated with functional abnormalities. Morphological changes of the corpus callosum were also significantly associated with lesions on both neonatal ultrasound and late MRI. Our results support the view that morphological abnormalities of the corpus callosum are frequent in children born prematurely. The association between these abnormalities and lesions on US or MRI suggests that they are likely to be secondary to pre- or perinatal lesions.

Agenesis of Corpus Callosum↗
PubMed1996

Visual function and perinatal focal cerebral infarction.

AIMS: To evaluate the visual function of infants with perinatal cerebral infarction in whom the site and size of the lesion has been determined using magnetic resonance imaging (MRI). METHODS: Twelve infants with cerebral infarction on MRI were studied with a battery of tests specifically designed to evaluate visual function in infancy. This included tests: for visual attention (fixation shifts); of cerebral asymmetry (optokinetic nystagmus, visual fields); for assessment of acuity (forced choice preferential looking); and neurophysiological measures of vision (phase reversal and orientation reversal visual evoked potential). RESULTS: A considerable incidence of abnormalities on at least one of the tests for visual function used was observed. The presence or severity of visual abnormalities could not always be predicted by the site and extent of the lesion seen on imaging. CONCLUSIONS: Early focal lesions affecting the visual pathway can, to some extent, be compensated for by the immature developing brain. These data suggest that all the infants presenting with focal lesions need to be investigated with a detailed assessment of various aspects of vision.

Cerebral Infarction↗
PubMed1996

Hypoxic-ischaemic encephalopathy: early and late magnetic resonance imaging findings in relation to outcome.

Sixteen infants with hypoxic-ischaemic encephalopathy (HIE) were studied using serial magnetic resonance imaging (MRI) up to the age of 2 years. The infants had regular neurological and developmental assessments. An nuclear magnetic resonance (NMR) score was devised to quantify the early and late MRI findings and a neurological optimality score was used to quantify abnormal neurological signs at the time of the final examination. The follow up MRI score was compared with the neonatal MRI score and the outcome of the child. There was a strong positive correlation between the neonatal and follow up MRI scores and between MRI scores and optimality score. All infants with a normal outcome had patchy white matter abnormalities. All infants with an abnormal outcome had extensive white matter abnormalities. The outcome was most severe in those infants with additional basal ganglia atrophy with or without cyst formation. Infants with mild HIE who are developmentally normal at the age of 2 years do not have normal MRI scans and may be at risk of minor neurological problems by school age. Bilateral basal ganglia abnormalities are associated with severe developmental delay, but infants with mainly white matter and cortical abnormalities have less severe problems despite extensive tissue loss.

Basal Ganglia↗
PubMed1996

Trends in mammography and Pap smear utilization in Canada.

We have examined trends in the utilization of two preventive health procedures for women in Canada based on our analysis of the 1994 National Population Health Survey (NPHS) and comparisons with two previous large population health surveys. The NPHS provides evidence that Canadian women's use of mammography has continued to increase between 1990 and 1994, while use of Pap smears has remained steady. Increases in mammographic utilization are seen for all age groups and in all provinces of Canada. Women who are less than the recommended age of 50-69 years for screening mammography access these services in considerable numbers. Large proportions of women aged 18-24 and 65 or over have never had a Pap smear, and recency of Pap smear is associated with age. Income adequacy and educational attainment are still strong predictors of which women utilize Pap smears and mammograms. We conclude that the NPHS is sufficiently broad-based to be used in a surveillance program to track Pap smear and mammography utilization.

Adolescent↗
PubMed1995

Familial concordance of brain magnetic resonance imaging changes in congenital muscular dystrophy.

Cerebral white matter changes have been described in a significant number of individual patients with "pure" congenital muscular dystrophy without clinical evidence of central nervous system involvement. The cause for the imaging changes is unknown but it is possible that they are the result of abnormal expression in the brain of the gene also responsible for the muscular dystrophy. In this study magnetic resonance imaging of the brain was performed on seven sibling pairs with congenital muscular dystrophy and normal intelligence to establish whether imaging changes are consistent within families. Diagnosis of congenital muscular dystrophy was based on clinical and muscle biopsy findings. Children from two families had normal scans; the remaining five sibling pairs showed white matter changes and within each family the changes were virtually identical in severity and distribution. Our data indicate that the central nervous system changes are consistent within individual families, suggesting that they probably relate to the mutation in the congenital muscular dystrophy genes involved in the respective families.

Adolescent↗
PubMed1995

Clinical phenotype in congenital muscular dystrophy: correlation with expression of merosin in skeletal muscle.

It has recently been shown that merosin, an extracellular matrix protein linked to the dystrophin-associated glycoproteins, is deficient in a proportion of patients with classical congenital muscular dystrophy (CMD). We have undertaken a detailed study of the clinical features and brain imaging in 24 cases of CMD in relation to the merosin status. Immunocytochemistry showed that merosin was present in 13 cases and markedly deficient in 11. In the merosin-positive cases, the maximum motor achievement was independent walking in 11, walking with support in one and sitting unsupported in one (currently 18 months old). In contrast, none of the merosin-deficient cases achieved independent ambulation. Two achieved walking with support, nine standing with support. In addition, nine of the 11 merosin-deficient cases had a creatine kinase level greater than 2000 whereas only one merosin-positive case had this degree of elevation. Magnetic resonance imaging of the brain was carried out on 15 of the children. All eight merosin-positive cases had normal scans whereas all seven of the merosin-deficient cases had significant changes in the white matter. This study has demonstrated that children with merosin-deficient CMD have a more severe clinical phenotype and associated white matter changes on brain imaging.

Child↗
PubMed1995

Somatosensory and visual evoked potentials in congenital muscular dystrophy: correlation with MRI changes and muscle merosin status.

Congenital muscular dystrophy comprises a heterogeneous group of disorders, that have in common an early onset and a dystrophic picture on the muscle biopsy. The "pure" form of congenital muscular dystrophy is not associated with severe mental retardation or structural changes in the brain, though white matter changes on brain imaging have been detected in a significant proportion of cases. In this study we evaluated the incidence of sensory abnormalities (somatosensory and visual evoked responses) in a group of 17 patients with "pure" congenital muscular dystrophy and correlated the results of the evoked responses with the presence or absence of white matter changes on brain magnetic resonance imaging. Our results show close correlation between the presence of MRI white matter changes and abnormalities in the sensory evoked potentials. Conversely, all patients with normal brain MRI had normal somatosensory evoked potentials (SEP). Visual evoked potentials were less sensitive than somatosensory evoked potentials in detecting abnormalities in children with white matter changes on MRI. With the recent discovery of deficiency in merosin expression in the skeletal muscle of a subgroup of patients with CMD, we also correlated the presence or absence of white matter changes and the SEP responses with the merosin status. The results indicate that all merosin-negative patients had abnormal SEP as well as abnormal MRI, whilst no patient with normal merosin expression had an abnormal scan or abnormal SEP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Minor neurological and perceptuo-motor deficits in children with congenital muscular dystrophy: correlation with brain MRI changes.

Diffuse white matter changes on magnetic resonance imaging (MRI) have been a consistent feature in some children with the "pure" form of congenital muscular dystrophy (CMD) in which there are no structural changes in the brain or severe mental retardation. The aim of this study was to assess fine motor and perceptuo-motor abilities in children with CMD with and without MRI changes. Twenty-two children with "pure" CMD were investigated with a standard neurological examination and a battery of tests (Manual dexterity from the Movement ABC, test of visual-motor integration, Zurich Neuromotor test) which have already been used to detect minor neurological signs related to white matter changes. The cohort was then divided in two groups for analysis depending on the presence or the absence of diffuse white matter changes. A significant difference was found for all the tests between the group of the CMD children with normal MRI and the group with diffuse white matter changes. The manual dexterity and the Zurich Neuromotor tests showed a greater sensitivity than the test of visual-motor integration, which had some false negatives. It is of interest that in the group with diffuse white matter changes the presence of contractures or weakness did not seem to affect the quality of the performance; all these children scored abnormally on the test, irrespective of the severity or the extent of contractures and weakness. In contrast, in children with normal MRI severe contractures and weakness did affect the performances. Our results demonstrate that perceptuo-motor difficulties and minor neurological soft signs are a consistent feature in CMD children with diffuse MRI changes but not with normal MRI.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Ischaemic and haemorrhagic brain lesions in newborns with seizures and normal Apgar scores.

Serial ultrasound scans and conventional and diffusion weighted magnetic resonance imaging (MRI) were performed on 16 neonates who presented with seizures. The Apgar scores were normal and subsequently no metabolic or infective cause could be found. The aim of the study was to evaluate the extent to which early sequential imaging can elucidate the cause of seizures in apparently neurologically normal infants. Fourteen of the infants had haemorrhagic or ischaemic lesions on MRI and these were detected by ultrasound scanning in 11. Early ultrasound scanning detected the haemorrhagic lesions but the ischaemic lesions were often not seen until the end of the first week of life. Early MRI, however, was able to detect all the ischaemic lesions. The evolution of the insult could be timed by using serial ultrasound scans and a combination of diffusion weighted and conventional MRI during the first week of life, confirming a perinatal insult even in the absence of fetal distress. Although the aetiology of these lesions remains obscure, serial ultrasound scans will detect the presence of cerebral lesions in neonates presenting with isolated seizures but additional MRI sequences will give better definition on type, site, and extent of the pathology.

Apgar Score↗
PubMed1995

Neurological 'soft' signs may identify children with sickle cell disease who are at risk for stroke.

UNLABELLED: Stroke is one of the most frequent complications of sickle cell disease (HbSS), occurring in 7-17% of children. Recent studies recognized more minor lesions on MRI, not associated with clinical signs on standard neurological examination, which however have been found to be a risk factor for developing stroke later. The aim of this study was to evaluate whether minor lesions observed on imaging could be associated with 'soft' neurological signs not detectable on conventional neurological examination. Fourteen children with HbSS were assessed with MRI, standard neurological examination and evaluation of 'soft' signs (Zurich Neuromotor Test) and motor function (Movement ABC). Eight of the 14 children scanned showed lesions on MRI but only 3 of the full cohort were abnormal on standard neurological examination. However, all of the eight children with MRI lesions also showed abnormal signs on at least one of the two tests (Zurich and Movement ABC). All the children with normal MRI were normal on all the tests performed. The sensitivity of Zurich Neuromotor Test and Movement ABC in the group of children with MRI lesions is 0.88 and 0.75, respectively, and increases to 1 when the two tests are used together. The specificity of both tests is 1 even when the tests are used separately. CONCLUSION: Although the number of cases is small, 'soft' signs may reliably identify the presence of even minor MRI lesions, allow the evaluation of the global incidence of major and minor neurological signs and may also help to identify the population at risk for developing strokes. This population could then be closely monitored and benefit from early intervention.

Adolescent↗
PubMed1995

Neonatal neurology, past present and future. A window on the brain.

Interest in the neurology of the newborn has been largely stimulated by the new advances of imaging; CT, cranial ultrasonography and MRI which for the first time allowed diagnosis of brain lesions in the live infant which in the past could only be made by post mortem examinations. (Ultrasound in particular, as it is safe, cheap and portable has been eminantly suitable for routine use in the nurseries to study the incidence, timing and evolution of the lesions in the neonatal period. While MRI is expensive and more difficult to perform it gives superb anatomical definition and is also safe for repeated examinations. It is thus very suitable to follow the evolution of the lesions into infancy). The aim of this presentation is to illustrate how an integrated approach with the combined use of imaging and clinical evaluations lead to a better understanding of antenatal and perinatal factors which may be responsible for the production of these lesions on one hand and the impact of these lesions on later development on the other.

Brain Diseases↗