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S Renowden

Publications and source records attributed to S Renowden.

At least 19 recordsLinked to original sources
PubMed2005

Neuroradiological aspects of subdural haemorrhages.

AIMS: To review the neuroimaging of a series of infants and young children admitted to hospital with subdural haemorrhage (SDH). METHODS: Neuroradiological investigations of 74 children under 2 years of age, from South Wales and southwest England, in whom an SDH or subdural effusion had been diagnosed between 1992 and 2001, were reviewed. Two paediatric neuroradiologists blinded to the original radiological report reviewed all the relevant images. RESULTS: Neuroradiological review of images identified radiological features which were highly suggestive of non-accidental head injury (NAHI). Interhemispheric haemorrhages and SDHs in multiple sites or of different densities were almost exclusively seen in NAHI. MRI was more sensitive in identifying SDHs of different signal characteristics, posterior and middle cranial fossa bleeds, and parenchymal changes in the brain. CT scans, if performed with suboptimal protocols, were likely to miss small subdural bleeds. CONCLUSIONS: Guidelines for neuroimaging in suspected NAHI are recommended. A radiologist with experience in NAHI should report or review these scans. The initial investigation should be CT, but MRI will also be necessary in most cases. Head CT should be an integral part of the skeletal survey in all infants less than 6 months of age referred for child protection investigation, and in children less than 2 years where child abuse is suspected and there are neurological signs, retinal haemorrhages, or fractures.

Brain Injuries↗
PubMed2005

Mild hypothermia and the distribution of cerebral lesions in neonates with hypoxic-ischemic encephalopathy.

Hypothermia induced by whole-body cooling (WBC) and selective head cooling (SHC) both reduce brain injury after hypoxia-ischemia in newborn animals, but it is not known how these treatments affect the incidence or pattern of brain injury in human newborns. To assess this, 14 term infants with hypoxic-ischemic encephalopathy (HIE) treated with SHC, 20 infants with HIE treated with WBC, and 52 noncooled infants with HIE of similar severity were studied with magnetic resonance imaging in the neonatal period. Infants fulfilling strict criteria for HIE were recruited into the study after assessment of an amplitude-integrated electroencephalography (aEEG). Cooling was commenced within 6 hours of birth and continued for 48 to 72 hours. Hypothermia was not associated with unexpected or unusual lesions, and the prevalence of intracranial hemorrhage was similar in all 3 groups. Both modes of hypothermia were associated with a decrease in basal ganglia and thalamic lesions, which are predictive of abnormal outcome. This decrease was significant in infants with a moderate aEEG finding but not in those with a severe aEEG finding. A decrease in the incidence of severe cortical lesions was seen in the infants treated with SHC.

Brain↗
PubMed2004

The relation of infantile spasms, tubers, and intelligence in tuberous sclerosis complex.

BACKGROUND: The aetiology of the learning difficulty in tuberous sclerosis is debated. It may be related to the amount of tubers in the brain or caused by the infantile spasms that occur in early life. AIMS: To examine the relative contributions to final intelligence (IQ) made by both cerebral tubers and infantile spasms. METHODS: As part of an epidemiological study of tuberous sclerosis in the south of England, patients were recruited who were able to undergo magnetic resonance imaging (MRI) without the need for an anaesthetic. Epilepsy history was determined by interview and review of clinical records. IQ was assessed using either Wechsler intelligence scales or Raven's matrices. RESULTS: A total of 41 patients consented to have an MRI scan. IQ scores were normally distributed about a mean of 91. Twenty six patients had a positive history of epilepsy, and 11 had suffered from infantile spasms. There was a significant relation between the number of tubers and IQ. Infantile spasm status partly confounded the relation between tubers and IQ, but did not render the relation statistically insignificant. The relation between infantile spasms and learning difficulty remained strong even when controlling for the number of tubers.

Adolescent↗
PubMed1999

Is the course of brain development in schizophrenia delayed? Evidence from onsets in adolescence.

A degree of ventricular enlargement, together with a reduction of total cortical mass and loss of asymmetry is reported in schizophrenia, but the meaning is obscure. These changes may reflect an anomaly of brain development. Brain structure was assessed on a 1.5-Tesla MRI scan in a series of 29 adolescents at the time of a first episode of schizophrenia and compared with 15 adolescents with other serious psychiatric disturbance (mostly psychotic) and 20 normal adolescent controls. The age at scan ranged between 13 and 20 years. In the adolescents with a diagnosis of schizophrenia, total brain volume increased with age in a way that differed significantly (p=0.007) from that seen in patients with other psychiatric disturbance and normal controls. Thus, brain growth, as assessed by this index, had reached a plateau in the control group by the age of 13 years, but this was not true of patients with schizophrenia. The measure that most clearly distinguished the groups (p<0.001 after co-varying for height and sex) was the volume of the left lateral ventricle the ventricle was significantly larger in patients with schizophrenic illness, and ventricular size increased with age to a greater extent in the patient group, although not significantly so, than in normal controls. Thus, aspects of brain growth are delayed in patients with early onset schizophrenia, and the greatest severity of illness is reflected in a component of growth that is lateralized to the dominant hemisphere. Individuals who develop serious psychiatric illness, including schizophrenia, represent a fraction of the population in whom a component of the relative development of the cerebral hemispheres occurs late.

Adolescent↗
PubMed1998

The left hemisphere and the selection of learned actions.

The left hemisphere's dominance for movement is well known. The basis of its dominance is less clear. We have tested 16 left hemisphere (LH) patients, 17 right hemisphere (RH) patients and 12 neurologically normal controls on a battery of five tasks. The tasks were based on animal lesion and recording studies, and human imaging and magnetic stimulation studies that identified two distributed systems that are important for the selection of motor responses and object-oriented responses. The LH patients were impaired on three response selection tasks: learning to select between joystick movement responses instructed by visual cues; learning to select between analogous object-oriented responses instructed by visual cues; learning to select movements in a sequence. Although we replicated the finding that LH damage impairs sequencing, some of the impaired tasks had no sequencing element. We therefore argue that the LH deficits are best explained as an impairment of response selection. This was confirmed by showing that LH subjects were unimpaired on a more demanding task-object discrimination learning-which imposed a greater memory load but had no response selection element. Moreover, the LH deficits could not be attributed to disorganization of movement kinematics. The lesions of the impaired LH group were widespread but always included the distributed systems known to be important for response selection-the dorsolateral frontal and parietal cortices, striatum, thalamus and white matter fascicles.

Adult↗
PubMed1997

Severe amnesia: an usual late complication after temporal lobectomy.

A patient developed the severe amnesic syndrome 8 years after temporal lobe surgery for epilepsy. He underwent left temporal lobectomy (6 cm, 43.5 g; hippocampal sclerosis) aged 19, and remained seizure free for 8 years until a convulsion followed a head injury. He became severely amnesic after a fourth convulsion 16 months later. He was right-handed, pre-operative IQ was average, verbal memory poor and non-verbal memory normal. Post-operatively, these were unchanged. After the first post-operative seizure he began professional training. After onset of amnesia IQ was unchanged, anterograde memory severely impaired and retrograde amnesia dense for at least 16 months. He died 2 years later. Magnetic resonance imaging before amnesia showed absence of anterior left temporal lobe, atrophy of left fornix and mamillary body, and normal right temporal lobe. Four months after onset of amnesia, right hippocampal volume had reduced by 36%. Autopsy showed: previous left temporal lobectomy with absence of left amygdala and hippocampus, atrophy of fornix and mamillary body; neuronal loss in the right hippocampus, severe in CA1 and CA4; intact right amygdala and parahippocampal gyrus; recent diffuse damage associated with cause of death. A convulsion can cause severe hippocampal damage in adult life. Hippocampal zones CA1 and/or CA4 are critical for maintaining memory and the amygdala and parahippocampal gyrus cortex alone cannot support acquisition of new memories.

Adult↗
PubMed1997

The left parietal cortex and motor attention.

The posterior parietal cortex, particularly in the right hemisphere, is crucially important for covert orienting; lesions impair the ability to disengage the focus of covert orienting attention from one potential saccade target to another (Posner, M. I. et al., Journal of Neuroscience, 1984, 4, 1863-1874). We have developed a task where precues allow subjects to covertly prepare subsequent cued hand movements, as opposed to an orienting or eye movement. We refer to this process as motor attention to distinguish it from orienting attention. Nine subjects with lesions that included the left parietal cortex and nine subjects with lesions including the right parietal cortex were compared with control subjects on the task. The left hemisphere subjects showed the same ability as controls to engage attention to a movement when they were forewarned by a valid precue. The left hemisphere subjects, however, were impaired in their ability to disengage the focus of motor attention from one movement to another when the precue was incorrect. The results support the existence of two distinct attentional systems allied to the orienting and limb motor systems. Damage to either system causes analogous problems in disengaging from one orienting/movement target to another. The left parietal cortex, particularly the supramarginal gyrus, is associated with motor attention. All the left hemisphere subjects had ideomotor apraxia and had particular problems performing sequences of movements. We suggest that the well documented left hemisphere and apraxic impairment in movement sequencing is the consequence of a difficulty in shifting the focus of motor attention from one movement in a sequence to the next.

Adult↗
PubMed1996

Endovascular treatment of intracranial aneurysms: a minimally invasive approach with advantages for elderly patients.

An endovascular approach, embolizing intracranial aneurysms with electrolytically detachable coils, is a new minimally invasive treatment of aneurysms. Reviewing our experience with 13 patients aged 70 years or more, 12 patients were treated successfully. Over an average follow-up period of 8 months, there was only one death which might be attributed to an intracranial aneurysm. This compares favourably with mortality rates approaching 50% for either conservative or traditional surgical management of aneurysms presenting with subarachnoid haemorrhage in this age group. Coil embolization, avoiding craniotomy, may offer particular advantages in managing intracranial aneurysms in the elderly patient.

Aged↗
PubMed1992

Impaired cyclic nucleotide-mediated vasorelaxation may contribute to closure of the human umbilical artery after birth.

1. The mechanical and biochemical effects of agents that relax vascular smooth muscle either through elevation of guanosine 3':5'-cyclic monophosphate (cyclic GMP) or adenosine 3':5'-cyclic monophosphate (cyclic AMP) levels were compared in isolated ring preparations of human umbilical artery and rat aorta. Tone was established by preconstriction with 5-hydroxytryptamine. 2. The endothelium-dependent vasodilator calcium ionophore (A23187) (which stimulates endothelium-derived relaxing factor [EDRF] release and thus acts through soluble guanylyl cyclase), sodium nitroprusside (which stimulates soluble guanylyl cyclase directly), and atrial natriuretic peptide (which stimulates particulate guanylyl cyclase) relaxed rat aorta but not human umbilical artery. 3. Sodium nitroprusside, 10 microM, increased cyclic GMP levels from 10 to 390 pmol mg-1 protein at 2 min in rat aorta, as compared with a slower, relatively attenuated rise from 5 to 116 pmol mg-1 protein after 15 min in human umbilical artery. The rise in cyclic GMP in the umbilical artery was not significantly augmented by the cyclic GMP phosphodiesterase inhibitor, MB22948. Atrial natriuretic peptide increased cyclic GMP levels in rat aorta but not in human umbilical artery. 4. Forskolin, 10 microM, which stimulates both soluble and particulate adenylyl cyclase, maximally relaxed rat aorta and increased cyclic AMP levels from 15 to 379 pmol mg-1 protein at 15 min, but did not significantly relax or increase cyclic AMP levels in human umbilical artery. After preincubation with the cyclic nucleotide phosphodiesterase inhibitor, IBMX, 10 microM forskolin increased cyclic AMP levels to 1365 pmol mg-1 protein at 30 min in human umbilical arteries, but these high levels were not accompanied by mechanical relaxation.5. 8-Bromo-cyclic GMP and 8-bromo-cyclic AMP which are lipophilic analogues of cyclic GMP and cyclic AMP, both maximally relaxed the rat aorta at a concentration of 10 microM, but did not significantly relax the human umbilical artery.6. The findings indicate that elevated cyclic nucleotide levels are not associated with mechanical relaxation of the post-partum human umbilical artery, as in other vessels such as rat aorta. This impaired response to cyclic nucleotides may contribute to closure of the umbilical artery after birth.

8-Bromo Cyclic Adenosine Monophosphate↗