Search PubMed⌕ Search

Biomedical subjects

F J Kirkham

Publications and source records attributed to F J Kirkham.

At least 19 recordsLinked to original sources
PubMed1996

Perturbations of cerebral hemodynamics in Kenyans with cerebral malaria.

The mechanisms of death and neurologic sequelae in African children with cerebral malaria are undetermined. Because pathologic features are confined to the cerebral vasculature, perturbations in cerebral hemodynamics may be responsible. We compared the transcranial Doppler findings in 50 children with cerebral malaria with those of 115 conscious Kenyan children. In addition, 10 children with cerebral malaria were studied during intracranial pressure monitoring and nine children were studied during the agonal stages. In the children with cerebral malaria, cerebral blood flow velocity was increased in 30%, usually associated with seizures. Of the 11 children who developed neurologic sequelae, six had sonographic abnormalities associated with lateralizing deficits, including four children with hemiparesis (in two children the contralateral middle cerebral artery could not be insonated and two had transient increases in blood flow velocity associated with seizures). In the children with severe intracranial hypertension, there was a significant linear relationship between the cerebral perfusion pressure and blood flow velocity, suggesting that autoregulation was impaired. Sonographic features of progressive intracranial hypertension, were observed in three children with cerebral malaria who died. Perturbations of cerebral hemodynamics are associated with a poor outcome in Kenyan children with cerebral malaria.

Blood Flow Velocity↗
PubMed1995

Inter-observer agreement of the assessment of coma scales and brainstem signs in non-traumatic coma.

The authors evaluated the inter-observer agreement between two experienced clinicians examining 19 unconscious children who were not paralysed or ventilated. Inter-observer reliability was assessed by proportion of agreement, disagreement rate and kappa statistics. Corneal reflexes, pupillary responses to light and motor responses were the most reliably elicited. Reduction of the number of categories improved inter-observer agreement. Some of the disagreement may be attributed to changes in the child's condition during the period of assessment. There was more agreement about the five-category 0-IV scale than the summated Adelaide (10-category) and Jacobi (13-category) scales. The ability of these scales to follow changes in the patient's condition and to predict outcome needs to be evaluated in a prospective trial.

Brain Stem↗
PubMed1995

Incidence of neurological complications of surgery for congenital heart disease.

A total of 523 cardiac surgical discharge summaries were searched for recorded evidence of adverse neurological events occurring between operation and time of discharge. Neurological events were recorded in 31 and included one or more of seizure disorder (n = 16), pyramidal signs (n = 11), extrapyramidal signs (n = 8), coma (n = 6), and neuro-ophthalmic deficits (n = 6). There were significantly more adverse neurological events after repairs for arch anomalies (16.6% of cases). There was also an association with the length of cardiopulmonary bypass and a period of low perfusion pressure either intraoperatively or postoperatively. Of the 19 out of 23 survivors in whom long term outcome data were available, four were normal and six had persisting neurological problems directly related to the perioperative period. In a further nine of the 19 survivors, established preoperative neurodevelopmental abnormality probably contributed to their present neurological status, in addition to perioperative events. In view of the way these data were collected, this study must represent the minimum incidence of neurological events in children undergoing cardiac surgery.

Blood Pressure↗
PubMed1994

Cerebral blood volume response to changes in carbon dioxide tension before and during cardiopulmonary bypass in children, investigated by near infrared spectroscopy.

Neurological impairment may occur following cardiopulmonary bypass (CPB) and the effect of CPB on cerebrovascular control may be important in the mechanism of cerebral injury. We have used near infrared spectroscopy (NIRS) to observe cerebral haemodynamics non-invasively before and during CPB. We measured the change in cerebral blood volume (CBV) associated with changing PaCO2 (CBVR). Patients (n = 19) were aged from 1 to 135 (median 14) months. The cerebral blood volume response was determined pre-operatively at normothermia under the influence of standardised anaesthesia employing isoflurane (up to ET conc 0.5%) and during steady-state hypothermic bypass (22-32 degrees C) at an arterial pump flow rate of 1.9-2.4 lm-2.min-1. Complete data was available for 10 patients. The relation between CBV, arterial carbon dioxide tension (PaCO2), mean arterial pressure (MAP) and central venous pressure (CVP) was examined using analysis of covariance (P < or = 0.05) was accepted as significant). The change in CBV associated with changing PaCO2 was corrected for the effects of MAP and CVP. Preoperatively the median CBVR was 0.130 (25th-75th percentile 0.079-0.243) ml.100 g-1.kPa-1 and during hypothermic bypass the median CBVR was 0.093 (25th-75th percentile 0.026-0.255) ml.100 g-1.kPa-1. These values were compared with our reference range derived for normal conscious children using the Kruskal-Wallis test. There was not statistically significant difference between the three groups (P = 0.35). These results, indicating preservation of CBVR during the conditions of anaesthesia and bypass used, are consistent with the observations of previous authors who measured cerebral blood flow response to carbon dioxide by a variety of other methods. Near infrared spectroscopy is proving to be a reliable, non-invasive technique for the investigation of cerebral haemodynamics during CPB.

Adolescent↗
PubMed1994

1H magnetic resonance spectroscopy in the investigation of intractable epilepsy.

We have been using proton magnetic resonance spectroscopy (1H MRS) in the investigation of adults and children with intractable epilepsy. Spectra were obtained from 2 x 2 x 2 cm cubes in the medial region of the temporal lobe, and were analyzed on the basis of signals from N-acetylaspartate (NAA), creatine+phosphocreatine (Cr), and choline-containing compounds (Cho). In comparison with control subjects, the epilepsy patients as a group show significant reductions in the NAA signal and in the NAA/Cho+Cr ratio, with increases in the Cho and Cr signals. The reduction in NAA is interpreted in terms of neuronal loss or damage, while the increase in Cr and Cho signals may be a reflection of reactive astrocytosis.

Adult↗
PubMed1994

Brain swelling and ischaemia in Kenyans with cerebral malaria.

Computed tomography was performed on 14 unconscious Kenyan children recovering from cerebral malaria (seven of whom had another scan 12-120 days later) to elucidate the cause of intracranial hypertension and neurological sequelae. Brain swelling, defined as a loss of cerebrospinal fluid spaces, was documented in six children, while a further two had conspicuously small ventricles only. There was severe intracranial hypertension in the two children with definite brain swelling in whom intracranial pressure was monitored. There was no evidence of acute hydrocephalus or vasogenic oedema. Four children with brain swelling also had widespread low density areas suggestive of ischaemic damage. The patterns of damage were not uniform but were consistent with a critical reduction in cerebral perfusion pressure (which was documented in the two in whom this was monitored), hypoglycaemia, or status epilepticus. All four had serious neurological sequelae. These data suggest that brain injury in cerebral malaria may be due in part to secondary systemic and intracranial factors as well as to the direct effect of intravascular sequestration.

Brain↗
PubMed1994

Case summary: Kate.

After an uneventful birth and normal early milestones, Kate presented with infantile spasms at the age of seven months. Seizures terminated within two days of initiation of ACTH but her subsequent development was delayed. At two-and-a-half years of age she developed complex partial seizures that responded to carbamazepine monotherapy. The dosage was increased when she developed generalized tonic-clonic seizures and she is currently maintained on a maximal dose of a controlled release formulation. The EEG strongly supports the clinical diagnosis of complex partial seizures and an MRI shows a classical neuronal migration defect with gross band heterotopia throughout both cerebral hemispheres. She attends a school for children with moderate learning difficulties.

Adrenocorticotropic Hormone↗
PubMed1993

Cerebral hemodynamics during cardiopulmonary bypass in children using near-infrared spectroscopy.

We describe a new noninvasive method using near-infrared spectroscopy for monitoring cerebral hemodynamics during cardiopulmonary bypass in children. All patients were undergoing open heart operations for repair of congenital heart defects. Standardized anesthesia, an alpha-stat method of blood gas management, and nonpulsatile flow were used in all cases. All measurements during bypass were made after steady-state conditions had been reached. Cerebral blood flow was measured on 13 occasions in 4 children, aged between 4 and 10 months (median, 5 months). Values of 15.9 to 53.5 mL x 100 g-1 x min-1 were obtained. Cerebral blood volume was measured in 1 patient, aged 4 months. Volumes of 4.3 to 8.0 mL x 100 g-1 were obtained on bypass at full pump flow (2.4 L.min-1 x m-2). On bypass at half flow, the volume increased to 14.7 mL x 100 g-1. Change in cerebral blood volume with changing carbon dioxide tension (CBVR) was measured in 13 patients aged from 1 to 90 months (median, 13.5 months). Preoperatively, CBVR was 0.12 +/- 0.07 mL x 100 g-1 x kPa-1 and was independent of mean arterial pressure, which remained between 40 and 80 mm Hg in all cases. During hypothermic bypass (25 degrees C), CBVR was significantly reduced to 0.05 +/- 0.02 mL x 100 g-1 x kPa-1. In addition, there were three values at mean arterial pressure of lower than 40 mm Hg in which CBVR was negative (-0.04 +/- 0.01 mL x 100 g-1 x kPa-1). We conclude that near-infrared spectroscopy is useful for the noninvasive investigation of cerebral hemodynamics during cardiopulmonary bypass.

Carbon Dioxide↗
PubMed1993

Early detection of abnormalities in partial epilepsy using magnetic resonance.

The incidence of brain abnormalities determined by magnetic resonance in 30 consecutive children presenting with intractable complex partial seizures is reported. Images were optimised to visualise the hippocampus and cortical grey matter. Abnormalities of the hippocampus or temporal lobe were seen in all 19 children with clinical features of temporal lobe epilepsy and in six of the seven children with clinically unlocalised epilepsy. By contrast, in the four children with a clinical diagnosis of extratemporal epilepsy, no temporal or hippocampal abnormalities were seen. Generalised cortical abnormalities of uncertain significance were found in a total of 14 children from all groups. The identification of focal brain abnormalities using optimised magnetic resonance imaging enables early non-invasive assessment of children with intractable seizure disorders and the identification of patients for whom epilepsy surgery may be appropriate. It may also lead to a better understanding of the structural basis of intractable epilepsy, and thereby contribute to early treatment decisions.

Adolescent↗
PubMed1993

Magnetic resonance spectroscopy shows increased brain glutamine in ornithine carbamoyl transferase deficiency.

We have performed localized in vivo proton magnetic resonance spectroscopy on two females with ornithine carbamoyl transferase deficiency during episodes of acute hyperammonemic encephalopathy with focal neurologic abnormalities. Spectra obtained from 2 x 2 x 2 cm cubic volumes at relatively long (135-ms) echo times contain additional signals that are characteristic of glutamine and indicate that glutamine is present in very high concentrations in the brain. The findings are consistent with the hypothesis that intracerebral accumulation of glutamine contributes to the encephalopathy associated with hyperammonemia. In one of the children, spectra obtained after treatment showed a marked decrease in the glutamine signals.

Amino Acid Metabolism, Inborn Errors↗
PubMed1992

Prophylactic phenobarbitone in young children with severe falciparum malaria: pharmacokinetics and clinical effects.

1. A method is described for the measurement of phenobarbitone (PB) by reversed phase high performance liquid chromatography (h.p.l.c.) from small samples of whole blood dried onto filter paper strips. 2. The disposition of PB given prophylactically to young children with severe malaria on parenteral quinine is contrasted with that in aparasitaemic Kenyan children on no antimalarial drugs. There were no differences in the disposition of PB between the two groups. 3. Peak blood PB concentrations were equal to or greater than 15 mg l-1 in 27% of the patients on quinine and 23% of those not on quinine; a concentration of 10 mg l-1 was achieved or exceeded by 100% and 92% of each group, respectively, and was maintained for 39 +/- 24 h (mean +/- s.d.), and 33 +/- 21 h, respectively. 4. In an open, dose-finding study, the progress of young children with cerebral malaria given prophylactic PB (10 mg kg-1), was contrasted with that of controls given no seizure prophylaxis. 5. The drug had no apparent effect on depth or duration of coma, but neither was the incidence of seizures reduced. 6. A controlled trial of prophylactic PB in young children with cerebral malaria is needed, but a larger dose than 10 mg kg-1 should be studied.

Child↗
PubMed1991

Intracranial pressure in African children with cerebral malaria.

Opening lumbar cerebrospinal fluid (CSF) pressure was measured with a paediatric spinal fluid manometer in 26 of 61 Kenyan children (mean age 39 months) with cerebral malaria. In all cases pressure was above normal (mean [SD]22.6 [7.4] cm CSF, range 10.5-36). Clinical features of our patients suggest that intracranial hypertension is important in the pathogenesis of cerebral malaria in children, especially as a cause of death. We suggest that raised intracranial pressure is secondary to increased cerebral blood volume. Lowering intracranial pressure may significantly reduce the mortality and morbidity of cerebral malaria. The potential risks and benefits of lumbar puncture should be considered carefully in patients with suspected cerebral malaria.

Animals↗
PubMed1991

Destructive lesions in demyelinating disease.

Three cases are presented in which clinical and radiological features suggested the diagnosis of glioma but surgical biopsy revealed a demyelinating process, with tissue destruction and cyst formation in two. One patient had clinically definite multiple sclerosis. Two had probable acute disseminated encephalomyelitis. Treatment with high dose steroids is appropriate when there is clinical or investigative evidence to suggest the presence of demyelinating disease, before deciding on biopsy.

Adolescent↗