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W Harkness

Publications and source records attributed to W Harkness.

At least 37 records · Page 2Linked to original sources

What to consider when conducting a cost-effectiveness analysis in a clinical setting.

More data are needed providing strong evidence that nutrition services are cost-effective. Economic evaluations, such as cost-effectiveness analyses, are excellent practice-based research projects. We conducted a cost-effectiveness analysis in a clinical setting to compare the cost-effectiveness of lipid-lowering medications plus diet therapy (medication + diet) with diet therapy alone (diet alone) for treating patients with hypercholesterolemia. Twenty-five adults with hypercholesterolemia (13 receiving medication + diet, 12 receiving diet alone) either participated in an 8-week, home-based, step 1 intervention or were counseled about diet and lifestyle by their care provider. Diet, cost, and laboratory data were collected at baseline, at 9 months, and at 19 months after participation in the intervention (follow-up). Cost per unit change in outcome was evaluated for each group. The diet-alone group made only small changes in dietary intake, changes that were smaller in magnitude than those made by the medication + diet group. Nevertheless, at 9 months, costs per unit change in total serum cholesterol level and low-density lipoprotein cholesterol (LDL-C) level were approximately $24 and $83 less, respectively, for the diet-alone group. At follow-up, however, the cost per unit change in LDL-C level was approximately $17 less for the medication + diet group, which can be explained by the medication + diet group's greater decrease in LDL-C level. The following elements should be considered when conducting a cost-effectiveness analysis of medical nutrition therapy: effectiveness of the nutrition intervention, adequate sample size, confounding variables, compliance with diet and drug therapy, direct and indirect costs of care, and follow-up evaluation.

Adult↗

Protein adsorption to hydrocephalus shunt catheters: CSF protein adsorption.

OBJECTIVE: To assess the quantity and nature of the proteins that adsorb to hydrocephalus shunt catheters after implantation, and to determine whether sufficient could accumulate to obstruct the catheter. DESIGN: Elution of proteins from 102 explanted shunt catheters, with protein assay and electrophoresis of the eluate, and scanning electron microscopy (SEM) of the catheters. RESULTS: The amount of protein elutable was extremely low, and significant protein, apart from a thin film, was not found on SEM. Qualitative analysis disclosed that most of the adsorbed protein was albumin. CONCLUSIONS: Protein deposition on hydrocephalus catheters does not occur in sufficient quantities to cause catheter obstruction.

Adsorption↗

Potential prognostic factors of relapse-free survival in childhood optic pathway glioma: a multivariate analysis.

There is still no consensus on the natural history and optimal management of optic pathway gliomas (OPG) in children. In order to tackle optimal management issues, we need to clearly understand the prognostic and confounding factors affecting relapse of OPG. We propose the use of the Cox proportional hazards (PH) model in a retrospective study of childhood OPG of 69 children seen from 1977 to 1994. We have developed a comprehensive model capable of multivariate analyses and handling time-dependencies. Our studies showed that relapse-free survival improves with increasing age, the presence of neurofibromatosis 1 (NF1), and chemotherapy and radiotherapy (p < 0.0005). Sex, tumor position and surgery do not significantly affect survival. Older children with NF1 have extremely good prognosis. We noted behavior that departs from the strictly proportional hazards model, but results were inconclusive.

Adolescent↗

Epileptic nystagmus in infancy.

Epileptic nystagmus (EN) is a rare form of nystagmus that occurs only during epileptic seizures. We report an infantile case in which EN was first noted at 10 days of age. Electronystagmography showed a right-beating nystagmus with predominantly linear slow phases that traversed the midline. Neuro-imaging revealed dysplasia of the left middle temporal gyrus extending posteriorly into the parieto-occipital cortex. The right hemisphere and subcortical structures appeared normal. Perfusion studies demonstrated interictal hypoperfusion with ictal hyperperfusion in the left temporal lobe. Electrocorticography demonstrated spiking over the left temporal-parieto-occipital region. Following extensive surgical resection of this area and weaning of anti-convulsants, the child has remained seizure-free without nystagmus. This case demonstrates the cortical origin of EN, and shows that infant cortex has functioning efferent connections to brainstem oculomotor centres from 10 days of age.

Electroencephalography↗

Periventricular nodular heterotopia and intractable temporal lobe epilepsy: poor outcome after temporal lobe resection.

We describe 5 women and 5 men with periventricular nodular heterotopia and electroclinical features suggestive of temporal lobe epilepsy, who were surgically treated for control of medically refractory seizures. Magnetic resonance imaging revealed bilateral periventricular nodular heterotopia in 7 of the 10 patients. Because of the lack of clear localization, 6 patients were studied with intracranial depth electrode recordings. Seizures were of hippocampal onset (3 patients), regional temporal lobe onset (2 patients), or occipital-temporal onset (1 patient). Anterior temporal lobectomy was performed in 6 patients; selective amygdalohippocampectomy, in 1; and anterior temporal lobectomy plus resection of the heterotopic tissue, in 3. None of the 9 patients followed for more than 12 months postoperatively were seizure free. Two patients were initially seizure free for approximately 18 months, but then seizures recurred. One patient had a major reduction in seizure frequency at a 39-month follow-up after most of the unilateral heterotopic tissue was included in the temporal resection. Temporal resection did not lead to a long-term favorable outcome in this group of patients with periventricular nodular heterotopia and epileptogenic discharges involving the temporal lobe. This suggests a more widespread disorder with epileptogenic activity possibly originating in or near the heterotopic tissue. The clinical and electrographic features of periventricular nodular heterotopia pointing to temporal lobe origin are misleading and temporal resection does not result in long-term cessation of seizures.

Adult↗

Intrinsic brainstem tumours in childhood: a report of 35 children followed for a minimum of 5 years.

The presentation, pathology and outcome of 35 children with intrinsic brainstem tumours treated at our institution between 1980 and 1990 have been reviewed. Eight children remain alive. There were 19 girls and 16 boys. Mean age at diagnosis was 5 years. The mean duration of symptoms prior to diagnosis was 5 months. The diagnosis was made by computed tomography (CT) in all children and magnetic resonance imaging (MRI), in addition, for 24 children. Twenty-seven tumours (77%) were diffuse, three (8.6%) were predominantly cystic, three (8.6%) were exophytic and two (5.7%) were focal. Cervicomedullary tumours were not included in this study. Definitive histology was obtained in 13 children (37.1%), eight (22.9%) by biopsy alone and five (14.3%) after surgery to debulk the tumours. Eleven of these cases were astrocytomas and two were primitive neuroectodermal tumours (PNET). Twelve children (34.3%) required shunt placement for hydrocephalus. Twenty-eight children (80%) were irradiated using conventionally fractionated radiotherapy to a total dose between 50 and 55 Gy. Six children (17.1%) also received chemotherapy. The overall mean survival time was 10 months, but five of six children who had their tumours debulked survived free of progressive disease for more than 5 years following their diagnosis. The prognosis for brainstem tumours in children remains poor with only a minority falling into the surgically resectable (good prognosis) group.

Adolescent↗

Aetiology of herniation of the hindbrain in craniosynostosis. An investigation incorporating intracranial pressure monitoring and magnetic resonance imaging.

The occurrence and extent of herniation of the hindbrain has been evaluated in a population of children with craniosynostosis by means of magnetic resonance imaging of the craniocervical junction. The role of intracranial pressure (ICP), posterior fossa size and hydrocephalus in the development of this deformity has also been assessed. Magnetic resonance imaging (Siemens Magnetom 1.5T) was reviewed in 27 cases of craniosynostosis in whom there had been no previous cranial vault surgery. The position of the cerebellar tonsils in relation to the plane of the foramen magnum was measured and an index of the size of the posterior fossa relative to the rest of the cranial vault was also calculated for each case. The presence of hydrocephalus (requiring a cerebrospinal fluid diversion procedure) was documented. In 22 of these cases overnight, subdural ICP monitoring using the Camino fibre optic device had also been performed. Herniation of the hindbrain below the plane of the foramen magnum occurred in 10 of 27 cases (37%). The level of ICP showed a significant correlation with the extent of hindbrain herniation (p < 0.001) as did small posterior fossa size (p = 0.0035). Hydrocephalus was present in 4 patients, all of whom had hindbrain herniation. The extent of hindbrain herniation did not correlate with age (p = 0.48). We propose that herniation of the hindbrain in craniosynostosis is a consequence of brain deformation occurring in response to the physical forces imposed by a combination of the anatomical deformity at the skull base and intracranial hypertension rather than a primary malformation of brain development as commonly supposed.

Arnold-Chiari Malformation↗

Consequences of cranial vault expansion surgery for craniosynostosis.

Remodelling the cranial vault in an attempt to increase the intracranial volume and thus control intracranial hypertension, whilst at the same time improving the patient's appearance, has been the mainstay of surgery for syndromic craniosynostosis. We report a case of craniosynostosis in whom cranial vault expansion was followed by the development of hind-brain herniation and hydrocephalus. This prompted a review of our other cases of craniosynostosis who had been evaluated by magnetic resonance imaging following surgery in order to assess the frequency of hind-brain herniation and hydrocephalus in these children. Magnetic resonance imaging had been performed in the postoperative evaluation of 34 cases of craniosynostosis who had undergone procedures intended to increase the intracranial volume. The position of the cerebellar tonsils and the presence or otherwise of hydrocephalus was recorded for all cases. The effectiveness of surgery in treating raised intracranial pressure (ICP) was evaluated by means of postoperative ICP monitoring and had been performed in 22 cases. Herniation of the hind-brain below the level of the foramen magnum was observed in 18 cases (53%). Hydrocephalus, requiring the insertion of a ventriculoperitoneal shunt, was present in 14 cases (41%) and had developed after the cranial vault procedure in 9. The mean sleeping ICP measured postoperatively was normal (<10 mm Hg) in 5, borderline (10-15) in 7, and raised (>15 mm Hg) in 10 cases. Cranial vault expansion in complex craniosynostosis may fail to address the underlying aetiology of intracranial hypertension. Furthermore, both hydrocephalus and hind-brain herniation may develop following such surgery. Neither the increase in intracranial volume afforded by cranial vault expansion nor the shunting of hydrocephalus precludes the persistence of abnormal ICP. These findings are discussed in the light of possible mechanisms, in addition to cephalocranial disproportion responsible for intracranial hypertension in complex craniosynostosis. The implications for the surgical management of complex craniosynostosis are reviewed.

Acrocephalosyndactylia↗

Surgical treatment of patients with single and dual pathology: relevance of lesion and of hippocampal atrophy to seizure outcome.

Modern neuroimaging can disclose epileptogenic lesions in many patients with partial epilepsy and, at times, display the coexistence of hippocampal atrophy in addition to an extrahippocampal lesion (dual pathology). We studied the postoperative seizure outcome of 64 patients with lesional epilepsy (median follow-up, 30 months) and considered separately the surgical results in the 51 patients with a single lesion and in the 13 who had dual pathology. In patients with a single lesion, 85% were seizure free or significantly improved (Engel's class I-II) when the lesion was totally removed compared with only 40% when there was incomplete resection (p < 0.007). All three patients with dual pathology who had both the lesion and the atrophic hippocampus removed became seizure free. In contrast, only 2 of the 10 patients with dual pathology undergoing surgery aimed at the lesion or at the hippocampus alone became seizure free (p < 0.05), although 4 of them showed significant improvement (Engel's class II). We conclude that the outcome in patients with single epileptogenic lesions is usually dependent upon the completeness of lesion resection. In patients with dual pathology, surgery should, if possible, include resection of both the lesion and the atrophic hippocampus.

Adolescent↗

Discrimination of speech sounds in a boy with Landau-Kleffner syndrome: an intraoperative event-related potential study.

A 7-year-old boy with severe acquired epileptic aphasia (Landau-Kleffner syndrome) was treated by multiple subpial transections to the left temporal lobe. In the course of electrocorticography, event-related potentials (ERP) were recorded to the phonemes /ba/ and /ga/; /ba/ occurred 72.5% of the time and /ga/ 27.5%, in a pseudo-random sequence. The ERPs were distributed over the middle and inferior temporal gyri and there was a marked overlap with the area of maximal spiking detected on the electrocorticogram. Repetition of the frequent syllable /ba/ was associated with diminution of the prominent negative component of the ERP culminating around 550 ms suggesting habituation. Presentation of the novel syllable /ga/ restored the amplitude of this negative component, showing that discrimination was preserved despite the apparent global aphasia. This finding supports clinical evidence that some children with epileptic aphasia can still process auditory speech input. Intraoperative ERP recording may help improve our understanding of the relationship between epileptiform activity and aspects of language processing in Landau-Kleffner syndrome where lack of cooperation precludes detailed clinical testing.

Aphasia↗

Ventriculo-peritoneal shunt requirement in children with posterior fossa tumours: an 11-year audit.

The authors reviewed 175 paediatric patients with posterior fossa tumours treated at the Hospital for Sick Children at Great Ormond Street, London, between 1983 and 1993, in an attempt to determine the requirement for shunt procedures in these children. The age of the patient population ranged from 4 months to 14 years 6 months. The factors evaluated included age at diagnosis, tumour type, extent of surgical resection, and the presence of CSF leak and/or infection. Shunt placement was required postoperatively in 18.9% of patients. Age of the patient was felt to be a significant factor in the need for shunt placement. Tumour type and completeness of tumour excision were also felt to be significant factors affecting the need for post-operative shunt insertion.

Adolescent↗

Removed shunt valves: reasons for failure and implications for valve design.

Most removed shunt valves are discarded with no investigation into why they had to be replaced or whether they still performed to specification. However, improvements in valve design will only occur if valves that have needed removal are examined and the reasons that they failed are determined. An in-depth study of 43 valves that were removed in this unit over a 15-month period was performed. They were submitted to a four-part study, comprising flow-pressure testing, opening and closing pressure measurement, assessment of the susceptibility to syphoning, and dismantling with internal inspection of the valve components. Overall, 81% of valves failed to meet the manufacturers' specified performance data, even though the peroperative cause of shunt failure was thought to lie outside the valve. Over 80% of valves with metallic parts were found to have accumulated debris internally, and this was thought to have impaired their performance. In contrast, only 25% of non-metallic valves contained debris, a significant difference (0.01 > p > 0.001). All of the valves had a high tendency to overdrainage. Attention is drawn to the high number of malfunctioning valves. It is recommended that a change of valve should be considered in all shunt revisions, and that future valve designs should avoid metal components.

Cerebrospinal Fluid Pressure↗

Does the cerebrospinal fluid protein concentration increase the risk of shunt complications?

A prospective study was performed to determine whether the popular opinion that a high CSF protein concentration increases the risk of shunt complications is true. Ninety-five patients were enrolled into the study and they had 116 shunt operations over 15 months. It was considered that the CSF protein content might influence the development of complications that occurred within 2 months of surgery. Shunt complications occurred following 24.6% of operations within this period. This included 12 infections, 13 obstructions and three cases of overdrainage. The distribution of complications, compared to CSF protein content, was non-significant on a chi 2-test (p > 0.5). The total protein content of each of the complication groups was also analysed using the Mann-Whitney U-test and the differences were non-significant for the infection (0.1 > p > 0.05) and obstruction groups (0.5 > p > 0.1). It is concluded that an elevated CSF protein content does not increase the risk of shunt complications, and that there is no reason why shunting should be delayed in patients with a high CSF protein content.

Adolescent↗

Use of near infrared spectroscopy to estimate cerebral blood flow in conscious and anaesthetized adult subjects.

Near infrared spectroscopy (NIRS) can be used to quantify cerebral haemodynamic states non-invasively and to estimate cerebral blood flow (CBF). In the first part of this study we have compared CBF measurements in conscious and anaesthetized subjects. In the second part we have compared paired measurements made during anaesthesia, first on the scalp and then the dura after craniotomy. Mean CBF was 17 (SD 7) ml 100 g-1 min-1 in the conscious subjects compared with 21 (8) ml 100 g-1 min-1 on the scalp during anaesthesia (P > 0.1). Mean CBF on the dura was 68 (21) ml 100 g-1 min-1 (P < 0.0001). Computer modelling suggests that the difference in magnitude between scalp and dura measurements of CBF is likely to be caused by the optical effect of extracerebral tissue which powerfully scatters light passing through it but does not contribute significantly to the measured CBF because it has only a small blood content itself. The results lend support to this method of estimating CBF although formal validation by comparison with an established technique is needed.

Adult↗

Cervical spine in Pfeiffer's syndrome.

Studies of cervical spine anomalies in patients with Crouzon's and Apert's syndromes have shown an increased incidence of fusions in comparison with that in the normal population. Currently, only small series of patients with Pfeiffer's syndrome who exhibit abnormalities have been published. The objective was to assess the incidence and pattern of radiological cervical spine abnormalities in patients with Pfeiffer's syndrome. All cervical spine radiographs of 22 patients with a confirmed diagnosis of Pfeiffer's syndrome treated at Great Ormond Street Hospital during the last 10 years were studied. All of the radiographs were reviewed by the craniofacial team along with a pediatric radiologist with experience in the assessment of skeletal dysplasias. Radiological abnormalities included hypoplasia of the neural arches, hemivertebrae, and a "butterfly" vertebra as well as vertebral fusion. Evidence of vertebral fusion was present in 16 (73%) of cases. Fusion of both the vertebral bodies and the posterior elements were noted. C2-C3 was the level most commonly involved, although fusion was noted at all levels within the cervical spine. Block fusions involving multiple vertebrae were noted. Analysis of sequential radiographs in 11 patients revealed evidence of progression in eight patients. These results reveal an incidence of anomalies that is higher than previously reported. The older age of the patients in our study demonstrates the progressive nature of the cervical fusions in Pfeiffer's syndrome.

Acrocephalosyndactylia↗

The effect of protein and blood cells on the flow-pressure characteristics of shunts.

It has long been assumed that a high cerebrospinal fluid protein concentration adversely affects the performance of shunts. There is little experimental evidence to support this viewpoint, however, and the few reports that have been published can be criticized for poor experimental design or presentation of results. A flow-dependent shunt perfusion model was constructed. PS Medical Flow Control valves (PS Medical Corporation, Goleta, CA) and Cordis-Hakim valves (Cordis Corporates, Miami, FL) were perfused with saline-plasma solutions in concentrations from 0 to 9 g/L of protein. Blood suspensions in dilutions from 0.25 to 1% were also studied. The opening and closing pressures of the valves were measured with a simple manometer, and the physical properties of the solutions were studied. The results indicated that the valves performed within the ranges specified by their manufacturers, even with markedly increased protein concentrations in the perfusate. Furthermore, the valve opening and closing pressures were lower with the protein-containing solutions than with the control solutions. Thus, the protein did not impair shunt function and we conclude that shunts can be inserted into patients who have elevated cerebrospinal fluid protein contents. However, blood cells did adversely affect performance and, therefore, patients with hemorrhagic cerebrospinal fluid should not receive shunts.

Cerebrospinal Fluid Pressure↗