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W S Poon

Publications and source records attributed to W S Poon.

At least 55 records · Page 3Linked to original sources
PubMed2004

Fluoroscopic frameless computer-assisted navigation for transsphenoidal surgery: a clinical assessment of accuracy in spatial position and trajectory.

OBJECTIVE: Fluoroscopic navigation technique in transsphenoidal surgery on the one hand provides multi-planar (antero-posterior and lateral views) navigation while on the other hand it does not need any preoperative preparation. To assess the clinical accuracy of the above technique in the transsphenoidal surgery, we performed this study. METHODS: 5 patients undergoing transsphenoidal surgery were assessed. Fluoroscopic images were compared with C-arm X-ray images for difference in spatial position and trajectory. RESULTS: 26 sets of data were collected for analysis. Mean pointer tip difference was 0.6 mm. The 95 % confidence interval was 1.3 mm. Mean trajectory difference was 1.2 degree. The 95 % confidence interval was 2.7 degree. CONCLUSION: With a good clinical accuracy, fluoroscopic navigation offers a distinct advantage to replace the traditional fluoroscopic approach for transsphenoidal surgery for its low X-ray exposure and multi-planar (antero-posterior and lateral views) navigation.

Adenoma↗
PubMed2003

The ISAT trial.

Explore the source record for details and available documents.

Angioplasty↗
PubMed2003

The role of haematoma aspiration in the management of patients with thalamic haemorrhage: a pilot study with continuous compliance monitoring.

OBJECTIVE: Thalamic brain haemorrhage is a common disabling and potentially fatal condition. Management is mainly supportive and very rarely do neurosurgeons have to resort to evacuation of the haematoma. We hypothesised that haematoma aspiration may help to improve the outcome of the group of patients with thalamic haemorrhage. MATERIAL AND METHODS: Patients with thalamic haemorrhage were selected on clinical group (intraventricular haemorrhage, hydrocephalus and haematoma size > 15 ml) for intracranial pressure (ICP) monitoring and management in the intensive care unit (ICU). A Spiegelberg double lumen intraventricular balloon catheter was inserted as a fluid-filled catheter on the side of the haematoma. Data of ICP, arterial blood pressure (ABP), cerebral perfusion pressure (CPP) and compliance were collected at one-minute intervals. Hourly averages were used for analysis. RESULTS: 94,448 set of data were collected from eight patients with thalamic haemorrhage. Significant reduction in ICP and improvement in intracranial compliance were detected. In patients with haematoma aspiration, intracranial compliance was improved within 48 hours of the procedure whereas ICP did not. CONCLUSIONS: This pilot study showed that haematoma aspiration in patients with thalamic haemorrhage could improve intracranial compliance. Whether this could be translated into clinical outcome benefits requires further study in a larger number of patients.

Aged↗
PubMed2003

The surgical treatment of intracranial aneurysms based on computer tomographic angiography alone--streamlining the acute mananagement of symptomatic aneurysms.

BACKGROUND: We aimed to prospectively assess the usefulness of computer tomographic angiography (CTA) in streamlining the management of symptomatic intracranial aneurysms in a tertiary neurosurgical unit, from admission to surgery. METHODS: We performed a prospective evaluation over a 2-year period of all symptomatic intracranial aneurysms managed according to a standardized departmental protocol, to assess how CTA has impacted the decision-making process pertaining to the suitability of this investigation to proceed directly to surgery. FINDINGS: A total of 90 patients with intracranial aneurysms were treated over the 2-year period. 23 (26%) underwent endovascular occlusion while 67 (74%) patients underwent a surgical clipping procedure. In the surgical group, 22 (33%) patients had their aneurysms clipped based on CTA alone, while 45 (67%) required additional conventional angiography prior to surgery. Thus around one quarter of all patients treated for symptomatic intracranial aneurysms in our unit had their aneurysm secured surgically based solely on CTA. INTERPRETATION: CTA significantly influences the acute management of symptomatic intracranial aneurysms by streamlining the decision-making process during the early and acute management of these lesions.

Aged↗
PubMed2003

Endovascular GDC-mediated flow-reversal for complex posterior circulation saccular aneurysms. A report of two cases and critical appraisal.

Two patients with giant complex saccular aneurysms of the proximal basilar artery were managed with flow-reversal using the endovascular route. Complete obliteration of the aneurysm was successful in one patient resulting in long term survival (8 year follow-up completed). Incomplete obliteration of the aneurysm persisted in the other patient, resulting in recurrence and a fatal haemorrhage one year after treatment. Endovascular flow-reversal is a good treatment option for these lesions with a high surgical risk. However, persistent incomplete thrombosis of these aneurysms following flow-reversal should lead to the consideration of alternate treatment strategies.

Adult↗
PubMed2003

LINAC radiosurgery in recurrent Cushing's disease after transsphenoidal surgery: a series of 5 cases.

INTRODUCTION: Oversecretion of ACTH from pituitary adenomas is associated with morbidity and reduced life expectancies. We hypothesized that radiosurgical treatment may provide effective tumour and hormonal control associated with minimal pituitary insufficiency. METHOD: Data of five patients who underwent LINAC radiosurgery for recurrent or residual Cushing's disease between 1999 and 2002 were prospectively collected. RESULT: Follow-up period ranged from 27 to 49 months (mean 38 months). All patients attained remission in 6-18 months (mean 8.4 months). One patient (20 %) developed biochemical recurrence 12 months after remission. One patient (20 %) developed hydrocortisone deficiency 24 months after radiosurgery. None of the patients had new visual field defect detected on follow-up. CONCLUSION: In this small case series, LINAC radiosurgery was shown to be an effective and safe treatment of persistent or recurrent Cushing's disease following transsphenoidal surgery. Long-term follow-up and larger patient series is recommended for further clarification.

Adenoma↗
PubMed2003

Intravascular lymphomatosis.

Intravascular lymphomatosis (IVL) is a rare angiotrophic large cell lymphoma producing vascular occlusion of arterioles, capillaries, and venules. Antigenic phenotyping shows that these lymphomas are mostly of B cell type, and less commonly T cell or Ki-1 lymphomas. The central nervous system and skin are the two most commonly affected organs; patients usually present with progressive encephalopathy with mental status changes and focal neurological deficits and skin petechia, purpura, plaques, and discolouration. Other involved organs include adrenal glands, lungs, heart, spleen, liver, pancreas, genital tract, and kidneys. Bone marrow, blood, cerebrospinal fluid, and lymph nodes are typically spared. Fever of unknown origin is another common presentation. Only one case of IVL presenting with disseminated intravascular coagulation and anasarca (generalised oedema) has been reported in the literature. This report describes a postmortem case of a patient with IVL who initially presented with disseminated intravascular coagulation complicated by intracerebral haemorrhage.

Adult↗
PubMed2003

Role of magnetic resonance imaging for preoperative evaluation of patients with refractory epilepsy.

OBJECTIVE: To investigate the magnetic resonance imaging characteristics of patients with refractory epilepsy and the relationship to progression to surgery. DESIGN: Prospective observational study. SETTING: University teaching hospital, Hong Kong. PATIENTS: Patients undergoing preoperative evaluation for epilepsy surgery. MAIN OUTCOME MEASURE: Cranial magnetic resonance imaging findings, correlation with electroencephalographic results, and percentage of patients who were considered suitable candidates for surgery. RESULTS: Structural abnormalities associated with refractory epilepsy in 100 consecutive patients were mesial temporal sclerosis (30%), neocortical sclerosis (23%), vascular malformation (7%), neuronal migration disorders (7%), and tumours (5%). Normal brain scans were found for 28% of patients. Fourteen of 30 (46%) patients with medial temporal lobe lesions at magnetic resonance imaging were suitable candidates for surgery compared with 8/42 (19%) patients with extrahippocampal lesions (odds ratio=3.7; 95% confidence interval, 1.3-10.6; P<0.012). CONCLUSION: Mesial temporal sclerosis was the most common pathology in patients with refractory epilepsy. At the Prince of Wales Hospital, for patients who have undergone a basic magnetic resonance imaging protocol and surface electroencephalography, the result of cranial magnetic resonance imaging is an important determinant for whether patients will undergo surgery.

Adolescent↗
PubMed2002

Is transcranial Doppler ultrasonography (TCD) good enough in determining CO2 reactivity and pressure autoregulation in head-injured patients?

Disturbance of cerebral haemodynamic status, cerebral vasoreactivity (CVR) to carbon dioxide (CO2) and pressure autoregulatory response (PAR) have been shown to be associated with severity of head injury and to correlate with neurological condition and clinical outcome. Information regarding impaired CVR and/or lost PAR has been shown to be of prognostic value in treating head-injured patients. The classic method of evaluating cerebral haemodynamic status requires an invasive measurement of cerebral blood flow (CBF) such as the technique of Kety and Schmidt or by the 133Xe inhalation method. Transcranial Doppler ultrasonography (TCD) is a simple and non-invasive method for its assessment. In this study, cerebral haemodynamic status as determined by TCD was compared with that of stable xenon-enhanced cerebral blood flow (XeCBF) which is generally regarded as a gold standard in CBF measurement with minimal complication, suggesting that employing CO2 and blood pressure challenge with TCD measurement to assess the CVR and PAR in head-injured patients, provides a relatively less invasive method and can be repeated at least daily to assess the cerebrovascular autoregulatory reserve.

Adult↗
PubMed2002

Neurochemical changes in ventilated head-injured patients with cerebral perfusion pressure treatment failure.

The goal of intensive care management of patients with head injury is to provide them with a favourable physiological and metabolic environment for recovery of injury-compromised cells, and to prevent secondary brain insults. Clinical intracerebral microdialysis has enabled documentation of the metabolic derangement after head injury. Treatment targeted at this derangement has emphasized maintenance of optimal cerebral perfusion pressure (CPP). To determine the relationships between CPP and five clinically relevant intracerebral extracellular metabolites (glucose, lactate, glycerol, glutamate and pyruvate) in relation to different therapy intensities, 23 moderate to severe head-injury patients with hourly microdialysis samples were studied. These five metabolites were correlated with CPP and showed a biphasic relation at CPP of 65 to 67 mmHg, which was believed to be the critical CPP indicating irreversible brain damage. Relationship between intracerebral metabolites and CPP in relation to different therapy intensities was studied and suggests the critical CPP threshold in head-injured patients with high ICP and maximum therapy is elevated and should be maintained above 70 mmHg to prevent irreversible brain damage.

Adult↗
PubMed2002

Diffusion MR imaging in glioma: does it have any role in the pre-operation determination of grading of glioma?

AIM: To investigate the role of the diffusion MR weighted sequence in the pre-operative grading of gliomas, and its application in defining the different components of these tumours. MATERIALS AND METHODS: Seventeen patients with gliomas (eight high grade, nine low grade) had diffusion weighted imaging. Apparent diffusion coefficients (ADCs) of different components of tumours were measured. RESULTS: ADC of the cystic portion of the tumour was significantly higher than ADCs of the enhanced tumour, non-enhanced tumour and perifocal oedema (P < 0.01). No significant difference in ADC values between low grade and high grade glioma (P > 0.7) was found nor was there any difference between oligoglioma and non-oligoglioma (P > 0.29). CONCLUSION: ADC value was useful to differentiate the cystic from the solid components of the tumours. However, it was not useful in pre-operative grading of glioma.

Adolescent↗
PubMed2002

Failure of regular external ventricular drain exchange to reduce cerebrospinal fluid infection: result of a randomised controlled trial.

BACKGROUND: It is controversial whether regular changes of external ventricular drains can reduce cerebrospinal fluid (CSF) infection. OBJECTIVE: To carry out a randomised controlled clinical trial over a two year period to determine whether a regular change of ventricular catheter every five days could reduce CSF infection and improve outcome. METHODS: 103 patients requiring external ventricular drains for more than five days and with no evidence of concurrent CSF infection were studied. The patients were randomised to regular change of ventricular catheter (every five days) and no change unless clinically indicated. RESULTS: The CSF infection rates were 7.8% for the catheter change group and 3.8% for the no change group, respectively (rate ratio = 1.80, 95% confidence interval 0.33 to 9.81, p = 0.50). No significant difference was found in intensive care unit stay, ward stay, or clinical outcome between the two groups. CONCLUSIONS: Regular changes of ventricular catheter at five day intervals did not reduce the risk of CSF infection. A single external ventricular drain can be employed for as long as clinically indicated.

Acinetobacter Infections↗
PubMed2002

Apolipoprotein e genotype and outcome in aneurysmal subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Active management of ruptured intracranial aneurysm in subarachnoid hemorrhage is indicated in patients with favorable prognosis. Outcome prediction is based on patient characteristics and clinical and radiological factors. Current clinical grading scales are imprecise, with low interobserver reproducibility. Therefore, outcome prediction remains inconsistent and decision making becomes difficult, especially for patients with poor clinical grade. METHODS: The possible relationship between apolipoprotein E genotype and the outcome of patients suffering spontaneous subarachnoid hemorrhage was investigated. A prospective study was conducted on all patients with spontaneous aneurysmal subarachnoid hemorrhage admitted to our unit during a 2-year period. All patients were managed according to standard protocol, and treatments were given according to their clinical grading. Patient characteristics, clinical grade, radiological grade, and apolipoprotein E genotype were documented. The focus of the study was the 6-month neurological outcome for this group of patients after they were discharged. RESULTS: Seventy-two patients with aneurysmal subarachnoid hemorrhage were admitted to the Prince of Wales Hospital in Shatin, Hong Kong, China, from February 1998 to February 2000. Their ages ranged from 24 to 95 years of age, with a mean (SD) age of 58.3 (15.0) years. Apolipoprotein E epsilon4 was found in 15 patients (21%). At 6 months, Glasgow Outcome Scale score < or = 3 was found in 29 patients (40%). Univariate analysis showed that older patients (odds ratio [OR], 1.03; 95% CI, 1.00 to 1.07; P=0.07) and patients with poor Fisher's grade (OR, 4.5; 95% CI, 1.3 to 15.2; P=0.01), poor World Federation of Neurological Surgeons grade (OR, 5.8; 95% CI, 1.9 to 17.8; P=0.002), or apolipoprotein E epsilon4 (OR, 6.0; 95% CI, 1.7 to 21.3; P=0.006) were more likely to attain unfavorable outcome at 6 months. The additional effect of apolipoprotein E epsilon4 remained significant in the multiple logistic regression model (OR, 11.3; 95% CI, 2.2 to 57.0; P=0.003); the gain in predictive performance was not significant (P=0.26). CONCLUSIONS: Apolipoprotein E epsilon4 genotype is related to poor outcome in patients with subarachnoid hemorrhage.

Adult↗
PubMed2002

The use of stereotactic navigation guidance in minimally invasive transnasal nasopharyngectomy: a comparison with the conventional open transfacial approach.

The purpose of this paper is to study the efficacy of applying stereotactic navigation guidance to nasopharyngectomy via a minimally invasive transnasal approach as compared with the conventional open transfacial approaches. The nasopharynx is the centre of the anterior skull base, which is remote from the surface of the facial skeleton. It is well known that there are several surgical approaches for access to resect tumours from the nasopharynx. However, the open techniques have been associated with much morbidity and only provide access to, and identification of, the ipsilateral internal carotid artery that forms the lateral boundary and resection limit of the nasopharynx. The coupling of stereotactic navigation guidance and a minimally invasive transnasal approach for nasopharyngectomy allows the surgeon to identify and protect the internal carotid artery bilaterally at the nasopharynx. This technique reduces operating time and morbidity to a minimum and yet is oncologically sound for resecting nasopharyngeal lesions. We compare 15 patients who underwent the stereotactic navigation guidance approach with 20 patients who received a conventional open transfacial approach.

Adult↗
PubMed2002

Vertebrobasilar artery dissections: current practice.

Nine patients with vertebrobasilar artery dissections who presented with neurological symptoms or subarachnoid haemorrhage were identified and treated in the Neurosurgical Unit at the Prince of Wales Hospital in Hong Kong. An account of these patients is given and their treatment described. This paper further reviews selected literature to outline the concepts and appropriate management of vertebrobasilar artery dissections.

Adolescent↗
PubMed2002

Lytic skull metastasis secondary to thyroid carcinoma in an adolescent.

We report an unusual case of skull metastasis secondary to thyroid carcinoma in an adolescent girl. The 18-year-old presented with an occipital scalp swelling of 5 years' duration. She reported having thyroid surgery in mainland China 10 years previously. Radiological investigations on presentation demonstrated a lytic hypervascular skull lesion. Preoperative angiography and embolisation was followed by surgical excision. Pathological examination showed the lesion to be a thyroid carcinoma with a predominantly follicular pattern and a completion hemithyroidectomy was subsequently performed. Computed tomography of the thorax showed small micronodules in both lung fields compatible with metastases. The patient was given whole body iodine-131 internal radiation treatment and subsequently commenced thyroid-stimulating hormone-suppressive treatment with thyroxine. The management of thyroid carcinoma and subsequent skull metastasis in children and adolescents is reviewed and controversial points are highlighted.

Adenocarcinoma, Follicular↗