Model-based iterative reconstruction in CT of paranasal sinuses in cystic fibrosis

AIM

To assess image quality and dose-reduction efficacy of model-based iterative reconstruction (MBIR) in computed tomography (CT) of the paranasal sinus (CTPNS) compared with adaptive statistical iterative reconstruction (ASIR) in cystic fibrosis (CF) patients.

MATERIALS AND METHODS

Unenhanced CTPNS studies performed in adult CF patients from 2014 to 2020 were included. MBIR and ASIR were used and compared. Two radiologists assessed the CT images blindly and randomly. Quantitative assessment of noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) was performed in the maxillary sinus, sphenoid body, temporalis, and background air. Qualitative assessment performed included image sharpness, noise and contrast.

RESULTS

Thirty-seven MBIR and 45 ASIR CT PNS studies were included. MBIR achieved a 74% effective median dose reduction (0.039 mSv) compared with ASIR (0.147 mSv). Measured noise was significantly lower in all regions using MBIR (p<0.001) with superior SNR (p<0.001). MBIR had higher CNR compared to ASIR (4.567 versus 2.03, p<0.001). MBIR images were sharper and less noisy, with equal contrast. Cohen's weighted kappa value was 0.824 for qualitative analysis, indicating good inter-rater agreement. Both methods had 100% diagnostic acceptability.

CONCLUSION

MBIR produces high-quality CTPNS images at a significantly lower dose compared with ASIR. It is the preferred imaging surveillance method in CF patients and may have roles in other patient cohorts.

Short- and potential long-term adverse health outcomes of COVID-19: a rapid review

The coronavirus disease 2019 (COVID-19) pandemic has resulted in millions of patients infected worldwide and indirectly affecting even more individuals through disruption of daily living. Long-term adverse outcomes have been reported with similar diseases from other coronaviruses, namely Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). Emerging evidence suggests that COVID-19 adversely affects different systems in the human body. This review summarizes the current evidence on the short-term adverse health outcomes and assesses the risk of potential long-term adverse outcomes of COVID-19. Major adverse outcomes were found to affect different body systems: immune system (including but not limited to Guillain-Barré syndrome and paediatric inflammatory multisystem syndrome), respiratory system (lung fibrosis and pulmonary thromboembolism), cardiovascular system (cardiomyopathy and coagulopathy), neurological system (sensory dysfunction and stroke), as well as cutaneous and gastrointestinal manifestations, impaired hepatic and renal function. Mental health in patients with COVID-19 was also found to be adversely affected. The burden of caring for COVID-19 survivors is likely to be huge. Therefore, it is important for policy makers to develop comprehensive strategies in providing resources and capacity in the healthcare system. Future epidemiological studies are needed to further investigate the long-term impact on COVID-19 survivors.

Dual-energy CT in musculoskeletal trauma

Dual-energy computed tomography (DECT) combines the advantages of conventional CT with the ability to detect bone marrow oedema (BMO), which was previously limited to magnetic resonance imaging (MRI). By analysing DECT virtual non-calcium (VNCa) maps, radiologists can improve the detection of subtle and occult fractures and approximate the acuity/healing of fractures of indeterminate age. This review highlights the role of DECT in the assessment of musculoskeletal trauma, particularly among elderly, post-menopausal women and those at risk for osteoporosis. DECT is especially useful in investigating trabecular bone predominant regions (e.g., vertebral bodies, pelvis, hip, and long bone metaphyses) for stress (i.e., fatigue or insufficiency) and fragility fractures. CT is often performed first due to its increased availability, especially in the emergency setting, shorter imaging duration, and possible patient contraindications to magnetic resonance imaging (MRI). By enabling BMO detection, DECT may have a role in triaging patients for definitive MRI assessment. Understanding the role of anatomical, pathological, and patient factors in image interpretation can improve radiologist adoption of DECT, increase diagnostic confidence, and improve patient management.

Physical property and gas transport studies of ultrathin polysulfone membrane from 298.15 to 328.15 K and 2 to 50 bar: atomistic molecular simulation and empirical modelling

Elucidation of ultrathin polymeric membrane at the laboratory scale is complicated at different operating conditions due to limitation of instruments to obtain in situ measurement data of membrane physical properties. This is essential since their effects are reversible. In addition, tedious experimental work is required to collect gas transport data at varying operating conditions. Recently, we have proposed a validated Soft Confining Methodology for Ultrathin Films that can be used to simulate ultrathin polysulfone (PSF) membranes upon confinement limited to 308.15 K and 2 bars. In industry application, these ultrathin membranes are operated within 298.15–328.15 K and up to 50 bars. Therefore, our proposed methodology using computational chemistry has been adapted to circumvent limitation in experimental study by simulating ultrathin PSF membranes upon confinement at different operating temperatures (298.15 to 328.15 K) and pressures (2 to 50 bar). The effect of operating parameters towards non-bonded and potential energy, free volume, specific volume and gas transport data (e.g. solubility and diffusivity) for oxygen and nitrogen of the ultrathin films has been simulated and collected using molecular simulation. Our previous empirical equations that have been confined to thickness dependent gas transport properties have been modified to accommodate the effect of operating parameters. The empirical equations are able to provide a good quantitative characterization with R² ≥ 0.99 consistently, and are able to be interpolated to predict gas transport properties within the range of operating conditions. The modified empirical model can be utilized in process optimization studies to determine optimal membrane design for typical membrane specifications and operating parameters used in industrial applications.

Pioneering work to elucidate and model the effect of operating conditions on physical and transport properties of ultrathin membranes.

Ray sum image: its efficacy in renal tract calculus detection

AIM

To determine the efficacy of a ray sum image derived from computed tomography of the kidneys, ureters and bladder (CT KUB) in detecting renal tract calculi and whether this can replace the baseline abdominal radiograph (AXR).

MATERIALS AND METHODS

This is a retrospective study performed at a tertiary referral centre examining adult patients referred for urolithiasis who had undergone AXR within 24 hours of the diagnostic CT KUB. AXR and ray sum image for calculus visibility were reviewed blindly by two readers. Anteroposterior thickness of the patient, presence of excess gas/faecal material, calculus size, location, and mean attenuation were analysed to determine effect on the AXR and ray sum sensitivity.

RESULTS

One hundred and fifty-two calculi were examined with ray sum image sensitivity of 44% (95% confidence interval [CI]: 36-52) and AXR 30% (95% CI: 22-38). Calculus size and mean attenuation significantly affected sensitivities of both ray sum and AXR. There was substantial agreement between the two techniques with κ(Kappa)=0.70 (95% CI: 0.58-0.81, p<0.001).

CONCLUSION

Ray sum image as a post-processed image derived from CT KUB dataset may be a viable alternative to the baseline AXR in patients with CT proven urolithiasis. This would reduce patient radiation dose and streamline workflow in busy radiology and emergency departments.

Lung nodules are reliably detectable on ultra-low-dose CT utilising model-based iterative reconstruction with radiation equivalent to plain radiography

AIM

To determine if ultra-low-dose (ULD) computed tomography (CT) utilising model-based iterative reconstruction (MBIR) with radiation equivalent to plain radiography allows the detection of lung nodules.

MATERIALS AND METHODS

Ninety-nine individuals undergoing surveillance of solid pulmonary nodules undertook a low-dose (LD) and ULD CT during the same sitting. Image pairs were read blinded, in random order, and independently by two experienced thoracic radiologists. With LD-CT as the reference standard, the number, size, and location of nodules was compared, and inter-rater agreement was established.

RESULTS

There was very good inter-rater agreement with regards nodules ≥4mm for both the LD- (k=0.931) and ULD-CT (k=0.869). One hundred and ninety-nine nodules were reported on the LD-CT by both radiologists and 196 reported on the ULD-CT, with no nodules reported only on the ULD-CT. This gives a sensitivity of 98.5% and specificity of 100% for ULD-CT with MBIR. The effective dose of radiation was significantly different between the two scans (p<0.0001), 1.67 mSv for the LD-CT and 0.13 mSv for the ULD-CT.

CONCLUSION

ULD-CT utilising MBIR and delivering radiation equivalent to plain radiography, allows detection of lung nodules with high sensitivity. The attendant 10-fold reduction in radiation may allow for dramatic reductions in cumulative radiation exposure.

Outcomes of Stent Retriever versus Aspiration-First Thrombectomy in Ischemic Stroke: A Systematic Review and Meta-Analysis

BACKGROUND

There is ongoing debate regarding the optimal first-line thrombectomy technique for large-vessel occlusion.

PURPOSE

We performed a systematic review and meta-analysis of comparative studies on stent retriever-first and aspiration-first thrombectomy.

DATA SOURCES

We searched Ovid MEDLINE, PubMed, and EMBASE from 2009 to February 2018.

STUDY SELECTION

Two reviewers independently selected the studies. The primary end point was successful reperfusion (TICI 2b/3).

DATA ANALYSIS

Random-effects meta-analysis was used for analysis.

DATA SYNTHESIS

Eighteen studies including 2893 patients were included. There was no significant difference in the rate of final successful reperfusion (83.9% versus 83.3%; OR = 0.87; 95% CI, 0.62%-1.27%) or good functional outcome (mRS 0-2) at 90 days (OR = 1.07; 95% CI, 0.80-1.44) between the stent-retriever thrombectomy and aspiration groups. The stent-retriever thrombectomy-first group achieved a statistically significant higher TICI 2b/3 rate after the first-line device than the aspiration-first group (74.9% versus 66.4%; OR = 1.53; 95% CI, 1.14%-2.05%) and resulted in lower use of a rescue device (19.9% versus 32.5%; OR = 0.36; 95% CI, 0.14%-0.90%). The aspiration-first approach resulted in a statistically shorter groin-to-reperfusion time (weighted mean difference, 7.15 minutes; 95% CI, 1.63-12.67 minutes). There was no difference in the number of passes, symptomatic intracerebral hemorrhage, vessel dissection or perforation, and mortality between groups.

LIMITATIONS

Most of the included studies were nonrandomized. There was significant heterogeneity in some of the outcome variables.

CONCLUSIONS

Stent-retriever thrombectomy-first and aspiration-first thrombectomy were associated with comparable final reperfusion rates and functional outcome. Stent-retriever thrombectomy was superior in achieving reperfusion as a stand-alone first-line technique, with lower use of rescue devices but a longer groin-to-reperfusion time.

Ambulance use affects timely emergency treatment of acute ischaemic stroke

INTRODUCTION

For acute ischaemic stroke patients, treatment with intravenous tissue plasminogen activator within a 4.5-hour therapeutic window is essential. We aimed to assess the time delays experienced by stroke patients arriving at the emergency department and to compare ambulance users and non-ambulance users.

METHODS

We performed a prospective cohort study in a tertiary hospital in Hong Kong. All acute stroke patients attending the emergency department from January to June 2017 were recruited. Patients who were in hospital at the time of stroke onset and those who transferred from other hospitals were excluded. Three phases were compared between ambulance users and non-ambulance users: phase I, between stroke onset and calling for help; phase II, between calling for help and arriving at the emergency department; and phase III, between arriving and receiving medical assessment.

RESULTS

Of 102 consecutive patients recruited, 48 (47%) patients arrived at the emergency department by ambulance. The percentage of stroke patients attending emergency department within the therapeutic window was significantly higher for ambulance users than for non-ambulance users (64.6% vs 29.6%; P<0.001). For phases I, II and III, the median times were significantly shorter for ambulance users (77.5, 32 and 8 min, respectively) than for non-ambulance users (720, 44.5 and 15 min, respectively; all P<0.001).

CONCLUSION

Transport of patients to the emergency department by ambulance is important for timely and effective stroke treatment.

Hot Water Immersion Therapy with a Thermal Isolator in Patient with Marine Envenomation

Objective

Hot water immersion (HWI) has been proven to be effective for the treatment of pain due to marine envenomation. Our preliminary study by simply measuring the temperature change over time on the hot water in our conventional metal tray method revealed a too rapid fall in water temperature that happened in minutes. The aim of this study was to review the current practice of HWI for patients with marine envenomation in the emergency departments in Hong Kong, and to look for the optimal equipment in performing HWI.

Method

We first conducted a phone survey to 16 registered nurses or nursing officers from 16 emergency departments of public hospitals in Hong Kong for the current practice of hot water immersion. The second part of our study was an in-vitro experiment done in observation room that a healthy subject immersed a hand into the water bath in metallic tray, sharp box and thermal isolator with and without covering of aluminum foil or plastic foil. The temperature change of the water bath in these containers was serially monitored.

Results

In our phone survey, 14 respondents used plastic tray or sharp box for hot water immersion. Nine of them claimed that they commonly encountered inadequate wound pain relief and early cooling of the hot water bath. The experiment showed that the water temperature dropped out of optimal range for 5 minutes and 15 minutes in metallic tray and sharp box respectively. The thermal isolator kept the optimal temperature throughout 30 minutes of the study time.

Conclusion

Our purposed thermal isolator is a safe, practical and effective device for HWI therapy.

Timolol Eye Drops Induced Bradycardia

We report a 25-year-old man with bradycardia after administration of ophthalmic timolol. The patient was asymptomatic, and his bradycardia resolved after stopping the eye drop. He was discharged after a four-hour observation. This case demonstrated that topical timolol eye drop may cause systemic adverse reaction. The use of timolol and its possible side-effects are discussed.

Prevalence of neutralising antibodies to interferon-beta and clinical response in Chinese patients with relapsing multiple sclerosis

Background

There are no data on neutralising antibodies to interferon-beta and its clinical implications in Chinese patients with multiple sclerosis (MS).

Objectives

The objectives of this study were to investigate the prevalence of neutralising antibodies among Chinese patients with relapsing MS receiving interferon-beta (1a or 1b) and to study the association between neutralising antibodies and the clinical-radiological response.

Methods

We performed a cross-sectional study on MS patients who received interferon-beta for 9 months or more, and evaluated the clinical response by relapses and magnetic resonance imaging lesions. Blood samples were evaluated for myxovirus resistance protein A (MxA) gene expression by polymerase chain reaction, anti-interferon-beta binding antibodies by enzyme-linked immunosorbent assay, and neutralising antibodies by cell-based MxA protein induction and luciferase reporter gene assays. Assay performances were evaluated by receiver operating characteristic analysis.

Results

Among 78 subjects recruited, 61/77 (79%) had anti-interferon-beta binding antibodies, and 22/78 (28%) had neutralising antibodies by MxA protein induction assay. The presence of high-titre neutralising antibodies was associated with poor clinical outcome (odds ratio 6.1, 95% confidence interval 1.5–25.6, P = 0.013). The sensitivity and specificity for neutralising antibodies using MxA gene expression assay (cut-off 0.20) was 80% and 68%, respectively (area under the curve 0.71).

Conclusions

Neutralising antibodies are associated with poor clinical outcome in Chinese patients with relapsing MS. MxA gene expression and protein induction assays are complimentary assays for neutralising antibody detection.

Atrial fibrillation patients who sustained warfarin-associated intracerebral haemorrhage have poor neurological outcomes: results from a matched case series

INTRODUCTION

Coagulopathy-associated intracerebral haemorrhage has become increasingly common because of the rising demand in the ageing population for anticoagulation for atrial fibrillation. This study compared the clinical features and neurological outcomes of intracerebral haemorrhage in patients with atrial fibrillation who were prescribed warfarin with those who were not.

METHODS

This was a retrospective matched case series of patients with intracerebral haemorrhage from three tertiary hospitals in Hong Kong from 1 January 2006 to 31 December 2011. Patients who developed intracerebral haemorrhage and who were prescribed warfarin for atrial fibrillation (ICH-W group) were compared with those with intracerebral haemorrhage and not prescribed warfarin (ICH-C group); they were matched for age and gender in 1:1 ratio. Clinical features and neurological outcomes were compared, and the impact of coagulopathy on haematoma size was also studied.

RESULTS

We identified 114 patients in the ICH-W group with a mean age of 75 years. Both ICH-W and ICH-C groups had a median intracerebral haemorrhage score of 2. There was a non-statistically significant trend of higher intracerebral haemorrhage volume in the ICH-W group (12.9 mL vs 10.5 mL). The median modified Rankin Scale and the proportion with good recovery (modified Rankin Scale score ≤3) at 6 months were comparable. Nonetheless, ICH-W patients had higher hospital mortality (51.8% vs 36.0%; P=0.02) and 6-month mortality (60.5% vs 43.0%; P=0.01) than ICH-C patients. Overall, 60% of ICH-W patients had their admission international normalised ratio within the therapeutic range during intracerebral haemorrhage, and 14% had a subtherapeutic admission international normalised ratio. International normalised ratio at admission was not associated with intracerebral haemorrhage volume or neurological outcome.

CONCLUSION

Warfarin-associated intracerebral haemorrhage in patients with atrial fibrillation carried a higher stroke mortality than the non-warfarinised patients.

High frequency ultrasonic-assisted CO2 absorption in a high pressure water batch system

Physical absorption process is always nullified by the presence of cavitation under low frequency ultrasonic irradiation. In the present study, high frequency ultrasonic of 1.7MHz was used for the physical absorption of CO2 in a water batch system under elevated pressure. The parameters including ultrasonic power and initial feed pressure for the system have been varied from 0 to 18W and 6 to 41bar, respectively. The mass transfer coefficient has been determined via the dynamic pressure-step method. Besides, the actual ultrasonic power that transmitted to the liquid was measured based on calorimetric method prior to the absorption study. Subsequently, desorption study was conducted as a comparison with the absorption process. The mechanism for the ultrasonic assisted absorption has also been discussed. Based on the results, the mass transfer coefficient has increased with the increasing of ultrasonic power. It means that, the presence of streaming effect and the formation of liquid fountain is more favorable under high frequency ultrasonic irradiation for the absorption process. Therefore, high frequency ultrasonic irradiation is suggested to be one of the potential alternatives for the gas separation process with its promising absorption enhancement and compact design.

Abnormal vocal cord movement in patients with and without airway obstruction and asthma symptoms

BACKGROUND

Abnormal vocal cord movements can cause laryngeal extrathoracic airway obstruction (often called vocal cord dysfunction - VCD) leading to asthma-like symptoms. These aberrant movements are characteristically present during inspiration and termed paradoxical vocal cord movement (PVCM). We have reported PVCM in up to 40% of severe asthmatics, but it is not known if PVCM is detectable in all patients with asthma-like symptoms and if the condition is more often associated with abnormal lung function.

OBJECTIVE

We hypothesized that PVCM is frequently associated with asthma symptoms accompanied by airflow limitation. Studies examined whether PVCM is solely linked to experiencing asthma symptoms, or if PVCM is related to airflow limitation and/or other disease characteristics.

METHODS

Patients with asthma symptoms were recruited from general practice and severe asthma clinics (n = 155). Pulmonary function measurements were conducted, asthma control and Nijmegen (dysfunctional breathing) questionnaires were administered and skin prick testing was carried out. PVCM was quantified using dynamic 320-slice computerized tomography of the larynx. Groups were divided into patients with FEV₁ ≥ 80% predicted or FEV₁ < 80% predicted and FEV₁ /FVC < 0.7. ATS/ERS definitions of severity were also applied and evaluated. Detection of PVCM in the groups was compared and analyses performed to identify features associated with PVCM.

RESULTS

Overall (n = 155), PVCM was detected in 42 cases (27.1%). Patients with FEV₁ < 80% predicted had PVCM more often (25/68, 36.8%) than individuals with normal spirometry (17/87, 19.5%; P = 0.016). PVCM was associated with older age (P = 0.003) and with Nijmegen scores > 20 (P = 0.04). Patients with FEV₁ < 80% predicted plus Nijmegen scores > 20 were more likely to have PVCM (OR = 9.3, P = 0.02).

CONCLUSIONS AND CLINICAL RELEVANCE

Paradoxical vocal cord movement is more often associated with asthma symptoms accompanied by airflow limitation and dysfunctional breathing. Further studies are needed to determine whether PVCM is induced by dysfunctional breathing practices and/or airway obstruction. How PVCM links with symptomatic asthma and VCD also requires evaluation.

Visit-to-visit systolic blood pressure variability predicts all-cause and cardiovascular mortality after lacunar infarct

BACKGROUND AND PURPOSE

Both blood pressure (BP) and its variability (BPV) are established risk factors for development of atherosclerotic disease and are associated with an increased risk for cardiovascular and all-cause mortality. The prognostic implications of outpatient clinic visit-to-visit BPV amongst patients with lacunar infarction are nevertheless unknown.

METHODS

The clinical outcome of 281 patients with lacunar infarction was prospectively followed up. The average BP and BPV, as determined by the standard deviation of the systolic and diastolic BP, were recorded during a mean 13 ± 6 outpatient clinic visits.

RESULTS

The mean age of the population was 70 ± 10 years. After a mean 78 ± 18 months follow-up, 65 patients died (23%), 31% (20/65) due to cardiovascular causes; 14% and 7% developed recurrent stroke and acute coronary syndrome. After adjusting for age, sex, mean systolic and diastolic BP, cardiovascular risk factors and comorbidities, patients with a systolic BPV of the third tertile had significantly higher risk of all-cause mortality [hazard ratio (HR) 1.97, 95% confidence interval (CI) 1.02-3.80, P = 0.04) and cardiovascular mortality (HR 7.64, 95% CI 1.65-35.41, P < 0.01) than those with systolic BPV of the first tertile. Nevertheless, systolic BPV did not predict recurrent stroke or acute coronary syndrome. Diastolic BPV did not predict various adverse clinical outcomes.

CONCLUSIONS

Visit-to-visit systolic BPV predicts long-term all-cause and cardiovascular mortality after lacunar infarct, independent of conventional risk factors including average BP control.

Garlic intake is an independent predictor of endothelial function in patients with ischemic stroke

OBJECTIVES

To investigate the effects of garlic on endothelial function in patients with ischemic stroke (ISS).

DESIGN

Cross-sectional study.

PARTICIPANTS

125 Chinese patients with prior ISS due to athero-thrombotic disease were recruited from the outpatient clinics during July 2005 to December 2006.

MEASUREMENTS

Daily allium vegetable intake (including garlic, onions, Chinese chives and shallots) was ascertained by means of a validated food frequency questionnaire for Chinese and brachial artery flow-mediated dilatation (FMD) was measured using high-resolution ultrasound in all subjects.

RESULTS

The mean age of the study population was 65.9±11.1 years and 69% were males. Mean allium vegetable intake and garlic intake of the study population was 7.5±12.7g/day and 2.9±8.8g/day respectively. Their mean FMD was 2.6±2.3%. Daily intake of total allium vegetable (r=0.36, P<0.01) and garlic (r=0.34, P<0.01) significantly correlated with FMD. Using the median daily allium intake as cut-off (3.37g/day), patients with a low allium intake <3.37g/day was noted to have a lower FMD compared to those with a normal allium intake (2.1±2.1% versus 3.0±2.4%, P<0.05). After adjusting for confounding factors, multi-variate analysis identified that daily allium vegetable (B=0.05, 95% confidence interval: 0.02, 0.09, P<0.01) and garlic (B=0.07, 95% confidence interval: 0.02, 0.12, P<0.01) intake, but not onions, Chinese chives and shallots were independent predictors for changes in FMD in patients with ISS.

CONCLUSIONS

Daily garlic intake is an independent predictor of endothelial function in patients with ISS and may play a role in the secondary prevention of atherosclerotic events.

Prospective observational study of isoflavone and the risk of stroke recurrence: potential clinical implications beyond vascular function

BACKGROUND

Whether isoflavone has any effect on recurrent cardiovascular events is unknown.

OBJECTIVE

To investigate the relations between isoflavone intake and the risk of stroke recurrence.

SUBJECTS AND METHODS

We recruited 127 consecutive patients with prior history of atherothrombotic/ hemorrhagic stroke (mean age: 67 ± 11 years, 69% male) and prospectively followed up for a mean duration of 30 months. Stroke recurrence and major adverse cardiovascular events (MACE) were documented. Brachial flow-mediated dilatation (FMD) was measured using high-resolution ultrasound. Isoflavone intake was estimated using a validated food frequency questionnaire.

RESULTS

Median isoflavone intake was 6.9 (range: 2.1 - 14.5) mg/day. Isoflavone intake was independently associated with increased FMD (Pearson R=0.23, p=0.012). At 30 months, there were 10 stroke recurrence and 12 MACE. Kaplan-Meier analysis showed that patients with isoflavone intake higher than median value had significantly longer median stroke recurrence-free survival time (19.0 [range: 10.4 - 27.6] mth versus 5.0 [range: 4.1 - 5.9] mth, p=0.021) and MACE-free survival time (19.0 [range: 10.4 - 27.6] mth versus 4.0 [range: 2.4 - 5.6] mth, p=0.013). Using multivariate cox regression, higher isoflavone intake was an independent predictor for lower risk of stroke recurrence (hazards ratio 0.18 [95%CI: 0.03 - 0.95], risk reduction 82%, p=0.043) and MACE (hazards ratio 0.16 [95%CI: 0.03 - 0.84], risk reduction 84%, p=0.030).

CONCLUSIONS

Higher isoflavone intake in stroke patients was associated with prolonged recurrence-free survival, and reduced risk of stroke recurrence and MACE independent of baseline vascular function. Whether isoflavone may confer clinically significant secondary protection in stroke patients should be further investigated in a randomized controlled trial.

Circulatory collapse in a patient with gastrinoma after metoclopramide administration

A patient who was given metoclopramide for vomiting and diarrhoea developed circulatory collapse with his blood pressure dropping to 50/20 mm Hg. A gastrinoma was diagnosed histologically. The extent of the tumour was defined by octreotide scanning and magnetic resonance imaging. Metoclopramide was again given for colicky abdominal pain and the patient developed circulatory collapse a second time. A laparotomy involving extensive resection of the tumour was performed. The MEN1 mutation was not detected in blood or tumour tissue. Follow-up octreotide scanning did not show any residual tumour. Possible causes for the circulatory collapse are discussed. Our case is probably the first patient with gastrinoma to develop circulatory collapse after being given metoclopramide.

Hereditary spastic paraplegias

We report a case of hereditary spastic paraplegia. This 38-year-old Chinese man has had lower limb weakness and spasticity for 10 years. He has normal cognition, no sensory deficits, ataxia or cataracts. There is a strong family history of spastic paraplegia. His paternal grandmother, great uncle, father, and elder brother all had weakness and spasticity. A genetic analysis showed that our patient was heterozygous for the mutation p.P361L in SPG4. He was diagnosed with spastic paraplegia type 4, autosomal dominant (SPG4, MIM#182601). About 40% of cases of hereditary spastic paraplegia are due to mutations in SPG4 encoding for spastin, while 10% are due to mutations in SPG3A encoding for atlastin. To date, 38 hereditary spastic paraplegia loci and 16 hereditary spastic paraplegia-related genes have been identified. Other features include sphincter disturbance and dorsal column disturbance. Our patient may be the first case of SPG4 confirmed by genetic analysis locally. We hope to raise clinicians' awareness of this disease and its possible molecular diagnosis.

Ins and outs of inferior vena cava filters in patients with venous thromboembolism: the experience at Monash Medical Centre and review of the published reports

BACKGROUND

Inferior vena cava (IVC) filters are an alternative management strategy to anticoagulation in patients with venous thromboembolism (VTE). However, an IVC filter has its own inherent risks and complications and may not be the best management strategy. The aims of this study were to evaluate our institution's practice of permanent Vena Tech (B. Braun Medical S.A., Boulogne, France) and retrievable Gunther Tulip (William Cook Europe, Bjaeverskov) IVC filters and to review the available published reports.

METHODS

Retrospective single centre audit from the medical record.

RESULTS

Eighty-three and 42 patients had a VT and GT filter inserted, respectively. Median age was 57 years for VT and 63 years for GT. The majority (75% for VT and 83% for GT) was inserted for acute VTE and contraindication to anticoagulation. Both filters were efficacious at preventing pulmonary embolism (PE) and there was a low rate of recurrent deep venous thrombosis in both groups. Insertion-related complications were low in both groups. Of the GT filters (n = 42), 16 were deemed an ongoing requirement, and thus, removal was not planned. In a further six patients, there was insufficient documentation as to why removal was not planned. Removal was attempted in 19 patients and was successful in 11. Failure of removal was as a result of clot in the filter (n = 7) or inability to snare it (n = 1).

CONCLUSIONS

Both the permanent and retrievable filters are efficacious at preventing PE and are associated with a low complication rate. Planned removal of the GT filter may not be possible in a significant proportion of cases.

Cardiac metastasis: a cause of recurrent pulmonary emboli

Intracavitary cardiac metastasis is rare. Apart from causing intracardiac obstruction, this type of metastasis can present as pulmonary emboli. It is important to suspect this diagnosis in an oncology patient with recurrent pulmonary emboli, particularly in the setting of a negative venous Doppler ultrasound of the lower limbs and pelvis. Early recognition may help in improving the prognosis. We present a case of intracavitary cardiac metastasis arising from a squamous carcinoma of the cervix, in a patient with recurrent pulmonary tumour emboli.

Patients with IgA nephropathy have increased serum galactose-deficient IgA1 levels

Immunoglobulin A (IgA) nephropathy is the most prevalent form of glomerulonephritis worldwide. A renal biopsy is required for an accurate diagnosis, as no convenient biomarker is currently available. We developed a serological test based upon the observation that this nephropathy is characterized by undergalactosylated IgA1 in the circulation and in mesangial immune deposits. In the absence of galactose, the terminal saccharide of O-linked chains in the hinge region of IgA1 is terminal or sialylated N-acetylgalactosamine. A lectin from Helix aspersa, recognizing N-acetylgalactosamine, was used to develop an enzyme-linked immunosorbent assay that measures galactose-deficient IgA1 in serum. The median serum lectin-binding IgA1 level was significantly higher for 153 Caucasian adult patients with IgA nephropathy without progression to end-stage renal disease as compared with that for 150 healthy Caucasian adult controls. As the lectin-binding IgA1 levels for the controls were not normally distributed, the 90th percentile was used for determination of significant elevation. Using a value of 1076 U/ml as the upper limit of normal, 117 of the 153 patients with IgA nephropathy had an elevated serum lectin-binding IgA1 level. The sensitivity as a diagnostic test was 76.5%, with specificity 94%; the positive predictive value was 88.6% and the negative predictive value was 78.9%. We conclude that this lectin-binding assay may have potential as a noninvasive diagnostic test for IgA nephropathy.

Extramedullary haematopoiesis in thalassaemia major causing spinal cord compression

A 33-year-old, homozygous beta-thalassaemic, Jehovah witness man presented with subacute spinal cord compression secondary to extramedullary haematopoiesis within the thoracic spinal canal. In this case, MRI showed characteristic features of extramedullary haematopoiesis, leading to an early diagnosis.

Burden of carotid atherosclerosis in patients with stroke: relationships with circulating endothelial progenitor cells and hypertension

Recent studies suggest that reductions in circulating endothelial progenitor cells (EPCs) may contribute to the development of atherosclerosis. However, whether reduced circulating EPCs contribute to cerebrovascular disease remains undefined. We tested the hypothesis that reduced circulating EPCs was associated with an increased burden of carotid atherosclerosis. The level of circulating CD34+/KDR+ EPCs and the extent of carotid atherosclerosis were determined in 30 patients with a history of atherothrombotic ischaemic stroke and 30 age- and sex-matched controls (mean age: 63+/-2 years; 63% men). Stroke patients, compared with controls, had significantly higher carotid mean maximum intima-media thickness (mmIMT) (1.08+/-0.05 versus 0.90+/-0.02 mm, P=0.002), prevalence of carotid plaque (60.0 versus 23.3%, P=0.004) and a lower number of circulating CD34+/KDR+ EPCs (235.7+/-45.5 versus 400.4+/-56.8 cells/mul, P=0.027). The circulating CD34+/KDR+ EPC count correlated negatively with carotid mmIMT (r=-0.50, P<0.001), and was an independent risk factor for increased carotid mmIMT>1 mm (odds ratio (OR): 7.71; 95% confidence interval (CI): 1.62-36.74, P=0.010) and the presence of carotid plaque (OR: 7.04; 95% CI: 1.95-25.43, P=0.003). Furthermore, stroke patients with low (<25th percentile of controls) as compared to those with normal CD34+/KDR+ EPC count had a significantly greater carotid mmIMT (1.21+/-0.07 versus 0.93+/-0.05 mm, P=0.005) and a significantly higher prevalence of carotid plaque (87.5% versus 28.6%; P=0.001). Our observations suggested that reduced circulating EPC may contribute to the progression of carotid atherosclerosis. Circulating EPC count may provide a novel marker for the burden of carotid atherosclerosis.

A registry of tuberculous meningitis in Hong Kong

BACKGROUND

A prospective observational study of the presentation, diagnosis, treatment and outcome of tuberculous meningitis (TBM).

METHODS

Demographic characteristics, clinical information, treatment and progress of TBM patients were followed. Their outcomes were ascertained every 6 months for 3 years after diagnosis. Prognostic factors associated with death or full recovery were examined using multivariate Cox's and logistic regression models, respectively.

RESULTS

Between 1993 and 2000, 166 TBM patients were recruited. Their mean age was 42.9, 153 were Chinese and 81 were males; 92% received HRZS (H = isoniazid; R = rifampicin; Z = pyrazinamide; S = streptomycin), HRZE (E = ethambutol) or HRZES. Steroids were given to 105 patients, with no significant effect on outcome. After 3 years of follow-up, 110 patients had completely recovered, 20 survived with disability and 26 died. Death was significantly associated with older age, lower cerebrospinal fluid (CSF) lymphocyte and poorer consciousness levels at the time of presentation, while full recovery was associated with younger age, being female and absence of complications.

CONCLUSIONS

Relatively good outcomes of TBM cases were documented in this Hong Kong study with a case-fatality ratio of 15.7% (26/166) up to 3 years. Early recognition, diagnosis and administration of effective treatment regimens were probably the most important factors in reducing mortality and morbidity.

Spinocerebellar ataxia type 6

We report a 39-year-old woman with spinocerebellar ataxia type 6. She presented with ataxia and a 3-year history of progressive ataxia and recurrent falls. There was no relevant family history. Genetic tests revealed an expanded allele of 24 CAG repeats at the spinocerebellar ataxia type 6 locus. This appears to be the first case reported in Hong Kong. As genetic testing becomes more widely available and clinical awareness increases, more such patients are expected to be diagnosed.

Japanese encephalitis in Hong Kong

OBJECTIVES

To review past and present patterns of occurrence of Japanese encephalitis in Hong Kong and across Asia. A better understanding of the disease should facilitate the formulation of an effective strategic plan to prevent a future epidemic.

DATA SOURCES

Report of local cases, and literature search of MEDLINE up to November 2004.

STUDY SELECTION

Literature and data related to Japanese encephalitis.

DATA EXTRACTION

Relevant information and data were reviewed by the authors.

DATA SYNTHESIS

Since 16 July 2004, under the ordinance of Hong Kong, Japanese encephalitis has been a notifiable disease. In the past, Japanese encephalitis has reached epidemic proportions in Japan, South Korea, and some areas in China. It has spread globally and has a worldwide incidence of 35 000 to 50 000 cases per year with 10 000 deaths. Mortality is about 30% and survivors often suffer serious long-term morbidity. In 2004, there were five local cases of Japanese encephalitis in Hong Kong. Subsequent serological surveillance of serum samples from 1547 local inhabitants revealed that 37 were positive, ie 2.4% of local inhabitants had been exposed to the Japanese encephalitis virus in the past. Most local inhabitants are immunologically naive to Japanese encephalitis virus. Most infections in endemic areas are asymptomatic. Patients with symptomatic Japanese encephalitis usually present with fever, headache, and confusion. Other signs include neurosis, poliomyelitis, and convulsion. Investigations including magnetic resonance imaging, electroencephalography, and single photon emission computed tomography are not specific. A definitive diagnosis depends on serological studies. Treatment is mainly supportive.

CONCLUSIONS

The control of Japanese encephalitis in Hong Kong relies on an accurate surveillance system, vector control, vector avoidance, and vaccination of the at-risk population. At present, vaccination should be limited to travellers to endemic areas who would stay for longer than 1 month.

Pediatric IgA nephropathy: clinical features at presentation and outcome for African-Americans and Caucasians

AIM

To determine the disease severity at onset and outcome for African-American and Caucasian pediatric patients with IgA nephropathy diagnosed at the Le Bonheur Children's Medical Center since 1990.

DESIGN/METHODS

The study population included all patients diagnosed with IgA nephropathy at the Le Bonheur Children's Medical Center from January 1990 through February 2004. All were below age 18 at biopsy. Clinical features assessed at diagnosis were age, gender, presence of hypertension, history of macroscopic hematuria, degree of proteinuria, severity of renal histology and pattern for immunofluorescent reactants.

STATISTICS

Student's t-test was used to compare age at biopsy and length of follow-up between the 2 groups. Fisher's exact test was used to compare features at presentation and patterns of immunofluorescence. Kidney survival was predicted by the Kaplan-Meier method.

RESULTS

Forty-seven patients (17 African-American, 29 Caucasian) were studied. Clinical features at diagnosis and pattern for all immunofluorescent reactants did not differ significantly between the 2 groups. Mesangial deposition of C1q occurred in 4/17 African-Americans as compared to 1/27 Caucasians (p = 0.06). Four patients (2 African-Americans, 2 Caucasians) progressed to end-stage renal disease. Predicted kidney survival was 96% (94% in African-Americans and 97% in Caucasians) at 1 year and 91% (94% in African-Americans and 89% in Caucasians) at 5 years from diagnosis. Mean time from diagnosis to end-stage renal disease or last follow-up was 3.3 years (3.8 for African-Americans, 3.0 for Caucasians). Macroscopic hematuria occurred prior to diagnosis for 90% of the Caucasian as compared to 61% of the African-American patients (p = 0.03). Urinalysis was normal at last follow-up visit for 24% of African-American patients and 32% of Caucasian patients.

CONCLUSION

In a relatively small sample from a single center, except for the difference in macroscopic hematuria, clinical features at diagnosis and outcome of IgA nephropathy appear similar for African-American and Caucasian pediatric patients.

Clinical features of hereditary spinocerebellar ataxia diagnosed by molecular genetic analysis

OBJECTIVE

To assess the frequency and clinical features of different types of hereditary spinocerebellar ataxia in Hong Kong.

DESIGN

Cross-sectional study using a questionnaire and clinical examination, with the majority of the information retrospectively collected.

SETTING

Three regional hospitals, Hong Kong.

PARTICIPANTS

All patients with spinocerebellar ataxia that was confirmed by molecular genetic tests between January 2001 and October 2003.

MAIN OUTCOME MEASURES

History, latest physical examination results, clinical investigation results, and genetic profiles.

RESULTS

A total of 16 Chinese patients had received diagnoses of spinocerebellar ataxia. These patients had spinocerebellar ataxia type 1 (n=3), spinocerebellar ataxia type 3 (Machado-Joseph disease; n=12), and dentatorubro-pallidoluysian atrophy (n=1). The most common manifestation was ataxia (15/16), followed by pyramidal signs (12/16). Other features such as bulbar dysfunction, ophthalmoplegia, neuropathy, and cognitive impairment were present but variable.

CONCLUSIONS

The clinical manifestations of different types of spinocerebellar ataxia overlap, and genetic study is necessary to confirm the diagnosis. The frequency of spinocerebellar ataxia type 3 is greater than that of other types among these Chinese patients. The age of onset of this type may correlate inversely with the number of CAG repeats.

Transcriptional profiling of human microvascular endothelial cells in the proliferative and quiescent state using cDNA arrays

Endothelial cells are known to be a rich source of transcriptional gene expression. Recent technological advances now permit the detailed profiling of mRNA expression using arrays of known cDNAs on blots. We have used such arrays to examine expression of mRNA by primary isolates of human foreskin microvascular endothelial cells in the proliferative and quiescent state. Cells were stimulated by a combination of known growth factors for these cells including epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), and 'endothelial cell growth supplement (ECGS)' either alone or in combination. Analysis showed the expression of many mRNAs but of the 588 examined, only one, namely monocyte chemotactic protein-1 (MCP-1), showed a decrease on treatment with EGF. A combination of image grabbing followed by subtractive densitometry enabled identification of the mRNAs upregulated in proliferating endothelium. In consideration of the possibility of selective vascular targeting, of particular interest was the increase in expression of the mRNA for the cell surface proteins vascular endothelial (VE-) and neural (N-) cadherin and alpha5, alphav, beta1 and beta3 integrins. The alpha5 integrin offers a previously unrecognized opportunity for vascular targeting.

Kennedy's disease

Kennedy's disease is an X-linked, neurodegenerative disorder, characterised by lower motor neuron syndrome. This report gives the clinical details of six male patients with Kennedy's disease diagnosed at Princess Margaret Hospital. Three were initially diagnosed with other neurological diseases, with the diagnosis of Kennedy's disease made after genetic testing. This hereditary disease should be considered in male patients with muscle weakness, particularly those with a presentation suggesting atypical motor neuron disease.

Epidemiological study of multiple sclerosis in Hong Kong Chinese: questionnaire survey

OBJECTIVE

To study the epidemiology of multiple sclerosis in Hong Kong Chinese.

DESIGN

Cross-sectional questionnaire survey.

SETTING

Neurology and paediatric neurology departments in Hong Kong from January through June 1999.

PARTICIPANTS

All confirmed multiple sclerosis patients.

MAIN OUTCOME MEASURES

Demographic data, investigation results, Kurtzke's Expanded Disability Status Scale during the last follow-up visit, number of relapses between 1997 and 1998, and treatments used/currently in use.

RESULTS

Fifty-three Chinese multiple sclerosis patients were identified. The prevalence was thus estimated to be 0.77 per 100,000 population. This low prevalence was also noted in other multiple sclerosis studies from South-East Asia (range, 0.8-4 per 100,000 population). The female to male ratio among the Chinese multiple sclerosis sufferers was 9.6:1, a figure somewhat higher than that reported in the other studies from South-East Asia (range, 3.2-6.6:1). The Chinese multiple sclerosis patients in this study also had a high spinal cord involvement (66%) and a low presence of cerebrospinal fluid oligoclonal banding (40%). These findings were different from those in Caucasian multiple sclerosis patients.

CONCLUSION

Multiple sclerosis in Hong Kong Chinese has a low prevalence, a high female to male ratio, and a low cerebrospinal fluid oligoclonal banding presence.

Respiratory insufficiency in a Chinese adult with mitochondrial myopathy

Mitochondrial myopathy is an important but uncommon cause of respiratory insufficiency in adults. We report the first case of respiratory insufficiency associated with adult-onset mitochondrial myopathy seen in a Chinese adult in Hong Kong. The patient presented with peripheral oedema and shortness of breath over 2 to 3 days. There was a history of gradual progressive limb weakness over approximately 2 years, hypertrophic cardiomyopathy, intermittent diarrhoea, and weight loss. The diagnosis was made by skeletal muscle biopsy and molecular study, which revealed the A3243G point mutation.

Necrotizing fasciitis in the lower extremity: a review and case presentation

Necrotizing fasciitis is a rare but potentially fatal disease which is often confused with cellulitis. By examining the pathogenesis, clinical presentation, treatment, and a representative case study, this article proposes to lend a broader perspective to this infection. Emphasis is placed on the necessity of surgical debridement in combination with antibiotic therapy to minimize the possible morbidity associated with this condition.