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George K. C. Wong, Simon C. H. Yu and Wai S. Poon

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George K. C. Wong and Wayne W. S. Poon

Object

The authors explored the relationship among the duration of external ventricular drainage, revision of external ventricular drains (EVDs), and cerebrospinal fluid (CSF) infection to shed light on the practice of electively revising these drains.

Methods

In a retrospective study of 199 patients with 269 EVDs in the intensive care unit at a major trauma center in Australasia, the authors found 21 CSF infections. Acinetobacter accounted for 10 (48%) of these infections. Whereas the duration of drainage was not an independent predictor of infection, multiple insertions of EVDs was a significant risk factor. Second and third EVDs in previously uninfected patients were more likely to become infected than first EVDs. An EVD infection was initially identified a mean of 5.5 ±0.7 days postinsertion (standard error of the mean); these data—that is, the number of days—were normally distributed.

Conclusions

This pattern of infection is best explained by EVD-associated CSF infections being acquired by the introduction of bacteria on insertion of the drain rather than by subsequent retrograde colonization. Elective EVD revision would be expected to increase infection rates in light of these results, and thus the practice has been abandoned by the authors' institution.

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George K. C. Wong and Wayne W. S. Poon

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David Y. C. Chan, Jill M. Abrigo, Tom C. Y. Cheung, Deyond Y. W. Siu, Wai S. Poon, Anil T. Ahuja and George K. C. Wong

OBJECT

The objective of this study was to generate data on the local prevalence of unruptured intracranial aneurysms (UIAs) in asymptomatic Hong Kong Chinese individuals. First-degree relatives of patients with aneurysmal subarachnoid hemorrhage (aSAH) were recruited as surrogates of the general population and to explore the potential role of screening in this locality.

METHODS

The authors identified first-degree relatives of consecutive patients with subarachnoid hemorrhage from a ruptured aneurysm who were admitted to a university hospital in Hong Kong from June 2008 to December 2010. Magnetic resonance angiography (MRA) was the imaging modality used to screen the cerebral vasculature of these asymptomatic individuals. If MRA showed abnormal findings, CT angiography was performed to confirm the MRA findings.

RESULTS

In total, 7 UIAs were identified from the 305 MR angiograms obtained. The prevalence of UIAs in first-degree relatives of patients with aSAH in the Hong Kong Chinese population was 2.30% (95% CI1.02%–4.76%). This percentage was lower than the prevalence rate of 3.2% from a meta-analysis of the literature. The sizes of the UIAs detected ranged from 1.4 mm to 7.5 mm; 85.7% of the UIAs detected in this study were < 5 mm, in contrast to 66% noted in the literature. One of the UIAs identified underwent endovascular stent placement with a flow diverter. None of the UIAs identified ruptured or became symptomatic during a median follow-up period of 3.5 years.

CONCLUSIONS

The prevalence of UIAs in first-degree relatives of patients with aSAH in the Hong Kong Chinese population was lower than that in Caucasians. At the same time, most of the UIAs detected in this study were small (85.7% were < 5 mm, vs 66% in a meta-analysis). With a similar incidence of aSAH in Hong Kong (7.5 per 100,000 person-years) as compared with data cited in the literature, the hypothesis that UIA rupture risk size threshold is different in Chinese patients should be further investigated.

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George K. C. Wong, David K. W. Yeung, Anil T. Ahuja, Ann D. King, Christopher W. K. Lam, Matthew T. V. Chan, Tony Gin and Wai S. Poon

Object

Disturbance of cerebral phosphorus-containing metabolites occurs in many disease entities and has not been widely studied in patients with subarachnoid hemorrhage (SAH). Pilot studies have indicated that hypermagnesemic treatment may improve outcome in patients with aneurysmal SAH, but the precise mechanism is not known. The authors hypothesized that, by raising intracellular brain free magnesium in aneurysmal SAH, hypermagnesemic treatment would alter the cerebral energy status.

Methods

The authors designed the current study to use 31P-MR spectroscopy (MRS) to investigate intracellular brain free magnesium and cerebral phosphorus-containing metabolites in patients with good-grade aneurysmal SAH, both those receiving and not receiving hypermagnesemic therapy. A total of 37 eligible patients and 23 healthy volunteers were recruited. A total of 81 MRS studies were performed.

Results

Hypermagnesemic treatment after aneurysmal SAH produced a small (mean difference 0.018 ± 0.007 mM [+ 13.0%]) but significant elevation of intracellular free magnesium during the 1st week. Aneurysmal SAH produced a depressed membrane metabolism with lower phosphodiester/total phosphate.

Conclusions

The MRS finding of elevated brain free intracellular magnesium after intravenous magnesium sulfate infusion is novel, and the changes in membrane metabolism provide insight into the metabolic effects of aneurysmal SAH and future pathophysiological studies.

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George K. C. Wong, Janice H. H. Yeung, Colin A. Graham, Xian-lun Zhu, Timothy H. Rainer and Wai S. Poon

Object

Traumatic subarachnoid hemorrhage (SAH) is a poor prognostic factor for traumatic brain injury. The authors aimed to further investigate neurological outcome among head injury patients by examining the prognostic values of CT patterns of traumatic SAH, in particular, the thickness and distribution.

Methods

The study was conducted using a database in a regional trauma center in Hong Kong. Data had been prospectively collected in consecutive trauma patients between January 2006 and December 2008. Patients included in the study had significant head injury (as defined by a head Abbreviated Injury Scale [AIS] score of 2 or more) with traumatic SAH according to admission CT.

Results

Over the 36-month period, 661 patients with significant head injury were admitted to the Prince of Wales Hospital in Hong Kong. Two hundred fourteen patients (32%) had traumatic SAH on admission CT. The mortality rate was significantly greater and a 6-month unfavorable outcome was significantly more frequent in patients with traumatic SAH. Multivariate analysis showed that the maximum thickness (mm) of traumatic SAH was independently associated with neurological outcome (OR 0.8, 95% CI 0.7–0.9) and death (OR 1.3, 95% CI 1.2–1.5) but not with the extent or location of hemorrhage.

Conclusions

Maximum thickness of traumatic SAH was a strong independent prognostic factor for death and clinical outcome. Anatomical distribution per se did not affect clinical outcome.