Ernest Wang

Comparison of infection rate with the use of antibiotic-impregnated vs standard extraventricular drainage devices: a prospective, randomized controlled trial.

BACKGROUND External ventricular drainage (EVD) catheters provide reliable and accurate means of monitoring intracranial pressure and alleviating elevated pressures via drainage of cerebrospinal fluid (CSF). CSF infections occur in approximately 9% of patients. Antibiotic-impregnated (AI) EVD catheters were developed with the goal of reducing the occurrence of EVD catheter-related CSF infections and their associated complications. OBJECTIVE To present an international, prospective, randomized, open-label trial to evaluate infection incidence of AI vs standard EVD catheters. METHODS Infection was defined as (1) proven infection, positive CSF culture and positive Gram stain or (2) suspected infection: (A) positive CSF culture with no organisms identified on initial Gram stain; (B) negative CSF culture with a gram-positive or -negative stain; (C) CSF leukocytosis with a white blood cell/red blood cell count >0.02. RESULTS Four hundred thirty-four patients underwent implantation of an EVD catheter. One hundred seventy-six patients in the AI-EVD cohort and 181 in the standard EVD catheter cohort were eligible for evaluation of infection. The 2 groups were similar in all clinical characteristics. Proven infection was documented in 9 (2.5%) patients (AI: 4 [2.3%] vs standard: 5 [2.8%], P = 1.0). Suspected infection was documented in 31 (17.6%) patients receiving AI and 37 (20.4%) patients receiving standard EVD catheters, P = .504. Duration of time to suspected infection was prolonged in the AI cohort (8.8 ± 6.1 days) compared with the standard EVD cohort (4.6 ± 4.2 days), P = .002. CONCLUSION AI-EVD catheters were associated with an extremely low rate of catheter-related infections. AI catheters were not associated with risk reduction in EVD infection compared to standard catheters. Use of AI-EVD catheters is a safe option for a wide variety of patients requiring CSF drainage and monitoring, but the efficacy of AI-EVD catheters was not supported in this trial.

Comparison of polyetheretherketone and titanium cranioplasty after decompressive craniectomy.

OBJECTIVE To characterize complication and failure rates and outcomes of patients who underwent cranioplasty with polyetheretherketone (PEEK) and titanium implants and to compare complication and failure rates between the 2 implants. METHODS A retrospective cohort study of patients who underwent cranioplasty with PEEK patient-specific implant (PEEK Optima-LT) and preformed titanium mesh at the National Neuroscience Institute, Singapore, between January 2001 and February 2012 was performed. Data related to initial decompressive craniectomy and cranioplasty, associated complications after cranioplasty, and indication for revision or removal of implants were collected. Cranioplasty failure was defined as revision or removal of a patients implant. RESULTS Overall complication rates for PEEK and titanium cranioplasty were 25.0% and 27.8%, respectively. The combined complication rate was 27.3%. A trend toward increase in exposed implant in titanium cranioplasty compared with PEEK cranioplasty was observed (P = 0.074). There were 3 of 24 (12.5%) cranioplasty failures with PEEK, and 27 of 108 (25%) cranioplasty failures with titanium (P = 0.129). Previous deep infection in patients after decompressive craniectomy was associated with cranioplasty complications (odds ratio, 23.3; confidence interval, 3.00-180.5; P = 0.003) and failure (odds ratio, 22.5; confidence interval, 2.82-179.0; P = 0.003). CONCLUSIONS The findings from this study highlight that cranioplasty is associated with significant complications, including the necessity for reoperation. It is hoped that the information in this study will provide better understanding of the risks associated with PEEK and titanium cranioplasty and contribute to decision making by the clinician and patient.

Uses and limitations of indocyanine green videoangiography for flow analysis in arteriovenous malformation surgery

Intra-operative indocyanine green (ICG) videoangiography is a useful addition to cerebrovascular neurosurgery. ICG videoangiography is useful in different phases of arteriovenous malformation (AVM) surgery. Additionally, it can be used to perform semi-quantitative flow analysis. We reviewed our initial assessment of 24 patients who underwent ICG videoangiography during AVM surgery to assess the utility and limitations of the technique as well as to demonstrate semi-quantitative flow analysis, a new capability of ICG videoangiography. Over the course of 3 years, we performed 49 ICG videoangiographies in 24 patients with AVM. In 85% of the pre-resection videos, ICG was useful in localising the arterial feeders, the draining veins and the nidus. Intra-resection ICG videos were recorded for eight of the 23 patients (the ICG from one patient was missing). Post-resection ICG videos were recorded for 14 out of the 23 patients, which were useful in confirming no evidence of nidus in the exposed resection cavity and an absence of flow in the main draining vein. Semi-quantitative flow analysis was performed in eight patients with superficial AVM. The average T(½) peak intensities (time to 50% of peak intensity) were 32 s, 33.5 s, and 35.6 s for the arterial feeder, the draining vein and normal cortex, respectively. The arteriovenous T(½) peak time was 1.5 s, and the arteriocortex T(½) peak time was 3.6 s. The T(½) peak fluorescence rates were 84 average intensity of fluorescence (AI)/s, 62.9 AI/s and 28.7 AI/s, for the arterial feeder, the draining vein and normal cortex, respectively. Only one patient of 23 (4.3%) showed residual AVM on post-operative digital subtraction angiography or CT angiography despite negative intra-operative ICG. ICG videoangiography is a useful addition to AVM surgery, but it has some limitations. Flow analysis is a new capability that allows for semi-quantitative AVM perfusion analysis.

The Cushing Response : A case for a review of its role as a physiological reflex

Despite a century of work on the subject, controversy still exists as to the physiological relevance of the Cushing response (CR), a state of raised systemic blood pressure and bradycardia associated with raised intracranial pressure. The alternative that has been proposed to the classical belief of pre-terminal brainstem damage is of a baroreflex that attempts to maintain cerebral perfusion in response to situations of extreme elevations in intracranial pressure or brainstem ischemia. We report a patient with spontaneous subarachnoid haemorrhage who demonstrated CR, which was later seen to self-abort with an eventual good outcome. We review the existing literature and propose that our clinical case may provide further support for a physiological role of CR.

A multicenter multinational registry for assessing ventriculoperitoneal shunt infections for hydrocephalus.

BACKGROUND:Reported infection rates after ventriculoperitoneal shunt surgery vary from 1 to 25%. Antibiotic-impregnated (AI) catheters may reduce shunt infection rates, but this is uncertain. OBJECTIVE:To establish a prospective shunt registry to evaluate short-term (3-month) infection rates associated with ventriculoperitoneal shunts and standard or AI catheters during surgical treatment of hydrocephalus. METHODS:A prospective, multicenter, noncontrolled, open-label registry investigated patients with de novo catheter implantation or catheter replacement of an existing ventriculoperitoneal shunt. The primary outcome was shunt infection. RESULTS:A total of 440 patients were entered into the registry at 10 sites: 3 in North America, 2 in Singapore, 4 in China and 1 in India. Seven patients were excluded. Of the 433 remaining patients, 314 had new shunts and 119 were revisions. Shunt infections occurred in 14 of 433 patients (3.2%) overall and in 2 of 37 infants (5.2%) younger than 1 year. AI catheters were used in 46 of 433 patients at 7 centers. The shunt infection rate was 0 of 46 for shunts with AI catheters and 14 of 387 (3.6%) without AI catheters. Infection rates were similar with AI catheters, adjusting for age and catheter type. CONCLUSION:The overall shunt infection rate was lower than in previous multicentered studies. The low infection rate and low rate of AI catheter use precludes any meaningful statement regarding the value of AI catheters in reducing the infection rate. Consideration should be given to performing a well designed, adequately powered, prospective randomized controlled trial to determine whether AI catheters reduce shunt infection rates.

Endoscopic assisted microneurosurgery for cerebral aneuryms

While there have been many advances in the field of microneurosurgery, the clipping of aneurysms remains an intricate procedure. Technical complications include residual aneurysm, perforator injuries, parent artery occlusion and cranial nerve injuries. The neuroendoscope is a useful tool and adjunct to the microsurgical clipping of these aneurysms. We study the usefulness of the neuroendoscope in enhancing visualisation during surgery. Twenty-four cases of ruptured cerebral aneurysms were operated on over a duration of 6 months in which a 1mm diameter rigid endoscope was used. We discuss our preliminary results and examine the advantages of the neuroendoscope. These include the ability to look around corners and behind obstructions. While this provides an additional view to the surgeon, the high magnification gives good definition of the surrounding structures. With less brain retraction, smaller operative exposures and yet better visualisation offered, neuroendoscopy may reduce operative morbidity.

Temporal changes in cerebral tissue oxygenation with cerebrovascular pressure reactivity in severe traumatic brain injury

Objective: To investigate the temporal relationship between cerebrovascular pressure reactivity and brain tissue oxygenation in patients with severe head injury. Methods: In 40 patients, brain tissue oxygenation and intracranial pressure were monitored. Time-averaged values for intracranial pressure (ICP), mean arterial pressure (MAP), cerebral perfusion pressure (CPP) and brain tissue oxygenation (PtiO2) were computed. The pressure reactivity index (PRx) was calculated. The mean values of the variables were obtained at the 6-h and 72-h post-injury time points, and the difference between the two time points for each of the variables was denoted as delta (δ). Results: Of the 40 patients, 32 were survivors and 8 were non-survivors. Statistically significant differences were present between these two groups with regard to δMAP (p = 0.013), ICP at 6 h (p = 0.027), CPP at 72 h (p = 0.018), δCPP (p = 0.033), PRx at 6 h (p = 0.029), PRx at 72 h (p = 0.002), PtiO2 at 72 h (p<0.0005) and δPtiO2 (p = 0.023) values, reflecting an improvement with time in survivors and a deterioration with time in non-survivors. In non-survivors, the magnitude of change in PtiO2 and CPP with time correlated in a negative linear fashion (p = 0.042 and 0.029, respectively) with the change in PRx with time, whereas no such relationship was seen in survivors. Conclusion: The severity of brain tissue oxygenation derangement correlates with increasing cerebrovascular dysautoregulation in patients succumbing to severe head injury, supporting the utility of PRx as a monitoring variable and the rationale for a target-driven approach to head injury management.

Use of programmable versus nonprogrammable shunts in the management of hydrocephalus secondary to aneurysmal subarachnoid hemorrhage: a retrospective study with cost-benefit analysis

OBJECTIVES The choice of programmable or nonprogrammable shunts for the management of hydrocephalus after aneurysmal subarachnoid hemorrhage (SAH) remains undefined. Variable intracranial pressures make optimal management difficult. Programmable shunts have been shown to reduce problems with drainage, but at 3 times the cost of nonprogrammable shunts. METHODS All patients who underwent insertion of a ventriculoperitoneal shunt for hydrocephalus after aneurysmal SAH between 2006 and 2012 were included. Patients were divided into those in whom nonprogrammable shunts and those in whom programmable shunts were inserted. The rates of shunt revisions, the reasons for adjustments of shunt settings in patients with programmable devices, and the effectiveness of the adjustments were analyzed. A cost-benefit analysis was also conducted to determine if the overall cost for programmable shunts was more than for nonprogrammable shunts. RESULTS Ninety-four patients underwent insertion of shunts for hydrocephalus secondary to SAH. In 37 of these patients, nonprogrammable shunts were inserted, whereas in 57 programmable shunts were inserted. Four (7%) of 57 patients with programmable devices underwent shunt revision, whereas 8 (21.6%) of 37 patients with nonprogrammable shunts underwent shunt revision (p = 0.0413), and 4 of these patients had programmable shunts inserted during shunt revision. In 33 of 57 patients with programmable shunts, adjustments were made. The adjustments were for a trial of functional improvement (n = 21), overdrainage (n = 5), underdrainage (n = 6), or overly sunken skull defect (n = 1). Of these 33 patients, 24 showed neurological improvements (p = 0.012). Cost-benefit analysis showed

A randomized, placebo-controlled pilot study of patients with spontaneous intraventricular haemorrhage treated with intraventricular thrombolysis

646.60 savings (US dollars) per patient if programmable shunts were used, because the cost of shunt revision is a lot higher than the cost of the shunt. CONCLUSIONS The rate of shunt revision is lower in patients with programmable devices, and these are therefore more cost-effective. In addition, the shunt adjustments made for patients with programmable devices also resulted in better neurological outcomes.

Telemedicine in Emergency Neurological Service Provision in Singapore: Using Technology to Overcome Limitations

Intraventricular hemorrhage (IVH) occurring after spontaneous intracerebral hemorrhage (ICH) is an independent risk factor for mortality. The use of intraventricular urokinase (Uk) to reduce intraventricular blood clot volume and improve outcome was investigated. Patients with IVH requiring external ventricular drainage were recruited and randomized into a double-blind placebo controlled study. Assessments of collected cerebrospinal fluid (CSF) haemoglobin (Hb) and serial CT scans were performed. The study outcomes were: infection rates, length of stay in the intensive care unit, survival, National Institutes of Health Stroke Scale score; and modified Rankin Scale scores. Our results showed an increase in both the drained CSF Hb concentration in patients treated with Uk compared to placebo and in the rate of resolution clot volume. No differences were found in the other outcome measures but there was a trend towards lowered mortality in the group treated with Uk. Therefore, intraventricular Uk resulted in faster resolution of IVH with no adverse events.