Tsz Lau

University of South Florida, Tampa, Florida, United States

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Publications (10)20.16 Total impact

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    ABSTRACT: Stereotactic radiosurgery is generally accepted as one of the best treatment options for vestibular schwannomas. We question whether growth control is an accurate measure of success in vestibular schwannoma treatment. We aim to clarify the success rate of stereotactic radiosurgery and adjust the reported results to the benign natural history of untreated tumors. All articles were taken from a PubMed search of the English literature from the years 2000–2011. Inclusion criteria were articles containing the number of patients treated, radiation technique, average tumor size, follow-up time, and percentage of tumors growing during follow-up. Data were extracted from 19 articles. Success rates were adjusted using published data that 17% to 30% of vestibular schwannomas grow. The average reported success rate for stereotactic radiosurgery across all articles was 95.5%. When considering 17% or 30% natural growth without intervention, the adjusted success rates became 78.2% and 86.9% respectively. These rates were obtained by applying the natural history growth percentages to any tumors not reported to be growing before radiosurgical intervention. Success in the treatment of vestibular schwannomas with stereotactic radiosurgery is often defined as lack of further growth. Recent data on the natural growth history of vestibular schwannomas raise the question of whether this is the best definition of success. We have identified a lack of continuity regarding the reporting of success and emphasize the importance of the clarification of the success of radiosurgery to make informed decisions regarding the best treatment options for vestibular schwannoma.
    Journal of Clinical Neuroscience 06/2014; 21(6). DOI:10.1016/j.jocn.2013.11.029 · 1.32 Impact Factor
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    ABSTRACT: Objectives/HypothesisRelative to microscopic transnasal surgery, endoscopic surgery provides improved visualization with an increased field of view. Advances such as high-definition (HD) and three-dimensional (3D) endoscopy have been introduced and clearly improve visualization. However, do both technologies maintain an increased field of view? We hypothesize that the field of view of 3D endoscopy is restricted relative to two-dimensional (2D) HD endoscopy. Study DesignLaboratory investigation, prospective case series. Methods Standard measurements at 6-cm and 2-cm working distances where made to determine the comparative field of view utilizing Storz 0° 2D HD and Visionsense 3D endoscopes. Relative measurements were then made to determine field of view. Five clinical patients were then utilized to confirm laboratory studies and demonstrate the relative field of view change. Results3D endoscopy demonstrates a 52% loss of field of view compared to 2D endoscopy in a controlled lab testing. This was confirmed in a small clinical patient series where a 55% ± 3% relative field of view reduction was observed. Conclusions When working with 3D endoscopy in a currently available commercial product, the operator should be aware that relative to HD 2D endoscopy, there is a field of view restriction of 52%. Level of EvidenceN/A. Laryngoscope, 124:387–390, 2014
    The Laryngoscope 02/2014; 124(2). DOI:10.1002/lary.24222 · 2.03 Impact Factor
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    ABSTRACT: High resolution MRI findings suggestive of mesial temporal sclerosis (MRI-MTS) correlate with good outcome after surgery. However, a large group of patients present with normal brain MRI (N-MRI) and temporal lobe epilepsy (TLE). We aim to compare pre-operative ictal EEG patterns in predicting surgical outcomes in the population with MRI-MTS vs. N-MRI after selective anterior-mesial temporal lobe (AMTL) resection. 241 patients with unilateral anterior ictal EEG findings underwent selective AMTL resection. 143 MRI-MTS and 98 N-MRI patients were identified. Outcome was based on the modified Engel classification, ictal EEG pattern at seizure onset, demographics and MRI findings. Seizure-free outcome was seen in the MRI-MTS in 79% of patients, compared to 59.1% (p<.005) of the N-MRI group. No significant difference was identified in ictal EEG patterns at presentation between groups. Class I outcome was achieved in 78.9% of patients that had theta rhythm and MRI-MTS compared to 57.9% of patients that had theta rhythm and N-MRI (p<0.05). Surgical treatment for mesial TLE is effective. Positive MRI suggestive of mesial temporal sclerosis (MTS) predicts better seizure control after surgery. Theta rhythm is the most common ictal pattern and seems to carry the best prognosis for TLE. However, a well-selected group of patients with N-MRI will benefit from surgical intervention, and similar outcome to MRI-MTS patients can be achieved if delta ictal EEG pattern is presented at initial onset. Early referral to an epilepsy center cannot be emphasized enough, even in situations when high-resolution brain MRI is normal.
    Seizure 09/2013; 23(1). DOI:10.1016/j.seizure.2013.09.004 · 2.06 Impact Factor
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    ABSTRACT: On average, every four minutes an individual dies from a stroke, accounting for 1 out of every 18 deaths in the United States. Apporximately 795,000 Americans have a new or recurrent stroke each year, with just over 600,000 of these being first attack [1]. There have been multiple animal models of stroke demonstrating that novel therapeutics can help improve the clinical outcome. However, these results have failed to show the same outcomes when tested in human clinical trials. This review will discuss the current in vivo animal models of stroke, advantages and limitations, and the rationale for employing these animal models to satisfy translational gating items for examination of neuroprotective, as well as neurorestorative strategies in stroke patients. An emphasis in the present discussion of therapeutics development is given to stem cell therapy for stroke.
    Translational Stroke Research 06/2013; 4(3):308-321. DOI:10.1007/s12975-012-0241-2 · 1.94 Impact Factor
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    ABSTRACT: In search of therapies for stroke, substantial progress has been made with the use of stem cells. A constellation of embryonic and extraembryonic sources provides researchers with the ability to harvest stem cells. However, these derivations also provide their individual difficulties as the optimal conditions of use are still being determined. This review will outline the current knowledge, including benefits and challenges, of the many current sources of stem cells for stroke therapy.
    Cell-Based Therapies in Stroke, 01/2013: pages 29-46; , ISBN: 978-3-7091-1174-1
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    ABSTRACT: Recent natural history studies of vestibular schwannomas (VSs) suggest that most of these tumors do not grow. The impact of these new data on management trends in the US is currently unknown. The aim in the present study was to evaluate current trends in the treatment of VS in the US by analyzing a national cancer database. The Surveillance, Epidemiology, and End Results Program is a national database maintained by the National Cancer Institute representing 26% of the US population. Data from the database were downloaded using provided software. Cases were isolated based on histology codes and the site code. Data from 2004 to 2007 were included in the analysis. The number of patients undergoing resection was compared with the number treated with beam radiation and observation, based on tumor size. Three thousand six hundred fifty cases were identified in the database. Over the study period, management choices for VSs showed a significant change only for tumors with a diameter < 2 cm. In this tumor category, a decrease in resection and an increase in radiation were observed, with observation showing a modest increase but remaining low at an average of 25%. Study data demonstrated a shift in the management of small VSs in the US between 2004 and 2007, with microsurgical removal giving way to radiation treatment and the overall rate for observation remaining low and stable. With recent literature suggesting that the majority of small tumors do not grow, the authors assert that VSs are being overtreated in the US.
    Journal of Neurosurgery 06/2012; 117(3):514-9. DOI:10.3171/2012.5.JNS111858 · 3.15 Impact Factor
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    ABSTRACT: Stroke remains a major cause of death in the US and around the world. Despite major scientific advances in our understanding of stroke pathology, the only FDA-approved drug for ischemic stroke is tissue plasminogen activator (tPA). Moreover, the therapeutic window for tPA is confined to the acute phase of stroke, thereby greatly limiting its benefits to less than 3% of ischemic stroke patients. Many treatment strategies for stroke have targeted the subacute or chronic phase in an effort to abrogate the secondary cell death that ensues after the initial stroke insult. Here, we advance the hypothesis that blood vessel disruption, or aneurysm, in the brain is an exacerbating factor for stroke, especially in the evolution of the penumbra or peri-infarct area. A better understanding of aneurysm, specifically its dynamic onset and juxtaposition to the ischemic brain tissue should facilitate the development of novel strategies for attenuating the secondary cell death associated with stroke. To this end, we discuss the laboratory and clinical evidence implicating aneurysm formation in stroke and also provide insights on how stem cell therapy may prove efficacious in combating aneurysm and stroke.
    Current pharmaceutical design 05/2012; 18(25):3663-9. DOI:10.2174/138161212802002724 · 3.29 Impact Factor
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    ABSTRACT: Moderate to severe traumatic brain injury (TBI) often results in malformations to the skull. Aesthetic surgical maneuvers may offer normalized skull structure, but inconsistent surgical closure of the skull area accompanies TBI. We examined whether wound closure by replacement of skull flap and bone wax would allow aesthetic reconstruction of the TBI-induced skull damage without causing any detrimental effects to the cortical tissue. Adult male Sprague-Dawley rats were subjected to TBI using the controlled cortical impact (CCI) injury model. Immediately after the TBI surgery, animals were randomly assigned to skull flap replacement with or without bone wax or no bone reconstruction, then were euthanized at five days post-TBI for pathological analyses. The skull reconstruction provided normalized gross bone architecture, but 2,3,5-triphenyltetrazolium chloride and hematoxylin and eosin staining results revealed larger cortical damage in these animals compared to those that underwent no surgical maneuver at all. Brain swelling accompanied TBI, especially the severe model, that could have relieved the intracranial pressure in those animals with no skull reconstruction. In contrast, the immediate skull reconstruction produced an upregulation of the edema marker aquaporin-4 staining, which likely prevented the therapeutic benefits of brain swelling and resulted in larger cortical infarcts. Interestingly, TBI animals introduced to a delay in skull reconstruction (i.e., 2 days post-TBI) showed significantly reduced edema and infarcts compared to those exposed to immediate skull reconstruction. That immediate, but not delayed, skull reconstruction may exacerbate TBI-induced cortical tissue damage warrants a careful consideration of aesthetic repair of the skull in TBI.
    PLoS ONE 03/2012; 7(3):e33646. DOI:10.1371/journal.pone.0033646 · 3.23 Impact Factor
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    ABSTRACT: Stoke remains a leading cause of death and disability with limited treatment options. Extensive research has been aimed at studying cell death events that accompany stroke and how to use these same cell death pathways as potential therapeutic targets for treating the disease. The mitochondrial permeability transition pore (MPTP) has been implicated as a major factor associated with stroke-induced neuronal cell death. MPTP activation and increased permeability has been shown to contribute to the events that lead to cell death. Cyclosporine A (CsA), a widely used immunosuppressant in transplantation and rheumatic medicine, has been recently shown to possess neuroprotective properties through its ability to block the MPTP, which in turn inhibits neuronal damage. This newfound CsA-mediated neuroprotection pathway prompted research on its use to prevent cell death in stroke and other neurological conditions. Preclinical studies are being conducted in hopes of establishing the safety and efficacy guidelines for CsA use in human trials as a potential neuroprotective agent against stroke. In this review, we provide an overview of the current laboratory and clinical status of CsA neuroprotection.
    Neuropeptides 05/2011; 45(6):359-68. DOI:10.1016/j.npep.2011.04.002 · 2.55 Impact Factor
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    ABSTRACT: Background The standard incision for far-lateral suboccipital approaches has been the classic "reverse hockey stick." Although that incision provides ample exposure, concern has been raised that excessive muscle dissection and skin elevation might lead to accumulation of cerebrospinal fluid (CSF) under the flap with increased risk of CSF leak. We hypothesize that the C-shaped incision can minimize the amount of muscle dissection and provide optimal exposure and surgical outcomes. Objective To describe the anatomical dissection for the C-shaped incision and clinical application of the C-shaped incision for the far-lateral approach. Methods A retrospective analysis of all the patients operated on at our center using this approach for the treatment of aneurysm of the posterior inferior cerebellar artery (PICA) from 2005 to 2011. Results of clinical and operative outcome are evaluated. Surgical techniques are described in detail. Cadaveric dissections using the C-shaped incision were performed to assess the exposure of the far-lateral suboccipital area. Results Eleven consecutive patients who had undergone this procedure were selected. All patients underwent clipping of PICA aneurysms. Nine patients (82%) presented with ruptured aneurysms and subarachnoid hemorrhage. All of them underwent suboccipital craniectomy and C1 laminectomy. The dura mater was closed in a watertight fashion in 10 patients (91%). No CSF leak or pseudomeningocele were reported. In nine SAH patients, two (22%) had postoperative dysphagia and required long-term percutaneous endoscopic gastrostomy tube placement. One patient (11%) had chronic respiratory failure and required a tracheostomy. Three patients (33%) developed hydrocephalus and required a ventriculoperitoneal shunt. Conclusions The C-shaped incision is a valid alternative to the classic reverse hockey-stick incision to gain exposure for far-lateral craniotomies. Knowing the anatomy and dissection techniques can provide an easy and safe route to address anterior lateral cranial-cervical lesions. Our results suggest the C-shaped incision is reliable in preventing CSF leak and the formation of pseudomeningocele.
    Skull Base Surgery 01/2011; 21(S 01). DOI:10.1055/s-2011-1274328 · 0.60 Impact Factor

Publication Stats

72 Citations
20.16 Total Impact Points


  • 2011–2014
    • University of South Florida
      • Department of Neurosurgery and Brain Repair
      Tampa, Florida, United States
  • 2012
    • University of California, San Francisco
      San Francisco, California, United States