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Soh RCC, Chen BZ, Hartono S, Lee MS, Lee W, Lim SL, Gan J, Maréchal B, Chan LL, Lo YL. The hindbrain and cortico-reticular pathway in adolescent idiopathic scoliosis. Clin Radiol 2024; 79:e759-e766. [PMID: 38388254 DOI: 10.1016/j.crad.2024.01.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 01/09/2024] [Accepted: 01/18/2024] [Indexed: 02/24/2024]
Abstract
AIM To characterise the corticoreticular pathway (CRP) in a case-control cohort of adolescent idiopathic scoliosis (AIS) patients using high-resolution slice-accelerated readout-segmented echo-planar diffusion tensor imaging (DTI) to enhance the discrimination of small brainstem nuclei in comparison to automated whole-brain volumetry and tractography and their clinical correlates. MATERIALS AND METHODS Thirty-four participants (16 AIS patients, 18 healthy controls) underwent clinical and orthopaedic assessments and brain magnetic resonance imaging (MRI) on a 3 T MRI machine. Automated whole-brain volume-based morphometry, tract-based spatial statistics analysis, and manual CRP tractography by two independent raters were performed. Intra-rater and inter-rater agreement of DTI metrics from CRP tractography were assessed by intraclass correlation coefficient. Normalised structural brain volumes and DTI metrics were compared between groups using Student's t-tests. Linear correlation analysis between imaging parameters and clinical scores was also performed. RESULTS AIS patients demonstrated a significantly larger pons volume compared to controls (p=0.006). Significant inter-side CRP differences in mean (p=0.02) and axial diffusivity (p=0.01) were found in patients only. Asymmetry in CRP fractional anisotropy significantly correlated with the Cobb angle (p=0.03). CONCLUSION Relative pontine hypertrophy and asymmetry in CRP DTI metrics suggest central supranuclear inter-hemispheric imbalance in AIS, and support the role of the CRP in axial muscle tone. Longitudinal evaluation of CRP DTI metrics in the prediction of AIS progression may be clinically relevant.
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Affiliation(s)
- R C C Soh
- Singapore General Hospital, Singapore; Duke-NUS Medical School, Singapore
| | - B Z Chen
- Singapore General Hospital, Singapore
| | - S Hartono
- Duke-NUS Medical School, Singapore; National Neuroscience Institute, Singapore
| | - M S Lee
- Singapore General Hospital, Singapore
| | - W Lee
- Singapore General Hospital, Singapore
| | - S L Lim
- Singapore General Hospital, Singapore
| | - J Gan
- Siemens Healthineers, Singapore
| | - B Maréchal
- Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland; Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland; Signal Processing Laboratory (LTS 5), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - L L Chan
- Singapore General Hospital, Singapore; Duke-NUS Medical School, Singapore.
| | - Y L Lo
- Duke-NUS Medical School, Singapore; National Neuroscience Institute, Singapore
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Chu TY, Zheng-Gérard C, Huang KY, Chang YC, Chen YW, I KY, Lo YL, Chiang NY, Chen HY, Stacey M, Gordon S, Tseng WY, Sun CY, Wu YM, Pan YS, Huang CH, Lin CY, Chen TC, El Omari K, Antonelou M, Henderson SR, Salama A, Seiradake E, Lin HH. GPR97 triggers inflammatory processes in human neutrophils via a macromolecular complex upstream of PAR2 activation. Nat Commun 2022; 13:6385. [PMID: 36302784 PMCID: PMC9613636 DOI: 10.1038/s41467-022-34083-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 10/13/2022] [Indexed: 12/25/2022] Open
Abstract
Neutrophils play essential anti-microbial and inflammatory roles in host defense, however, their activities require tight regulation as dysfunction often leads to detrimental inflammatory and autoimmune diseases. Here we show that the adhesion molecule GPR97 allosterically activates CD177-associated membrane proteinase 3 (mPR3), and in conjugation with several protein interaction partners leads to neutrophil activation in humans. Crystallographic and deletion analysis of the GPR97 extracellular region identified two independent mPR3-binding domains. Mechanistically, the efficient binding and activation of mPR3 by GPR97 requires the macromolecular CD177/GPR97/PAR2/CD16b complex and induces the activation of PAR2, a G protein-coupled receptor known for its function in inflammation. Triggering PAR2 by the upstream complex leads to strong inflammatory activation, prompting anti-microbial activities and endothelial dysfunction. The role of the complex in pathologic inflammation is underscored by the finding that both GPR97 and mPR3 are upregulated on the surface of disease-associated neutrophils. In summary, we identify a PAR2 activation mechanism that directs neutrophil activation, and thus inflammation. The PR3/CD177/GPR97/PAR2/CD16b protein complex, therefore, represents a potential therapeutic target for neutrophil-mediated inflammatory diseases.
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Affiliation(s)
- Tai-Ying Chu
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | | | - Kuan-Yeh Huang
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Yu-Chi Chang
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Ying-Wen Chen
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Kuan-Yu I
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Yu-Ling Lo
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Nien-Yi Chiang
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Hsin-Yi Chen
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Martin Stacey
- Faculty of Biological Sciences, School of Molecular and Cellular Biology, University of Leeds, Leeds, UK
| | - Siamon Gordon
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Wen-Yi Tseng
- Division of Rheumatology, Allergy and Immunology, Chang Gung Memorial Hospital-Keelung, Keelung, Taiwan
| | - Chiao-Yin Sun
- Department of Nephrology, Chang Gung Memorial Hospital-Keelung, Keelung, Taiwan
- Department of Medicine, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Yen-Mu Wu
- Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Division of Infectious Diseases, Department of Internal Medicine, Chang Gung Memorial Hospital-Linkou, Taoyuan, Taiwan
| | - Yi-Shin Pan
- Department of Gastroenterology and Hepatology, Chang Gung Memorial Hospital-Linkou, Taoyuan, Taiwan
| | - Chien-Hao Huang
- Department of Gastroenterology and Hepatology, Chang Gung Memorial Hospital-Linkou, Taoyuan, Taiwan
| | - Chun-Yen Lin
- Department of Gastroenterology and Hepatology, Chang Gung Memorial Hospital-Linkou, Taoyuan, Taiwan
| | - Tse-Ching Chen
- Department of Anatomic Pathology, Chang Gung Memorial Hospital-Linkou, Taoyuan, Taiwan
| | - Kamel El Omari
- Diamond Light Source Limited, Harwell Science and Innovation Campus, Didcot, UK
| | | | | | - Alan Salama
- Department of Renal Medicine, Royal Free Campus, UCL, London, UK
| | - Elena Seiradake
- Department of Biochemistry, University of Oxford, Oxford, UK.
| | - Hsi-Hsien Lin
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
- Division of Rheumatology, Allergy and Immunology, Chang Gung Memorial Hospital-Keelung, Keelung, Taiwan.
- Department of Anatomic Pathology, Chang Gung Memorial Hospital-Linkou, Taoyuan, Taiwan.
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Lo YL. Effect of Focal Traumatic Injury in Nondystrophic Myotonic Disorders. J Clin Neuromuscul Dis 2021; 22:234-236. [PMID: 34019012 DOI: 10.1097/cnd.0000000000000323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Y L Lo
- National Neuroscience Institute, Singapore Duke-NUS Medical School, Singapore
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Lin HH, Lo YL, Wang WC, Huang KY, I KY, Chang GW. Overexpression of FAM46A, a Non-canonical Poly(A) Polymerase, Promotes Hemin-Induced Hemoglobinization in K562 Cells. Front Cell Dev Biol 2020; 8:414. [PMID: 32528962 PMCID: PMC7264091 DOI: 10.3389/fcell.2020.00414] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 05/05/2020] [Indexed: 01/11/2023] Open
Abstract
FAM46A belongs to the FAM46 subfamily of the nucleotidyltransferase-fold superfamily and is predicted to be a non-canonical poly(A) polymerase. FAM46A has been linked to several human disorders including retinitis pigmentosa, bone abnormality, cancer, and obesity. However, its molecular and functional characteristics are largely unknown. We herein report that FAM46A is expressed in cells of the hematopoietic system and plays a role in hemin-induced hemoglobinization. FAM46A is a nucleocytoplasmic shuttle protein modified by Tyr-phosphorylation only in the cytosol, where it is closely associated with ER. On the other hand, it is located proximal to the chromatin regions of active transcription in the nucleus. FAM46A is a cell cycle-dependent poly-ubiquitinated short-lived protein degraded mostly by proteasome and its overexpression inhibits cell growth and promotes hemin-induced hemoglobinization in K562 cell. Site-directed mutagenesis experiments confirm the non-canonical poly(A) polymerase activity of FAM46A is essential for enhanced hemin-induced hemoglobinization. In summary, FAM46A is a novel poly(A) polymerase that functions as a critical intracellular modulator of hemoglobinization.
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Affiliation(s)
- Hsi-Hsien Lin
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan.,Department of Anatomic Pathology, Chang Gung Memorial Hospital-Linkou, Taoyuan, Taiwan
| | - Yu-Ling Lo
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Wen-Chih Wang
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Kuan-Yeh Huang
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Kuan-Yu I
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Gin-Wen Chang
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
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Li YM, Lee HHC, Lo YL, Chao HL. Perineal Assessment Tool (PAT-C): Validation of a Chinese Language Version and Identification of a Clinically Validated Cut Point Using ROC Curve Analysis. J Wound Ostomy Continence Nurs 2019; 46:150-153. [PMID: 30844871 DOI: 10.1097/won.0000000000000510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE The purpose of this study was to evaluate content validity and feasibility of the Chinese language perineal assessment tool (PAT-C), to assess its use in the clinical setting, and establish an optimal cut point for identifying patients at high risk for incontinence-associated dermatitis (IAD). DESIGN Psychometric evaluation of existing instrument. SUBJECTS AND SETTING The sample comprised 440 patients managed in intensive care units of 3 hospitals across the island of Taiwan and an affiliated home care service. One hundred three nurses practicing throughout Taiwan participated in the workshops in the third phase of the experiment. METHODS The content validity of the PAT-C was evaluated by 3 experienced nurses using the content validity index statistic. We calculated a receiver operating characteristics (ROC) curve to determine a cut point of high-risk IAD. The curve was based on assessment of patients from receiving care from the intensive care unit and home care service of Cathay General Hospital (located in Taipei, New Paipei and Hsinchu). Nurse perceptions on the feasibility of PAT-C were assessed using an investigator-developed survey. RESULTS Three experienced nurses rated the PAT-C and gave a robust overall content validity index score of 97.22%. The cut point for identifying patients at high risk for developing IAD via ROC curve analysis of 440 patients was 7.5 (sensitivity: 0.85; specificity: 0.79, area under curve: 0.82, P value < .001). One hundred three enrolled nurses attended the workshops and evaluated the feasibility using the PAT-C. Most of the participants considered the PAT-C as necessary (97.90%), 49.7% of participants suggested IAD risk assessment should be implemented by first-line (generalist) nurses, and 40% of participants recommended assessment on a daily basis. CONCLUSIONS Study findings indicate robust content validity, and results of the investigator survey of nurse perceptions of the PAT-C indicate the potential for its widespread use in the clinical setting. We found that a cut point score 8 or more indicates a high risk for developing IAD.
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Affiliation(s)
- Yi-Min Li
- Yi-Min Li, Cathay General Hospital, Taipei, Taiwan. Henry Hsin-Chung Lee, PhD, Hsinchu Cathay General Hospital, Hsinchu, Taiwan; Graduate Institute of Translational and Interdisciplinary Medicine, College of Health Sciences and Technology, National Central University, Taoyuan, Taiwan; and School of Medicine, Fu Jen Catholic University, New Taipei, Taiwan. Yu-Ling Lo, Cathay General Hospital, Taipei, Taiwan. Hui-Lin Chao, Cathay General Hospital, Taipei, Taiwan
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Lo YL, Ng S. T29. Radial mixed nerve conduction study: Preliminary findings in controls and patients. Clin Neurophysiol 2018. [DOI: 10.1016/j.clinph.2018.04.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Beshir SA, Aziz Z, Yap LB, Chee KH, Lo YL. Evaluation of the predictive performance of bleeding risk scores in patients with non-valvular atrial fibrillation on oral anticoagulants. J Clin Pharm Ther 2017; 43:209-219. [PMID: 29030869 DOI: 10.1111/jcpt.12634] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 09/07/2017] [Indexed: 12/11/2022]
Abstract
WHAT IS KNOWN AND OBJECTIVE Bleeding risk scores (BRSs) aid in the assessment of oral anticoagulant-related bleeding risk in patients with atrial fibrillation. Ideally, the applicability of a BRS needs to be assessed, prior to its routine use in a population other than the original derivation cohort. Therefore, we evaluated the performance of 6 established BRSs to predict major or clinically relevant bleeding (CRB) events associated with the use of oral anticoagulant (OAC) among Malaysian patients. METHODS The pharmacy supply database and the medical records of patients with non-valvular atrial fibrillation (NVAF) receiving warfarin, dabigatran or rivaroxaban at two tertiary hospitals were reviewed. Patients who experienced an OAC-associated major or CRB event within 12 months of follow-up, or who have received OAC therapy for at least 1 year, were identified. The BRSs were fitted separately into patient data. The discrimination and the calibration of these BRSs as well as the factors associated with bleeding events were then assessed. RESULTS A total of 1017 patients with at least 1-year follow-up period, or those who developed a bleeding event within 1 year of OAC use, were recruited. Of which, 23 patients experienced a first major bleeding event, whereas 76 patients, a first CRB event. Multivariate logistic regression results show that age of 75 or older, prior bleeding and male gender are associated with major bleeding events. On the other hand, prior gastrointestinal bleeding, a haematocrit value of less than 30% and renal impairment are independent predictors of CRB events. All the BRSs show a satisfactory calibration for major and CRB events. Among these BRSs, only HEMORR2 HAGES (C-statistic = 0.71, 95% CI 0.60-0.82, P < .001) and ATRIA score (C-statistic = 0.70, 95% CI 0.58-0.82, P < .001) show acceptable discrimination performance for major bleeding events. All the 6 BRSs, however, lack acceptable predictive performance for CRB events. WHAT IS NEW AND CONCLUSION To the best of our knowledge, this is the first evaluation study of the predictive performance of these 6 BRSs on clinically relevant bleeding events applied to the same cohort consisting of mainly Asian novel oral anticoagulant users. These BRSs show poor to acceptable predictive performance on OAC-induced major or CRB events. An improvement in the existing BRSs for OAC users is warranted.
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Affiliation(s)
- S A Beshir
- Department of Pharmacy, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Z Aziz
- Department of Pharmacy, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - L B Yap
- National Heart Institute, Kuala Lumpur, Malaysia
| | - K H Chee
- Department of Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Y L Lo
- Department of Pharmacy, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.,Department of Pharmacy Practice, School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
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Lo YL, Lim KH, Cheng XM, Mesenas S. Steroid Responsive Mononeuritis Multiplex in the Cronkhite-Canada Syndrome. Front Neurol 2016; 7:207. [PMID: 27899913 PMCID: PMC5110953 DOI: 10.3389/fneur.2016.00207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 11/02/2016] [Indexed: 11/13/2022] Open
Abstract
The Cronkhite-Canada syndrome (CCS) is a rare disorder of unknown origin characterized by generalized gastrointestinal polyposis, alopecia, hyperpigmentation, and onychodystrophy. We report a case of CCS with concomitant presentation of mononeuritis multiplex. The electrophysiological findings and steroid responsiveness suggests presence of an autoimmune mechanism.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Singapore; Due-NUS Medical School, Singapore
| | - K H Lim
- Department of Anatomical Pathology, Singapore General Hospital , Singapore
| | - X M Cheng
- Department of Anatomical Pathology, Singapore General Hospital , Singapore
| | - S Mesenas
- Department of Gastroenterology and Hepatology, Singapore General Hospital , Singapore
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Abstract
BACKGROUND The stiff person syndrome (SPS) is a rare disorder characterized by muscular rigidity and stiffness. CASE PRESENTATIONS We describe an SPS patient presenting with longstanding fatigue and electrophysiological evidence of presynaptic neuromuscular transmission defect, who responded to administration of pyridostigmine. In contrast, no electrophysiolgical evidence of neuromuscular transmission defect was demonstrated in 2 other SPS patients without fatigue symptoms. CONCLUSIONS Our findings suggest that glutamic acid decarboxylase (GAD) antibodies may play a role in presynaptic neuromuscular transmission defect of SPS patients with fatigue.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Outram Road, Academia Level 4, Singapore, 169608, Singapore. .,Duke-NUS Graduate Medical School, Singapore, Singapore.
| | - Y E Tan
- Department of Neurology, Singapore General Hospital, Singapore, Singapore
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Li HY, Lee LA, Yu JF, Lo YL, Chen NH, Fang TJ, Hsin LJ, Lin WN, Huang CG, Cheng WN. Changes of snoring sound after relocation pharyngoplasty for obstructive sleep apnoea: the surgery reduces mean intensity in snoring which correlates well with apnoea-hypopnoea index. Clin Otolaryngol 2016; 40:98-105. [PMID: 25311724 DOI: 10.1111/coa.12325] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/05/2014] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To investigate objective changes of snoring after surgery in patients with obstructive sleep apnoea (OSA) and correlate these with changes in the apnoea-hypopnoea index (AHI). DESIGN Prospective case series. SETTING A novel measurement, Snore Map, was used to analyse full-night snore sounds in terms of the maximal/mean intensity, peak/mean frequency, snoring index and energy type (Snore Map type, 0-4). Snore sound was classified into three bands according to frequency energy spectrum: B1 (40-300 Hz), B2 (301-850 Hz) and B3 (851-2000 Hz). PARTICIPANTS Thirty-four male and two female OSA patients (mean age, 39 years; mean AHI, 53.1/h; mean body mass index, 26.8 kg/m(2) ) with favourable anatomic structure were consecutively enrolled. MAIN OUTCOME MEASURES Parameters of polysomnographies and Snore Maps at baseline and six months after operation were compared. Statistical significance was set at P < 0.05. RESULTS Thirty-two patients completed this study. The mean reduction in the total-snoring index was insignificant but there were significant decreases in total mean intensity, total peak frequency, total mean frequency and Snore Map type after surgery. There were also significant decreases in the mean intensity in all three bands, the snoring index in B2/B3 and the mean frequency in B1 postoperatively. Changes in the total mean intensity, total mean frequency, B2 mean intensity and B3 snoring index positively correlated with change in the AHI. CONCLUSIONS Relocation pharyngoplasty significantly decreases both the snoring sound intensity and snoring frequency. These reductions are directly proportional to the improvement of OSA.
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Affiliation(s)
- H Y Li
- Department of Otolaryngology, Sleep Center, Linkou Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan; Department of Sleep Medicine, Royal Infirmary Edinburgh, Edinburgh, UK
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Abstract
Myasthenia gravis is the most common chronic autoimmune neuromuscular disease. Anti-acetylcholine receptor (AChR) antibodies are found in at least 80% of patients with generalized myasthenia and have been implicated in disease pathogenesis. Thymic abnormalities are frequently found in seropositive patients, and the thymus is thought to be involved in generation of autoimmunity. This article reviews existing literature on the role of AChR antibodies in the pathogenesis of myasthenia gravis, and the correlation between AChR antibody titers and thymic pathology. Most studies found that highest titers are seen in thymic hyperplasia, followed by intermediate titers in thymoma, and lowest titers in atrophic or normal thymus. One publication found no difference between titers in thymoma and normal thymus.
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Affiliation(s)
- G Z Huang
- Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore
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Yip CW, Cheong PWT, Green A, Prakash PK, Fook-Cheong SK, Tan EK, Lo YL. A prospective pilot study of repetitive transcranial magnetic stimulation for gait dysfunction in vascular parkinsonism. Clin Neurol Neurosurg 2012; 115:887-91. [PMID: 22980521 DOI: 10.1016/j.clineuro.2012.08.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 07/18/2012] [Accepted: 08/20/2012] [Indexed: 10/27/2022]
Abstract
OBJECTIVE Vascular Parkinsonism (VP) causes significant gait dysfunction in patients who otherwise have good lower limb strength. Its pathophysiology is not clearly understood, and current treatment with physical therapy remains unsatisfactory. The study explores repetitive transcranial magnetic stimulation (rTMS) as a potential new and safe therapy for VP. MATERIALS AND METHODS We prospectively applied 5 Hz rTMS treatment to 5 patients who satisfied all the criteria for VP. Repetitive TMS was performed on 5 consecutive days and patients were assessed on (1) timed 10 m walk (T10MW), (2) Unified Parkinson's Disease Rating Scale (UPDRS) motor subsection, (3) Clinician's Global Impression of Change (CGIC), and (4) Patient's Global Impression of Change (PGIC), for up to 6 weeks post-rTMS. RESULTS All the outcome measures were found to have improved ratings post-rTMS when compared with baseline, and were statistically significant. The T10MW showed significant improvement at 4 weeks post-rTMS with a trend towards improvement at 2 weeks post-rTMS. The UPDRS motor subscores was significantly reduced at 2 weeks, 4 weeks and 6 weeks post-rTMS. The PGIC and CGIC scores were significantly better post-rTMS. The treatment was well-tolerated and all patients completed the study. CONCLUSION This study demonstrated for the first time that 5 sessions of rTMS could improve gait in a measurable way for up to 6 weeks without any significant side-effects. Repetitive TMS could be a potentially useful adjunct in rehabilitation of VP patients and further research is warranted.
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Affiliation(s)
- C W Yip
- National Neuroscience Institute, Singapore General Hospital Campus, Singapore.
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Chen KR, Chu WH, Fang HC, Liu CP, Huang CH, Chui HC, Chuang CH, Lo YL, Lin CY, Hwung HH, Fuh AYG. Beyond-limit light focusing in the intermediate zone. Opt Lett 2011; 36:4497-4499. [PMID: 22139221 DOI: 10.1364/ol.36.004497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We experimentally verify that a new nanolens of a designed plasmonic aperture can focus visible light to a single line with its width smaller than the limit of half the wavelength in the intermediate zone. The experimental measurement indicates that while the near field plays a role to increase the spot size in the near zone, it is negligible at the beyond-limit focused region; i.e., the focused light is dominated by the radiative fields. The image taken by the optical microscope shows that the fields focused have propagated to the far zone. Besides being of academic interest, the nanolens capable in achieving a lower diffraction limit in the intermediate zone is important for application possibilities.
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Affiliation(s)
- K R Chen
- Department of Physics, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan.
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Abstract
BACKGROUND Concurrence of migraine and hallucinations is extremely rare and the underlying mechanism is poorly understood. METHODS We report a 22-year-old man with migraine associated with auditory hallucinations. Concurrent psychotic illness has been excluded. RESULTS Brain MR scans showed a stable, patchy FLAIR hyperintensity over the posterolateral aspect of the left cerebral peduncle, just below the level of the red nucleus. This was felt to represent an area of gliosis based on the interval stability over 19 months. There was absence of features for aggressive neoplasms, such as lesional high cellular turnover (choline/NAA ratio >1.0) or high cerebral blood volume on advanced MR imaging with MR spectroscopy and dynamic perfusion MR. EEG and brainstem auditory evoked potentials were unremarkable. CONCLUSIONS To our knowledge, there are no reports to date on similar auditory hallucinations in adult migraine patients, as well as with associated MRI brainstem lesions. The peduncular lesion could represent a previous migrainous infarct, and a possible analogy can be drawn from the descriptions of peduncular hallucinosis. Brainstem lesions, particularly in the midbrain and pons, have rarely been associated with this condition. It has been postulated that the damage to ascending reticular systems or thalamocortical circuitry may contribute to its pathogenesis.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Outram Road, Singapore.
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Lo YL, Cui SL, Lum SY, Chong SF, Siow HC. A study of acupuncture in Asian patients: clinical aspects and effects on cortical excitability. Acupunct Med 2010; 28:74-7. [PMID: 20615860 DOI: 10.1136/aim.2009.002055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To determine the effect of acupuncture on the phosphene threshold, by transcranial magnetic stimulation (TMS), and the clinical effect of acupuncture on headache frequency, duration and severity. METHODS Twenty-one patients (16 women; mean age 46 years; range 23-61 years, 17 Chinese, 2 Malays, 2 Indians) underwent 10 acupuncture sessions scheduled twice a week for 5 weeks. The lowest TMS intensity to elicit phosphene perception is defined as the phosphene threshold. TMS was performed before the first and last sessions, and at 2 months' follow-up. RESULTS Acupuncture resulted in reduction of headache frequency, duration and severity over the course of treatment. However, this was not accompanied by a corresponding increase in the phosphene threshold over a similar time course. The baseline threshold before acupuncture treatment had no predictive value for outcome of treatment. CONCLUSIONS Although acupuncture was effective in treating migraine, the use of occipital cortex excitability as an adjunctive parameter to evaluate treatment response was not suitable. The relief of migraine with acupuncture may be related to separate neural pathways independent of occipital or visual processes in the human brain.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Singapore 169608, Singapore.
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Lo YL, Lum SY, Fook-Chong S, Siow HC. A pilot study of topiramate dosages for migraine prophylaxis in an Asian population. J Headache Pain 2010; 11:175-8. [PMID: 20143246 PMCID: PMC3452284 DOI: 10.1007/s10194-010-0193-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Accepted: 01/18/2010] [Indexed: 11/29/2022] Open
Abstract
Topiramate is known to be efficacious in migraine prophylaxis, but its optimal dose has not been systematically studied in the Asian population. Here, we show that a fixed low dose of topiramate 25 mg/day is efficacious in migraine prophylaxis and also attest to advantages in terms of medication cost savings and more favourable side effect profile.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Outram Road, Singapore, Singapore.
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Abstract
INTRODUCTION Bell's palsy is a commonly encountered paralysis of the facial nerve occurring worldwide. Prognosis for Bell's palsy is good, but the proportion of patients with poor outcomes may reach 30%. Ultrasound (US) may provide a novel approach for evaluating and prognosticating Bell's palsy, in comparison with known electrophysiological techniques. METHODS In this study, we measured the diameter of the distal facial (VII) nerve using US in patients with Bell's palsy treated with prednisolone, in comparison with healthy controls. Blink reflex and VII nerve conduction studies were also performed. Studies were prospective and performed within 1 week of disease onset. RESULTS Our results have shown that diameter of the distal VII nerve is a good predictor of favorable (positive predictive value: 100%) and bad outcomes (negative predictive value: 77%) in Bell's palsy at 3 months after clinical presentation. Furthermore, we also noted the lack of correlation of VII diameter with conventional VII nerve conduction studies (NCS) and blink reflex studies. US was superior to VII nerve conduction and blink reflex studies in outcome prediction. CONCLUSIONS This first study utilizing US in Bell's palsy highlights its role in outcome prediction and contributes to our understanding of recovery processes in this common neurological disorder.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Singapore.
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Lo YL, Fook-Chong S, Chan LL, Ong WY, Ratnagopal P. Electrophysiological evidence of cerebellar fiber system involvement in the Miller Fisher syndrome. J Neurol Sci 2009; 288:49-53. [PMID: 19863971 DOI: 10.1016/j.jns.2009.10.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Revised: 09/30/2009] [Accepted: 10/07/2009] [Indexed: 11/18/2022]
Abstract
BACKGROUND In the Miller Fisher syndrome (MFS), ataxia may be due involvement of Ia afferents and the cerebellum. Transcranial magnetic stimulation (TMS) over the cerebellum is known to interfere transiently with normal function. METHODS In this study, we utilized a previously described TMS protocol over the cerebellum in combination with ballistic movements to investigate cerebellar dysfunction in MFS patients. RESULTS The agonist (biceps) reaction time in MFS patients during a motor cancellation task was not significantly reduced during the initial TMS study. However, during the repeat TMS study, significant reduction was seen for all patients, in tandem with clinical recovery. There was significant correlation between anti-GQ1b IgG titers and change in agonist reaction time between the initial and repeat TMS studies. CONCLUSIONS TMS likely affected horizontally orientated parallel fibers in the cerebellar molecular layer. During disease onset, antibody binding may have interfered with facilitation of reaction time during motor cancellation tasks seen in normal subjects. Normalization of reaction time facilitation corresponded to resolution of antibody-mediated interference in the molecular layer. Our study has provided evidence suggesting parallel fiber involvement in MFS, and suggested a role of anti-GQ1b IgG antibody in these changes.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Singapore.
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Abstract
Acute gastroenteritis (AGE) is a common illness among infants and children contributing to significant mortality and morbidity. As such, appropriate treatment received prior to hospital admission is of utmost importance. This retrospective observational study aimed to determine preadmission management in paediatric patients prior to hospital admission. Two hundred and twenty-two case notes of paediatric AGE patients were reviewed over a 12-month period. One hundred and fifty-four patients received medications prior to admission with 143 (92.9%) patients received known classes of medications. Antipyretic agents were the most commonly prescribed (69.2%), followed by antibiotics (38.5%), anti-emetics (35.7%), oral rehydration salts (29.4%) and antidiarrhoeals (28.0%). The mean duration of stay in hospital was slightly shorter in patients, who received prior medications than those who did not (2.22 vs. 2.32 days respectively). Seventy per cent of children admitted for AGE were treated suboptimally prior to hospital admission with oral rehydration salts being largely under-utilized, despite their proven efficacy and safety. Sex, race and age had no influence on the type of preadmission treatment. A greater effort should be made to educate the general public in the appropriate treatment of AGE.
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Affiliation(s)
- Y J Ng
- Department of Pharmacy, Faculty of Medicine, University of Malaysia, Kuala Lumpur, Malaysia
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Abstract
Cervical spondylosis occurs universally, with cervical spondylotic myelopathy (CSM) as its most serious consequence. The electrical property of the spinal cord and its susceptibility to injury renders electrophysiology relevant to the management of CSM, as addressed in this review. Somatosensory-evoked potentials evaluate spinal cord integrity with regards to posterior column functions exclusively. Although motor-evoked potentials may be more sensitive than the former and may be utilized intraoperatively, they are susceptible to interference by inhalational anaesthetics. Electromyography may play a role in minimizing C5 root damage and spinal cord-evoked potentials can localize spinal conduction block during CSM surgery. Critically reviewing the available evidence, electrophysiology cannot be universally recommended as mandatory in the management of CSM at present. It may, however, play emergent, isolated roles in the diagnosis, follow-up and treatment of this common disorder.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Singapore.
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Abstract
A low arousal threshold is believed to predispose to breathing instability during sleep. The present authors hypothesised that trazodone, a nonmyorelaxant sleep-promoting agent, would increase the effort-related arousal threshold in obstructive sleep apnoea (OSA) patients. In total, nine OSA patients, mean+/-sd age 49+/-9 yrs, apnoea/hypopnoea index 52+/-32 events.h(-1), were studied on 2 nights, one with trazodone at 100 mg and one with a placebo, in a double blind randomised fashion. While receiving continuous positive airway pressure (CPAP), repeated arousals were induced: 1) by increasing inspired CO(2) and 2) by stepwise decreases in CPAP level. Respiratory effort was measured with an oesophageal balloon. End-tidal CO(2 )tension (P(ET,CO(2))) was monitored with a nasal catheter. During trazodone nights, compared with placebo nights, the arousals occurred at a higher P(ET,CO(2)) level (mean+/-sd 7.30+/-0.57 versus 6.62+/-0.64 kPa (54.9+/-4.3 versus 49.8+/-4.8 mmHg), respectively). When arousals were triggered by increasing inspired CO(2) level, the maximal oesophageal pressure swing was greater (19.4+/-4.0 versus 13.1+/-4.9 cm H(2)O) and the oesophageal pressure nadir before the arousals was lower (-5.1+/-4.7 versus -0.38+/-4.2 cm H(2)O) with trazodone. When arousals were induced by stepwise CPAP drops, the maximal oesophageal pressure swings before the arousals did not differ. Trazodone at 100 mg increased the effort-related arousal threshold in response to hypercapnia in obstructive sleep apnoea patients and allowed them to tolerate higher CO(2) levels.
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Affiliation(s)
- R C Heinzer
- Sleep Medicine Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
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Abstract
The Miller Fisher syndrome (MFS), characterized by ataxia, areflexia, and ophthalmoplegia, was first recognized as a distinct clinical entity in 1956. MFS is mostly an acute, self-limiting condition, but there is anecdotal evidence of benefit with immunotherapy. Pathological data remain scarce. MFS can be associated with infectious, autoimmune, and neoplastic disorders. Radiological findings have suggested both central and peripheral involvement. The anti-GQ1b IgG antibody titer is most commonly elevated in MFS, but may also be increased in Guillain-Barré syndrome (GBS) and Bickerstaff's brainstem encephalitis (BBE). Molecular mimicry, particularly in relation to antecedent Campylobacter jejuni and Hemophilus influenzae infections, is likely the predominant pathogenic mechanism, but the roles of other biological factors remain to be established. Recent studies have demonstrated the presence of neuromuscular transmission defects in association with anti-GQ1b IgG antibody, both in vitro and in vivo. Collective findings from clinical, radiological, immunological, and electrophysiological techniques have helped to define MFS, GBS, and BBE as major disorders within the proposed spectrum of anti-GQ1b IgG antibody syndrome.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Outram Road, 169608 Singapore.
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Lo YL, Fook-Chong S, Leoh TH, Dan YF, Tan YE, Lau WH, Chan LL. High-resolution ultrasound as a diagnostic adjunct in common peroneal neuropathy. ACTA ACUST UNITED AC 2008; 64:1798-800. [PMID: 18071050 DOI: 10.1001/archneur.64.12.1798] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Lo YL, Lum SY, Fook-Chong S, Cui SL, Siow HC. Clinical correlates of phosphene perception in migraine without aura: An Asian study. J Neurol Sci 2008; 264:93-6. [PMID: 17720202 DOI: 10.1016/j.jns.2007.07.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Revised: 07/25/2007] [Accepted: 07/26/2007] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Although controversy exists with regard to the presence of hypoexcitability versus hyperexcitability of the visual cortex in migraine patients, there remain a group who do not perceive phosphenes (P-). However, its clinical implications have not been systematically addressed. In this study, we hypothesize that P- patients classified as migraine without aura (MO) have distinct clinical features. METHODS Twenty-nine Asian MO patients (7 men; mean age: 44; median: 45; range: 25 to 65) were consecutively entered into the study. Visual cortex transcranial magnetic stimulation (TMS) was performed in the migraine interictum. RESULTS Of the 19 patients, 19 (66%) were able to perceive phosphenes (P+), while 10 (34%) were not able to after repeated TMS (P-). P- patients had significantly higher headache frequency (p=0.008) and pain score (p=0.002) compared with P+ patients. In addition, there was significant positive correlation of phosphene threshold with pain score (r=0.52, p=0.02) in P+ patients. There was no significant difference between P+ and P- patients in terms of age (t-test, p=0.6). CONCLUSIONS Our study is inkeeping with the hypothesis that interictal visual cortex excitability is reduced in relation to the severity of migraine in Asian MO patients, and lack of phosphene perception may be related to significantly elevated thresholds beyond the output of TMS stimulators.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Outram Road, Singapore 169608, Singapore.
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Lo YL, Chuang CH. Analytical analysis of modulated signal in apertureless scanning near-field optical microscopy. Opt Express 2007; 15:15782-15796. [PMID: 19550863 DOI: 10.1364/oe.15.015782] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Eliminating background-scattering effects from the detected signal is crucial in improving the performance of super-high-resolution apertureless scanning near-field optical microscopy (A-SNOM). Using a simple mathematical model of the A-SNOM detected signal, this study explores the respective effects of the phase modulation depth, the wavelength and angle of the incident light, and the amplitude of the tip vibration on the signal contrast and signal intensity. In general, the results show that the background-noise decays as the order of the Bessel function increases and that higher-order harmonic frequencies yield an improved signal contrast. Additionally, it is found that incident light with a longer wavelength improves the signal contrast for a constant order of modulation frequency. The signal contrast can also be improved by reducing the incident angle of the incident light. Finally, it is demonstrated that sample stage scanning yields an improved imaging result. However, tip scanning provides a reasonable low-cost and faster solution in the smaller scan area. The analytical results presented in this study enable a better understanding of the complex detected signal in A-SNOM and provide insights into methods of improving the signal contrast of the A-SNOM measurement.
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Lo YL, Dan YF, Teo A, Tan YE, Yue WM, Raman S, Tan SB. The value of bilateral ipsilateral and contralateral motor evoked potential monitoring in scoliosis surgery. Eur Spine J 2007; 17 Suppl 2:S236-8. [PMID: 17874145 PMCID: PMC2525889 DOI: 10.1007/s00586-007-0498-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Accepted: 08/28/2007] [Indexed: 10/22/2022]
Abstract
Intraoperative monitoring (IOM) of the motor pathways is a routine procedure for ensuring integrity of corticospinal tracts during scoliosis surgery. We have previously demonstrated presence of ipsilateral motor evoked potentials (MEPs) during IOM for scoliosis surgery, but its significance was uncertain. In this case series, we show concurrent ipsilateral and contralateral MEP amplitude changes obtained with cortical stimulation are of value in reducing false positive observations during IOM. The use of this easily recordable MEP is thus advocated as a diagnostic adjunct to contralateral MEPs for scoliosis and spinal surgery.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Outram Road, Singapore, Singapore 169608.
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Cheng CC, Lo YL, Li WY, Kuo CT, Cheng HC. Estimations of fiber Bragg grating parameters and strain gauge factor using optical spectrum and strain distribution information. Appl Opt 2007; 46:4555-62. [PMID: 17609700 DOI: 10.1364/ao.46.004555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
An inverse approach based on an optimization technique is proposed to characterize a fiber Bragg grating (FBG) and the strain gauge factor (GF) when the FBG is bonded on a structure. By bonding an FBG on a substrate and simply straining this FBG into a chirped fiber Bragg grating with a predesignated strain, the proposed method, based on an optimization technique, can be used to reconstruct seven parameters of the FBG from the corresponding reflective spectrum. The parameters identified are the length of an FBG, the grating period, the average refractive index, the index modulation, the apodization coefficient, the starting point bonded on the plate, and the strain GF. The information from the predesignated strain, as well as the measured reflective spectrum, is used as the objective function during the optimal search. As a result, the design sensitivity for the optimal search is much improved compared with the design sensitivity when only the reflective spectrum is used. In particular, the strain GF, which depends on the adhesive, the bonding layer characteristics, etc., can be determined in order to provide a reference for an FBG used as a strain sensor. Results from numerical simulations and experiments show that seven parameters of an FBG can be obtained accurately and efficiently.
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Affiliation(s)
- C C Cheng
- Department of Mechanical Engineering, National Chung Cheng University, Chia-Yi, Taiwan.
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Lo YL, Ratnagopal P. Cortico-hypoglossal and corticospinal conduction abnormality in Bickerstaff's brainstem encephalitis. Clin Neurol Neurosurg 2007; 109:523-5. [PMID: 17482346 DOI: 10.1016/j.clineuro.2007.03.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2006] [Revised: 03/13/2007] [Accepted: 03/14/2007] [Indexed: 10/23/2022]
Abstract
The Miller Fisher syndrome, Guillain-Barre syndrome and Bickerstaff's brainstem encephalitis are related conditions in which anti-GQ1b antibody positivity occur in varied frequencies. This report demonstrates the presence of corticobulbar and corticospinal dysfunction in BBE, by means of a novel transcranial magnetic stimulation technique. It further supports the presence of protean manifestations in anti-GQ1b IgG antibody-positive spectrum of disorders.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Singapore
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Lo YL, Fook-Chong S. Intersensory facilitation in rapid single-joint voluntary activation and cancellation of arm movements. Int J Neurosci 2007; 117:823-35. [PMID: 17454246 DOI: 10.1080/00207450600910648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The ability to initiate and cancel actions is a basic requirement for motor control in humans. Rapid movements to stationary targets over single joints are characterized by triphasic bursts of electromyographic (EMG) activity. While analysis of reaction time in motor activation tasks, in relation to different modalities of sensory inputs, has studied, its diametrically opposite task of motor cancellation has not been adequately addressed. We studied 9 normal right-handed subjects using biceps (agonist) and triceps (antagonist) EMG recordings. Each underwent 3 motor activation and 3 motor cancellation tasks to light, sound and dual stimuli (6 blocks). The former consisted of ballistic elbow flexion over 45 degrees, while the latter involved dropping of the forearm from a 45-degree elbow flexion angle. For motor activation, onset latencies and duration of agonist (Lat1, Dur1) and antagonist (Lat2, Dur2) muscles were recorded. For motor cancellation, onset latencies and duration of agonist (Lat1 only) and antagonist (Lat2, Dur2) were noted. Motor cancellation showed significantly shorter Dur2 EMG bursts (p < .0005) for all 3 stimuli conditions. Lat1 and Lat2 demonstrated significant correlation (p < 0.0005 for all), with the exception of dual stimulus condition during motor cancellation (p = 0.089). While dual stimulus during motor cancellation resulted in significantly shorter Lat2 (p = .013) in comparison with light and sound stimuli, this was not evident for motor activation tasks. The findings suggest that while a common central program exists for executing motor activation and cancellation, generation of antagonist activity in the latter may involve distinct neural pathways specifically robust to the effects of intersensory facilitation. This is discussed in relation to reciprocal motor oscillatory activity manifestations at the level of single joint movements.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Outram Road, Singapore, 169608, Singapore.
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Prakash KM, Ratnagopal P, Puvanendran K, Lo YL. Mycophenolate mofetil – as an adjunctive immunosuppressive therapy in refractory myasthenia gravis: The Singapore experience. J Clin Neurosci 2007; 14:278-81. [PMID: 16597503 DOI: 10.1016/j.jocn.2005.12.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2005] [Revised: 12/03/2005] [Accepted: 12/08/2005] [Indexed: 11/16/2022]
Abstract
We report our experience, using mycophenolate mofetil (MyM) as an adjunctive immunosuppressive therapy in patients with severe, refractory and high dose steroid-dependent myasthenia gravis (MG). Five patients were commenced on MyM in addition to other immunosuppressive therapies. All had significant clinical improvement and no subsequent myasthenic crisis requiring intensive care unit admission. MyM was well tolerated and no serious adverse effects were observed. MyM is an effective adjunctive therapy for the treatment of severe, refractory and steroid-dependent MG in our experience.
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Affiliation(s)
- K M Prakash
- National Neuroscience Institute (SGH campus), Department of Neurology, Block 6 Level 8, Singapore General Hospital, Outram Road, Singapore 169608.
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Lo YL, Tan YE, Dan YF, Leoh TH, Tan SB, Tan CT, Chan LL. Cutaneous silent periods in the evaluation of cord compression in cervical spondylosis. J Neurol 2007; 254:14-9. [PMID: 17508136 DOI: 10.1007/s00415-007-0142-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2006] [Accepted: 11/30/2006] [Indexed: 10/23/2022]
Abstract
OBJECTIVE The clinical diagnosis of cervical spondylotic myelopathy (CSM) may be challenging in patients with cervical spondylosis (CS). Routine nerve conduction studies (NCS) may not evaluate cord compression adequately. METHODS We obtained cutaneous silent periods (CSP) in 26 consecutive patients presenting with clinical features of CS, in comparison with 30 normal controls. The results were also compared with transcranial magnetic stimulation (TMS) findings, and magnetic resonance imaging of the cervical cord as the gold standard. RESULTS CSP findings showed similarly high sensitivity of up to 96% with TMS in evaluating cervical cord dysfunction. CONCLUSION In specific clinical settings, CSP is of value for the diagnosis of CSM in CS. CSP measurement is advocated as a simple and rapid diagnostic adjunct to NCS in evaluating CS patients with possible cord compromise.
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Affiliation(s)
- Y L Lo
- Dept. of Neurology, National Neuroscience Institute, Singapore General Hospital, Outram Road, Singapore, 169608, Singapore.
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Abstract
We present a digital programmable light spectrum synthesis system based on a digital micromirror device (DMD) from Texas Instruments. A DMD pattern-scanning calibration method is developed and applied to the synthesis of various infrared C-band (1530-1565 nm) spectral profiles, including a fast programmable tunable light source with a bandwidth of approximately 3.8 nm, a square profile, a sawtooth waveform, and a triangular spectrum profile. The experimental results show that the wavelength resolution of the DMD spectrum synthesis system is approximately 0.076 nm/pixel. The proposed spectrum synthesis system has a number of key advantages, including a rapid and stable performance and multichannel compatibility. The spectrum synthesis system is suitable for various applications, including pulse shaping for coherent control and harmonic generation, a tunable light source, an equalizer for erbium-doped fiber amplifiers, and a wavelength scanner.
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Affiliation(s)
- C H Chuang
- National Cheng Kung University, Tainan, Taiwan
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Lo YL, Dan YF, Tan YE, Fook-Chong S, Tan SB, Tan CT, Raman S. Intraoperative monitoring study of ipsilateral motor evoked potentials in scoliosis surgery. Eur Spine J 2006; 15 Suppl 5:656-60. [PMID: 16858594 PMCID: PMC1602201 DOI: 10.1007/s00586-006-0190-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Revised: 06/15/2006] [Accepted: 07/02/2006] [Indexed: 12/02/2022]
Abstract
Ipsilateral motor evoked potentials (MEPs) in spinal cord surgery intraoperative monitoring is not well studied. We show that ipsilateral MEPs have significantly larger amplitudes and were elicited with lower stimulation intensities than contralateral MEPs. The possible underlying mechanisms are discussed based on current knowledge of corticospinal pathways. Ipsilateral MEPs may provide additional information on the integrity of descending motor tracts during spinal surgery monitoring.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Singapore, Singapore.
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Abstract
Electrophysiological evaluation of motor pathways to the lingual muscles is technically challenging. Previous studies utilizing transcranial magnetic stimulation (TMS) of the parieto-occipital region with a round coil reported difficulties in eliciting tongue motor responses. In this study, we utilized TMS with a double cone coil at the posterior head region to obtain tongue motor evoked potentials. Our findings suggest activation at or distal to the hypoglossal nuclear level, but proximal to the hypoglossal canal region. Our method can be usefully applied in future studies of brainstem and cranial nerve function.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore.
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Lo YL, Xu LQ, Leoh TH, Dan YF, Tan YE, Nurjannah S, Ratnagopal P. Superficial peroneal sensory and sural nerve conduction studies in peripheral neuropathy. J Clin Neurosci 2006; 13:547-9. [PMID: 16678425 DOI: 10.1016/j.jocn.2005.07.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2005] [Accepted: 07/14/2005] [Indexed: 11/19/2022]
Abstract
The objective of this study was to prospectively evaluate sensory nerve conduction studies (NCS) in the distal lower limbs in the electrodiagnosis of peripheral neuropathy. We prospectively studied 316 consecutive patients with surface stimulation and recording, in comparison with 90 control subjects. A total of 310 patients were found to have lower limb sensory NCS abnormalities. In these patients, the rate of detection of peripheral neuropathy with superficial peroneal NCS (88.5%) was significantly higher (P<0.001) compared with sural NCS (75%). The superficial peroneal NCS appeared to have a higher detection rate for peripheral neuropathy in our study, and its study can be adjunctive to sural NCS.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Outram Road, Singapore 169608, Singapore.
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Lo YL, Chan LL, Lim W, Tan SB, Tan CT, Chen JLT, Fook-Chong S, Ratnagopal P. Transcranial magnetic stimulation screening for cord compression in cervical spondylosis. J Neurol Sci 2006; 244:17-21. [PMID: 16478626 DOI: 10.1016/j.jns.2005.12.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2005] [Revised: 10/28/2005] [Accepted: 12/12/2005] [Indexed: 10/25/2022]
Abstract
OBJECTIVE Cervical spondylosis (CS) often results in various degrees of cord compression, which can be evaluated functionally with transcranial magnetic stimulation (TMS). We investigate the use of TMS as a screening tool for myelopathy in CS. METHODS We prospectively studied 231 patients classified into Groups 1 to 4 based on MRI grading of severity of cord compromise. TMS elicited central motor conduction times and motor evoked potential (MEP) amplitudes in all 4 limbs. The results were compared with those from 45 healthy controls. RESULTS TMS showed 98% sensitivity and 98% specificity for cord abnormality using MRI as reference standard. CONCLUSIONS MEP abnormalities are useful for electrophysiological evaluation of cord compression in CS. While TMS is not a substitute for MRI, it is of value as a rapid, inexpensive and non-invasive technique for screening patients before MRI studies.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Singapore 169608, Singapore.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Singapore.
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Abstract
In a patient-controlled study, the authors demonstrated a significantly higher prevalence of rostral ventrolateral medulla (VLM) compression in hypertensive patients with hemifacial spasm (HFS) compared with age-, sex-, race-, disease duration-, and disease severity-matched normotensive patients with HFS (p = 0.02). Hypertensive HFS patients were more likely to have a greater severity of neurovascular compression at the VLM compared with normotensive HFS patients (p = 0.008). VLM compression is associated with risk of hypertension in this study population.
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Affiliation(s)
- L L Chan
- Department of Diagnostic Radiology, Singapore General Hospital, Republic of Singapore
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Lo YL, Chan LL, Tan CT, Chen JLT, Tan SB. Pectoralis major motor evoked potentials in cervical spondylosis. J Neurol Sci 2005; 235:55-9. [PMID: 15939436 DOI: 10.1016/j.jns.2005.04.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2005] [Revised: 03/09/2005] [Accepted: 04/04/2005] [Indexed: 10/25/2022]
Abstract
Myelopathy is a severe complication of cervical spondylosis (CS). We studied 27 consecutive patients with CS referred for evaluation for possible myelopathy using transcranial magnetic stimulation. The findings were compared with those from 20 normal controls. Magnetic resonance imaging was utilized to assess the degree of cord compromise. Central motor conduction time (CMCT) abnormalities showed equivalent diagnostic yield with pectoralis major (PM) recordings, as compared with combined first dorsal interossei and abductor hallucis recordings. Our findings show that CMCT measurement with PM recordings is of value as a diagnostic adjunct in the electrophysiological evaluation of myelopathy in CS.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Singapore.
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Lo YL, Leong HN, Hsu LY, Tan TT, Kurup A, Fook-Chong S, Tan BH. Autonomic dysfunction in recovered severe acute respiratory syndrome patients. Can J Neurol Sci 2005; 32:264. [PMID: 16018168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
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Cheng YW, Kang JJ, Shih YL, Lo YL, Wang CF. Cholesterol-3-beta, 5-alpha, 6-beta-triol induced genotoxicity through reactive oxygen species formation. Food Chem Toxicol 2005; 43:617-22. [PMID: 15721210 DOI: 10.1016/j.fct.2005.01.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2004] [Revised: 01/04/2005] [Accepted: 01/09/2005] [Indexed: 12/20/2022]
Abstract
The mutagenicity of oxysterols, cholesterol-3beta,5alpha,6beta-triol (alpha-Triol), 7-keto-cholesterol (7-Keto) and cholesterol-5alpha,6alpha-epoxide (alpha-Epox) were examined by the Ames method and chromosome aberration test in this study. Only alpha-Triol concentration-dependently caused an increase of bacterial revertants in the absence of metabolic activating enzymes (S9), but not 7-keto and alpha-Epox. The mutagenic effect of alpha-Triol was reduced by the addition of S9. On the other hand, although alpha-Triol significantly induced chromosome aberration in CHO-K1 cells with and without S9. However, the addition of S9 reduced the degree of abnormal structure chromosome compared to without S9 mix. Catalase and superoxide dismutase (SOD) inhibited alpha-Triol induced increase of revertants in Salmonella typhimurium and chromosome aberration frequency in CHO cells, suggesting that reactive oxygen species (ROS) might be involved in the genotoxic effect of alpha-Triol. Treatment with alpha-Triol increased the ROS production in CHO cells, which could be attenuated by catalase and SOD. Results in this study suggested, for the first time that alpha-Triol, causes genotoxic effect in an ROS-dependent manner.
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Affiliation(s)
- Y W Cheng
- School of Pharmacy, Taipei Medical University, No. 250, Wu-Shing Street, Taipei 101, Taiwan.
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Lo YL, Fook-Chong S. A transcranial magnetic stimulation study of the ipsilateral silent period in lower limb muscles. Neurosci Lett 2005; 368:337-40. [PMID: 15364423 DOI: 10.1016/j.neulet.2004.07.080] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2004] [Revised: 07/13/2004] [Accepted: 07/26/2004] [Indexed: 11/28/2022]
Abstract
The lower limb ipsilateral silent periods (ISP) were determined with transcranial magnetic stimulation in 30 normal subjects using a round coil. The mean duration and transcallosal conduction time were comparable to values obtained from upper limb recordings. No age-related correlation was found for either parameter, corroborating previous imaging and pathological studies of interhemispheric pathways. Our results highlight the feasibilty of eliciting ISPs in the lower limbs, relevant for future studies of interhemispheric interaction in clinical and research settings.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Outram Road, Singapore 169608, Singapore.
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Lo YL, Leoh TH, Xu LQ, Nurjannah S, Dan YF. Short-segment nerve conduction studies in the localization of ulnar neuropathy of the elbow: Use of flexor carpi ulnaris recordings. Muscle Nerve 2005; 31:633-6. [PMID: 15645413 DOI: 10.1002/mus.20250] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Short-segment nerve conduction studies were performed in 17 limbs with clinical features suggestive of ulnar neuropathy at the elbow. Recording from flexor carpi ulnaris yielded 93% sensitivity, compared with 71.4% when recording from abductor digiti minimi. The rationale underlying the technique is discussed. This approach should be of value as a diagnostic adjunct in technically challenging cases of ulnar neuropathy at the elbow.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Outram Road, 169608, Singapore.
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Abstract
Chemical and biological agents have been used as weapons of mass destruction for a long time and presents as a serious threat to mankind. They have been used in many great wars and terrorist attacks with devastating results. The knowledge about these weapons of mass destruction is crucial to health care providers. Early recognition of the clinical characteristics of poisoning as a result of these chemical and biological agents is important to initiate appropriate therapy and minimizing casualties. Neurophysiological investigations when integrated with clinical features are helpful in early identification of some of these agents, especially when serological confirmation is not rapidly available. In this review, we have focused on chemical and biological weapons, which affect the nervous system and the role of clinical neurophysiology in such conditions.
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Affiliation(s)
- K M Prakash
- National Neuroscience Institute, Singapore General Hospital Campus, Singapore.
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Abstract
A 31-year old man sustained severe left brachial plexus traction injury. Electrical stimulation demonstrated multilevel motor root conduction block, which reversed after a 4-month period. Motor root conduction studies are useful diagnostic and prognostic adjuncts in the management of brachial plexopathy.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Outram Road, Singapore 169608, Singapore.
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Abstract
Carpal tunnel syndrome (CTS) is a nerve entrapment disorder, involving the median nerve when it passes the carpal tunnel at the wrist. Using a case-control methodology, 312 electrophysiologically confirmed CTS patients with mean age of 51.3+/-9.4 (27-74) years (81.7% women) and 100 controls with mean age of 50.4+/-9.2 (21-88) years (75% women) were examined utilising a questionnaire similar to the clinical diagnostic criteria of restless legs syndrome (RLS). Forty-four (14.1%) of the CTS patients have symptoms compatible with restless hand syndrome compared with none (0%) in the control group (p < 0.0001). The severity of CTS was not significantly associated with the motor restlessness. Our observations suggest that entrapment syndromes such as CTS can be associated with a form of restlessness in the hands, analogous to RLS.
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Affiliation(s)
- E K Tan
- Department of Neurology, Singapore General Hospital, Singapore.
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Lo YL, Chan LL, Tan SH, Tan CT. Overriding fifth finger: an unusual sign in lower brachial plexopathy. J Clin Neurosci 2004; 11:902-4. [PMID: 15519873 DOI: 10.1016/j.jocn.2004.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2003] [Accepted: 02/03/2004] [Indexed: 10/26/2022]
Abstract
Hand deformities are often useful clinical signs. To our knowledge, they have not been described in association with brachial plexus lesions. A 28-year-old female presented with sudden left shoulder pain and medial forearm parasthesia. Examination showed the left fifth finger adducting and flexing over the dorsal aspect of the fourth finger. Neurophysiological studies and MRI supported a brachial plexus lesion. The physical sign was not present 5 months post onset and the patient experienced near complete clinical improvement. The unusual physical sign occurred in association with neuralgic amyotrophy. Its occurrence can be explained in terms of transient patchy involvement of nerve fascicles in the brachial plexus.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Outram Road, Singapore 169608, Singapore.
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Lo YL, Fook-Chong S. Ipsilateral and contralateral motor inhibitory control in musical and vocalization tasks. Exp Brain Res 2004; 159:258-62. [PMID: 15452675 DOI: 10.1007/s00221-004-2032-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2004] [Accepted: 05/21/2004] [Indexed: 11/26/2022]
Abstract
The inhibitory motor control mechanisms in human singing and vocalization are not well understood. Using transcranial magnetic stimulation (TMS), we show that singing resulted in right-sided prolongation of ipsilateral silent period and bilateral reduction in contralateral silent period. Reading led to reduced contralateral silent period duration with right-sided TMS only, but no significant inhibitory changes, both ipsilateral and contralateral, were evident with humming. The findings support the presence of enhanced interhemispheric inhibitory motor interaction during singing, as opposed to reading tasks, in dynamic word generation coupled with production of melody.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Outram Road, 169608, Singapore, Singapore.
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