The Experts below are selected from a list of 573 Experts worldwide ranked by ideXlab platform
Nobuhiro Yuki - One of the best experts on this subject based on the ideXlab platform.
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two sets of nerve conduction studies may suffice in reaching a reliable Electrodiagnosis in guillain barre syndrome
Clinical Neurophysiology, 2013Co-Authors: Nortina Shahrizaila, Khean Jin Goh, Suhailah Abdullah, Rishikesan Kuppusamy, Nobuhiro YukiAbstract:highlights The existing electrodiagnostic criteria in Guillain-Barre syndrome are unreliable when applied at the initial stages of disease onset. Nerve conduction studies performed at two time courses, within 2 weeks and 3-8 weeks, may better reflect the final Electrodiagnosis of Guillain-Barre syndrome. The pattern of recovery in Guillain-Barre syndrome is heterogeneous and validation of the current Erasmus Guillain-Barre syndrome outcome score in different patient populations is required. abstract Objective: Recent studies have advocated the use of serial nerve conduction studies (NCS) in the electro- diagnosis of Guillain-Barre syndrome (GBS). The current study aims to elucidate when and how frequent NCS can be performed to reflect the disease pathophysiology. Methods: A prospective study of GBS patients documenting the initial and final electrodiagnoses follow- ing serial NCS performed at three time intervals: 1-2 weeks, 3-8 weeks and 8-12 weeks. Results: Twenty-one patients were recruited over a period of 2 years. Electrodiagnosis within 2 weeks revealed 17 acute inflammatory demyelinating polyneuropathy; two acute motor axonal neuropathy and two unclassified. After 12 weeks the final diagnoses were: 12 acute inflammatory demyelinating polyneuropathy; seven acute motor axonal neuropathy and two unclassified. NCS performed within the 3-8 week period reflected the true Electrodiagnosis. Patients with acute inflammatory demyelinating polyneuropathy had persistent demyelination features at the 8-12 week NCS. Conclusion: Two sets of NCS performed within the first 2 weeks and between 3-8 weeks of disease onset is likely to suffice in elucidating the true Electrodiagnosis of GBS. Significance: These findings can be incorporated into a much-needed revision of the existing GBS electro- diagnostic criteria.
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acute motor axonal neuropathy after mycoplasma infection evidence of molecular mimicry
Neurology, 2004Co-Authors: Keiichiro Susuki, Masahiro Mori, Masaaki Odaka, Koichi Hirata, Nobuhiro YukiAbstract:Background: Patients with Guillain-Barre syndrome (GBS) after Mycoplasma pneumoniae infection often have antibodies to galactocerebroside (GalC). Electrodiagnosis may show acute inflammatory demyelinating polyneuropathy (AIDP). Methods: The authors report a patient with acute motor axonal neuropathy (AMAN) after Mycoplasma infection and review seven cases of Mycoplasma -associated GBS. They investigated anti-GalC serology under various conditions associated with Mycoplasma infection. Results: The patient had immunoglobulin (Ig)G and IgM antibodies against GM1 and GalC, which cross-reacted. During the acute phase, IgM selectively immunostained axons. The cholera toxin B-subunit and rabbit anti-GM1 IgG stained a band in the lipid extract from M pneumoniae , indicative of the presence of a GM1 epitope. Six Mycoplasma -associated GBS patients with anti-GalC antibodies had non-AIDP electrodiagnoses, whereas one with Mycoplasma -associated AIDP had no anti-GalC antibodies. Anti-GalC antibodies were positive in two of five patients who had neurologic diseases other than GBS after Mycoplasma infection and in one of 12 who had acute respiratory disease caused by M pneumoniae not followed by a neurologic disease. Conclusions: Anti-GalC antibodies in Mycoplasma -associated GBS may be an epiphenomenon. In certain cases, anti-GM1 antibodies induced by molecular mimicry with M pneumoniae may cause acute motor axonal neuropathy.
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acute motor axonal neuropathy after mycoplasma infection evidence of molecular mimicry
Neurology, 2004Co-Authors: Keiichiro Susuki, Masahiro Mori, Masaaki Odaka, Koichi Hirata, Nobuhiro YukiAbstract:Background: Patients with Guillain-Barre syndrome (GBS) after Mycoplasma pneumoniae infection often have antibodies to galactocerebroside (GalC). Electrodiagnosis may show acute inflammatory demyelinating polyneuropathy (AIDP). Methods: The authors report a patient with acute motor axonal neuropathy (AMAN) after Mycoplasma infection and review seven cases of Mycoplasma -associated GBS. They investigated anti-GalC serology under various conditions associated with Mycoplasma infection. Results: The patient had immunoglobulin (Ig)G and IgM antibodies against GM1 and GalC, which cross-reacted. During the acute phase, IgM selectively immunostained axons. The cholera toxin B-subunit and rabbit anti-GM1 IgG stained a band in the lipid extract from M pneumoniae , indicative of the presence of a GM1 epitope. Six Mycoplasma -associated GBS patients with anti-GalC antibodies had non-AIDP electrodiagnoses, whereas one with Mycoplasma -associated AIDP had no anti-GalC antibodies. Anti-GalC antibodies were positive in two of five patients who had neurologic diseases other than GBS after Mycoplasma infection and in one of 12 who had acute respiratory disease caused by M pneumoniae not followed by a neurologic disease. Conclusions: Anti-GalC antibodies in Mycoplasma -associated GBS may be an epiphenomenon. In certain cases, anti-GM1 antibodies induced by molecular mimicry with M pneumoniae may cause acute motor axonal neuropathy.
David C. Preston - One of the best experts on this subject based on the ideXlab platform.
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indications for neuromuscular ultrasound expert opinion and review of the literature
Clinical Neurophysiology, 2018Co-Authors: Francis O. Walker, David C. Preston, Michael S. Cartwright, Katharine E Alter, Leo H Visser, Lisa D Hobsonwebb, Luca Padua, Jeffery A Strakowski, Andrea J BoonAbstract:Abstract Over the last two decades, dozens of applications have emerged for ultrasonography in neuromuscular disorders. We wanted to measure its impact on practice in laboratories where the technique is in frequent use. After identifying experts in neuromuscular ultrasound and Electrodiagnosis, we assessed their use of ultrasonography for different indications and their expectations for its future evolution. We then identified the earliest papers to provide convincing evidence of the utility of ultrasound for particular indications and analyzed the relationship of their date of publication with expert usage. We found that experts use ultrasonography often for inflammatory, hereditary, traumatic, compressive and neoplastic neuropathies, and somewhat less often for neuronopathies and myopathies. Usage significantly correlated with the timing of key publications in the field. We review these findings and the extensive evidence supporting the value of neuromuscular ultrasound. Advancement of the field of clinical neurophysiology depends on widespread translation of these findings.
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Electrodiagnosis of ulnar neuropathy at the elbow une a bayesian approach
Muscle & Nerve, 2014Co-Authors: Eric L. Logigian, David C. Preston, Raissa Villanueva, Paul Twydell, Bennett Myers, Marlene Downs, Milind J Kothari, David N HerrmannAbstract:Introduction: In ulnar neuropathy at the elbow (UNE), we determined how electrodiagnostic cutoffs [across-elbow ulnar motor conduction velocity slowing (AECV-slowing), drop in across-elbow vs. forearm CV (AECV-drop)] depend on pretest probability (PreTP). Methods: Fifty clinically defined UNE patients and 50 controls underwent ulnar conduction testing recording abductor digiti minimi (ADM) and first dorsal interosseous (FDI), stimulating wrist, below-elbow, and 6-, 8-, and 10-cm more proximally. For various PreTPs of UNE, the cutoffs required to confirm UNE (defined as posttest probability = 95%) were determined with receiver operator characteristic (ROC) curves and Bayes Theorem. Results: On ROC and Bayesian analyses, the ADM 10-cm montage was optimal. For PreTP = 0.25, the confirmatory cutoffs were >23 m/s (AECV-drop), and 14 m/s, and <47 m/s, respectively. Conclusions: (1) In UNE, electrodiagnostic cutoffs are critically dependent on PreTP; rigid cutoffs are problematic. (2) AE distances should be standardized and at least 10 cm. Muscle Nerve 49:337–344, 2014
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Optimal recording electrode placement in the lumbrical-interossei comparison study.
Muscle & nerve, 2006Co-Authors: Amer Alshekhlee, Jose A. Fernandes Filho, Devraj Sukul, David C. PrestonAbstract:The lumbrical-interossei comparison study is commonly employed in the Electrodiagnosis of carpal tunnel syndrome. Placement of the recording electrodes relies on anatomic landmarks as the muscles being recorded cannot be seen or palpated. To determine the optimal active electrode location, 15 controls and 5 patients were studied using a grid of 12 electrodes placed over the lateral palm. Amplitudes, rise-times, and latencies of the responses at each location were measured. The lowest control latency difference was located in the lateral mid-proximal palm (mean 0 ms, upper range of 0.5 ms). This location also had the highest lumbrical amplitude and rise-time. More distal in the palm, the mean latency difference increased to 0.5 ms with an upper range of 0.9 ms. When performing the lumbrical-interossei comparison study, it is essential to place the active recording electrode in the optimal location. Failure to do so will result in an increased number of false-positive studies.
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Electrodiagnosis of ulnar neuropathy at the wrist conduction block versus traditional tests
Neurology, 2002Co-Authors: Susan R Cowdery, David C. Preston, David N Herrmann, Eric L. LogigianAbstract:Background: Compared to ulnar neuropathy at the elbow (UNE), ulnar neuropathy at the wrist (UNW) is rarer and more difficult to localize with routine electrophysiologic studies. Methods: By stimulating the ulnar nerve at the wrist and palm, and recording from first dorsal interosseous (FDI), the sensitivity and specificity of conduction block (CB) and slow conduction velocity (CV) of FDI fibers across the wrist was compared to traditional electrodiagnostic techniques for localization of UNW. Twenty patients with clinically defined UNW (due mainly to wrist trauma), 30 normal controls, and 20 disease controls with severe (n = 10) and mild (n = 10) UNE were evaluated prospectively. The upper (mean +2.5 SD) and lower (mean −2.5 SD) limits for all measurements were derived from the normal controls. Results: The UNW patients showed: slow wrist-palm FDI CV ( 4.5 milliseconds) in 12 (60%), to ulnar-innervated palmar interosseous (PI) versus median-innervated lumbrical (L) in 12 (60%), and to abductor digiti minimi (ADM) in 11 (55%). However, only CB and slow wrist-palm FDI CV ( Conclusions: In UNW, an additional palmar stimulation site improves electrodiagnostic yield, and demonstrates that CB is an important cause of muscle weakness.
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Sensory and mixed nerve conduction studies in the evaluation of ulnar neuropathy at the elbow
Muscle & nerve, 1994Co-Authors: Elizabeth M. Raynor, David C. Preston, Jeremy M. Shefner, Eric L. LogigianAbstract:The relative sensitivities of sensory, mixed nerve, and motor conduction studies in assessing ulnar neuropathy at the elbow have not yet been established. Using surface electrodes, we performed conduction studies across the elbow segment in 43 patients with symptoms referable to the ulnar nerve and 40 control subjects. Segmental slowing of motor conduction localized the lesion to the elbow in 14 of 21 patients (67%) with clear evidence of ulnar neuropathy on physical examination but only in 2 of 22 (9%) with subtle or no physical examination abnormalities. The diagnostic yield was increased by the finding of segmental slowing of sensory or mixed nerve conduction across the elbow to 86% and 68%, respectively, for each of the groups. We conclude that surface-recorded sensory and mixed nerve conduction studies appear to be more sensitive than motor studies in the Electrodiagnosis of ulnar neuropathy at the elbow and are especially valuable in patients with subtle clinical involvement.
Satoshi Kuwabara - One of the best experts on this subject based on the ideXlab platform.
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optimizing the electrodiagnostic accuracy in guillain barre syndrome subtypes criteria sets and sparse linear discriminant analysis
Clinical Neurophysiology, 2017Co-Authors: Antonino Uncini, Nortina Shahrizaila, Luigi Ippoliti, Yukari Sekiguchi, Satoshi KuwabaraAbstract:Abstract Objective To optimize the Electrodiagnosis of Guillain-Barre syndrome (GBS) subtypes at first study. Methods The reference Electrodiagnosis was obtained in 53 demyelinating and 45 axonal GBS patients on the basis of two serial studies and results of anti-ganglioside antibodies assay. We retrospectively employed sparse linear discriminant analysis (LDA), two existing electrodiagnostic criteria sets (Hadden et al., 1998; Rajabally et al., 2015) and one we propose that additionally evaluates duration of motor responses, sural sparing pattern and defines reversible conduction failure (RCF) in motor and sensory nerves at second study. Results At first study the misclassification error rates, compared to reference diagnoses, were: 15.3% for sparse LDA, 30% for our criteria, 45% for Rajabally’s and 48% for Hadden’s. Sparse LDA identified seven most powerful electrophysiological variables differentiating demyelinating and axonal subtypes and assigned to each patient the diagnostic probability of belonging to either subtype. At second study 46.6% of axonal GBS patients showed RCF in two motor and 8.8% in two sensory nerves. Conclusions Based on a single study, sparse LDA showed the highest diagnostic accuracy. RCF is present in a considerable percentage of axonal patients. Significance Sparse LDA, a supervised statistical method of classification, should be introduced in the electrodiagnostic practice.
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Sensory Nerve Conduction in Demyelinating and Axonal Guillain-Barré Syndromes
European neurology, 2004Co-Authors: Satoshi Kuwabara, Kazue Ogawara, Sonoko Misawa, Keiko Mizobuchi, Jia Ying Sung, Yukiko Kitano, Masahiro Mori, Takamichi HattoriAbstract:Guillain-Barre syndrome is divided into acute inflammatory demyelinating polyneuropathy (AIDP) and acute motor axonal neuropathy (AMAN) based on motor nerve conduction studies. We investigated whether sensory nerve conduction studies contribute to the Electrodiagnosis of AIDP and AMAN. In consecutive 59 patients with AIDP (n = 26) or AMAN (n = 33), results of sensory nerve conduction studies in the median, ulnar and sural nerves were reviewed. Sensory nerve conduction abnormalities were found for 85% of AIDP patients and for only 6% of AMAN patients. In AIDP patients, the abnormalities were present in 85% of patients in the median nerves, 85% in the ulnar nerves and 38% in the sural nerves. AMAN is very rarely associated with sensory nerve involvement. Abnormal sensory nerve conduction is supportive of AIDP and is more frequently found for the median and ulnar nerves than sural nerves.
Antonino Uncini - One of the best experts on this subject based on the ideXlab platform.
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optimizing the electrodiagnostic accuracy in guillain barre syndrome subtypes criteria sets and sparse linear discriminant analysis
Clinical Neurophysiology, 2017Co-Authors: Antonino Uncini, Nortina Shahrizaila, Luigi Ippoliti, Yukari Sekiguchi, Satoshi KuwabaraAbstract:Abstract Objective To optimize the Electrodiagnosis of Guillain-Barre syndrome (GBS) subtypes at first study. Methods The reference Electrodiagnosis was obtained in 53 demyelinating and 45 axonal GBS patients on the basis of two serial studies and results of anti-ganglioside antibodies assay. We retrospectively employed sparse linear discriminant analysis (LDA), two existing electrodiagnostic criteria sets (Hadden et al., 1998; Rajabally et al., 2015) and one we propose that additionally evaluates duration of motor responses, sural sparing pattern and defines reversible conduction failure (RCF) in motor and sensory nerves at second study. Results At first study the misclassification error rates, compared to reference diagnoses, were: 15.3% for sparse LDA, 30% for our criteria, 45% for Rajabally’s and 48% for Hadden’s. Sparse LDA identified seven most powerful electrophysiological variables differentiating demyelinating and axonal subtypes and assigned to each patient the diagnostic probability of belonging to either subtype. At second study 46.6% of axonal GBS patients showed RCF in two motor and 8.8% in two sensory nerves. Conclusions Based on a single study, sparse LDA showed the highest diagnostic accuracy. RCF is present in a considerable percentage of axonal patients. Significance Sparse LDA, a supervised statistical method of classification, should be introduced in the electrodiagnostic practice.
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Pitfalls in Electrodiagnosis of GuillaineBarré syndrome subtypes
2016Co-Authors: Antonino Uncini, Claudia Manzoli, Francesca Notturno, Margherita CapassoAbstract:Objective To electrophysiologically classify an Italian GuillaineBarre ́ syndrome (GBS) population into demyelinating and axonal subtypes, to investigate how serial recordings changed the classification and to underline the pitfalls in Electrodiagnosis of GBS subtypes. Methods The authors applied two current electrodiagnostic criteria sets for demyelinating and axonal GBS subtypes in 55 patients who had at least two serial recordings in three motor and sensory nerves. Results At first test, the Electrodiagnosis was almost identical with both criteria: 65e67 % of patients were classifiable as acute inflammatory demyelinating polyradiculoneuropathy (AIDP), 18 % were classifiable as axonal GBS, and 14e16 % were equivocal. At follow-up, 24 % of patients changed classification: AIDP decreased to 58%, axonal GBS increased to 38%, and equivocal patients decreased to 4%. The majority of shifts were from AIDP and equivocal groups to axonal GBS, and the main reason was the recognition by serial recordings of the reversible conduction failure and of the length-dependent compound muscle action potential amplitude reduction patterns as expression of axonal pathology. Conclusions Axonal GBS is pathophysiologically characterised not only by axonal degeneration but also by reversible conduction failure at the axolemma of the Ranvier node. The lack of distinction among demyelinating conduction block, reversible conduction failure and length-dependent compound muscle action potential amplitude reduction may fallaciously classify patients with axonal GBS as having AIDP. Serial electrophysiological studies are mandatory for proper diagnosis of GBS subtypes and the identification of pathophysiological mechanisms of muscle weakness. More reliable electrodiagnostic criteria taking into consideration the reversible conduction failure pattern should be devised
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pitfalls in Electrodiagnosis of guillain barre syndrome subtypes
Journal of Neurology Neurosurgery and Psychiatry, 2010Co-Authors: Antonino Uncini, Claudia Manzoli, Francesca Notturno, Margherita CapassoAbstract:Objective To electrophysiologically classify an Italian Guillain–Barre syndrome (GBS) population into demyelinating and axonal subtypes, to investigate how serial recordings changed the classification and to underline the pitfalls in Electrodiagnosis of GBS subtypes. Methods The authors applied two current electrodiagnostic criteria sets for demyelinating and axonal GBS subtypes in 55 patients who had at least two serial recordings in three motor and sensory nerves. Results At first test, the Electrodiagnosis was almost identical with both criteria: 65–67% of patients were classifiable as acute inflammatory demyelinating polyradiculoneuropathy (AIDP), 18% were classifiable as axonal GBS, and 14–16% were equivocal. At follow-up, 24% of patients changed classification: AIDP decreased to 58%, axonal GBS increased to 38%, and equivocal patients decreased to 4%. The majority of shifts were from AIDP and equivocal groups to axonal GBS, and the main reason was the recognition by serial recordings of the reversible conduction failure and of the length-dependent compound muscle action potential amplitude reduction patterns as expression of axonal pathology. Conclusions Axonal GBS is pathophysiologically characterised not only by axonal degeneration but also by reversible conduction failure at the axolemma of the Ranvier node. The lack of distinction among demyelinating conduction block, reversible conduction failure and length-dependent compound muscle action potential amplitude reduction may fallaciously classify patients with axonal GBS as having AIDP. Serial electrophysiological studies are mandatory for proper diagnosis of GBS subtypes and the identification of pathophysiological mechanisms of muscle weakness. More reliable electrodiagnostic criteria taking into consideration the reversible conduction failure pattern should be devised.
Nortina Shahrizaila - One of the best experts on this subject based on the ideXlab platform.
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optimizing the electrodiagnostic accuracy in guillain barre syndrome subtypes criteria sets and sparse linear discriminant analysis
Clinical Neurophysiology, 2017Co-Authors: Antonino Uncini, Nortina Shahrizaila, Luigi Ippoliti, Yukari Sekiguchi, Satoshi KuwabaraAbstract:Abstract Objective To optimize the Electrodiagnosis of Guillain-Barre syndrome (GBS) subtypes at first study. Methods The reference Electrodiagnosis was obtained in 53 demyelinating and 45 axonal GBS patients on the basis of two serial studies and results of anti-ganglioside antibodies assay. We retrospectively employed sparse linear discriminant analysis (LDA), two existing electrodiagnostic criteria sets (Hadden et al., 1998; Rajabally et al., 2015) and one we propose that additionally evaluates duration of motor responses, sural sparing pattern and defines reversible conduction failure (RCF) in motor and sensory nerves at second study. Results At first study the misclassification error rates, compared to reference diagnoses, were: 15.3% for sparse LDA, 30% for our criteria, 45% for Rajabally’s and 48% for Hadden’s. Sparse LDA identified seven most powerful electrophysiological variables differentiating demyelinating and axonal subtypes and assigned to each patient the diagnostic probability of belonging to either subtype. At second study 46.6% of axonal GBS patients showed RCF in two motor and 8.8% in two sensory nerves. Conclusions Based on a single study, sparse LDA showed the highest diagnostic accuracy. RCF is present in a considerable percentage of axonal patients. Significance Sparse LDA, a supervised statistical method of classification, should be introduced in the electrodiagnostic practice.
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Understanding the pathogenesis of guillain-barre syndrome through neurophysiology and serological analyses / Nortina Shahrizaila
2016Co-Authors: Nortina ShahrizailaAbstract:Guillain-Barré syndrome (GBS) is the leading cause of post-infectious flaccid paralysis worldwide. Over the years, research on the neurophysiological characteristics and serological profile of GBS patients has contributed towards our greater understanding of its pathogenesis. GBS can be classified into demyelinating and axonal subtypes, based on their neurophysiological features. In axonal GBS, antibodies against several glycolipids have been identified whereas target antigens in demyelinating GBS remain unknown. In this thesis, a series of published original work addressing the current limitations in GBS Electrodiagnosis and serological associations with disease features are presented. In the first series of publications, prospective serial nerve conduction studies (NCS) in a cohort of multi-ethnic Malaysian GBS patients are described. We found that in order to make a true Electrodiagnosis of GBS, at least two sets of NCS were required performed with the first 2 weeks of disease onset and 3 to 8 weeks later. Based on NCS, we also found an almost exclusive involvement of sensory fibres in patients with the GBS variant, Miller Fisher syndrome irrespective of their symptoms. The second series of publication investigated the presence of antibodies against glycolipid complexes in GBS patients from Asian and Western cohorts. The relationship between these antibodies and the clinical features as well as neurophysiological characteristics of GBS based on serial NCS was also investigated. Our studies provided robust evidence that antibodies to single glycolipids and glycolipid complexes are associated with axonal forms of GBS and not acute inflammatory demyelinating polyneuropathy. Future studies incorporating standardized methods of neurophysiological assessment and serological analyses in heterogeneous populations are required to better understand GBS pathophysiology. Existing on-going international research collaboration is one platform in which findings from the current work can be further validated
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two sets of nerve conduction studies may suffice in reaching a reliable Electrodiagnosis in guillain barre syndrome
Clinical Neurophysiology, 2013Co-Authors: Nortina Shahrizaila, Khean Jin Goh, Suhailah Abdullah, Rishikesan Kuppusamy, Nobuhiro YukiAbstract:highlights The existing electrodiagnostic criteria in Guillain-Barre syndrome are unreliable when applied at the initial stages of disease onset. Nerve conduction studies performed at two time courses, within 2 weeks and 3-8 weeks, may better reflect the final Electrodiagnosis of Guillain-Barre syndrome. The pattern of recovery in Guillain-Barre syndrome is heterogeneous and validation of the current Erasmus Guillain-Barre syndrome outcome score in different patient populations is required. abstract Objective: Recent studies have advocated the use of serial nerve conduction studies (NCS) in the electro- diagnosis of Guillain-Barre syndrome (GBS). The current study aims to elucidate when and how frequent NCS can be performed to reflect the disease pathophysiology. Methods: A prospective study of GBS patients documenting the initial and final electrodiagnoses follow- ing serial NCS performed at three time intervals: 1-2 weeks, 3-8 weeks and 8-12 weeks. Results: Twenty-one patients were recruited over a period of 2 years. Electrodiagnosis within 2 weeks revealed 17 acute inflammatory demyelinating polyneuropathy; two acute motor axonal neuropathy and two unclassified. After 12 weeks the final diagnoses were: 12 acute inflammatory demyelinating polyneuropathy; seven acute motor axonal neuropathy and two unclassified. NCS performed within the 3-8 week period reflected the true Electrodiagnosis. Patients with acute inflammatory demyelinating polyneuropathy had persistent demyelination features at the 8-12 week NCS. Conclusion: Two sets of NCS performed within the first 2 weeks and between 3-8 weeks of disease onset is likely to suffice in elucidating the true Electrodiagnosis of GBS. Significance: These findings can be incorporated into a much-needed revision of the existing GBS electro- diagnostic criteria.