The Initial Clinical and Electrophysiological Characteristics of Different Subtypes of Guillain-Barré Syndrome Diagnosed Based on Serial Electrophysiological Examinations.

BACKGROUND: We aimed to identify different Guillain-Barré syndrome (GBS) subtypes, demyelination, axonal degeneration, and reversible conduction failure (RCF) as early as possible by analyzing the initial clinical and electrophysiological examinations. METHODS: This study retrospectively collected GBS patients between October 2018 and December 2022 at Beijing Tiantan Hospital. The diagnostic criteria for the initial electrophysiological study were based on Rajabally's criteria, and the criteria for the serial electrophysiological study were based on Uncini's criteria. All subjects underwent clinical and electrophysiological evaluations at least twice within 8 weeks. RESULTS: A total of 47 eligible patients with GBS were included, comprising 19 acute inflammatory demyelinating polyradiculoneuropathy (AIDP), 18 axonal degenerations, and 10 RCFs. In the RCF group, 40%, 30%, and 30% patients were diagnosed as AIDP, axonal, and equivocal at the initial study, respectively. The AIDP group had significantly higher cerebrospinal fluid (CSF) protein than the RCF (123.8 [106.4, 215.1] mg/dL vs. 67.1 [36.8, 85.6] mg/dL, p = 0.002) and axonal degeneration (123.8 [106.4, 215.1] mg/dL vs. 60.8 [34.8, 113.0] mg/dL, p < 0.001) groups. The RCF group had significantly lower Hughes functional grades at admission (3 [2, 4] vs. 4 [4, 4], p = 0.012) and discharge (1.0 [1.0, 2.0] vs. 3.0 [2.0, 3.0], p < 0.001) than the axonal degeneration group and showed significantly shorter distal motor latency (DML), Fmin, Fmean, Fmax, and lower F% than the AIDP group (p < 0.05). DISCUSSION: The early identification of RCF from AIDP had relatively obvious features, including slightly elevated CSF protein levels and normal or slightly prolonged DML and F-wave latencies, contrasting with the apparent elevation and prolongation seen in AIDP. Differentiating RCF from axonal degeneration remains challenging. One potential distinguishing factor is that the motor function in RCF tends to be better than in the latter.

Electrodiagnostic subtyping in Guillain-Barré syndrome patients in the International Guillain-Barré Outcome Study.

BACKGROUND AND PURPOSE: Various electrodiagnostic criteria have been developed in Guillain-Barré syndrome (GBS). Their performance in a broad representation of GBS patients has not been evaluated. Motor conduction data from the International GBS Outcome Study (IGOS) cohort were used to compare two widely used criterion sets and relate these to diagnostic amyotrophic lateral sclerosis criteria. METHODS: From the first 1500 patients in IGOS, nerve conduction studies from 1137 (75.8%) were available for the current study. These patients were classified according to nerve conduction studies criteria proposed by Hadden and Rajabally. RESULTS: Of the 1137 studies, 68.3% (N = 777) were classified identically according to criteria by Hadden and Rajabally: 111 (9.8%) axonal, 366 (32.2%) demyelinating, 195 (17.2%) equivocal, 35 (3.1%) inexcitable and 70 (6.2%) normal. Thus, 360 studies (31.7%) were classified differently. The areas of differences were as follows: 155 studies (13.6%) classified as demyelinating by Hadden and axonal by Rajabally; 122 studies (10.7%) classified as demyelinating by Hadden and equivocal by Rajabally; and 75 studies (6.6%) classified as equivocal by Hadden and axonal by Rajabally. Due to more strictly defined cutoffs fewer patients fulfilled demyelinating criteria by Rajabally than by Hadden, making more patients eligible for axonal or equivocal classification by Rajabally. In 234 (68.6%) axonal studies by Rajabally the revised El Escorial (amyotrophic lateral sclerosis) criteria were fulfilled; in axonal cases by Hadden this was 1.8%. CONCLUSIONS AND DISCUSSION: This study shows that electrodiagnosis in GBS is dependent on the criterion set utilized, both of which are based on expert opinion. Reappraisal of electrodiagnostic subtyping in GBS is warranted.

Covid-19 associated Guillain-Barré syndrome: A series of a relatively uncommon neurological complication.

BACKGROUND AND AIMS: The COVID-19 pandemic has turned the world topsy turvy since its emergence and has claimed innumerable lives worldwide. Neurological manifestations of the disease have raised several eyebrows around the world among which Guillain-Barré syndrome (GBS) deserve special mention. Although majority of the cases of the coronavirus disease 2019 (COVID-19) present with respiratory symptoms, extrapulmonary manifestations are being increasingly reported. We conducted this study to analyze detailed clinical presentations and outcome in a series of eight cases (n = 8) with COVID-19 associated GBS. METHODS: An observational prospective study was conducted among patients with post-infectious/para-infectious GBS. 8 patients were subclassified into acute inflammatory demyelinating polyneuropathy (AIDP), acute motor axonal neuropathy (AMAN) and acute motor and sensory axonal neuropathy (AMSAN) as per electrodiagnostic criteria and were followed up from admission to 6 months post discharge, to obtain a comprehensive clinical profile and outcome in these patients. RESULTS: The diagnosis of GBS was confirmed as per Asbury criteria, supported by electrodiagnostic features in nerve conduction velocity test. Among the series of 8 patients, 3 were diagnosed as AIDP, 3 had AMAN and the remaining 2 patients had AMSAN. 3 patients of GBS were afebrile and were diagnosed as COVID-19 after a positive assay on routine screening. Cerebro-spinal fluid analysis for SARS-Cov-2 RT-PCR and serum anti-ganglioside antibodies were negative in all the patients. CONCLUSION: GBS in patients with COVID-19 should be differentiated from critical illness neuropathy and myopathy. Early diagnosis is important as it is associated with poor outcome and prolonged invasive ventilation.

Finger drop sign as a new variant of acute motor axonal neuropathy.

We propose the finger drop sign as a new clinical variant of acute motor axonal neuropathy (AMAN) defined by immunological and radiological evidence. We identified eight consecutive patients who had AMAN. All of them developed prominent involvement of the finger extensors. We performed magnetic resonance imaging (MRI) of the extremity muscles and serological assays for antiganglioside antibodies and Campylobacter jejuni. Patients with AMAN showed characteristic and a markedly sustained weakness of the finger extensors with a distinctive pattern of the finger drop sign. Limb MRI revealed unevenly distributed abnormal signals in the muscles mainly innervated by the posterior interosseous nerve. All tested patients showed positivity for immunoglobulin G antibody against ganglioside complex of GM1 and phosphatidic acid. A pathophysiological understanding of this unique syndrome can provide further insight into antiganglioside-antibody-mediated axonal injury in Guillain-Barré syndrome.

Nodal conduction block: A unifying concept.

A newly introduced term, "axonal conduction block," brought a confusion in the electrodiagnostic diagnosis of Guillain-Barrè syndrome (GBS). I am proposing the term "nodal conduction block" for "axonal conduction block." This unifying concept of nodal conduction block will accommodate both the traditional concept of demyelination as well as the new concept of nodopathy in the "axonal form of GBS,", making the practice of electrodiagnosis much easier.

Anti-GQ1b antibody syndrome presenting with visual deterioration as the initial symptom: A case report.

RATIONALE: Anti-GQ1b antibody syndrome refers to a distinct variant of Guillain- Barré syndrome. Involvement of the optic nerve in anti-GQ1b antibody syndrome is extremely rare. PATIENT CONCERNS: Here, we report a case of anti-GQ1b antibody syndrome presenting with visual deterioration as the initial symptom. A 73-year-old man presented with a 5-day history of bilateral blurred vision and ptosis. He had a previous history of diarrhea starting 10 days before admission. Physical examination showed visual deterioration, ophthalmoplegia, and peripheral facial paralysis. Testing of both serum and cerebrospinal fluid was positive for anti-GQ1b immunoglobulin G antibodies and negative for anti-aquaporin 4antibodies. DIAGNOSIS: Anti-GQ1b antibody syndrome. INTERVENTIONS: The patient was treated with intravenous methylprednisolone and human immunoglobulin. OUTCOMES: After a 20-day follow-up, the patient's condition took a favorable turn. LESSONS: This case reminds us that anti-GQ1b antibody syndrome should be suspected in patients with visual deterioration and preceding infection.

Cerebrospinal fluid total protein in Guillain-Barré syndrome variants: correlations with clinical category, severity, and electrophysiology.

The discriminative value of CSF total protein (CSF-TP) in subtypes of Guillain-Barré syndrome has not been well documented in North-American patients. We reviewed 173 cases from a single institution, comprising the following clinical categories of neuropathy: 134 Sensorimotor (SM) GBS, 13 Motor (M) GBS, 8 Localized (L) GBS, and 18 Miller Fisher syndrome (MFS). We grouped the electrophysiological interpretation in primarily demyelinating, primarily axonal and normal / equivocal categories. Mean CSF-TP were substantially higher for SM and L-GBS, as well as cases classified as Acute-onset chronic inflammatory demyelinating polyneuropathy. They were lower for M-GBS and L-GBS. The most statistically significant correlation was found for elevated CSF-TP in GBS cases showing an electrophysiologic pattern classified as demyelinating (1.56 g/L) compared with axonal (0.68 g/L) or normal/ equivocal patterns (0.65 g/L). There was a correlation between CSF-TP and time interval between symptom onset and lumbar puncture. There was a weak correlation between CSF-TP and maximal overall-clinical severity grade, which was likely mostly determined by the electorphysiological pattern. Though CSF-TP is a sensitive test for GBS in the second week after onset, it may not be a reliable predictor of clinical severity. There is a robust association of CSF-TP elevation and a demyelinative electrophysiologic pattern and a suggestion that lower mean CSF-TP values can be expected in GBS-spectrum disorders thought to represent nodo-paranodopathies.

A model to predict the probability of acute inflammatory demyelinating polyneuropathy.

OBJECTIVE: We aimed to develop a model that can predict the probabilities of acute inflammatory demyelinating polyneuropathy (AIDP) based on nerve conduction studies (NCS) done within eight weeks. METHODS: The derivation cohort included 90 Malaysian GBS patients with two sets of NCS performed early (1-20days) and late (3-8 weeks). Potential predictors of AIDP were considered in univariate and multivariate logistic regression models to develop a predictive model. The model was externally validated in 102 Japanese GBS patients. RESULTS: Median motor conduction velocity (MCV), ulnar distal motor latency (DML) and abnormal ulnar/normal sural pattern were independently associated with AIDP at both timepoints (median MCV: p = 0.038, p = 0.014; ulnar DML: p = 0.002, p = 0.003; sural sparing: p = 0.033, p = 0.009). There was good discrimination of AIDP (area under the curve (AUC) 0.86-0.89) and this was valid in the validation cohort (AUC 0.74-0.94). Scores ranged from 0 to 6, and corresponded to AIDP probabilities of 15-98% at early NCS and 6-100% at late NCS. CONCLUSION: The probabilities of AIDP could be reliably predicted based on median MCV, ulnar DML and ulnar/sural sparing pattern that were determined at early and late stages of GBS. SIGNIFICANCE: A simple and valid model was developed which can accurately predict the probability of AIDP.

Antecedent infections in Guillain-Barré syndrome: a single-center, prospective study.

OBJECTIVE: To investigate the spectrum of antecedent infections in Chinese patients with Guillain-Barré syndrome (GBS) and analyze the infections-related clinical phenotypes locally. METHODS: A prospective case-control study of 150 patients diagnosed with GBS and age- and sex-matched neurological and healthy controls was performed to investigate recent infections of 14 pathogens serologically and collect the clinical data during a follow-up of 12 months. RESULTS: In total, 53% of patients with GBS had a positive serology for recent infection, including Campylobacter jejuni (27%), influenza A (17%) and B (16%), hepatitis A virus (5%), dengue virus (3%), cytomegalovirus (3%), Epstein-Barr virus (3%), Mycoplasma pneumoniae (2%), herpes simplex virus (2%), varicella-zoster virus (1%), and rubella virus (1%). Serology for infections of hepatitis E virus, Haemophilus influenzae, and Zika virus was negative. There was a higher frequency of C. jejuni, influenza A, influenza B, and hepatitis A virus infections in GBS patients than both the neurological and healthy controls. C. jejuni infection was more frequent in younger GBS patients and was associated with antibodies against GM1, GalNAc-GD1a, and GM1:galactocerebroside complex. Influenza B infection was associated with a pure motor form of GBS. INTERPRETATION: C. jejuni, influenza A, influenza B, and hepatitis A virus serve as the most common cause of antecedent infections in GBS locally. Influenza B-related GBS may represent a pure motor phenotype. Differences in the infectious spectrum worldwide may contribute to the geographical clinical heterogeneity of GBS.

[An elderly case of Guillain-Barré syndrome with anti-GT1b antibodies].

An 85-year-old Japanese female was admitted with sudden onset of quadriparesis with areflexia. Preceding infection was not present. IgG anti-GT1b antibodies were prominently positive in serum. Nerve conduction study results suggested Guillain-Barré syndrome (GBS) classified as acute motor sensory axonal neuropathy (AMSAN). While intravenous immunoglobulin (IVIg) was started, bulbar palsy and respiratory failure progressed and the condition deteriorated. Although mechanical ventilation was required, second IVIg course led to gradual improvement of quadriparesis and bulbar palsy. In the present case with elderly-onset disease, the levels of anti-GT1b antibodies were elevated, which is relatively rare in GBS. It was suggested that anti-GT1b antibodies may be related to the development of axonal GBS with bulbar palsy.

Increased incidence of axonal Guillain-Barré syndrome in La Spezia area of Italy: A 13-year follow-up study.

Guillain-Barré syndrome (GBS) is an acute immune-mediated polyradiculoneuropathy with a worldwide incidence of 0.81-1.89 per 100 000 person-years. In Europe and North America only 5% of patients with GBS have axonal subtypes, which in South America and Asia account for 30%-47% of cases. The aim of our study is to assess the annual incidence and clinical features of GBS in La Spezia area in Italy. A retrospective (from 1 January 2003 to 31 December 2011) followed by a prospective (from 1 January 2012 to 31 December 2015) analysis was carried out on patients admitted to La Spezia hospital who fulfilled the GBS diagnostic criteria. A total of 86 patients (58 men), mean age of 62.7 years (range 21-90), were included. The mean annual incidence rate was 3/100 000 (range: 0.9/100 000-5.37/100 000) significantly higher than the European incidence (P < 0.001). Forty-seven percent were classified as acute inflammatory demyelinating polyradiculoneuropathy (AIDP), 35% as acute motor and motor-sensory axonal neuropathy (AMAN-AMSAN), 13% as variant forms, and 5% were not defined. AIDP was most common in "Golfo dei Poeti" (50%) and "Val di Magra" (63.2%), whereas AMAN/AMSAN prevailed in "Val di Vara" (63.6%) and "Riviera Spezzina" (62.5%) (P = 0.024). In La Spezia area GBS incidence (especially the AMAN subtype) is significantly higher than the incidence reported in Europe. AIDP predominates in the eastern area whereas AMAN/AMSAN in the western, with a significantly different incidence rate (P = 0.003). Prospective studies to assess possible predisposing environmental factors are needed.

Guillain-Barré syndrome subtypes: A clinical electrophysiological study of 100 patients.

INTRODUCTION: A retrospective analysis was performed to document the clinical and electrophysiological features of Guillain-Barré syndrome (GBS) subtypes using different diagnostic criteria. METHODS: One hundred GBS patients were included. Clinical and laboratory features were analyzed, and patients were classified according to four sets of diagnostic criteria. Electrodiagnostic criteria were also analyzed. RESULTS: A total of 69 patients met Asbury and Cornblath's criteria, 96 met Van der Meché's criteria, 99 met Wakerley's diagnostic classification and 86 met level 1 or 2 of the Brighton criteria. Rates of GBS subtypes were: 69% classic GBS; 8% Miller-Fisher syndrome; 12% paraparetic GBS; 2% pharyngeal-cervical-brachial GBS; and 9% unclassified. Those for electrodiagnostic subtypes were 52% demyelinating and 9% axonal according to Hadden's criteria vs 41% demyelinating and 41% axonal as per Rajabally's criteria. CONCLUSION: In this study of case distribution within the GBS spectrum of a retrospective cohort of French patients, the application of new diagnostic criteria enabled accurate diagnoses and classifications of the different subtypes, and also increased the recognition of axonal GBS.

A Predictive Model for Guillain-Barré Syndrome Based on Ensemble Methods.

Nowadays, Machine Learning methods have proven to be highly effective on the identification of various types of diseases, in the form of predictive models. Guillain-Barré syndrome (GBS) is a potentially fatal autoimmune neurological disorder that has barely been studied with computational techniques and few predictive models have been proposed. In a previous study, single classifiers were successfully used to build a predictive model. We believe that a predictive model is imperative to carry out adequate treatment in patients promptly. We designed three classification experiments: (1) using all four GBS subtypes, (2) One versus All (OVA), and (3) One versus One (OVO). These experiments use a real-world dataset with 129 instances and 16 relevant features. Besides, we compare five state-of-the-art ensemble methods against 15 single classifiers with 30 independent runs. Standard performance measures were used to obtain the best classifier in each experiment. Derived from the experiments, we conclude that Random Forest showed the best results in four GBS subtypes classification, no ensemble method stood out over the rest in OVA classification, and single classifiers outperformed ensemble methods in most cases in OVO classification. This study presents a novel predictive model for classification of four subtypes of Guillain-Barré syndrome. Our model identifies the best method for each classification case. We expect that our model could assist specialized physicians as a support tool and also could serve as a basis to improved models in the future.

The electrodiagnosis of Guillain-Barré syndrome subtypes: Where do we stand?

It is controversial as to whether the electrophysiological Guillain-Barré syndrome (GBS) subtypes can be diagnosed on the basis of a single study and which criteria sets and cut-offs should be used. Serial electrophysiologic studies have shown that a significant number of patients changed electrodiagnostic subtype largely because of the recognition of reversible conduction failure as a possible evidence of axonal pathology. However, other reports concluded that electrodiagnosis can be made by a single study, the subtypes depending on the characteristic of the criteria set applied. Such divergent views, although explicable by the different methodology employed, can be confusing in the everyday practice. We argue that the pathophysiology of GBS is dynamic and that serial studies allow a more accurate diagnosis of subtypes. A second study, although not always practicable, is recommended in patients showing no clear demyelinating features, low amplitude distal compound muscle action potentials or conduction block without temporal dispersion. For practical purposes, we propose that at a first study Uncini's or Rajabally's criteria sets can be employed for an indicative subtype diagnosis. Finally, although the GBS subtype diagnosis has currently no impact on treatment, we believe that is important for understanding the underlying pathophysiology and prognostication.

Caracterización general de Zika / General characterization of Zika

El Zika es un arbovirosis que causa enfer-medad febril caracterizada por fiebre, rash, artralgias y conjuntivitis no purulenta. En 2015 se registraron casos autóctonos en Brasil, en menos de un año el Zika se exten-dió a más de 30 países y territorios de Améri-ca Central, América del Sur, el Caribe y México, entre estos Honduras. Se ha rela-cionado con aumento de los casos de Gui- llain Barré y microcefalia en zonas donde produce epidemia. En Honduras, entre la semana epidemiológica 1 del 2016 a la 33 del 2017, hubo un total acumulado de 681 mujeres embarazadas con sospecha de Zika identificadas en el país, 125 de las cuales han sido confirmadas en laboratorio por reacción en cadena de polimerasa. Se reali-zó una revisión bibliográfica de 30 artículos tomando como referencia: artículos de revis-tas, normas y recomendaciones menores de 5 años de haber sido publicados o aquellos con importancia histórica, con el fin de brin-dar información útil al lector acerca del tema. Zika es una enfermedad que puede generar un impacto negativo en la salud de la niñez, dejando secuelas a largo plazo...(AU)

Prospective comparison of acute motor axonal neuropathy and acute inflammatory demyelinating polyradiculoneuropathy in 140 children with Guillain-Barré syndrome in India.

INTRODUCTION: There have been few reports on subtypes of Guillain-Barré syndrome (GBS) in children. We compared clinical and laboratory findings of acute inflammatory demyelinating polyradiculoneuropathy (AIDP) and acute motor axonal neuropathy (AMAN). METHODS: One hundred forty children with GBS were included. Based on nerve conduction study (NCS) findings, patients were subclassified as AIDP, AMAN, acute motor sensory axonal neuropathy (AMSAN), and equivocal. RESULTS: Clinically, 72.1% of patients had pure motor, 24.3% motor sensory, and 3.4% Miller Fisher syndrome. Based on NCS, 67.8% of patients had AIDP, 23.6% had AMAN, and 4.3% had AMSAN. By 3 months, 2.1% patients had died, 47.1% had complete recovery, and 24.3% had poor recovery (wheelchair-bound). Children with AMAN had more frequent lower limb weakness (P = 0.02) and a lower probability of complete recovery (P = 0.01) at 3 months than children with AIDP (56% vs. 30%). DISCUSSION: AIDP is the most common GBS subtype in children. It is characterized by better recovery at 3 months when compared with AMAN. Muscle Nerve 57: 761-765, 2018.

Associations between tumor necrosis factor-α gene polymorphisms and the risk of Guillain-Barré syndrome and its subtypes: A systematic review and meta-analysis.

This meta-analysis aimed to assess the relationship between tumor necrosis factor-α (TNF-α) polymorphisms and Guillain-Barré syndrome (GBS) or its subtypes of acute inflammatory demyelinating polyneuropathy (AIDP), acute motor axonal neuropathy (AMAN), and acute motor-sensory axonal neuropathy (AMSAN). A total of six studies with 1013 cases and 1029 controls were included. Our pooled data indicated that TNF-α 308G/A polymorphism was significantly associated with GBS, AMAN, and AMSAN but not with AIDP; TNF-α 857C/T polymorphism was significantly associated with AMAN but not with GBS or AIDP. Besides, no association was found between TNF-α 238G/A and 863C/A polymorphisms and GBS or its subtypes.

A rating scale for the severity of Guillain-Barré syndrome.

INTRODUCTION: The objective of this study was to develop a rating scale to assess the severity of Guillain-Barré syndrome (GBS). METHODS: The preliminary rating scale, which contained 11 items, was developed by the Delphi method, and data of 258 patients were collected to evaluate it. Item analysis was accomplished by 100 patients; the additional 158 patients were used to evaluate the reliability, validity, and discriminative ability of the rating scale. The structure of the rating scale was testified by the confirmatory factor analysis and also made a further evaluation by the correlation analysis. RESULTS: The rating scale contained 10 items. The three factors mainly generalized the motor function, cranial nerve function and autonomic function. The results of reliability and validity showed that the structure of the rating scale was good (χ2 =68.25, df=32, χ2 /df=2.13, normed fit index (NFI)=0.919, non-normed fit index (NNFI)=0.936, comparative fit index (CFI)=0.96, a root mean square error of approximation (RMSEA)=0.085), and the Cronbach's α coefficient for the scale was .852, with the three dimensions ranging from .585 to .752. CONCLUSION: Reliability and validity of the rating scale are all satisfied. The scale contained the main clinical presentations of GBS, and it is suitable to evaluate the severity of GBS.

Guillain-Barré Syndrome, variants & forms fruste: Reclassification with new criteria.

OBJECTIVES: This study aimed to evaluate the clinical and electrophysiological characteristics of various distinctive classical and localised Guillain-Barré syndrome (GBS) subtypes. PATIENTS AND METHODS: Clinical characteristics and electrophysiological data of sixty-one consecutive patients admitted between 2012 and 2015 were systematically analysed and reclassified according to the new GBS clinical classification. Neurophysiology was evaluated with Hadden et al.'s vs recently proposed Rajabally et al.'s criteria. Functional severity and clinical outcome of various GBS subtypes were ascertained. RESULTS: All patients initially identified as GBS or related disorders can be sub-classified into having classical GBS (41, 67%), classic Miller-Fisher Syndrome (MFS) (6, 10%), Pharyngeal-cervical-brachial (PCB) (3, 5%), paraparetic GBS (4, 7%), bifacial weakness with paresthesia (3, 5%), acute ophthalmoparesis (AO) (1, 2%) and overlap syndrome (3, 5%): one (2%) with GBS/Bickerstaff brainstem encephalitis overlap and 2 (3%) with GBS/MFS overlap. Greater proportion of axonal classical GBS (67% vs 55%, p=0.372) seen with Rajabally et al.'s criteria and a predominantly axonal form of paraparetic variant (75%) independent of electrodiagnostic criteria were more representative of Asian GBS cohort. Classical GBS patients had lowest admission and discharge Medical Research Council Sum Score (MRCSS), greater functional disability and longest length of in-patient stay. Twenty (20/21, 95%) patients who needed mechanical ventilation had classical GBS. Patients required repeated dose of intravenous immunoglobulin (5/6, 3%) or plasma exchange (4/4, 100%) more frequently had axonal form of classical GBS. CONCLUSION: Phenotype recognition based on new GBS clinical classification, supported by electrodiagnostic study permits more precise clinical subtypes determination and outcome prognostication.

Early discrimination of sensorimotor Guillain-Barré syndrome into demyelinating or axonal subtype by automated nerve excitability testing.

In the early stage of disease, differentiating acute inflammatory demyelinating polyneuropathy (AIDP) and acute motor sensory axonal neuropathy (AMSAN) using only a conventional nerve conduction studies (NCS) may be difficult. We evaluated the differences in the motor axonal excitability properties of 16 cases of sensorimotor Guillain-Barré syndrome by nerve excitability testing (NET). The antiganglioside antibody assay and follow-up NCS resulted in 12 patients diagnosed as AIDP and 4 patients as AMSAN. Clinical and excitability parameters in each group were compared with those in 30 normal controls. Automated NET with threshold tracking techniques was used to calculate the strength-duration time constant (SDTC), threshold electrotonus (TE), current-threshold relationship (CTR), and recovery cycle (RC) of excitability. Except for subtle changes in excitability parameters, AIDP showed no definitive difference relative to normal controls. Comparison between AMSAN and normal controls also revealed no significant differences in the SDTC, TE, and CTR parameters. However, there were clear differences in some of the RC parameters: the relative refractory period was significantly longer in the AMSAN group than in the AIDP group (4.40 ± 1.11 vs. 3.09 ± 1.01 ms, mean ± SEM; p < 0.001), while superexcitability was significantly less prominent in the AMSAN group (-6.80 ± 10.30 vs. -26.48 ± 1.17%, mean ± SEM; p < 0.001). Our study identified that both AIDP and AMSAN were associated with subtle changes in excitability properties. Nonetheless, the prominent increase in refractoriness in AMSAN suggests the presence of a nodal conduction block.