Neurophysiologic findings in early acute inflammatory demyelinating polyradiculoneuropathy

Guillain-Barré syndrome: a comprehensive review

Guillain-Barré syndrome (GBS) is a potentially devastating yet treatable disorder. A classically postinfectious, immune-mediated, monophasic polyradiculoneuropathy, it is the leading global cause of acquired neuromuscular paralysis. In most cases, the immunopathological process driving nerve injury is ill-defined. Diagnosis of GBS relies on clinical features, supported by laboratory findings and electrophysiology. Although previously divided into primary demyelinating or axonal variants, this dichotomy is increasingly challenged, and is not endorsed by the recent European Academy of Neurology (EAN)/Peripheral Nerve Society (PNS) guidelines. Intravenous immunoglobulin and plasma exchange remain the primary modalities of treatment, regardless of the electrophysiological subtype. Most patients recover, but approximately one-third require mechanical ventilation, and 5% die. Disease activity and treatment response are currently monitored through interval neurological examination and outcome measures, and the potential role of fluid biomarkers is under ongoing scrutiny. Novel potential therapies for GBS are being explored but none have yet modified clinical practice. This review provides a comprehensive update on the pathological and clinical aspects of GBS for clinicians and scientists.

Utilizing nerve conduction studies to identify very early Guillain-Barré syndrome and distinguish it from mimics in emergency settings

INTRODUCTION/AIMS

Accurately diagnosing Guillain-Barré syndrome (GBS) in its early stages and distinguishing it from mimics poses challenges. This study aimed to evaluate the utility of an existing electrodiagnostic criterion in very early GBS (VEGBS) for discerning mimics. Additionally, we explored specific electrophysiological abnormalities in VEGBS to design a new diagnostic criterion for more accurate VEGBS diagnosis.

METHODS

We retrospectively identified all patients with flaccid quadriparesis initially suspected of GBS who underwent nerve conduction studies (NCS) ≤4 days from symptom onset. We then retrieved their NCS data and applied an existing electrodiagnostic criterion for sensitivity and specificity analyses based on the final discharge diagnosis. Furthermore, we designed a new criterion based on the observed electrophysiological abnormalities that have maximum specificity and at least 50% sensitivity.

RESULTS

Among 70 patients suspected of VEGBS, 44 (63%) received a final diagnosis of GBS, while in 26 (37%), the GBS diagnosis was later refuted. Umapathi's definite criterion exhibited a sensitivity of 61.36% and a specificity of 92.31%. The probable and possible groups showed very high sensitivity (90.91% and 100%, respectively); however, specificity was low (57.69% and 30.77%, respectively) in the very early stage. Our proposed criterion demonstrated a sensitivity of 88.64% (CI: 75.44%-96.21%) and a specificity of 96.15% (CI: 80.36%-99.90%).

DISCUSSION

The criterion based on presumed electrophysiological correlates of specific early GBS pathophysiology proved more effective than the existing electrodiagnostic criterion in differentiating VEGBS from mimics.

Electrodiagnostic studies and new diagnostic modalities for evaluation of peripheral nerve disorders

Electrodiagnostic studies (EDx) are frequently performed in the diagnostic evaluation of peripheral nerve disorders. There is increasing interest in the use of newer, alternative diagnostic modalities, in particular imaging, either to complement or replace established EDx protocols. However, the evidence to support this approach has not been expansively reviewed. In this paper, diagnostic performance data from studies of EDx and other diagnostic modalities in common peripheral nerve disorders have been analyzed and described, with a focus on radiculopathy, plexopathy, compressive neuropathies, and the important neuropathy subtypes of Guillain-Barré syndrome, chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), vasculitic neuropathy and diabetic neuropathy. Overall EDx retains its place as a primary diagnostic modality in the evaluated peripheral nerve disorders. Magnetic resonance imaging and ultrasound have developed important complementary diagnostic roles in compressive and traumatic neuropathies and atypical CIDP, but their value is more limited in other neuropathy subtypes. Identification of hourglass constriction in nerves of patients with neuralgic amyotrophy may have therapeutic implications. Investigation of radiculopathy is confounded by poor correlation between clinical features and imaging findings and the lack of a diagnostic gold standard. There is a need to enhance the literature on the utility of these newer diagnostic modalities.

Clinical and Electrophysiological Characteristics of Very Early Guillain-Barré Syndrome

PURPOSE

This study compared the clinical and electrodiagnostic (EDX) features and long-term outcomes of patients with very early Guillain-Barré syndrome (VEGBS, duration of illness ≤4 days) and those with early/late (>4 days)-presenting GBS.

METHODS

One hundred patients with GBS were clinically evaluated and categorized into VEGBS and early/late GBS groups. Electrodiagnostic studies were performed on the bilateral median, ulnar, and fibular motor nerves and the bilateral median, ulnar, and sural sensory nerves. Admission and peak disability were assessed using the 0 to 6 Guillain-Barré Syndrome Disability Scale (GBSDS). The primary outcome was disability at 6 months, which was categorized as complete (GBSDS ≤1) or poor (GBSDS ≥2). The secondary outcomes were frequencies of abnormal electrodiagnostic findings, in-hospital progression, and mechanical ventilation (MV).

RESULTS

Patients with VEGBS had higher peak disability (median 5 vs. 4; P = 0.02), frequent in-hospital disease progression (42.9% vs. 19.0%, P < 0.01), needed MV (50% vs. 22.4%; P < 0.01), and less frequent albuminocytologic dissociation (52.4% vs. 74.1%; P = 0.02) than those with early/late GBS. Thirteen patients were lost to follow-up at 6 months (nine patients with VEGBS and four patients with early/late GBS). The proportion of patients with complete recovery at 6 months was comparable (60.6% vs. 77.8%; P = ns ). Reduced d-CMAP was the most common abnormality, noted in 64.7% and 71.6% of patients with VEGBS and early/late GBS, respectively ( P = ns). Prolonged distal motor latency (≥130%) was more common in early/late GBS than in VEGBS (36.2% vs. 25.4%; P = 0.02), whereas absent F-waves were more frequent in VEGBS (37.7% vs. 28.7%; P = 0.03).

CONCLUSIONS

Patients with VEGBS were more disabled at admission than those with early/late GBS. However, 6 month's outcomes were similar between the groups. F-wave abnormalities were frequent in VEGBS, and distal motor latency prolongation was common in early/late GBS.

Factors Associated with Respiratory Insufficiency in Children with Guillain-Barré Syndrome

OBJECTIVE

 The risk factors for respiratory insufficiency in children with Guillain-Barré syndrome (GBS) are poorly known. This study aimed to investigate the factors associated with respiratory insufficiency in children with GBS.

METHODS

 This retrospective study included children diagnosed with GBS by pediatric neurologists and admitted at the Wuhan Children's Hospital and other hospitals from January 2013 to October 2022. The patients were divided into the respiratory insufficiency and nonrespiratory insufficiency groups according to whether they received assist breathing during treatment.

RESULTS

 The median (interquartile range) age of onset of 103 patients were 5 (3.1-8.5) years, 69 (67%) were male, and 64 (62.1%) had a history of precursor infection. Compared with the nonrespiratory insufficiency group, the respiratory insufficiency group showed more facial and/or bulbar weakness (p = 0.002), a higher Hughes Functional Grading Scale (HFGS) at admission (p < 0.001), and a shorter onset-to-admission interval (p = 0.017). Compared with the acute motor axonal neuropathy (AMAN) subtype, the acute inflammatory demyelinating polyneuropathy (AIDP) subtype showed longer days from onset to lumbar (p = 0.000), lower HFGS at admission (p = 0.04), longer onset-to-admission interval (p = 0.001), and more cranial nerve involvement (p = 0.04). The incidence of respiratory insufficiency between AIDP and AMAN showed no statistical difference (p > 0.05).

CONCLUSION

 In conclusion, facial and/or bulbar weakness, HFGS at admission, and onset-to-admission interval were associated with respiratory insufficiency and might be useful prognostic markers in children with GBS.

Serial Nerve Conduction Studies in Guillain-Barré Syndrome: Its Usefulness and Precise Timing

PURPOSE

Nerve conduction study (NCS) is essential for subclassifying Guillain-Barré syndrome (GBS). It is well known that the GBS subclassification can change through serial NCSs. However, the usefulness of serial NCSs is debatable, especially in patients with early stage GBS.

METHODS

Follow-up NCS data within 3 weeks (early followed NCS, EFN) and within 3 to 10 weeks (late-followed NCS, LFN) were collected from 60 patients with GBS who underwent their first NCS (FN) within 10 days after symptom onset. Each NCS was classified into five subtypes (normal, demyelinating, axonal, inexcitable, and equivocal), according to Hadden's and Rajabally's criteria. We analyzed the frequency of significant changes in classification (SCCs) comprising electrodiagnostic aggravation and subtype shifts between demyelinating and axonal types according to follow-up timing.

RESULTS

Between FN and EFN, 33.3% of patients with Hadden's criteria and 18.3% with Rajabally's criteria showed SCCs. Between FN and LFN, 23.3% of patients with Hadden's criteria and 21.7% with Rajabally's criteria showed SCCs, of which 71.4% (Hadden's criteria) and 46.2% (Rajabally's criteria) already showed SCCs from the EFN. The conditions of delayed SCCs between EFN and LFN were very early FN, mild symptoms at the FN, or persistent electrophysiological deterioration 3 weeks after symptom onset.

CONCLUSIONS

A substantial proportion of patients with GBS showed significant changes in neurophysiological classification at the early stage. Serial NCS may be helpful for precise neurophysiological classification. This study suggests that follow-up NCSs should be performed within 3 weeks of symptom onset in patients with GBS in whom FN was performed within 10 days of symptom onset.

European Academy of Neurology/Peripheral Nerve Society Guideline on diagnosis and treatment of Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is an acute polyradiculoneuropathy. Symptoms may vary greatly in presentation and severity. Besides weakness and sensory disturbances, patients may have cranial nerve involvement, respiratory insufficiency, autonomic dysfunction and pain. To develop an evidence-based guideline for the diagnosis and treatment of GBS, using Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology a Task Force (TF) of the European Academy of Neurology (EAN) and the Peripheral Nerve Society (PNS) constructed 14 Population/Intervention/Comparison/Outcome questions (PICOs) covering diagnosis, treatment and prognosis of GBS, which guided the literature search. Data were extracted and summarised in GRADE Summaries of Findings (for treatment PICOs) or Evidence Tables (for diagnostic and prognostic PICOs). Statements were prepared according to GRADE Evidence-to-Decision (EtD) frameworks. For the six intervention PICOs, evidence-based recommendations are made. For other PICOs, good practice points (GPPs) are formulated. For diagnosis, the principal GPPs are: GBS is more likely if there is a history of recent diarrhoea or respiratory infection; CSF examination is valuable, particularly when the diagnosis is less certain; electrodiagnostic testing is advised to support the diagnosis; testing for anti-ganglioside antibodies is of limited clinical value in most patients with typical motor-sensory GBS, but anti-GQ1b antibody testing should be considered when Miller Fisher syndrome (MFS) is suspected; nodal-paranodal antibodies should be tested when autoimmune nodopathy is suspected; MRI or ultrasound imaging should be considered in atypical cases; and changing the diagnosis to acute-onset chronic inflammatory demyelinating polyradiculoneuropathy (A-CIDP) should be considered if progression continues after 8 weeks from onset, which occurs in around 5% of patients initially diagnosed with GBS. For treatment, the TF recommends intravenous immunoglobulin (IVIg) 0.4 g/kg for 5 days, in patients within 2 weeks (GPP also within 2-4 weeks) after onset of weakness if unable to walk unaided, or a course of plasma exchange (PE) 12-15 L in four to five exchanges over 1-2 weeks, in patients within 4 weeks after onset of weakness if unable to walk unaided. The TF recommends against a second IVIg course in GBS patients with a poor prognosis; recommends against using oral corticosteroids, and weakly recommends against using IV corticosteroids; does not recommend PE followed immediately by IVIg; weakly recommends gabapentinoids, tricyclic antidepressants or carbamazepine for treatment of pain; does not recommend a specific treatment for fatigue. To estimate the prognosis of individual patients, the TF advises using the modified Erasmus GBS outcome score (mEGOS) to assess outcome, and the modified Erasmus GBS Respiratory Insufficiency Score (mEGRIS) to assess the risk of requiring artificial ventilation. Based on the PICOs, available literature and additional discussions, we provide flow charts to assist making clinical decisions on diagnosis, treatment and the need for intensive care unit admission.

European Academy of Neurology/Peripheral Nerve Society Guideline on diagnosis and treatment of Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is an acute polyradiculoneuropathy. Symptoms may vary greatly in presentation and severity. Besides weakness and sensory disturbances, patients may have cranial nerve involvement, respiratory insufficiency, autonomic dysfunction and pain. To develop an evidence-based guideline for the diagnosis and treatment of GBS, using Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology, a Task Force (TF) of the European Academy of Neurology (EAN) and the Peripheral Nerve Society (PNS) constructed 14 Population/Intervention/Comparison/Outcome questions (PICOs) covering diagnosis, treatment and prognosis of GBS, which guided the literature search. Data were extracted and summarised in GRADE Summaries of Findings (for treatment PICOs) or Evidence Tables (for diagnostic and prognostic PICOs). Statements were prepared according to GRADE Evidence-to-Decision (EtD) frameworks. For the six intervention PICOs, evidence-based recommendations are made. For other PICOs, good practice points (GPPs) are formulated. For diagnosis, the principal GPPs are: GBS is more likely if there is a history of recent diarrhoea or respiratory infection; CSF examination is valuable, particularly when the diagnosis is less certain; electrodiagnostic testing is advised to support the diagnosis; testing for anti-ganglioside antibodies is of limited clinical value in most patients with typical motor-sensory GBS, but anti-GQ1b antibody testing should be considered when Miller Fisher syndrome (MFS) is suspected; nodal-paranodal antibodies should be tested when autoimmune nodopathy is suspected; MRI or ultrasound imaging should be considered in atypical cases; and changing the diagnosis to acute-onset chronic inflammatory demyelinating polyradiculoneuropathy (A-CIDP) should be considered if progression continues after 8 weeks from onset, which occurs in around 5% of patients initially diagnosed with GBS. For treatment, the TF recommends intravenous immunoglobulin (IVIg) 0.4 g/kg for 5 days, in patients within 2 weeks (GPP also within 2-4 weeks) after onset of weakness if unable to walk unaided, or a course of plasma exchange (PE) 12-15 L in four to five exchanges over 1-2 weeks, in patients within 4 weeks after onset of weakness if unable to walk unaided. The TF recommends against a second IVIg course in GBS patients with a poor prognosis; recommends against using oral corticosteroids, and weakly recommends against using IV corticosteroids; does not recommend PE followed immediately by IVIg; weakly recommends gabapentinoids, tricyclic antidepressants or carbamazepine for treatment of pain; does not recommend a specific treatment for fatigue. To estimate the prognosis of individual patients, the TF advises using the modified Erasmus GBS outcome score (mEGOS) to assess outcome, and the modified Erasmus GBS Respiratory Insufficiency Score (mEGRIS) to assess the risk of requiring artificial ventilation. Based on the PICOs, available literature and additional discussions, we provide flow charts to assist making clinical decisions on diagnosis, treatment and the need for intensive care unit admission.

Electrophysiological and functional signs of Guillain-Barré syndrome predicted by a multiscale neuromuscular computational model

Objective. The diagnosis of nerve disorders in humans has relied heavily on the measurement of electrical signals from nerves or muscles in response to electrical stimuli applied at appropriate locations on the body surface. The present study investigated the demyelinating subtype of Guillain-Barré syndrome using multiscale computational model simulations to verify how demyelination of peripheral axons may affect plantar flexion torque as well as the ongoing electromyogram (EMG) during voluntary isometric or isotonic contractions. Approach. Changes in axonal conduction velocities, mimicking those found in patients with the disease at different stages, were imposed on a multiscale computational neuromusculoskeletal model to simulate subjects performing unipodal plantar flexion force and position tasks. Main results. The simulated results indicated changes in the torque signal during the early phase of the disease while performing isotonic tasks, as well as in torque variability after partial conduction block while performing both isometric and isotonic tasks. Our results also indicated changes in the root mean square values and in the power spectrum of the soleus EMG signal as well as changes in the synchronisation index computed from the firing times of the active motor units. All these quantitative changes in functional indicators suggest that the adoption of such additional measurements, such as torques and ongoing EMG, could be used with advantage in the diagnosis and be relevant in providing extra information for the neurologist about the level of the disease. Significance. Our findings enrich the knowledge of the possible ways demyelination affects force generation and position control during plantarflexion. Moreover, this work extends computational neuroscience to computational neurology and shows the potential of biologically compatible neuromuscular computational models in providing relevant quantitative signs that may be useful for diagnosis in the clinic, complementing the tools traditionally used in neurological electrodiagnosis.

Axonal pathology in early stages of Guillain-Barré syndrome

INTRODUCTION

Guillain-Barré syndrome (GBS) is an acute-onset, immune-mediated disease of the peripheral nervous system. It may be classified into 2 main subtypes: demyelinating (AIDP) and axonal (AMAN). This study aims to analyse the mechanisms of axonal damage in the early stages of GBS (within 10 days of onset).

DEVELOPMENT

We analysed histological, electrophysiological, and imaging findings from patients with AIDP and AMAN, and compared them to those of an animal model of myelin P2 protein-induced experimental allergic neuritis. Inflammatory oedema of the spinal nerve roots and spinal nerves is the initial lesion in GBS. The spinal nerves of patients with fatal AIDP may show ischaemic lesions in the endoneurium, which suggests that endoneurial inflammation may increase endoneurial fluid pressure, reducing transperineurial blood flow, potentially leading to conduction failure and eventually to axonal degeneration. In patients with AMAN associated with anti-ganglioside antibodies, nerve conduction block secondary to nodal sodium channel dysfunction may affect the proximal, intermediate, and distal nerve trunks. In addition to the mechanisms involved in AIDP, active axonal degeneration in AMAN may be associated with nodal axolemma disruption caused by anti-ganglioside antibodies.

CONCLUSION

Inflammatory oedema of the proximal nerve trunks can be observed in early stages of GBS, and it may cause nerve conduction failure and active axonal degeneration.

Axonal pathology in early stages of Guillain-Barré syndrome

INTRODUCTION

Guillain-Barré syndrome (GBS) is an acute-onset, immune-mediated disease of the peripheral nervous system. It may be classified into 2 main subtypes: demyelinating (AIDP) and axonal (AMAN). This study aims to analyse the mechanisms of axonal damage in the early stages of GBS (within 10days of onset).

DEVELOPMENT

We analysed histological, electrophysiological, and imaging findings from patients with AIDP and AMAN, and compared them to those of an animal model of myelin P2 protein-induced experimental allergic neuritis. Inflammatory oedema of the spinal nerve roots and spinal nerves is the initial lesion in GBS. The spinal nerves of patients with fatal AIDP may show ischaemic lesions in the endoneurium, which suggests that endoneurial inflammation may increase endoneurial fluid pressure, reducing transperineurial blood flow, potentially leading to conduction failure and eventually to axonal degeneration. In patients with AMAN associated with anti-ganglioside antibodies, nerve conduction block secondary to nodal sodium channel dysfunction may affect the proximal, intermediate, and distal nerve trunks. In addition to the mechanisms involved in AIDP, active axonal degeneration in AMAN may be associated with nodal axolemma disruption caused by anti-ganglioside antibodies.

CONCLUSION

Inflammatory oedema of the proximal nerve trunks can be observed in early stages of GBS, and it may cause nerve conduction failure and active axonal degeneration.

Acute nitrous oxide-induced neuropathy mimicking Guillain-Barré Syndrome

BACKGROUND AND OBJECTIVE

The early clinical features of nitrous oxide (N₂ O)-induced neuropathy were mimicking that of Guillain-Barré Syndrome (GBS). We aimed to explore clinical and laboratory characteristics of N₂ O-induced neuropathy in comparison with GBS.

METHODS

We retrospectively reviewed data of 15 patients with N₂ O-induced neuropathy and compared them with 15 GBS patients.

RESULTS

The age of the N₂ O-induced neuropathy group was significantly younger than that in the GBS group (22 ± 5 vs 45 ± 17). Paresthesia was more common in N₂ O-induced neuropathy group (100% vs 53.3%). The proportion of distal upper limbs weakness was lower than that in GBS group (20.0% vs 93.3%). There was no significant difference in distal weakness of the lower limbs (100% vs 80.0%). The incidence of motor conduction block and compound muscle action potential amplitude reduction in upper limbs was lower than that in GBS group (6.7% vs 60.0%; 26.7% vs 80.0%). The sensory nerve action potential amplitude drop in the lower limbs was more severe than that in GBS group (53.3% vs 0). The increase of Mean corpuscular volume (MCV) was more pronounced compared to GBS group (96.97 ± 6.00 vs 88.55 ± 5.41). High homocysteine levels were more common in N₂ O-related group [29.80(11.60, 70.50) vs 14.35(9.22, 19.30)].

CONCLUSION

Typical clinical features of the acute N₂ O neuropathy appears to be a myeloneuropathy, affecting the lower limbs more than the upper limbs, mixed axonal-demyelinating electrophysiological performance, higher homocysteine level and larger MCV and common posterior spinal cord involvement in cervical segment. This article is protected by copyright. All rights reserved.

The Presence and Significance of A-Waves-A Retrospective Review of 679 Patients

PURPOSE

A-waves are late responses that have been reported in healthy individuals and patients with neurologic conditions. The mechanism(s) responsible for their generation and their clinical significance are not fully understood. The aim was to better characterize A-waves.

METHODS

A retrospective study was conducted in a high-volume Neurophysiology Department in a tertiary hospital in Melbourne, Australia. Consecutive neurophysiological tests including F-wave studies performed between July 2017 and September 2018 were reviewed to identify A-waves. Patients' characteristics and neurophysiological diagnoses were recorded.

RESULTS

A total of 679 patients were included in the analysis and a total of 2,730 nerves were studied. A-waves were most commonly found in tibial nerves, followed by peroneal, median, and ulnar nerves. A-waves were seen in 39.4% of individuals with otherwise normal nerve conduction studies and 39.1% of individuals with entrapment neuropathy. They were most seen in demyelinating neuropathy (85.7%), followed by mixed neuropathy (73.3%), anterior horn cell disease (66.7%), axonal neuropathy (61.2%), and radiculopathy (53.1%). Most patients with demyelinating neuropathy had multiple A-waves (61.9%), but these were also seen in 15.2% of individuals with otherwise normal nerve conduction studies and in 40% of those with other neurologic conditions. A-waves were more often seen in individuals older than 60 years.

CONCLUSIONS

A-waves are commonly seen in symptomatic individuals with otherwise normal nerve conduction studies and individuals with various neurologic conditions but are more commonly found in nerves with otherwise abnormal electrophysiological testing. A-waves are most seen in tibial nerves. Multiple A-waves were more commonly seen in demyelinating neuropathy than other conditions.

[Pathophysiological and diagnostic aspects of Guillain-Barré syndrome]

Guillain-Barré syndrome (GBS) is the most common cause of acute neuropathy. It usually onset with a rapidly progressive ascending bilateral weakness with sensory disturbances, and patients may require intensive treatment and close monitoring as about 30% have a respiratory muscle weakness and about 10% have autonomic dysfunction. The diagnosis of GBS is based on clinical history and examination. Complementary examinations are performed to rule out a differential diagnosis and to secondarily confirm the diagnosis. GBS is usually preceded by an infectious event in ≈ 2/3 of cases. Infection leads to an immune response directed against carbohydrate antigens located on the infectious agent and the formation of anti-ganglioside antibodies. By molecular mimicry, these antibodies can target structurally similar carbohydrates found on host's nerves. Their binding results in nerve conduction failure or/and demyelination which can lead to axonal loss. Some anti-ganglioside antibodies are associated with particular variants of GBS: the Miller-Fisher syndrome, facial diplegia and paresthesias, the pharyngo-cervico-brachial variant, the paraparetic variant, and the Bickerstaff brainstem encephalitis. Their semiological differences might be explained by a distinct expression of gangliosides among nerves. The aim of this review is to present pathophysiological aspects and the diagnostic approach of GBS and its variants.

Re-evaluating the accuracy of optimized electrodiagnostic criteria in very early Guillain-Barré syndrome: a sequential study

Using recent optimized electrodiagnostic criteria sets, we aimed at verifying the accuracy of initial nerve conduction studies (NCS) in classic very early Guillain-Barré syndrome (VEGBS), ≤ 4 days after onset, compared with the results of serial NCS. This is a retrospective study based on unreported and consecutive VEGBS patients admitted to two university hospitals between 2015 and 2019. Each patient had serial NCS in at least four nerves. Initial NCS studies were done within 4 days after onset, and serial ones from days 20 to 94. Electrophysiological recordings were blinded evaluated by four of the authors, GBS subtype being established accordingly. Seven adult classic VEGBS patients were identified with a median age of 58 years. At first NCS, GBS subtyping was only possible in 1 case that exhibited an axonal pattern, the remaining patterns being equivocal in 3, and mixed (combining axonal and demyelinating criteria) in the remaining 3. Upon serial NSC there was a rather intricate evolution of electrophysiological GBS patterns, 3 of them being classified as axonal or demyelinating, and the remaining 4 as equivocal or mixed. NCS in VEGBS systematically allows detection of changes suggestive of peripheral neuropathy, though even after serial studies accurate GBS subtyping was only possible in 43% of cases. We provide new pathophysiological insights for better understanding of the observed electrophysiological changes.

Klinische Neurophysiologie auf der pädiatrischen Intensivstation

Auf pädiatrischen Intensivstationen kommt es häufig zum Einsatz neurophysiologischer Untersuchungsmethoden. Bei akuten Enzephalopathien oder in Situationen, in denen ein hohes Risiko für epileptische Anfälle besteht, werden verschiedene Varianten des EEGs verwendet. Bei Hinweisen auf neuromuskuläre Erkrankungen sind die Neurographie, die evozierten Potentiale, und die Elektromyographie die entscheidenden diagnostischen Methoden. Im Falle erworbener Hirnschädigungen wie z. B. nach Reanimationsereignissen oder bei Schädel-Hirn-Traumata können sowohl das EEG, als auch die evozierten Potentiale zur Prognoseabschätzung verwendet werden. Die Umstände auf der Intensivstation erschweren bei all diesen Methoden die Durchführung und die Interpretation. Viele Patienten werden mit Medikamenten behandelt, die die Untersuchungsergebnisse beeinflussen (insbesondere Sedativa und Muskelrelaxantien). Elektronische Geräte, z. B. für die Beatmung der Patienten, können zum Auftreten deutlicher Artefakte bei den neurophysiologischen Untersuchungen führen. Im vorliegenden Artikel werden die Einsatzbereiche neurophysiologischer Methoden auf pädiatrischen Intensivstationen beschrieben und auf Details bei der Anwendung eingegangen.

Very early and early neurophysiological abnormalities in Guillain-Barré syndrome: A 4-year retrospective study

Background and purpose

In its initial stages, Guillain–Barré syndrome (GBS) is difficult to identify, because diagnostic criteria may not always be fulfilled. With this retrospective study, we wanted to identify the most common electrophysiological abnormalities seen on neurophysiological examination of GBS patients and its variants in the early phases.

Methods

We reviewed the clinical records of patients admitted to our Neurology Unit with a confirmed diagnosis of GBS. The study sample was divided in two subgroups according to whether the neurophysiological examination was performed: within 7 days (very early group) or within 7–15 days (early group). H reflex, F waves, and motor and sensory conduction parameters were judged abnormal if they were outside the normal range for at least two nerves. We evaluated neurophysiological findings in Miller–Fisher syndrome (MFS) separately.

Results

The study sample comprised 36 patients. In GBS, the most frequent abnormal neurophysiological parameter was the bilateral absence of the H reflex, followed by F wave abnormalities. Motor conduction parameters were altered in less than 50% of patients, and even less common were sensory nerve action potential reduction and the "sural‐sparing" pattern. In MFS, H reflex was absent bilaterally in 100% of patients, followed by a predominant peripheral sensory involvement, whereas motor conduction parameters were frequently normal.

Conclusions

Bilateral absence of the H reflex is the most sensitive parameter in early diagnosis of GBS and its variants.

Neuromuscular Respiratory Failure

Neuromuscular respiratory failure can result from any disease that causes weakness of bulbar and/or respiratory muscles. Once compensatory mechanisms are overwhelmed, hypoxemic and hypercapnic respiratory failure ensues. The diagnosis of neuromuscular respiratory failure is primarily clinical, but arterial blood gases, bedside spirometry, and diaphragmatic ultrasonography can help in early assessment. Intensive care unit (ICU) admission is indicated for patients with severe bulbar weakness or rapidly progressing appendicular weakness. Intubation should be performed electively, particularly in patients with dysautonomia. Patients with an underlying treatable cause have the potential to regain functional independence with meticulous ICU care.

Elektrodiagnostik im frühen Stadium des Guillain-Barré-Syndroms

Das Guillain-Barré-Syndrom (GBS) ist eine entzündliche Erkrankung des Nervensystems mit fortschreitenden Lähmungen und Sensibilitätsstörungen. Es ist umstritten, ob GBS-Subtypen bereits durch einzelne elektrophysiologische Untersuchungen sicher klassifizierbar sind. In dieser Studie verglichen die Autoren elektrophysiologische Tests in frühen und späten Stadien des GBS und bewerteten im Ultraschall sichtbare Nervenveränderungen.

Case Report and Literature Analysis: Guillain-Barré Syndrome With Delayed Unilateral Facial Palsy

Guillain-Barré syndrome (GBS) is an acute inflammatory polyradiculoneuropathy in which most patients have cranial nerve involvement, with facial nerve involvement being the most common. However, delayed facial palsy (DFP) with asymmetric facial palsy is a rare manifestation of GBS, and the mechanism is unclear. We report a case of GBS combined with delayed unilateral facial palsy and review previously reported cases of GBS combined with DFP. A total of 28 cases of GBS with DFP, including the case in this report, were included in this study. The occurrence of DFP may be related to early subclinical demyelination of the facial nerve, the blood-nerve barrier of the facial nerve, facial movement, and descending reversible paralysis. The occurrence of unilateral facial palsy may be related to Campylobacter jejuni, specific anti-ganglioside antibodies, and the site of central nervous system anatomical involvement. There is no evidence that immunotherapy is related to the shortening of DFP course and improving patients' prognosis.

The value of sensory nerve conduction studies in the diagnosis of Guillain-Barré syndrome

Electrophysiology plays a determinant role in Guillain-Barré syndrome (GBS) diagnosis, classification, and prognostication. However, traditional electrodiagnostic (EDX) criteria for GBS rely on motor nerve conduction studies (NCS) and are suboptimal early in the course of the disease or in the setting of GBS variants. Sensory nerve conduction studies, including the sural-sparing pattern and the sensory ratio are not yet included in EDX criteria despite their well-established role in GBS diagnosis. The aim of this review is to discuss the diagnostic value of sensory NCS in GBS, their role in establishing the diagnosis and predicting the outcome according to the various subtypes of the disease.

Guillain-Barré syndrome

Guillain-Barré syndrome is the most common cause of acute flaccid paralysis worldwide. Most patients present with an antecedent illness, most commonly upper respiratory tract infection, before the onset of progressive motor weakness. Several microorganisms have been associated with Guillain-Barré syndrome, most notably Campylobacter jejuni, Zika virus, and in 2020, the severe acute respiratory syndrome coronavirus 2. In C jejuni-related Guillain-Barré syndrome, there is good evidence to support an autoantibody-mediated immune process that is triggered by molecular mimicry between structural components of peripheral nerves and the microorganism. Making a diagnosis of so-called classical Guillain-Barré syndrome is straightforward; however, the existing diagnostic criteria have limitations and can result in some variants of the syndrome being missed. Most patients with Guillain-Barré syndrome do well with immunotherapy, but a substantial proportion are left with disability, and death can occur. Results from the International Guillain-Barré Syndrome Outcome Study suggest that geographical variations exist in Guillain-Barré syndrome, including insufficient access to immunotherapy in low-income countries. There is a need to provide improved access to treatment for all patients with Guillain-Barré syndrome, and to develop effective disease-modifying therapies that can limit the extent of nerve injury. Clinical trials are currently underway to investigate some of the potential therapeutic candidates, including complement inhibitors, which, together with emerging data from large international collaborative studies on the syndrome, will contribute substantially to understanding the many facets of this disease.

Recurrent Miller Fisher: A Case Report Along With a Literature and an EMG/NCS Review

MFS has been reported to recur in 10-12% of patients. There may be a genetic component related to HLA-DR2. Anti-GAD antibodies can be present in MFS along with anti-GQ1b. Common EMG/NCS associations consist of a predominantly axonal, sensory polyneuropathy and absent H reflexes. A 32-year-old female with a history of hypothyroidism presented to our institution twice with symptoms of diplopia, lower extremity weakness and distal paresthesias occurring a year apart. She had ophthalmoplegia, reduced reflexes, and ataxia on exam. CSF showed a borderline elevated protein of 47 and white blood cells <3. She was positive for anti-GQ1b both times. Her anti-GAD65 antibody was elevated during both admissions. EMG/NCS on her first admission revealed comparatively reduced sensory nerve action potentials (SNAPs) and a normal blink reflex. Her SNAPs improved on the second admission, however, the EMG was performed only 2 days after the onset of her symptoms, limiting some early findings that may have not matured electrophysiologically. She was treated with IVIG on both occasions with rapid recovery within 5 days. This case highlights the fact that MFS can be recurrent. It also provides further evidence that anti-GAD antibodies may be associated with MFS. Reported findings of the blink reflex in MFS are diverse and further data is needed to determine if certain findings are more predominant than others. Treatment typically consists of IVIG, though steroids may also be considered for recurrence. Prognosis is generally favorable, regardless of treatment.

Inflammatory oedema of nerve trunks may be pathogenic in very early Guillain-Barré syndrome

The aim of this paper is to analyse the pathological background of very early Guillain-Barré (VEGBS) (≤ 4 days after onset) comparing it with initial stages of experimental autoimmune neuritis (EAN). The pathological hallmark of VEGBS is inflammatory oedema predominating in proximal nerve trunks. In EAN inflammatory oedema precedes the development of demyelination or axonal degeneration; such oedema may increase endoneurial fluid pressure (EFP) stretching the perineurium and constricting the transperineurial microcirculation. Centrofascicular or wedge-shaped areas of nerve ischemia have been reported in GBS and EAN. Additional support for proximal VEGBS pathology comes from electrophysiology showing alterations in late responses as the most frequent features, and ultrasonography illustrating that main changes rely on ventral rami of spinal nerves. Selective inefficiency of the blood-nerve barrier would explain the topography of changes in VEGBS. Increased serum neurofilament light chain concentration has recently been reported in VEGBS, with no difference between demyelinating and axonal subtypes. This is a marker of axonal damage, which could be correlated with endoneurial ischemia caused by increased EFP. Inflammatory oedema of proximal nerve trunks may be pathogenic in VEGBS, and consequently there is a pressing need for therapeutic strategies to stop its rapid impact on the axons.

Utility and practice of electrodiagnostic testing in the pediatric population: An AANEM consensus statement

Nerve conduction studies and needle electromyography, collectively known as electrodiagnostic (EDX) studies, have been available for pediatric patients for decades, but the accessibility of this diagnostic modality and the approach to testing vary significantly depending on the physician and institution. The maturation of molecular diagnostic approaches and other diagnostic technologies such as neuromuscular ultrasound indicate that an analysis of current needs and practices for EDX studies in the pediatric population is warranted. The American Association of Neuromuscular & Electrodiagnostic Medicine convened a consensus panel to perform literature searches, share collective experiences, and develop a consensus statement. The panel found that electrodiagnostic studies continue to have high utility for the diagnosis of numerous childhood neuromuscular disorders, and that standardized approaches along with the use of high-quality reference values are important to maximize the diagnostic yield of these tests in infants, children, and adolescents.

Very early Guillain-Barré syndrome: A clinical-electrophysiological and ultrasonographic study

Objectives

Using recent optimized electrodiagnostic criteria sets, we primarily aimed at verifying the accuracy of the initial electrophysiological test in very early Guillain-Barré syndrome (VEGBS), ≤4 days of onset, compared with the results of serial electrophysiology. Our secondary objective was to correlate early electrophysiological results with sonographic nerve changes.

Methods

This is a retrospective study based on consecutive VEGBS patients admitted to the hospital. Each patient had serial nerve conduction studies (NCS) in at least 4 nerves. Initial NCS were done within 4 days after onset, and serial ones from the second week onwards. Electrophysiological recordings of each case were re-evaluated, GBS subtype being established accordingly. Nerve ultrasonography was almost always performed within 2 weeks after onset.

Results

Fifteen adult VEGBS patients were identified with a mean age of 57.8 years. At first NCS, VEGBS sub-typing was only possible in 3 (20%) cases that showed an axonal pattern, the remaining patterns being mixed (combining axonal and demyelinating features) in 6 (40%), equivocal in 5 (33.3%), and normal in 1 (6.7%). Upon serial NCS, 7 (46.7%) cases were categorized as acute demyelinating polyneuropathy, 7 (46.7%) as axonal GBS, and 1 (6.6%) as unclassified syndrome. Antiganglioside reactivity was detected in 5 out of the 7 axonal cases. Nerve US showed that lesions mainly involved the ventral rami of scanned cervical nerves.

Conclusions

Serial electrophysiological evaluation is necessary for accurate VEGBS subtype classification. Ultrasonography helps delineate the topography of nerve changes.

Significance

We provide new VEGBS pathophysiological insights into nerve conduction alterations within the first 4 days of the clinical course.

Diagnosis and management of Guillain-Barré syndrome in ten steps

Guillain-Barré syndrome (GBS) is a rare, but potentially fatal, immune-mediated disease of the peripheral nerves and nerve roots that is usually triggered by infections. The incidence of GBS can therefore increase during outbreaks of infectious diseases, as was seen during the Zika virus epidemics in 2013 in French Polynesia and 2015 in Latin America. Diagnosis and management of GBS can be complicated as its clinical presentation and disease course are heterogeneous, and no international clinical guidelines are currently available. To support clinicians, especially in the context of an outbreak, we have developed a globally applicable guideline for the diagnosis and management of GBS. The guideline is based on current literature and expert consensus, and has a ten-step structure to facilitate its use in clinical practice. We first provide an introduction to the diagnostic criteria, clinical variants and differential diagnoses of GBS. The ten steps then cover early recognition and diagnosis of GBS, admission to the intensive care unit, treatment indication and selection, monitoring and treatment of disease progression, prediction of clinical course and outcome, and management of complications and sequelae.

Prognostic Value of "A" Waves in Patients With Guillain Barre Syndrome

INTRODUCTION

The "A" wave is a compound action potential evoked consistently from a muscle by submaximal electric stimulation to the nerve. "A" waves were usually associated with the presence of conduction block and abounded in lower limbs more than in upper limbs. Guillain Barre syndrome is an autoimmune polyradiculoneuropathy that usually follows respiratory or gastrointestinal infections.

PURPOSE

To study the prognostic value of "A" waves in patients with Guillain Barre syndrome with different recovery patterns.

METHODS

In this study, 50 patients with GuillainBarreSyndrome were enrolled. They were divided into two groups based on the presence or absence of "A" waves in their neurophysiologic study at onset of illness. Strength of limb muscles of the involved patients was assessed at onset of the study and 6 weeks later (short-term clinical recovery) using the Medical Research Council Scale.

RESULTS

Patients with waves (29 patients: 58%) showed poorer short-term follow-up parameters than those without "A" waves (21 patients: 42%).

CONCLUSIONS

Presence of "A" waves is usually associated with conduction block and marked degree of demyelination. "A" waves carry poor prognostic value in short-term follow-up parameters in patients with Guillain Barre syndrome.

Intensive Care Management of the Neuromuscular Patient

Neuromuscular emergencies are a distinct group of acute neurological diseases with distinct characteristic presentations. Patients who suffer from this group of diseases are at immediate risk of losing protection of their native airway as well as aspirating orogastric contents. This is secondary to weakness of the muscles of the oropharynx and respiratory muscles. Although some neuromuscular emergencies such as myasthenia gravis or Guillain-Barré syndrome are well understood, others such as critical illness myopathy and neuropathy are less well characterized. In this chapter, we have discussed the pathophysiology, diagnostic evaluation, and management options in patients who are admitted to the intensive care unit. We have also emphasized the importance of a thorough understanding of the use of pharmacological anesthetic agents in this patient population.

Prognostic factors of Guillain-Barré syndrome: a 111-case retrospective review

Background

To identify the predictive factors associated with worse prognosis in the Guillain-Barré syndrome (GBS), which can be helpful to fully evaluate the disease progression and provide proper treatments.

Methods

Clinical data of 111 GBS patients who were diagnosed from 2010 to 2015 were collected and retrospectively analyzed.

Results

Patients with diabetes (P=0.031), high blood pressure at admission (P=0.034), uroschesis (P=0.028), fever (P<0.001), ventilator support (P<0.001) during hospitalization, disorder of consciousness (p=0.007) and absence of preceding respiratory infection(P=0.016) were associated with worse outcome at discharge, while abnormal sensation, ataxia, weakness and decrease of tendon reflex seemed not correlated with the Medical Research Council(MRC) score at discharge. Compared with the subtype of acute inflammatory demyelinating polyneuropathy, prognosis of Miller-Fisher syndrome (p<0.001) and cranial nerve variant (p<0.038) were better, but prognosis of acute motor axonal neuropathy(AMAN) was worse (p<0.032). Laboratory examinations at admission showed that hyperglycemia (P=0.002), high leukocyte count (P=0.010), hyperfibrinogenemia (P=0.001), hyponatremia (P=0.020), hypoalbuminemia (P=0.005), abnormal hepatic (P=0.048) and renal (P=0.009) functions were associated with poorer prognosis at discharge, while albuminocytologic dissociation in cerebrospinal fluid, GM1 and GQ1b antibody showed no correlation with the MRC score at discharge. γ-Globulin and glucocorticoid therapies showed no difference in the MRC score at the discharge.

Conclusions

AMAN, diabetes, high blood pressure, uroschesis, high body temperature, ventilator support, consciousness disorder, absence of upper respiratory tract preceding infection, hyperglycemia, hyponatremia, hypoalbuminemia, high leukocyte count, hyperfibrinogenemia, abnormal hepatic and renal function were demonstrated as poor prognostic factors.

Clinical Significance of A Waves in Acute Inflammatory Demyelinating Polyradiculoneuropathy

PURPOSE

A wave is a late response recognized during recording of F waves. Though they might be seen in healthy subjects, their presence assumes significance in a patient presenting with polyradiculoneuropathy.

METHODS

In this prospective study, 75 patients with acute inflammatory demyelinating polyradiculoneuropathy (AIDP) were enrolled. They were divided into two groups based on the presence or absence of A waves. Clinical features, electrophysiological parameters and extent of clinical recovery in short-term follow-up were analyzed.

RESULTS

A waves were present in 49 out of 75 patients (65%). Most common pattern observed was multiple A waves. Prevalence of A waves was more in lower limb nerves than upper limb nerves. Occurrence of A waves correlated with the presence of conduction block. Patients with A waves had higher Hughes grade (P = 0.003) and lower Medical Research Council sum score at 6 weeks of follow-up (P = 0.04) as compared to patients without A waves.

CONCLUSIONS

A waves are common in acute inflammatory demyelinating polyradiculoneuropathy form of Guillain Barre syndrome and are considered as a marker of demyelination. Long-term follow-up studies are required to ascertain their significance in prognostication and assessing recovery.

Spinal nerve involvement in early Guillain-Barré syndrome: The Haymaker and Kernohan's legacy

Pathological studies of early Guillain-Barré syndrome (GBS), defined as of 10days of disease onset, are scanty making it difficult to interpret the physiopathology of clinical and electrophysiological features. In 1949, Webb Haymaker and James Kernohan reported 50 clinico-pathological studies of fatal GBS cases, 32 of them having died between days 2 and 10 after onset. They established that the brunt of initial lesions, consisting of endoneurial oedema interpreted as degenerative, relied on spinal nerves. That this oedema was inflammatory was soon thereafter recognized. Two decades later, however, the pathogenic role of endoneurial oedema was disputed. In experimental allergic neuritis, considered an animal model of GBS, the initial lesion appearing on day 4 post-inoculation is marked inflammatory oedema in the sciatic nerve and lumbosacral nerve roots. Additional detailed clinico-pathological studies corroborated that the appearance of epi-perineurium at the subarachnoid angle, where anterior and posterior roots join to form the spinal nerve, is a pathological hotspot in early GBS, there developing inflammatory oedema, incipient demyelination and endoneurial ischemic zones with axonal degeneration. Furthermore, nerve ultrasonography has demonstrated predominant spinal nerve changes in early GBS, either demyelinating or axonal. Other outstanding Haymaker and Kernohan's contributions were to clarify the complex nosology of the syndrome bringing under the same rubric Landry's paralysis, acute febrile polyneuritis and GBS, and critically analyzing GBS exclusion criteria by then prevailing. It is concluded that the authors' legacy remains as relevant as ever.

Detection of proximal conduction blocks using a triple stimulation technique improves the early diagnosis of Guillain-Barré syndrome

OBJECTIVE

Current diagnostic electrophysiological criteria can miss the early stages of Guillain-Barré syndrome (GBS). We evaluated the diagnostic efficiency of the triple stimulation technique (TST) in highlighting proximal conduction blocks (CBs) in patients who do not meet the electrophysiological criteria for GBS.

METHODS

All patients with a diagnosis of clinical GBS referred to our center between September 2014 and January 2016 were included in the study. For patients who did not fulfill the electrophysiological criteria of GBS, we performed the TST examination.

RESULTS

Among the 44 included patients, 86% fulfilled the electrophysiological criteria of GBS during the initial nerve conduction study (NCS). The six remaining patients had proximal CBs revealed by TST examination. Therefore, a combination of a conventional NCS and the TST allowed 100% of the patients to be electrophysiologically diagnosed.

CONCLUSIONS

TST is useful for the diagnosis of GBS in association with NCS, particularly in the early stages of the disease.

SIGNIFICANCE

TST is a useful tool for GBS diagnosis at the early stages of the disease.

Guillain-Barré syndrome

Guillain-Barré syndrome is the most common and most severe acute paralytic neuropathy, with about 100,000 people developing the disorder every year worldwide. Under the umbrella term of Guillain-Barré syndrome are several recognisable variants with distinct clinical and pathological features. The severe, generalised manifestation of Guillain-Barré syndrome with respiratory failure affects 20-30% of cases. Treatment with intravenous immunoglobulin or plasma exchange is the optimal management approach, alongside supportive care. Understanding of the infectious triggers and immunological and pathological mechanisms has advanced substantially in the past 10 years, and is guiding clinical trials investigating new treatments. Investigators of large, worldwide, collaborative studies of the spectrum of Guillain-Barré syndrome are accruing data for clinical and biological databases to inform the development of outcome predictors and disease biomarkers. Such studies are transforming the clinical and scientific landscape of acute autoimmune neuropathies.

Acute Neuromuscular Respiratory Failure

PURPOSE OF REVIEW

Neurologists working in the hospital are often called to evaluate patients with severe muscle weakness. Some of these patients can develop ventilatory compromise and require admission to the intensive care unit (ICU). This article reviews the general evaluation of neuromuscular respiratory failure, discusses its differential diagnosis, and provides practical advice on the management of its most common causes.

RECENT FINDINGS

Determining the cause of acute neuromuscular respiratory failure is crucial because functional prognosis is poor in patients for whom the cause cannot be defined. The differential diagnosis is extensive, but the first step is to discriminate between cases related to a primary neurologic disease (primary neuromuscular respiratory failure) and those provoked by systemic disease, most often critical illness from sepsis and multiorgan failure (secondary neuromuscular respiratory failure). Guillain-Barré syndrome (GBS) and myasthenic crisis are the two most frequent causes of primary neuromuscular respiratory failure. Although they are both autoimmune conditions that benefit from the administration of plasma exchange or IV immunoglobulin (IVIg), they are otherwise very different disorders with unique features and distinct complications. Optimal strategies for mechanical ventilation also differ between these two conditions; while myasthenic crisis is ideally managed with noninvasive bilevel positive airway pressure (BiPAP) ventilation, GBS demands early intubation.

SUMMARY

Prompt recognition of neuromuscular respiratory failure can be lifesaving, and identification of its cause has substantial prognostic implications. Adequate management of these patients requires a multidisciplinary team with the neurologist at its center, not only to guide the diagnostic evaluation but often also to prescribe the optimal management.

Proximal nerve lesions in early Guillain-Barré syndrome: implications for pathogenesis and disease classification

Guillain-Barré syndrome (GBS) is an acute-onset, immune-mediated disorder of the peripheral nervous system. In early GBS, arbitrarily established up to 10 days of disease onset, patients could exhibit selective manifestations due to involvement of the proximal nerves, including nerve roots, spinal nerves and plexuses. Such manifestations are proximal weakness, inaugural nerve trunk pain, and atypical electrophysiological patterns, which may lead to delayed diagnosis. The aim of this paper was to analyze the nosology of early GBS reviewing electrophysiological, autopsy and imaging studies, both in acute inflammatory demyelinating polyneuropathy (AIDP) and acute motor/motor-sensory axonal neuropathy (AMAN/AMSAN). Early electrophysiology showed either well-defined demyelinating or axonal patterns, or a non-diagnostic pattern with abnormal late responses; there may be attenuated M responses upon lumbar root stimulation as the only finding. Pathological changes predominated in proximal nerves, in some studies, most prominent at the sides where the spinal roots unite to form the spinal nerves; on very early GBS endoneurial inflammatory edema was the outstanding feature. In the far majority of cases, spinal magnetic resonance imaging showed contrast enhancement of cauda equina, selectively involving anterior roots in AMAN. Both in AIDP and AMAN/AMSAN, ultrasonography has demonstrated frequent enlargement of ventral rami of C5-C7 nerves with blurred boundaries, whereas sonograms of upper and lower extremity peripheral nerves exhibited variable and less frequent abnormalities. We provide new insights into the pathogenesis and classification of early GBS.

Serial electrophysiological findings in Guillain-Barré syndrome not fulfilling AIDP or AMAN criteria

Guillain-Barré syndrome (GBS) is categorized into two major subtypes: acute inflammatory demyelinating polyneuropathy (AIDP) and acute motor axonal neuropathy (AMAN). However, a proportion of patients are electrophysiologically unclassified because of electrophysiological findings that do not fulfil AIDP or AMAN criteria, and underlying pathophysiological mechanisms and lesion distributions of unclassified patients are not well defined. The aims of this study are to elucidate disease pathophysiology and lesion distribution in unclassified patients. We retrospectively studied 48 consecutive GBS patients. Patients were classified on the basis of initial electrophysiological findings according to Ho's criteria. Clinical and serial electrophysiological examinations of unclassified patients were conducted. Twelve (25 %) GBS patients were unclassified. All unclassified patients were able to walk independently at 21 days after onset. No unclassified patients, except one patient with diabetes mellitus, had sensory nerve involvement. Eight patients underwent a follow-up study within 15 days of the initial study. Distal motor latencies (DMLs) of the left median motor nerve were found to be significantly and uniformly decreased compared with initial studies (p = 0.008). DMLs (p < 0.0001) and distal compound action potential (CMAP) durations (p = 0.002) of all nerves were significantly decreased, and distal CMAP amplitudes (p = 0.026) significantly increased compared with initial studies. In unclassified GBS patients, DML values during initial electrophysiological studies would be prolonged compared with expected values in the same patient unaffected by GBS and later improve rapidly with increased distal CMAP amplitudes without the development of excessive temporal dispersions. Lesions are also present in distal nerve segments caused by reversible conduction failure.

Clinical uses of H reflexes of upper and lower limb muscles

H reflexes can be recorded from virtually all muscles that have muscle spindles, but reflex reinforcement may be required for the reflex response to be demonstrable. This can allow conduction across proximal nerve segments and most nerve root segments commonly involved by pathology. Stimulus rate is critical in subjects who are at rest. However the reflex attenuation with higher rates is greatly reduced during a background contraction of the test muscle, with only minor changes in latency if any. In addition the contraction ensures that the reflex response occurs in the desired muscle. Reflex latencies should be corrected for height (or limb length) and age. Because the reflex discharge requires a synchronised volley in group Ia afferents, large increases in reflex latency occur rarely with purely sensory lesions. If the H reflex of soleus, quadriceps femoris or flexor carpi radialis is absent at rest but appears during a voluntary contraction at near-normal latency, there is either low central excitability or a predominantly sensory abnormality. With the former H reflexes will be difficult to elicit throughout the body. If H reflexes can be recorded at rest from muscles for which no reflex can normally be demonstrated, there is good evidence for hyperreflexia. In the context of possible ALS, this is an important finding when there is EMG evidence of chronic partial denervation in that muscle.

Diagnostic accuracy of neurophysiological criteria for early diagnosis of AIDP: A prospective study

OBJECTIVE

To assess the diagnostic accuracy of electrodiagnostic (EDX) criteria for the early detection and characterization of Guillain-Barré syndrome (GBS) in clinical practice.

METHODS

We conducted a prospective study in patients referred for an EDX exam with clinical suspicion of GBS. We evaluated four sets of neurophysiological criteria and four neurophysiological tests among those recently proposed for the early diagnosis of GBS.

RESULTS

We recruited 84 patients. Acute inflammatory demyelinating polyneuropathy (AIDP) was the final diagnosis in 23 patients. No axonal forms were found. The best sensitivity was obtained using Rajabally et al.'s criteria (82.1%), whereas the specificity was 90.0% for Ho et al.'s and Hadden et al.'s criteria and 100% for the Dutch GBS study group and Rajabally's criteria. Regarding the neurophysiological tests proposed for early diagnosis, the sensitivity ranged from 16.6 to 100%, whereas specificity ranged from 73.1 to 98.3%.

CONCLUSION

The Dutch GBS study group and Rajabally et al.'s criteria showed an optimal combination of sensitivity and specificity for clinical practice, although with a slightly higher sensitivity for Rajabally et al.'s criteria. None of the neurophysiological parameters recently proposed for early diagnosis have good diagnostic accuracy for clinical application.

SIGNIFICANCE

In a real clinical setting with patients referred by neurologists and emergency doctors, an EDX study performed within a week of symptom onset supports the diagnosis of AIDP in 82% of cases.

Guillain-Barré syndrome: clinical profile and management

INTRODUCTION

Guillain-Barré syndrome (GBS) is a fulminant polyradiculoneuropathy that is acute, frequently severe and autoimmune in nature. Etiology of GBS is incompletely understood, prognosis is usually good with early detection and prompt treatment. This retrospective study was done to evaluate clinical profile, epidemiological, laboratory, and electrodiagnostic features of patients with GBS and mode of management, complications and prognostic factors.

METHODS

Data of 1,166 patients admitted with GBS or presented to outpatient department (previous medical records) with GBS between January 2003 and January 2014 were analyzed.

RESULTS

No difference in genders noted. Around 35% of patients are above 50 years of age. Poor control of diabetes with mean HbA1c of 8.1 ± 2.11 is found on analysis. Seasonal occurrence in GBS is prominent in winter 484 (41.50%) and mechanically ventilated were 449 (38.50%) patients. 48 (4.11%) deaths were attributed to GBS. Neurological analysis revealed cranial nerve involvement in 407 (34.90%) patients, facial palsy in 401 (34.39%) and ataxia in 88 (7.54%) patients. Most patients in plasma exchange group belonged to the lower socio-economic status. Mean cerebrospinal fluid (CSF) protein levels was (n=962) 113.8 ± 11.8 mg/dl. Conduction block determined indirectly by absent H-reflex was noted in 891 (90.64%) patients. No difference in complications and outcome is found in treatment regimens of intravenous immunoglobulin (IVIG) and plasma exchange.

CONCLUSION

Seasonal occurrence predominantly in winter is noted. Peak flow test may be a predictor of assessing requirement of mechanical ventilation and prognosis. Conduction block is the major abnormality noted in electrophysiological studies and proximal nerve segment assessing with Erb's point stimulation has high predictive value. IVIG treatment is more expensive but is associated with less duration of hospital stay.

Subtypes and Prognosis of Guillain-Barré Syndrome in Southwest China

The proportion of different subtypes of Guillain-Barré syndrome (GBS) and their prognosis varied significantly among different regions. This study attempts to investigate the clinical subtypes and outcome of GBS in southwest China. Patients with GBS admitted to The First Affiliated Hospital of Chongqing Medical University from January 2006 to March 2013 were included in our study. Patients were classified into acute inflammatory demyelinating polyneuropathy (AIDP) group, acute motor axonal neuropathy (AMAN) group, Miller-Fisher syndrome (MFS) group, cranial nerve variants(CNV), Bickerstaff's brainstem encephalitis overlaps with GBS (BBE-GBS) group and unclassifiable group based on clinical features and electrophysiological findings. Hughes function grade score (HFGS) was used to assess the prognosis at 3 and 6 months. The prognosis of different subtypes and outcome predictors were analyzed. The most common subtype of GBS was AIDP (57%), followed by AMAN (22%) and MFS (7%). The prognosis of AMAN and BBE-GBS is similar at 3 month(P = 0.0704)and 6 month (P = 0.1614) follow-up. The prognosis of AMAN group was poorer than that of AIDP group at 3 month and 6 month follow-up (P<0.001). Outcome of MFS group and that of CNV group at 6 months were both good(Hughes≤1). Hughes≥3(P<0.0001,OR = 6.650,95%CI = 2.865 to 15.023))and dysautonomia (P = 0.043,OR = 2.820,95%CI = 1.031 to 7.715)) were associated with poor outcome at 6 month follow-up. AIDP is the most common subtype of GBS. Prognosis of AMAN group and BBE-GBS group is poorer than that of AIDP group at 3 month and 6 month follow-up. Hughes≥3 at nadir and dysautonomia are predictors of poor prognosis at 6 month follow-up.

Sural sparing pattern discriminates Guillain-Barré syndrome from its mimics

INTRODUCTION

Electrodiagnostic features of demyelination are essential for establishing the diagnosis in demyelinating subtypes of Guillain-Barré syndrome (GBS), but they may also occur in disorders that mimic GBS clinically. Information about their frequency in GBS mimics is sparse.

METHODS

Evaluation of electrodiagnostic features from 38 patients with suspected GBS in whom the diagnosis was later refuted (GBS mimics). Their diagnostic accuracy was analyzed by comparison with nerve conduction studies (NCS) from 73 confirmed GBS patients.

RESULTS

Disorders that mimicked GBS clinically at the time of hospital admission included other inflammatory, metabolic, toxic, or infectious neuropathies and spinal cord disorders. The sural sparing pattern was the most specific electrodiagnostic feature for demyelinating GBS.

CONCLUSIONS

Common electrodiagnostic abnormalities in early demyelinating GBS do not usually exclude other rare differential diagnoses. An exception to this is the sural sparing pattern described here, which strongly supports the diagnosis of demyelinating GBS.

Spinal nerve involvement in early Guillain-Barré syndrome: a clinico-electrophysiological, ultrasonographic and pathological study

OBJECTIVE

Although prevailing spinal nerve involvement has been recognized in a few detailed Guillain-Barré syndrome (GBS) autopsy reports, imaging studies addressing this question in cervical nerves are lacking.

METHODS

We describe clinical, electrophysiological, ultrasonographic (US) and pathological findings in six consecutive early GBS patients, evaluated within 10 days of onset.

RESULTS

Patients' ages ranged from 37 to 80 years. Five patients required mechanical ventilation, two of them having died 9 and 28 days after onset. Upper- and lower-limb nerve US showed abnormal findings in just 8.8% of scanned peripheral nerves. In comparison with 46 aged-matched control subjects, US of the fifth to seventh cervical nerves showed changes in four cases, which consisted of significant nerve enlargement, blurred boundaries of the corresponding ventral rami, or both. Autopsy study in one case demonstrated that pathology, consisting of demyelination and endoneurial inflammatory oedema, mainly involved cervical and lumbar nerves.

CONCLUSIONS

In early GBS inflammatory oedema of spinal nerves is a pathogenically relevant feature to understanding the mechanism of ascending paralysis, particularly when conventional electrophysiological studies are normal or not diagnostic.

SIGNIFICANCE

Findings advocate the use of cervical nerve US in early GBS.