Enhancing Tone and Strength in a Patient With Autoimmune Encephalitis and Guillain-Barré Syndrome Using Rood's Facilitatory Techniques and Neuromuscular Electrical Stimulation: A Case Report.

This case report documents the comprehensive management of a 21-year-old female resident of Gadchiroli presenting with a 10-day history of fever, altered consciousness, and neurological sequelae following a traumatic incident. The patient exhibited a Glasgow Coma Scale score of 6/15, hypotonia in both upper and lower limbs, diminished deep tendon reflexes, and respiratory complications. This case study describes a thorough physiotherapeutic strategy that focuses on tone facilitation and muscle weakness improvement. The intervention used Rood's facilitative approaches as well as neuromuscular electrical stimulation (NMES). Rood's treatments, which emphasized mobilizing touch and tactile stimulation, brushing, quick icing, quick stretching, tapping, massaging the skin, heavy joint compression, and rolling, were used deliberately to move the patient from flaccidity to better muscle tone. These techniques' repetitive and task-specific nature coincided with motor learning principles, enabling adaptive modifications in brain networks. Concurrently, NMES was used to improve muscle activation, create a controlled environment for neurorehabilitation, and promote strength increases. The successful integration of various modalities highlights the possibility of favorable neuronal adaptations and functional improvements in individuals suffering from complicated neuromuscular disorders. This case demonstrates the need for individualized and diversified physiotherapeutic techniques in improving rehabilitation outcomes.

Rehabilitation of a 51-Year-Old Patient With Miller Fisher Syndrome: A Case Report.

Miller Fisher syndrome is a rare and atypical variation of Guillain-Barré syndrome, which includes the clinical triad of areflexia, ataxia, and ophthalmoplegia. Miller Fisher syndrome is commonly associated with the involvement of the lower cranial and facial nerves. Miller Fisher syndrome is one of the types of Guillain-Barré syndrome. Guillain-Barré syndrome has been defined to be the foremost incapacitating form of neurological disease following the disease polio. Guillain-Barré syndrome is a broad category that encompasses several types of acute immune-mediated polyneuropathies, the most common of which is acute inflammatory demyelinating polyradiculoneuropathy. Here, we describe a case report of a 51-year-old patient who displayed the characteristic symptoms of Miller Fisher syndrome. We also describe the patient's clinical course, diagnostic method, and therapy. This case demonstrates the value of early detection, quick action in treating Miller Fisher syndrome, and the possibility of full recovery with adequate therapy. Techniques utilized in physical therapy emphasize performing everyday tasks along with strengthening muscles.

Miller-Fisher Syndrome Following Influenza A Infection.

Miller-Fisher syndrome (MFS), characterized by ophthalmoplegia, ataxia, and areflexia, is a Guillain-Barré syndrome (GBS) variant. It is well-known that the causative antibody for MFS is anti-GQ1b antibody. This report describes a rare case of MFS with not only anti-GQ1b antibodies but also anti-GT1a antibodies following Influenza A infection. The patient, a 47-year-old woman, contracted Influenza A three weeks before admission. She complained of double vision followed by areflexia, ataxia in the four extremities, and complete gaze palsy. She was treated with intravenous methylprednisolone pulse and intravenous immunoglobulin therapies. Her neurological symptoms were recovered after these immunotherapies.

Guillain Barre syndrome mimicking brain death.

A 49-year-old female patient presented at the hospital with a history of herpetic blisters, frequent episodes of vomiting and loose stools, bilateral upper and lower limb weakness, and diminishing sensorium. She was diagnosed with hyponatraemia and respiratory failure and later became unconscious with absent brainstem reflexes. The patient was initially treated for herpetic encephalitis, a chronic obstructive pulmonary disease with acute exacerbation, hyponatraemia and neuroparalytic snake bite. Further evaluation, however, identified the uncommon Guillain Barre syndrome presentation with overlap of Bickerstaff brainstem encephalitis. This is an uncommon disorder characterised by the involvement of higher mental functions, fixed dilated pupils, absent brainstem reflexes and quadriplegia that resembles a neuroparalytic snake bite and brain death. After receiving intravenous immunoglobulins for treatment, the patient completely recovered.

Takotsubo cardiomyopathy in Guillain-Barré syndrome.

BACKGROUND AND PURPOSE: Takotsubo cardiomyopathy (TCM) is a serious autonomic complication of Guillain-Barré syndrome (GBS). However, the association between TCM and GBS has not been investigated in detail. We investigated the characteristics of GBS patients with TCM (GBS-TCM). METHODS: Clinical features and anti-ganglioside antibody between the GBS-TCM patients and 62 classical GBS patients without TCM as control patients were compared. RESULTS: Eight GBS-TCM patients were identified, in whom TCM was diagnosed at a mean of 6.5 [range 3-42] days after the onset of GBS. The age at onset of GBS was elder in the GBS-TCM patients than in the control GBS patients (76.5 [56-87] vs. 52 [20-88] years, p < 0.01). Notably, cranial nerve deficits, particularly in the lower cranial nerves, were observed in all GBS-TCM patients (100% vs. 41.9%, p < 0.01). Additionally, the GBS-TCM patients showed a higher GBS disability score at nadir (5 [4-5] vs. 4 [1-5], p < 0.01), and lower Medical Research Council sum scores at admission and nadir (37 [30-44] vs. 48 [12-60] at admission, p < 0.05, and 20 [12-44] vs. 40 [0-60] at nadir, p < 0.05, respectively). Mechanical ventilation was more frequently required in the GBS-TCM patients (62.5% vs. 11.3%, p < 0.01). Three GBS-TCM patients were positive for anti-ganglioside antibodies. CONCLUSIONS: TCM occurred at a relatively early phase of GBS. The characteristics of GBS-TCM were the elder, lower cranial nerve involvements, severe limb weakness, and respiratory failure.

Postpartum Guillain-Barré Syndrome: A Case Report and Literature Review.

Guillain-Barré syndrome (GBS) is a rare acute-onset neurological disease with significant morbidity and mortality. The risk of GBS increases after delivery. Labor and delivery presents many possible risk factors for GBS. However, risk factors and prognosis of postpartum GBS remain unclear due to its low incidence. Here, we first present a patient with a history of postpartum GBS who returned for an elective repeat cesarean section (C-section). For her previous delivery, the patient received spinal anesthesia for an urgent C-section. She presented postpartum with jaw pain, facial palsy, respiratory difficulty, progressive bilateral lower extremity weakness, and areflexia. The diagnosis of GBS was confirmed by cerebrospinal fluid (CSF) examination, nerve conduction studies (NCS), and electromyography (EMG). Her symptoms of GBS improved after intravenous immunoglobulin (IVIG) treatment. The patient also had an Escherichia coli-positive urinary tract infection (UTI), which was treated with nitrofurantoin. For her repeat elective C-section, we performed a dural puncture epidural (DPE) anesthesia. After delivery, she was discharged to home uneventfully. She did not report any new neurological symptoms at her three-week follow-up. Here, we also review published cases of postpartum GBS and discuss peripartum anesthetic considerations for patients with GBS, aiming to inform clinical management of postpartum GBS in the future.

Antiganglioside antibody frequency in routine clinical care settings.

BACKGROUND AND PURPOSE: Antiganglioside antibodies (AGAs) might be involved in the etiopathogenesis of many neurological diseases, such as Miller-Fisher syndrome (MFS) and Guillain-Barré syndrome (GBS). Available comprehensive reference data regarding AGA positivity rates and cross-responsiveness among AGAs (where one line immunoblot is positive for ≥1 AGA) during routine clinical care are scant. METHODS: In this 10-year monocentric retrospective study, 3560 immunoglobulin (Ig) G and IgM line blots (GA Generic Assays' Anti-Ganglioside Dot kit) obtained using cerebrospinal fluid (CSF) and serum samples from 1342 patients were analyzed for AGA positivity in terms of 14 diagnosis categories and AGA cross-responsiveness. RESULTS: Of all 3560 line blots 158 (4.4%) and of all CSF samples 0.4% (4/924) CSF line blots were AGA positive. For serum IgG, blots with positivity rates higher than the standard deviation of 15.6% were associated with MFS (GD3, GD1a, GT1a and GQ1b) and acute motor axonal neuropathy (AMAN) (GM1, GD1a and GT1a). For serum IgM, blots with positivity rates higher than the standard deviation of 8.1% were associated with AMAN (GM2, GT1a and GQ1b), MFS (GM1, GT1a and GQ1b), multifocal motor neuropathy (MMN) (GM1, GM2 and GQ1b) and chronic inflammatory demyelinating polyneuropathy (CIDP) (GM1). Cross-responsiveness was observed in 39.6% of all positive serum AGA. CONCLUSIONS: Testing for AGAs during routine clinical care rarely led to positive findings, both in serum and even less in CSF, except for the diagnoses AMAN, MFS, MMN and CIDP. Nonspecific findings found as cross-responsiveness between different AGA samples occur frequently, impacting the positivity of most AGA subtypes.

Guillain-Barre syndrome following COVID-19 vaccination: a study of 70 case reports.

Background and objective: Guillain-Barre syndrome (GBS) has been found to have some interesting association with vaccinations. This paper mainly focuses on exploring different associations between COVID-19 vaccination and GBS. Methods: Electronic databases such as PubMed, Google Scholar, Cochrane, and Embase were searched using MESH terms for case reports published till 1 August 2023 from which 70 case reports were documented involving 103 individuals from 23 different countries. Result and discussion: The case reports were from a wide range of individuals aged from 13 to 87 years with an average age of 53±20 interquartile range years along with male predominance. The average time between receiving the vaccine and the onset of symptoms was 13.08±2.14 days. Prominent clinical features included back pain, facial diplegia, weakness, and paraesthesia whereas the main diagnostic studies were cerebrospinal fluid (CSF) analysis and electromagnetic studies. The principal diagnostic clue was albumin-cytological dissociation in CSF while being negative for anti-ganglioside antibodies or SARS-CoV-2. Available treatment options consisted of intravenous immunoglobulin and Plasmapheresis. Patients with comorbidities such as diabetes mellitus, hypertension, dyslipidemia, permanent atrial fibrillation, hypothyroidism, Hashimoto's thyroiditis, Chronic Obstructive Pulmonary Disease, asthma, osteoporosis, migraine, rheumatoid arthritis, osteoarthritis, ulcerative colitis, coeliac disease, seizures, bipolar disorder, endometriosis, multiple sclerosis, bell's palsy, squamous cell carcinoma, prostate cancer were included in our study. Conclusion: Overall, this review evaluated innovative and clinically relevant associations between COVID-19 vaccination and GBS. Understanding of this uncommon potential side effect of COVID-19 vaccination is crucial for prompt diagnosis and appropriate treatment. Importantly, GBS should not be considered a contraindication to vaccination. This underscores the importance of ongoing research to enhance the safety and efficacy of COVID-19 vaccination efforts.

Guillain-Barré syndrome after surgery: a literature review.

Guillain-Barré syndrome (GBS) is a rare postoperative complication that is sometimes characterized by serious motor weakness and prolonged weaning from mechanical ventilation. Although the exact nature of the relationship between GBS and the surgical procedure is still unclear, there is a clear increased incidence of GBS in post-surgical patients compared to non-surgical patients. GBS after surgery is unique in several ways. The course of post-surgical GBS unfolds more rapidly than in other situations where GBS develops, the condition is often more severe, and respiratory muscles are more commonly involved. Prompt diagnosis and appropriate treatment are essential, and the condition can worsen if treated inappropriately. Postoperative sedation, intubation, and restraint use make the diagnosis of GBS difficult, as the onset of symptoms of weakness or numbness in those contexts are not obvious. GBS is often misdiagnosed, being attributed to other postoperative complications, and subsequently mishandled. The lack of relevant information further obscures the clinical picture. We sought to better understand post-surgical GBS by performing an analysis of the relevant literature, focusing on clearly documenting the clinical characteristics, diagnosis, and management of GBS that emerges following surgery. We underscore the importance of physicians being aware of the possibility of GBS after major surgery and of performing a variety of laboratory clinical investigations early on in suspected cases.

Guillain-barré syndrome (GBS) with antecedent chikungunya infection: a case report and literature review.

Guillain-Barré Syndrome (GBS) is an autoimmune neuropathy. Antecedent infections have been seen to be significant triggering factors for developing GBS. Among them, arboviral infections are rapidly gaining importance as significant triggers, especially in the areas where they are endemic. Chikungunya, an arboviral infection that usually causes a self-limiting acute febrile illness can lead to GBS as one its severe complications. Herein, we describe a case of a 21-year-old female who presented with weakness in all four limbs and paresthesia. Nerve conduction study and cerebrospinal fluid (CSF) analysis showed axonal, demyelinating motor and sensory neuropathy with albuminocytological dissociation indicating Acute Motor and Sensory Axonal Neuropathy (AMSAN) variant of GBS. Serum IgM antibodies against ganglioside GM1 were detected. Anti-Chikungunya IgM antibodies were found in both serum and CSF samples. The patient was initiated with Intravenous Immunoglobulin (IVIG) therapy. In view of hypoxia, she was intubated and was on mechanical ventilation. After 2 weeks of being comatose, the patient gradually improved and was discharged with no sequelae.A literature review on antecedent infections in GBS is presented alongside the case report to better understand the association of GBS with antecedent infections, especially the endemic arboviral infections like Chikungunya, Dengue and Zika. This will help in reinforcing the significance of having robust surveillance and public health control measures for infectious diseases.

GBS as unusual presentation of neurobrucellosis: A rare case report.

Brucellosis is a zoonotic disease caused by small intracellular aerobic Gram-negative bacilli. The literature has frequently documented instances of the gastrointestinal, hepatobiliary, and skeletal systems being involved. In 3%-5% of brucellosis patients, neurobrucellosis has been identified. Guillain-Barré syndrome (GBS) is a disorder of the peripheral nervous system. Acute peripheral neuropathy mimicking GBS caused by brucellosis is rarely reported. Our case is of a 34-year-old male presenting with a 3-week history of weakness in the upper limbs. There was a clear history of milk product consumption preceding the onset of symptoms. Examination showed paraesthesia and muscles paralysis. Brucellosis was confirmed via blood test, and GBS was confirmed via imaging and neuroelectrophysiological assessment. The patient was treated with plasma exchange (PLEX) and commenced on rifampicin, doxycycline and gentamicin during their hospitalization. The patient was discharged with a course of rifampicin and doxycycline to complete. In patients with acute paralysis and GBS-like symptoms, Imaging should be done in addition to serological tests for brucellosis.

Reusing Plasma Filters in Resource-Poor Settings: Experience From a Tertiary Care Hospital.

INTRODUCTION: Therapeutic plasma exchange (TPE) is used to manage various life-threatening illnesses. It is widely performed by nephrologists, intensivists, pathologists, or experts in transfusion medicine worldwide. However, the costs of TPE sessions are exceedingly high, and they have a huge impact on patients' financial burden. Herein, we investigated the outcomes of the reuse of plasma filters in TPE on several occasions. METHODS: This is a retrospective analysis of patients receiving TPE from January 1, 2020, to April 30, 2023, in the Department of Nephrology. A formulation of 4.5% peracetic acid and 24% hydrogen peroxide acid with RO water dilution was used for reprocessing. Clinical outcomes, risks, and cost-benefit were evaluated and compared between the plasma filter reuse group (GP-1) and the no-reuse group (GP-2). RESULTS: A total of 70 patients were included in this study. 200 and 112 TPE sessions were performed in GP-1 and GP-2, respectively. The most common indication for TPE in both groups was neurological. The clinical efficacy of TPE was similar in both groups. There was no difference in the clotting of the plasma filter, any allergic reaction, infection, or bleeding in the group. However, there was a significant difference in levels of fibrinogen (p=0.03) pre and post-procedure in both groups. The incidence of hypotension was found to be higher in GP-1 (26%) compared to GP-2 (15.6%), p = 0.05. The cost of overall treatment was 38% less in GP-1. CONCLUSION: The reuse of plasma filters is a safe and effective method for cost minimization in patients requiring TPE. This method can be effectively utilized in resource-poor settings without any increased risk of adverse effects.

Rehabilitation of a Chronic Guillain-Barré Syndrome Patient With Vibratory Motor Stimulation of Dorsiflexors: A Case Report.

There are various reports describing physiotherapy rehabilitation in Guillain-Barré syndrome (GBS) but the use of current to rehabilitate GBS patients has remained an untouched topic. To elaborate on this work, we describe a case report focusing on the intervention plan for the rehabilitation of a chronic GBS case by the use of vibratory motor stimulation (VMS) current. The study aimed to describe the therapeutic application of VMS current in improving muscle power of dorsiflexors and overall outcome measures in a case of GBS presenting in a tertiary care hospital in North India. A 29-year-old male patient came to Teerthanker Mahaveer University Hospital and consulted in the Department of Physiotherapy after 1.4 years of being diagnosed with acute motor axonal neuropathy-type GBS. Rehabilitation of this case included strengthening exercises of the upper and lower limbs along with balance exercises. Specifically, in this case, we gave VMS current after assessing the muscle power of the dorsiflexors, which was found to be grade-0 over the bilateral dorsiflexors, combined with passive dorsiflexion. Different outcome measures were used for assessment, including manual muscle testing, functional independence measurement, and the Berg Balance Scale. Improvement in the patient's condition was observed in his outcome measures after two months of treatment. There was an overall improvement in the muscle power of our patient's dorsiflexors, where muscle power was upgraded from grade-0 to grade-I and grade-I+ in the bilateral lower limbs by the use of VMS current. This study marks a novel application of VMS to the dorsiflexors of a GBS patient, yielding positive outcomes in upgrading muscle power grades from grade-0 to grade-I and grade-I+. Further research is needed to confirm VMS efficacy as an early intervention in GBS patient rehabilitation.

Guillain-Barré syndrome and checkpoint inhibitor therapy: insights from pharmacovigilance data.

Background There are increasing reports of cases of Guillain-Barré syndrome (GBS), as an adverse event of an immune checkpoint inhibitor (ICI) but postmarket data on the incidence of this remains scarce. This study sought to conduct a comprehensive review of GBS events arising as a secondary outcome of ICI treatments in real-world patients, using the Food and Drug Administration Adverse Event Reporting System (FAERS). Methods Data covering the period from the third quarter of 2003 to the second quarter of 2023 were extracted from the FAERS database. GBS cases (associated with the usage of avelumab, atezolizumab, ipilimumab, nivolumab and pembrolizumab) were subjected to disproportionality analysis to detect potential signals. Results A total of 2208 reports of GBS were identified within the FAERS database, with 242 of these cases (10.9%) being associated with ICIs. All five drugs exhibited a disproportionality in the reporting of adverse events, with the highest observed for avelumab (reporting OR, ROR: 29.8), followed by atezolizumab (ROR: 17.0), ipilimumab (ROR: 16.0), pembrolizumab (ROR: 11.9) and nivolumab (ROR: 8.2). Conclusion These checkpoint inhibitors are associated with a statistically significant disproportionate number of reports of GBS as an adverse event, with avelumab being the ICI with the highest association. The present pharmacovigilance study serves as a valuable tool, offering a more comprehensive and nuanced perspective on GBS associated with ICIs. This study contributes to a deeper comprehension of this rare adverse drug effect.

Bickerstaff's Brainstem Encephalitis and Miller Fisher Syndrome: A Rare Overlap.

A rare illness known as "Bickerstaff's brainstem encephalitis" (BBE) is characterized by an abrupt brainstem dysfunction and includes the triad of diminished consciousness, ataxia, and ophthalmoplegia. It differs from the Guillain-Barré syndrome (GBS) and Miller Fisher syndrome (MFS) by involving the central nervous system (CNS) and frequently manifesting as reduced consciousness. Here, we describe a rare instance of Bickerstaff's encephalitis coexisting with MFS, where the patient had rapidly progressing quadriplegia, VII cranial nerve palsy, and episodes of unconsciousness.

Efficacy and safety of intravenous immunoglobulin retreatment amongst Guillain-Barré syndrome patients who poorly responded to initial IVIG cycle: a systematic review.

INTRODUCTION: Small cross-sectional studies and case reports observed improvement after administration of second IVIG dose (SID) amongst Guillain-Barré Syndrome (GBS) patients not responsive to initial IVIG cycle. Nevertheless, recent clinical trial and larger observational studies did not find any positive effects of SID. Instead, an increased risk of thromboembolism and mortality was noted. The conclusions of these studies however were not robust as confounding and selection bias were present. METHODOLOGY: Two neurologists conducted the search process (KBA and MBP) using the following terms in Medline: [(" Guillain-Barré Syndrome"[MeSH Terms] or GBS or Acute Motor Axonal Neuropathy or Acute Motor Axonal Neuropathy or Acute Inflammatory Demyelinating Polyneuropathy) AND (Poorly Responsive or Poor Prognosis or Progressive)] AND [("Intravenous Immunoglobulin"[MeSH Terms] or IVIG or IGIV) AND (second dose or retreatment or SID)]. RESULTS: Only 7 articles were included in this review. In terms of primary outcomes, although the cross-sectional study found improvement in GBS DS score at 4 weeks (Median GBS DS: 3 vs 5, p = 0.033) and the 2 case series observed improvement after SID, no significant differences between the control and intervention groups were found in the cohort [Early SIV OR: 0.7 (95% CI 0.16-3.04), Late SIV OR: 0.66 (CI: 0.18-2.5)] and clinical trial studies (Adjusted OR: 1.4 (95% CI:0.6-3.3, p = 0.45). Moreover, 4 patients who died in the clinical trial were from the intervention group. CONCLUSION: Based on studies with research designs of higher quality, SID is not effective in the management of GBS patients who poorly responded to initial IVIG. Nevertheless, an adequately powered, randomized, double-blinded, placebo-controlled clinical trial, using GBS-DS of 3 and above after first IVIG dose should be done to effectively establish the efficacy and safety of SID as intervention for this cohort of patients.

Practical approach to the child presenting with acute generalised weakness.

Acute generalised muscle weakness in children is a paediatric emergency with a broad differential diagnosis. A careful history and neurologic examination guides timely investigation and management. We review some of the more common causes of acute generalised muscle weakness in children, highlighting key history and examination findings, along with an approach to lesion localisation to guide differential diagnosis and further investigation.

P2X7 receptor antagonists modulate experimental autoimmune neuritis via regulation of NLRP3 inflammasome activation and Th17 and Th1 cell differentiation.

BACKGROUND: Guillain-Barré syndrome (GBS), a post-infectious, immune-mediated, acute demyelinating disease of the peripheral nerves and nerve roots, represents the most prevalent and severe acute paralyzing neuropathy. Purinergic P2X7 receptors (P2X7R) play a crucial role in central nervous system inflammation. However, little is known about their role in the immune-inflammatory response within the peripheral nervous system. METHODS: Initially, we assessed the expression of purinergic P2X7R in the peripheral blood of patients with GBS using flow cytometry and qRT-PCR. Next, we explored the expression of P2 X7R in CD4+ T cells, CD8+ T cells, and macrophages within the sciatic nerves and spleens of rats using immunofluorescence labeling and flow cytometry. The P2X7R antagonist brilliant blue G (BBG) was employed to examine its therapeutic impact on rats with experimental autoimmune neuritis (EAN) induced by immunization with the P0180 - 199 peptide. We analyzed CD4+ T cell differentiation in splenic mononuclear cells using flow cytometry, assessed Th17 cell differentiation in the sciatic nerve through immunofluorescence staining, and examined the expression of pro-inflammatory cytokine mRNA using RT-PCR. Additionally, we performed protein blotting to assess the expression of P2X7R and NLRP3-related inflammatory proteins within the sciatic nerve. Lastly, we utilized flow cytometry and immunofluorescence labeling to examine the expression of NLRP3 on CD4+ T cells in rats with EAN. RESULTS: P2X7R expression was elevated not only in the peripheral blood of patients with GBS but also in rats with EAN. In rats with EAN, inhibiting P2X7R with BBG alleviated neurological symptoms, reduced demyelination, decreased inflammatory cell infiltration of the peripheral nerves, and improved nerve conduction. BBG also limited the production of pro-inflammatory molecules, down-regulated the expression of P2X7R and NLRP3, and suppressed the differentiation of Th1 and Th17 cells, thus protecting against EAN. These effects collectively contribute to modifying the inflammatory environment and enhancing outcomes in EAN rats. CONCLUSIONS: Suppression of P2X7R relieved EAN manifestation by regulating CD4+ T cell differentiation and NLRP3 inflammasome activation. This finding underscores the potential significance of P2X7R as a target for anti-inflammatory treatments, advancing research and management of GBS.

Dynamics and prognostic value of serum neurofilament light chain in Guillain-Barré syndrome.

BACKGROUND: Neurofilament light chain (NfL) is a biomarker for axonal damage in several neurological disorders. We studied the longitudinal changes in serum NfL in patients with Guillain-Barré syndrome (GBS) in relation to disease severity, electrophysiological subtype, treatment response, and prognosis. METHODS: We included patients with GBS who participated in a double-blind, randomised, placebo-controlled trial that evaluated the effects of a second course of intravenous immunoglobulin (IVIg) on clinical outcomes. Serum NfL levels were measured before initiation of treatment and at one, two, four, and twelve weeks using a Simoa HD-X Analyzer. Serum NfL dynamics were analysed using linear mixed-effects models. Logistic regression was employed to determine the associations of serum NfL with clinical outcome and the prognostic value of serum NfL after correcting for known prognostic markers included in the modified Erasmus GBS Outcome Score (mEGOS). FINDINGS: NfL levels were tested in serum from 281 patients. Serum NfL dynamics were associated with disease severity and electrophysiological subtype. Strong associations were found between high levels of serum NfL at two weeks and inability to walk unaided at four weeks (OR = 1.74, 95% CI = 1.27-2.45), and high serum NfL levels at four weeks and inability to walk unaided at 26 weeks (OR = 2.79, 95% CI = 1.72-4.90). Baseline serum NfL had the most significant prognostic value for ability to walk, independent of predictors included in the mEGOS. The time to regain ability to walk unaided was significantly longer for patients with highest serum NfL levels at baseline (p = 0.0048) and week 2 (p < 0.0001). No differences in serum NfL were observed between patients that received a second IVIg course vs. IVIg and placebo. INTERPRETATION: Serum NfL levels are associated with disease severity, axonal involvement, and poor outcome in GBS. Serum NfL potentially represents a biomarker to monitor neuronal damage in GBS and an intermediate endpoint to evaluate the effects of treatment. FUNDING: Prinses Beatrix Spierfonds W.OR19-24.