Current practice patterns in CIDP: A cross-sectional survey of neurologists in the United States

New chronic inflammatory demyelinating polyneuropathy/Guillain-Barré syndrome guidelines - impact on clinical practise

PURPOSE OF REVIEW

There is no diagnostic biomarker that can reliably detect Guillain-Barré syndrome (GBS) or chronic inflammatory demyelinating polyneuropathy (CIDP). Diagnosis relies upon integrating key clinical characteristics and relevant supportive data. Consequently, misdiagnosis and delayed diagnosis are common. Diagnostic criteria have proven valuable resources to improve diagnosis, but are underutilized during routine clinical care.

RECENT FINDINGS

In 2021, the EAN/PNS CIDP criteria was published, and were followed by the EAN/PNS GBS criteria in 2023. Both guidelines utilized GRADE methodology to formulate evidence-based recommendations that are intended to be used by adult and paediatric clinicians across diverse care settings to optimize diagnostic accuracy and improve patient outcomes during routine clinical care.

SUMMARY

The EAN/PNS GBS and CIDP criteria detail specific clinical, electrophysiological, and laboratory features that raise diagnostic confidence, and call attention to diagnostic mimics. The sensitivity of EAN/PNS and other modern criteria to detect GBS and CIDP is high, but utilization during clinical practice is low. Complexity is one factor limiting widespread application. Strategies are needed to optimize criteria adoption during routine clinical care such that GBS and CIDP diagnosis can be achieved with greater speed and accuracy.

Physician awareness and understanding of chronic inflammatory demyelinating polyradiculoneuropathy in Japan: a web-based study

OBJECTIVES

To investigate potential knowledge gaps between neurologists and non-specialists and identify challenges in the current management of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), with a focus on 'early diagnosis' and 'appropriate treatment' for CIDP.

DESIGN

A non-interventional, cross-sectional, web-based quantitative survey of physicians working in healthcare clinics or hospitals in Japan.

SETTING

Participants were recruited from the Nikkei Business Publications panel from 18 August to 14 September 2022.

PARTICIPANTS

Responses from 360 physicians (120 each of internists, orthopaedists and neurologists) were collected.

OUTCOME MEASURES

Responses relating to a CIDP hypothetical case and current understanding were assessed to determine awareness, collaboration preferences and diagnosis and treatment decisions.

RESULTS

Understanding of CIDP was 90.8% among neurologists, 10.8% among orthopaedists and 13.3% among internists; >80% of orthopaedists and internists answered that neurologists are preferable for treatment. Diagnostic assessment using a hypothetical case showed 95.0% of neurologists, 74.2% of orthopaedists and 72.5% of internists suspected CIDP. Among orthopaedists and internists suspecting CIDP, >70% considered referring to neurology, while ~10% considered continuing treatment without a referral. Among neurologists, 69.4% chose intravenous immunoglobulin (IVIg) as first-line treatment and determined effectiveness to be ≤3 months.

CONCLUSIONS

Orthopaedists and internists had lower CIDP awareness compared with neurologists, which may lead to inadequate referrals to neurology. Evaluation of IVIg effectiveness for maintenance therapy occurred earlier than the guideline recommendations (6-12 months), risking premature discontinuation. Improving CIDP knowledge among orthopaedists and internists is critical for better diagnosis and collaboration with neurologists. Neurologists should consider slow and careful evaluation of IVIg maintenance therapy.

TRIAL REGISTRATION NUMBER

UMIN000048516.

Intravenous Immunoglobulin Initiation in Patients with Chronic Inflammatory Demyelinating Polyradiculoneuropathy: A US Claims-based Cohort Study

INTRODUCTION

Intravenous immunoglobulin (IVIG) is recommended as first-line therapy for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), an immune-mediated neuropathy. The clinical profile of patients with CIDP newly initiating IVIG is poorly characterized. This claims-based cohort study describes characteristics of US patients with CIDP initiating IVIG treatment.

METHODS

Adult immunoglobulin (IG)-naïve patients with CIDP diagnosed between 2008 and 2018 and a subgroup of patients subsequently initiating IVIG were identified in the Merative MarketScan Research Databases. Demographics, clinical characteristics, and diagnostic procedures were described for patients initiating IVIG.

RESULTS

Of 32,090 patients with CIDP identified, 3975 (mean age 57 years) subsequently initiated IVIG. In the 6 months prior to IVIG initiation, diagnoses of comorbidities including neuropathy (75%), hypertension (62%), and diabetes (33%) were frequent, as were CIDP features/symptoms/markers of functional status including chronic pain (80%), difficulty walking (30%), and weakness (30%). CIDP-related laboratory/diagnostic procedures were performed in approximately 20- > 40% of patients in the 3 months prior to IVIG initiation (63.7% underwent electrodiagnostic/nerve conduction testing in the 6 months prior to IVIG initiation). Patient characteristics by initial IVIG product differed only in IVIG initiation year, US geographic region, and insurance type. Comorbidities, CIDP severity or functional status markers, and other clinical variables were generally well balanced across initial IVIG product groups.

CONCLUSION

A heavy burden of symptoms, comorbidities, and diagnostic testing exists in patients with CIDP initiating IVIG. Characteristics of patients with CIDP initiating different IVIG products are well balanced, suggesting an absence of clinical or demographic determinants underlying IVIG selection.

Fatigue, depression, and product tolerability during long-term treatment with intravenous immunoglobulin (Gamunex® 10%) in patients with chronic inflammatory demyelinating polyneuropathy

INTRODUCTION/AIMS

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is characterized by progressive weakness and sensory loss, often affecting patient's ability to walk and perform activities of daily living independently. Furthermore, patients often report fatigue and depression which can affect their quality of life. These symptoms were assessed in CIDP patients receiving long-term intravenous immunoglobulin (IVIG) treatment.

METHODS

GAMEDIS was a multi-center, prospective, non-interventional study in adult CIDP patients treated with IVIG (10%) and followed for two years. Inflammatory Neuropathy Cause and Treatment (INCAT) disability score, Hughes Disability Scale (HDS), Fatigue Severity Scale (FSS), Beck Depression Inventory II (BDI), Short Form-36 health survey (SF-36) and Work Productivity and Activity Impairment Score Attributable to General Health (WPAI-GH) were assessed at baseline and quarterly. Dosing and treatment intervals, changes in outcome parameters, and adverse events (AEs) were analyzed.

RESULTS

148 evaluable patients were followed for a mean of 83.3 weeks. The mean maintenance IVIG dose was 0.9 g/kg/cycle (mean cycle interval 38 days). Disability and fatigue remained stable throughout the study. Mean INCAT score: 2.4 ± 1.8 at baseline and 2.5 ± 1.9 at study end. HDS: 74.3% healthy/minor symptoms at baseline and 71.6% at study end. Mean FSS: 4.2 ± 1.6 at baseline and 4.1 ± 1.7 at study end. All patients reported minimal/no depression at baseline and throughout. SF-36 and WPAI-GH scores remained stable. Fifteen patients (9.5%) experienced potentially treatment-related AEs. There were no AEs in 99.3% of infusions.

DISCUSSION

Long-term treatment of CIDP patients with IVIG 10% in real-world conditions maintained clinical stability on fatigue and depression over 96 weeks. This treatment was well-tolerated and safe.

Using a scenario approach to assess for the current and future demand of immunoglobulins: An interview and literature study from The Netherlands

OBJECTIVES

To explore the current and future demand of immunoglobulins globally and specifically for the Netherlands by assessing: (I) which specialties contribute to current demand, (II) new areas of medical need, (III) which transformational factors may impact demand and to what effect, by using a scenario approach.

BACKGROUND

As immunoglobulin demand continues to increase globally, there is concern of increasing shortages and questions of whether and how future demand will continue based on medical need.

METHODS/MATERIALS

In line with scenario principles, a scoping review of Pubmed, Web of Science, Embase and Cochrane and grey literature was conducted. Semi-structured interviews with subject matter experts were held. The results of the review and interviews were analysed for major themes.

RESULTS

The scoping review resulted in 97 articles, 74 regarding clinical uses, and 23 regarding organisational and other themes. Fifteen clinical and non-clinical experts were interviewed. I) Neurology, immunology, and haematology were specialties that contribute most to current demand. II) Regarding potential new areas of medical need, the literature review resulted in more indications than the interviews, for example, post-renal transplants. III) Four groups of key transformational factors were found: factors that could increase immunoglobulin demand (e.g., EMA revisions), decrease demand (e.g., replacement products, Dutch Transfer Act 2021), factors that remain to be seen how it impacts demand (e.g., further evidence), and miscellaneous factors (e.g., supply-related).

CONCLUSION

Having identified the specialties and relevant transformational factors that affect immunoglobulin demand, more research is needed on what clinical or organisational strategies would be effective in controlling demand in general for the Netherlands and abroad. Other blood establishments may also use a scenario approach to increase preparedness for future (un)expected developments.

Withdrawal of intravenous immunoglobulin in chronic inflammatory demyelinating polyradiculoneuropathy

Intravenous immunoglobulins are an efficacious treatment for chronic inflammatory demyelinating polyradiculoneuropathy. Biomarkers for disease activity are lacking, making the need for ongoing treatment difficult to assess, leading to potential overtreatment and high health-care costs. Our objective was to determine whether intravenous immunoglobulin withdrawal is non-inferior to continuing intravenous immunoglobulin treatment and to determine how often patients are overtreated.

We performed a randomized, double-blind, intravenous immunoglobulin-controlled non-inferiority trial in seven centres in the Netherlands (Trial registration: ISRCTN 13637698; www.isrctn.com/ISRCTN13637698). Adults with clinically stable chronic inflammatory demyelinating polyradiculoneuropathy using intravenous immunoglobulin maintenance treatment for at least 6 months were included. Patients received either intravenous immunoglobulin withdrawal (placebo) as investigational treatment or continuation of intravenous immunoglobulin treatment (control). The primary outcome was the mean change in logit scores from baseline to 24-week follow-up on the patient-reported Inflammatory Rasch–Overall Disability Scale. The non-inferiority margin was predefined as between-group difference in mean change scores of −0.65. Patients who deteriorated could reach a relapse end point according to predefined criteria. Patients with a relapse end point after intravenous immunoglobulin withdrawal entered a restabilization phase. All patients from the withdrawal group who remained stable were included in an open-label extension phase of 52 weeks.

We included 60 patients, of whom 29 were randomized to intravenous immunoglobulin withdrawal and 31 to continuation of treatment. The mean age was 58 years (SD 14.7) and 67% was male. The between-group difference in mean change Inflammatory Rasch–Overall Disability Scale scores was −0.47 (95% CI −1.24 to 0.31), indicating that non-inferiority of intravenous immunoglobulin withdrawal could not be established. In the intravenous immunoglobulin withdrawal group, 41% remained stable for 24 weeks, compared to 58% in the intravenous immunoglobulin continuation group (−17%; 95% CI −39 to 8). Of the intravenous immunoglobulin withdrawal group, 28% remained stable at the end of the extension phase. Of the patients in the restabilization phase, 94% restabilized within 12 weeks.

In conclusion, it remains inconclusive whether intravenous immunoglobulin withdrawal is non-inferior compared to continuing treatment, partly due to larger than expected confidence intervals leading to an underpowered study. Despite these limitations, a considerable proportion of patients could stop treatment and almost all patients who relapsed were restabilized quickly. Unexpectedly, a high proportion of intravenous immunoglobulin-treated patients experienced a relapse end point, emphasizing the need for more objective measures for disease activity in future trials, as the patient-reported outcome measures might not have been able to identify true relapses reliably. Overall, this study suggests that withdrawal attempts are safe and should be performed regularly in clinically stable patients.

CIDP: Current Treatments and Identification of Targets for Future Specific Therapeutic Intervention

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired immune-mediated inflammatory disorder of the peripheral nervous system. This clinically heterogeneous neurological disorder is closely related to Guillain–Barré syndrome and is considered the chronic counterpart of that acute disease. Currently available treatments are mostly empirical; they include corticosteroids, intravenous immunoglobulins, plasma exchange and chronic immunosuppressive agents, either alone or in combination. Recent advances in the understanding of the underlying pathogenic mechanisms in CIDP have brought a number of novel ways of possible intervention for use in CIDP. This review summarizes selected pre-clinical and clinical findings, highlights the importance of using adapted animal models to evaluate the efficacy of novel treatments, and proposes the outlines of future directions to ameliorate the conditions of patients with CIDP.

Update on Intravenous Immunoglobulin in Neurology: Modulating Neuro-autoimmunity, Evolving Factors on Efficacy and Dosing and Challenges on Stopping Chronic IVIg Therapy

In the last 25 years, intravenous immunoglobulin (IVIg) has had a major impact in the successful treatment of previously untreatable or poorly controlled autoimmune neurological disorders. Derived from thousands of healthy donors, IVIg contains IgG1 isotypes of idiotypic antibodies that have the potential to bind pathogenic autoantibodies or cross-react with various antigenic peptides, including proteins conserved among the "common cold"-pre-pandemic coronaviruses; as a result, after IVIg infusions, some of the patients' sera may transiently become positive for various neuronal antibodies, even for anti-SARS-CoV-2, necessitating caution in separating antibodies derived from the infused IVIg or acquired humoral immunity. IVIg exerts multiple effects on the immunoregulatory network by variably affecting autoantibodies, complement activation, FcRn saturation, FcγRIIb receptors, cytokines, and inflammatory mediators. Based on randomized controlled trials, IVIg is approved for the treatment of GBS, CIDP, MMN and dermatomyositis; has been effective in, myasthenia gravis exacerbations, and stiff-person syndrome; and exhibits convincing efficacy in autoimmune epilepsy, neuromyelitis, and autoimmune encephalitis. Recent evidence suggests that polymorphisms in the genes encoding FcRn and FcγRIIB may influence the catabolism of infused IgG or its anti-inflammatory effects, impacting on individualized dosing or efficacy. For chronic maintenance therapy, IVIg and subcutaneous IgG are effective in controlled studies only in CIDP and MMN preventing relapses and axonal loss up to 48 weeks; in practice, however, IVIg is continuously used for years in all the aforementioned neurological conditions, like is a "forever necessary therapy" for maintaining stability, generating challenges on when and how to stop it. Because about 35-40% of patients on chronic therapy do not exhibit objective neurological signs of worsening after stopping IVIg but express subjective symptoms of fatigue, pains, spasms, or a feeling of generalized weakness, a conditioning effect combined with fear that discontinuing chronic therapy may destabilize a multi-year stability status is likely. The dilemmas of continuing chronic therapy, the importance of adjusting dosing and scheduling or periodically stopping IVIg to objectively assess necessity, and concerns in accurately interpreting IVIg-dependency are discussed. Finally, the merit of subcutaneous IgG, the ineffectiveness of IVIg in IgG4-neurological autoimmunities, and genetic factors affecting IVIg dosing and efficacy are addressed.

Subcutaneous immunoglobulin treatment for chronic inflammatory demyelinating polyneuropathy

Immunoglobulin G (IgG) therapy is an established long‐term treatment in chronic inflammatory demyelinating polyneuropathy (CIDP) that is commonly administered intravenously (IVIg). The subcutaneous immunoglobulin (SCIg) administration route is a safe and effective alternative option, approved by the United States Food and Drug Administration (FDA) in 2018, for maintenance treatment of adults with CIDP. Physicians and patients alike need to be aware of all their treatment options in order to make informed decisions and plan long‐term treatment strategies. In this review, we collate the evidence for SCIg in CIDP from all published studies and discuss their implications and translation to clinical practice. We also provide guidance on the practicalities of how and when to transition patients from IVIg to SCIg and ongoing patient support. Evidence suggests that IVIg and SCIg have comparable long‐term efficacy in CIDP. However, SCIg can provide additional benefits for some patients, including no requirement for venous access or premedication, and reduced frequency of systemic adverse events. Local‐site reactions are more common with SCIg than IVIg, but these are mostly well‐tolerated and abate with subsequent infusions. Data suggest that many patients prefer SCIg following transition from IVIg. SCIg preference may be a result of the independence and flexibility associated with self‐infusion, whereas IVIg preference may be a result of familiarity and reliance on a healthcare professional for infusions. In practice, individualizing maintenance dosing based on disease behavior and determining the minimally effective IgG dose for individuals are key considerations irrespective of the administration route chosen.

What Is in the Literature

What is in the Literature focuses on peripheral neuropathies with new and practical information related to the diagnosis, treatment, and management. Diagnostic and treatment guidelines are available for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) but not all clinicians follow them resulting in erroneous diagnoses and prolonged treatment. Secondary axonal loss in CIDP causes increased connective tissue in muscle. Antibodies to proteins at the node of Ranvier are found in a small percentage of patients with CIDP. The differential diagnosis for CIDP-like neuropathies includes amyloid neuropathy and POEMS (polyneuropathy, organomegaly, endocrinopathy, M-protein, skin changes) and amyloidosis. Upper limits for cerebral spinal fluid protein are 0.45 g/L and cell count <10/µL, but both may be too low. Hyperactive reflexes may occur in Guillain-Barré syndrome and should not exclude the diagnosis. In severely affected Guillain-Barré syndrome patients, a second dose of intravenous immune globulin within 4 weeks of onset is not likely to be effective.

Clinical outcome of CIDP one year after start of treatment: a prospective cohort study

OBJECTIVE

To assess clinical outcome in treatment-naive patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).

METHODS

We included adult treatment-naive patients participating in the prospective International CIDP Outcome Study (ICOS) that fulfilled the European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) diagnostic criteria for CIDP. Patients were grouped based on initial treatment with (1) intravenous immunoglobulin (IVIg), (2) corticosteroid monotherapy or (3) IVIg and corticosteroids (combination treatment). Outcome measures included the inflammatory Rasch-built overall disability scale (I-RODS), grip strength, and Medical Research Council (MRC) sum score. Treatment response, treatment status, remissions (improved and untreated), treatment changes, and residual symptoms or deficits were assessed at 1 year.

RESULTS

Forty patients were included of whom 18 (45%) initially received IVIg, 6 (15%) corticosteroids, and 16 (40%) combination treatment. Improvement on ≥ 1 of the outcome measures was seen in 31 (78%) patients. At 1 year, 19 (48%) patients were still treated and fourteen (36%) patients were in remission. Improvement was seen most frequently in patients started on IVIg (94%) and remission in those started on combination treatment (44%). Differences between groups did not reach statistical significance. Residual symptoms or deficits ranged from 25% for neuropathic pain to 96% for any sensory deficit.

CONCLUSIONS

Improvement was seen in most patients. One year after the start of treatment, more than half of the patients were untreated and around one-third in remission. Residual symptoms and deficits were common regardless of treatment.

Evaluation of the EFNS/PNS diagnostic criteria in a cohort of CIDP patients

Objective

To evaluate the European Federation of Neurological Societies (EFNS)/Peripheral Nerve Society (PNS) diagnostic criteria for chronic inflammatory demyelinating polyneuropathy (CIDP) in a cohort of patients diagnosed and treated for CIDP in a tertiary university hospital.

Methods

In a monocentric retrospective study of 203 CIDP patients, diagnosed according to expert opinion, we evaluated the EFNS/PNS diagnostic criteria. Clinical course and nerve conduction studies (NCS) over 1 year from first referral were studied. Secondarily, we compared the clinical and paraclinical characteristics, including nerve ultrasound, of patients who failed with those who fulfilled the criteria in order to identify clinically relevant differences.

Results

At 1 year, 182 (89.7%) patients fulfilled the criteria (156/76.9% definite, 22/10.8% probable, and 4/2% possible). Twenty‐one (10.3%) patients did not because the electrodiagnostic criteria remained negative. These still showed signs of demyelination but did not reach the cut‐off values. They also presented typical, albeit less pronounced, multifocal nerve enlargement in ultrasonography. Mean disability at presentation and 1 year after was significantly lower. Most importantly, a relevant proportion of these patients also responded to therapy (6/21 = 28.6% vs. 82/182 = 45.3% of those fulfilling the criteria).

Interpretation

CIDP diagnosis could be established for 89.7% of patients over the course of 1 year using EFNS/PNS criteria. The remaining patients (10.3%) presented with milder disability, less accentuated demyelination, but otherwise similar characteristics and still considerable probability of treatment response. Failure to fulfill diagnostic criteria should not automatically preclude treatment. Nerve ultrasound should be considered as a complementary diagnostic tool to detect signs of inflammation in CIDP.

Diagnosis and treatment of chronic inflammatory demyelinating polyradiculoneuropathy in clinical practice: A survey among Dutch neurologists

The diagnosis and treatment of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is often a challenge. The clinical presentation is diverse, accurate biomarkers are lacking, and the best strategy to initiate and maintain treatment is unclear. The aim of this study was to determine how neurologists diagnose and treat CIDP. We conducted a cross‐sectional survey on diagnostic and treatment practices among Dutch neurologists involved in the clinical care of CIDP patients. Forty‐four neurologists completed the survey (44/71; 62%). The respondents indicated to use the European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) 2010 CIDP guideline for the diagnosis in 77% and for treatment in 50%. Only 57% of respondents indicated that the presence of demyelinating electrophysiological findings was mandatory to confirm the diagnosis of CIDP. Most neurologists used intravenous immunoglobulins (IVIg) as first choice treatment, but the indications to start, optimize, or withdraw IVIg, and the use of other immune‐modulatory therapies varied. University‐affiliated respondents used the EFNS/PNS 2010 diagnostic criteria, nerve imaging tools, and immunosuppressive drugs more often. Despite the existence of an international guideline, there is considerable variation among neurologists in the strategies employed to diagnose and treat CIDP. More specific recommendations regarding: (a) the minimal set of electrophysiological requirements to diagnose CIDP, (b) the possible added value of nerve imaging, especially in patients not meeting the electrodiagnostic criteria, (c) the most relevant serological examinations, and (d) the clear treatment advice, in the new EFNS/PNS guideline, would likely support its implementation in clinical practice.

Electrodiagnostic accuracy in polyneuropathies: supervised learning algorithms as a tool for practitioners

OBJECTIVE

The interpretation of electrophysiological findings may lead to misdiagnosis in polyneuropathies. We investigated the electrodiagnostic accuracy of three supervised learning algorithms (SLAs): shrinkage discriminant analysis, multinomial logistic regression, and support vector machine (SVM), and three expert and three trainee neurophysiologists.

METHODS

We enrolled 434 subjects with the following diagnoses: chronic inflammatory demyelinating polyneuropathy (99), Charcot-Marie-Tooth disease type 1A (124), hereditary neuropathy with liability to pressure palsy (46), diabetic polyneuropathy (67), and controls (98). In each diagnostic class, 90% of subjects were used as training set for SLAs to establish the best performing SLA by tenfold cross validation procedure and 10% of subjects were employed as test set. Performance indicators were accuracy, precision, sensitivity, and specificity.

RESULTS

SVM showed the highest overall diagnostic accuracy both in training and test sets (90.5 and 93.2%) and ranked first in a multidimensional comparison analysis. Overall accuracy of neurophysiologists ranged from 54.5 to 81.8%.

CONCLUSIONS

This proof of principle study shows that SVM provides a high electrodiagnostic accuracy in polyneuropathies. We suggest that the use of SLAs in electrodiagnosis should be exploited to possibly provide a diagnostic support system especially helpful for the less experienced practitioners.

Improving Intravenous Immunoglobulin Dosing in Autoimmune Neuropathies

This symposium took place on Monday 24th June 2019, as part of the 2019 Peripheral Nerve Society (PNS) Annual Meeting in Genoa, Italy. Immune-mediated neuropathies such as Guillain–Barré Syndrome (GBS), chronic inflammatory demyelinating polyneuropathy (CIDP), and multifocal motor neuropathy (MMN) are diverse inflammatory peripheral nerve disorders. International consensus guidelines recommend intravenous Ig (IVIG) as Level A for the treatment of GBS, CIDP, and MMN. Suggested induction doses of IVIG are 2 g/kg divided over 2–5 days, but maintenance doses are purposely less clearly defined and left up to the judgement of the clinician, depending upon the specific needs of the individual patient. Community-based neurologists treating patients with these rare inflammatory neuropathies may be unaware of optimal dosing regimens and patient response to treatment may therefore be inadequate. In this symposium, world-renowned experts in GBS, CIDP, and MMN shared their expertise and review of the literature to provide reasonable dosing regimens for neurologists who may rarely encounter these conditions.

Sodium Fluorescein as Intraoperative Visualization Tool During Peripheral Nerve Biopsies

OBJECTIVE

Owing to technical development of specific fluorophore filters, the neurosurgical application of sodium fluorescein (SF) has regained value in brain tumor surgery. The aim of this study was to determine the usefulness of SF during nerve biopsies.

METHODS

This single-center study included 5 cases of nerve biopsies performed under microscope-based fluorescence with SF performed between March 2016 and February 2017. SF was applied intravenously (1 mg/kg body weight). After microsurgical dissection of the involved nerve segment, fluorescence-guided fascicular biopsy was performed. Selection of target fascicles was at the surgeon's discretion and took into account nerve stimulation for preservation of motor function and fluorescence intensity. Correlation to histopathologic examination was examined. Video analysis of intraoperative images comparing target fascicles with intense fluorescent response to adjacent fascicles of the same nerve segment was performed using ImageJ.

RESULTS

All patients had motor or sensory deficits. Magnetic resonance imaging findings were similar, depicting long segments of gadolinium enhancement (minimum 11.7 cm). Each biopsy sample was positive resulting in diverse histopathologic results. Digital image analysis revealed a statistically significant difference of the complementary color green (P = 0.0473).

CONCLUSIONS

Magnetic resonance imaging is the gold standard in diagnostic work-up of peripheral nerve disorders. Longitudinal nerve thickening with positive contrast enhancement is an unspecific magnetic resonance imaging finding. Various pathologies, such as tumors and inflammatory lesions, may cause this morphologic phenomenon. Nerve biopsies may be needed for diagnostic work-up. Intraoperative SF may help to depict the most affected fascicles and identify target fascicles for biopsy and increase diagnostic certainty of nerve biopsies.