Boundaries of chronic inflammatory demyelinating polyradiculoneuropathy

Clinical relevance of distinguishing autoimmune nodopathies from CIDP: longitudinal assessment in a large cohort

BACKGROUND

The aim of this study was to determine treatment response and whether it is associated with antibody titre change in patients with autoimmune nodopathy (AN) previously diagnosed as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), and to compare clinical features and treatment response between AN and CIDP.

METHODS

Serum IgG antibodies to neurofascin-155 (NF155), contactin-1 (CNTN1) and contactin-associated protein 1 (CASPR1) were detected with cell-based assays in patients diagnosed with CIDP. Clinical improvement was determined using the modified Rankin scale, need for alternative and/or additional treatments and assessment of the treating neurologist.

RESULTS

We studied 401 patients diagnosed with CIDP and identified 21 patients with AN (10 anti-NF155, 6 anti-CNTN1, 4 anti-CASPR1 and 1 anti-NF155/anti-CASPR1 double positive). In patients with AN ataxia (68% vs 28%, p=0.001), cranial nerve involvement (34% vs 11%, p=0.012) and autonomic symptoms (47% vs 22%, p=0.025) were more frequently reported; patients with AN improved less often after intravenous immunoglobulin treatment (39% vs 80%, p=0.002) and required additional/alternative treatments more frequently (84% vs 34%, p<0.001), compared with patients with CIDP. Antibody titres decreased or became negative in patients improving on treatment. Treatment withdrawal was associated with a titre increase and clinical deterioration in four patients.

CONCLUSIONS

Distinguishing CIDP from AN is important, as patients with AN need a different treatment approach. Improvement and relapses were associated with changes in antibody titres, supporting the pathogenicity of these antibodies.

Application of the 2021 EAN/PNS criteria for chronic inflammatory demyelinating polyneuropathy

BACKGROUND

The diagnostic value of new criteria of the European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) for chronic inflammatory demyelinating polyneuropathy (CIDP) is unknown.

METHODS

We performed a retrospective study of fulfilment of EAN/PNS 2021 criteria on 120 consecutive patients with a clinical diagnosis of 'suspected CIDP' and objective treatment response, attending University Hospitals Birmingham, UK. Specificity was evaluated versus 100 consecutive controls.

RESULTS

The sensitivity of EAN/PNS criteria for 'CIDP' was 83.3%. The sensitivity for 'CIDP' or 'possible CIDP' was 93.3%. Specificity was of 94% for 'CIDP' and 79% for 'CIDP' or 'possible CIDP'. No sensitivity/specificity differences were ascertained with previous versions ('CIDP': sensitivity: 83.3% vs 81.3%, p=0.74, specificity: 94% vs 96.1%, p=0.38, respectively; 'CIDP' or 'possible CIDP': sensitivity: 93.3% vs 96.7%, p=0.25 and specificity: 79% vs 69.2 %, p=0.09, respectively). F-wave prolongation, proximal and distal temporal dispersion were the most likely parameters to contribute to false positives, whereas distal motor latency was the least likely. No impact of sensory electrophysiology could be ascertained. 'Typical CIDP' represented 79% of the CIDP cohort. The largest component of the 'variant CIDP' group was represented by focal/multifocal forms (14%). With new criteria, 6.7% of the cohort did not meet requirements, among whom the majority (75%) had paranodopathy or chronic immune sensory polyradiculopathy (CISP).

DISCUSSION

The sensitivity and specificity of new EAN/PNS criteria for CIDP is equivalent to that of previous versions. The exclusion of paranodopathies and CISP from the CIDP spectrum impacts on management of a non-negligible proportion of treatment-responsive patients.

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.

What is in the Literature

This edition of What is in the Literature focuses on chronic immune neuropathies as they represent treatable conditions. There are formal criteria to solidify the diagnosis of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), but patients are encountered who have clinical and electrodiagnostic features of CIDP but do not fulfill diagnostic criteria. These patients are addressed in recent publications. CIDP (and variants) and other forms of immune-mediated neuropathies (multifocal motor neuropathy) are responsive early on to treatment, but long-term factors are less well described, and a number of publications focus on extended consequences. Acute immune neuropathies have been described in the setting of viral illness, and recent publications look at the question as to whether they are associated with the COVID-19 pandemic. Finally, idiopathic sensory neuropathies are the most common polyneuropathy, and consensus efforts to codify features into subtypes can be used clinically for a more precise diagnosis.

A Systematic Review and Meta-Analysis of Autoantibodies for Diagnosis and Prognosis in Patients With Chronic Inflammatory Demyelinating Polyradiculoneuropathy

Objectives: To review the available evidence on sensitivity and specificity of anti-NF155 antibody detection in diagnosing a specific subset of patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and to calculate the frequencies of different autoantibodies to paranodal proteins. Background: Diagnosis of CIDP relies on clinical and neurophysiologic criteria and lacks useful diagnostic biomarkers. A subset of CIDP patients exhibit atypical clinical phenotypes and impaired response to conventional treatments. These patients were reported as having autoantibodies targeting paranodal protein neurofascin isoform 155 (NF155), contactin-1 (CNTN1), and contactin-associated protein-1 (CASPR1). Here, we conducted a meta-analysis to summarize evidence on the diagnostic and prognostic value of these autoantibodies, especially for anti-NF155 antibody. Methods: We searched the following electronic bibliographic databases: PubMed, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science. Eligible studies provided information to calculate the frequencies of anti-NF155 antibody and anti-CNTN1 antibody, the sensitivity and specificity of anti-NF155 antibody, and the incidence of improvement and deterioration among anti-NF155 antibody seropositive CIDP patients. Heterogeneity was assessed using Q and I ² statistics. Results: The pooled frequency of anti-NF155 autoantibody across 14 studies was 7% [95% confidence interval (CI): 0.05-0.10] with high heterogeneity; the overall pooled sensitivity and specificity of anti-NF155 antibody for the diagnosis of a specific subgroup of CIDP patients were 0.45 (95% CI: 0.29-0.63) and 0.93 (95% CI: 0.86-0.97), respectively. Conclusions: For diagnosing of a specific subset of CIDP characterized by poor response to intravenous immunoglobulin (IVIg), we found a moderate sensitivity and a high specificity. The anti-NF155 antibody test should be used as a confirmatory test rather than a screening test. Systematic Review Registration: PROSPERO, identifier: CRD42020203385 and CRD42020190789.

Elucidating autoimmune nodopathies and the CIDP spectrum

This scientific commentary refers to ‘Antibodies to the Caspr1/contactin-1 complex in chronic inflammatory demyelinating polyradiculoneuropathy’, by Pascual-Goñi et al. (doi:10.1093/brain/awab014).

Misdiagnosis and diagnostic pitfalls of chronic inflammatory demyelinating polyradiculoneuropathy

Background and purpose

The aim of this study was to determine the frequency of over‐ and underdiagnosis of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and to identify related diagnostic pitfalls.

Methods

We conducted a retrospective study in Dutch patients referred to the Erasmus University Medical Centre Rotterdam between 2011 and 2017 with either a diagnosis of CIDP or another diagnosis that was revised to CIDP. We used the European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) 2010 diagnostic criteria for CIDP to classify patients into three groups: overdiagnosis, underdiagnosis, or confirmed diagnosis of CIDP. Clinical and laboratory features and treatment history were compared between groups.

Results

A referral diagnosis of CIDP was revised in 32% of patients (31/96; overdiagnosis). Of 81 patients diagnosed with CIDP, 16 (20%) were referred with another diagnosis (underdiagnosis). In the overdiagnosed patients, 20% of muscle weakness was asymmetric, 48% lacked proximal muscle weakness, 29% only had distal muscle weakness, 65% did not fulfil the electrodiagnostic criteria for CIDP, 74% had an elevated cerebrospinal fluid (CSF) protein level, and 97% had another type of neuropathy. In the underdiagnosed patients, all had proximal muscle weakness, 50% had a clinically atypical CIDP, all fulfilled the electrodiagnostic criteria for CIDP, and 25% had an increased CSF protein level.

Conclusion

Over‐ and underdiagnosis of CIDP is common. Diagnostic pitfalls include lack of attention to proximal muscle weakness as a diagnostic hallmark of CIDP, insufficient recognition of clinical atypical phenotypes, overreliance on CSF protein levels, misinterpretation of nerve conduction studies and poor adherence to electrodiagnostic criteria, and failure to exclude other causes of polyneuropathy.

Proximal Nerve Root Involvement in immunoglobulin M Anti-Myelin-Associated Glycoprotein Neuropathy Presenting as Cauda Equina Syndrome

Typical distal symptoms in anti-myelin-associated glycoprotein (anti-MAG) neuropathy are believed to be due to the binding of immunoglobulin M to distal nerve terminals. We describe the case of a 56-year-old man diagnosed with immunoglobulin M anti-MAG neuropathy in the setting of Waldenström macroglobulinemia, which developed acute neurological worsening presenting as cauda equina syndrome. Lumbosacral magnetic resonance imaging revealed enlarged nerve roots with diffuse heterogeneous gadolinium enhancement. Treatment with steroids resulted in substantial clinical improvement. Increased recognition of atypical presentations may lead to improved characterization of anti-MAG neuropathy as a more widespread disease.

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.