Chronic Inflammatory Demyelinating Polyradiculoneuropathy: Five New Things

Neurofilaments as biomarkers in neurological disorders - towards clinical application

Neurofilament proteins have been validated as specific body fluid biomarkers of neuro-axonal injury. The advent of highly sensitive analytical platforms that enable reliable quantification of neurofilaments in blood samples and simplify longitudinal follow-up has paved the way for the development of neurofilaments as a biomarker in clinical practice. Potential applications include assessment of disease activity, monitoring of treatment responses, and determining prognosis in many acute and chronic neurological disorders as well as their use as an outcome measure in trials of novel therapies. Progress has now moved the measurement of neurofilaments to the doorstep of routine clinical practice for the evaluation of individuals. In this Review, we first outline current knowledge on the structure and function of neurofilaments. We then discuss analytical and statistical approaches and challenges in determining neurofilament levels in different clinical contexts and assess the implications of neurofilament light chain (NfL) levels in normal ageing and the confounding factors that need to be considered when interpreting NfL measures. In addition, we summarize the current value and potential clinical applications of neurofilaments as a biomarker of neuro-axonal damage in a range of neurological disorders, including multiple sclerosis, Alzheimer disease, frontotemporal dementia, amyotrophic lateral sclerosis, stroke and cerebrovascular disease, traumatic brain injury, and Parkinson disease. We also consider the steps needed to complete the translation of neurofilaments from the laboratory to the management of neurological diseases in clinical practice.

Aggressive Acquired Demyelinating Neuropathy Caused by NF-155: Initially Treatment-Resistant

OBJECTIVES

Anti-neurofascin-155 IgG4 (NF-155) antibody disease has previously been associated with a subset of patients with chronic inflammatory demyelinating polyradiculoneuropathy. We report a case of NF-155 positive polyneuropathy that initially presented as an acute inflammatory demyelinating polyradiculoneuropathy. The patient responded appropriately to treatment but subsequently progressed over a 3-month period, resulting in quadriplegia, areflexia, and oculobulbar paralysis.

METHODS

Case report and literature review.

RESULTS

A 40-year-old male presented with acute bilateral arm and thigh weakness, areflexia, and distal sensory loss. Treatment with intravenous immunoglobulin (IVIg) for acute acquired demyelinating neuropathy resulted in initial improvement but subsequent decline. Lack of response to additional IVIg and plasmapheresis (PLEX) prompted testing for NF-155. Treatment with rituximab and steroids resulted in virtually complete recovery.

CONCLUSIONS

Early testing for nodal and paranodal proteins is indicated in patients who present with acute acquired demyelinating neuropathy but fail to respond to conventional treatments, such as IVIg or PLEX. Identification of nodal and paranodal antibodies should prompt treatment with rituximab and steroids to increase likelihood of recovery.

The 2022 Lady Estelle Wolfson lectureship on neurofilaments

Neurofilament proteins (Nf) have been validated and established as a reliable body fluid biomarker for neurodegenerative pathology. This review covers seven Nf isoforms, Nf light (NfL), two splicing variants of Nf medium (NfM), two splicing variants of Nf heavy (NfH), α -internexin (INA) and peripherin (PRPH). The genetic and epigenetic aspects of Nf are discussed as relevant for neurodegenerative diseases and oncology. The comprehensive list of mutations for all Nf isoforms covers Amyotrophic Lateral Sclerosis, Charcot-Marie Tooth disease, Spinal muscular atrophy, Parkinson Disease and Lewy Body Dementia. Next, emphasis is given to the expanding field of post-translational modifications (PTM) of the Nf amino acid residues. Protein structural aspects are reviewed alongside PTMs causing neurodegenerative pathology and human autoimmunity. Molecular visualisations of NF PTMs, assembly and stoichiometry make use of Alphafold2 modelling. The implications for Nf function on the cellular level and axonal transport are discussed. Neurofilament aggregate formation and proteolytic breakdown are reviewed as relevant for biomarker tests and disease. Likewise, Nf stoichiometry is reviewed with regard to in vitro experiments and as a compensatory mechanism in neurodegeneration. The review of Nf across a spectrum of 87 diseases from all parts of medicine is followed by a critical appraisal of 33 meta-analyses on Nf body fluid levels. The review concludes with considerations for clinical trial design and an outlook for future research.