Neuropathies and paraproteins

PURPOSE OF REVIEW: There is an increasingly recognized association between haematological and neurological disease. This is especially true in the peripheral nervous system in which, to an extent, proof of a link is easier to achieve. The most sensitive low level paraprotein detection methods should always be employed in which a paraprotein is suspected. Peripheral nerves can be damaged not only by the immunological targeting of the myelin by the paraprotein, but by deposition (light chain amyloid and cryoglobulins) or direct infiltration (neurolymphomatosis). This has resulted in other defined paraprotein-related disease pathogeneses. RECENT FINDINGS: Our opportunities for treating these patients are greater not only through better recognition of disease but also treatments introduced from haematological research. Beyond rituximab, combination therapies, proteasome inhibition and novel biological treatments are being described in haematological practice with early efficacy in neurology. Important developments here should be exploited in neurology to improve outcomes. SUMMARY: This review of the current literature focuses not only on the long-term outcome studies in anti-myelin-associated glycoprotein neuropathy, but developments in the diagnosis and treatment of monoclonal gammopathy of undetermined significance and Waldenström's Macroglobulinaemia

Fatal autonomic failure due to premanifesting Parkinson's disease only diagnosed at autopsy

A 46‐year‐old male had 11‐year history of cryptic autonomic dysfunction. He developed a fatal autonomic failure with diffuse hypoxic brain injury. Histology examination of medulla oblongata and the celiac ganglion revealed many α‐synuclein immunoreactive Lewy bodies confirming the diagnosis of premanifesting Parkinson's disease (PD). PNS involvement in PD is underappreciated

POEMS syndrome

PURPOSE OF REVIEW: To provide an overview of polyneuropathy organomegaly endocrinopathy M-protein and skin changes (POEMS) syndrome, detailing new insights into pathogenesis, prognostic factors, treatments, and outcome scores. RECENT FINDINGS: With the development of large multicentre national cohorts of patients, POEMS syndrome is evolving into a well characterized multisystem hematoneurological syndrome. Without early diagnosis significant disability results from the neuropathy. Vascular endothelial growth factor (VEGF) is a useful and accurate biomarker supporting diagnosis and following disease activity. The past decade has seen a number of therapeutics become available to patients with POEMS, repurposed from myeloma treatment. Simple treatment algorithms are based on the extent of monoclonal proliferation and the performance status of patients. Risk factors, prognostic scores, and their impact on outcome measures have been developed from deeply phenotyped patient cohorts to predict response rate, progression-free survival and overall survival. SUMMARY: Understanding links between the monoclonal lambda plasma cell disorder and resulting proinflammatory cytokine milieu is fundamental to determining POEMS syndrome pathophysiology. Similarities to chronic inflammatory demyelinating polyradiculoneuropathy and some other monoclonal proliferative diseases makes POEMS misdiagnosis common. A range of treatments are available, and more work to identify pathogenic mechanisms and treatment targets and prognostic scores will further enable treatment stratification for optimum outcomes

Fluid Biomarkers for Monitoring Structural Changes in Polyneuropathies: Their Use in Clinical Practice and Trials

Reliable and responsive tools for monitoring disease activity and treatment outcomes in patients with neuropathies are lacking. With the emergence of ultrasensitive blood bioassays, proteins released with nerve damage are potentially useful response biomarkers for many neurological disorders, including polyneuropathies. In this review, we provide an overview of the existing literature focusing on potential applications in polyneuropathy clinical care and trials. Whilst several promising candidates have been identified, no studies have investigated if any of these proteins can serve as response biomarkers of longitudinal disease activity, except for neurofilament light (NfL). For NfL, limited evidence exists supporting a role as a response biomarker in Guillain-Barré syndrome, vasculitic neuropathy, and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Most evidence exists for NfL as a response biomarker in hereditary transthyretin-related amyloidosis (hATTR). At the present time, the role of NfL is therefore limited to a supporting clinical tool or exploratory endpoint in trials. Future developments will need to focus on the discovery of additional biomarkers for anatomically specific and other forms of nerve damage using high-throughput technologies and highly sensitive analytical platforms in adequality powered studies of appropriate design. For NfL, a better understanding of cut-off values, the relation to clinical symptoms and long-term disability as well as dynamics in serum on and off treatment is needed to further expand and proceed towards implementation

Dramatic clinical response to ultra-high dose IVIg in otherwise treatment resistant inflammatory neuropathies

Background Intravenous immunoglobulin (IVIg) has short and long-term efficacy in both chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy with conduction block (MMNCB). There is potential for under and over-treatment if trial regimens are strictly adhered to in clinical practice where titrating dose to clinical response is recommended. Methods We report the response to high-dose IVIg (>2 g/kg/6 weeks) in a subgroup of patients with definite CIDP or MMNCB who were unresponsive to ‘usual’ dosing. IVIg frequency and dosing was determined for each individual by subjective and objective outcome measures for impairment, grip strength, and activity and participation. Results Six patients (three with chronic inflammatory demyelinating polyneuropathy (CIDP), three with MMN) were included. Two patients (one CIDP and one MMNCB) returned to full-time work on fractionated IVIg doses of 5 g/kg/month and 9 g/kg/month. Patient three (CIDP) failed numerous other immunosuppressants but responded to short-term fractionated 4 g/kg/month of IVIg. Patient four has severe, refractory, childhood-onset CIDP, remains stable but dependent currently on 6.9 g/kg/month of IVIg. Patients five and six, both with MMNCB, required short term 4.5–5 g/kg/month to recover significant bilateral hand strength. No IVIg-related adverse events occurred in any individual. Conclusions These six cases demonstrate the safety and effectiveness of a treatment approach that includes individualised but evidence-based clinical assessment and, when necessary, high-doses of IVIg to restore patients’ strength and ability to participate in activities of daily activities. Careful patient selection is important

Early VEGF testing in inflammatory neuropathy avoids POEMS syndrome misdiagnosis and associated costs

BACKGROUND: Prompt diagnosis and early treatment prevents disability in Polyneuropathy Organomegaly Endocrinopathy Monoclonal-protein and Skin Changes (POEMS) syndrome. Delay in diagnosis is common with 55% of patients initially incorrectly diagnosed with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Patients are often treated with intravenous immunoglobulin which is both expensive and ineffective in the treatment of POEMS. Testing patients with acquired demyelinating neuropathy with serum vascular endothelial growth factor (VEGF) more accurately identifies POEMS syndrome than the current standard of care. Incorporating VEGF testing into screening could prevent misdiagnosis and reduce costs. METHODS: We used observed treatment information for patients in the University College London Hospital's POEMS syndrome database (n=100) and from the National Immunoglobulin Database to estimate costs associated with incorrect CIDP diagnoses across our cohort. We conducted a model-based cost-effectiveness analysis to compare the current diagnostic algorithm with an alternative which includes VEGF testing for all patients with an acquired demyelinating neuropathy. RESULTS: Treatment associated with an incorrect CIDP diagnosis led to total wasted healthcare expenditures of between £808 550 and £1 111 756 across our cohort, with an average cost-per-POEMS-patient misdiagnosed of £14 701 to £20 214. Introducing mandatory VEGF testing for patients with acquired demyelinating neuropathy would lead to annual cost-savings of £107 398 for the National Health Service and could prevent misdiagnosis in 16 cases per annum. CONCLUSIONS: Misdiagnosis in POEMS syndrome results in diagnostic delay, disease progression and significant healthcare costs. Introducing mandatory VEGF testing for patients with acquired demyelinating neuropathy is a cost-effective strategy allowing for early POEMS diagnosis and potentially enabling prompt disease-directed therapy

High rates of venous and arterial thrombotic events in patients with POEMS syndrome: results from the UCLH (UK) POEMS Registry

Arterial and venous thromboses occur in patients with POEMS (polyneuropathy, organomegaly, endocrinopathy, M-protein level, and skin changes) syndrome at a previously reported rate of 20%. We reviewed the University College London Hospitals (UCLH) POEMS Registry to determine the rate of venous thromboembolism (VTE), arterial events, and risk factors. This registry, established in 1999 and comprising 103 patients at the time of this study, is the largest single-center cohort in Europe. Of the 83 assessable patients, median age at presentation was 52 years (range, 31-84). Twenty-five patients experienced clinically apparent arterial or venous events, and 2 had concurrent arterial and venous thromboses. Eleven patients had VTEs, including deep vein thrombosis (DVT; 3 of 11), pulmonary embolism (4 of 11), and peripherally inserted central catheter–associated DVT, which occurred during autologous stem cell transplantation (3 of 11). Sixteen patients experienced arterial events: stroke (7 of 16), peripheral arterial occlusion (5 of 16), myocardial infarction (3 of 16), and microvascular disease (1 of 16), with no discernible relationship with thrombocytosis or polycythemia. Thirty percent of POEMS patients have arterial and venous thromboses, higher than previously reported. There were more arterial than venous events, and most occurred during active disease, before the start of chemotherapy, indicating the need for a preemptive approach to thromboprophylaxi

IgM paraprotein-associated peripheral neuropathy: small CD20-positive B-cell clones may predict a monoclonal gammopathy of neurological significance and rituximab responsiveness

IgM paraprotein‐associated peripheral neuropathy (PN) in patients without overt evidence of lymphoma is a recognised clinical entity of unknown aetiology. Interrogating the bone marrow B‐cell or plasma cell clones underlying paraproteinemic neuropathies may improve our understanding of both pathogenesis and treatment options. This retrospective observational analysis of IgM paraprotein‐associated PN identified five patients with small pathological MYD88 L265P and CD20‐positive B‐cell clones in their bone marrow using multi‐parametric flow cytometry, who have shown durable neurological response to rituximab. We posit that multi‐parametric flow cytometry may be instrumental in identifying the cellular source of the paraprotein in IgM paraprotein‐associated PN, and thus directing appropriate immunomodulatory therapy. Further understanding of these small pathological B‐cell clones may also provide additional insight into mechanisms of monoclonal gammopathy of clinical significance overall