Marieke van Rosmalen

Chapter 1 18 More recently, nerve ultrasound has been explored as another imaging technique in diagnosis of chronic inflammatory neuropathies. 18,19 These studies showed that a quantitative assessment, i.e. with objective cut-off values for abnormality, results in good test characteristics. Just as MRI, nerve ultrasound may show thickening of the brachial plexus and peripheral nerves. Unfortunately, nerve ultrasound is not yet widely available as its implementation in clinical practice requires experience. However, nerve ultrasound is a promising technique that might be added to the diagnostic criteria in the future. The combined role of nerve ultrasound and MRI in the diagnostic process of chronic inflammatory neuropathies should be evaluated to optimize the diagnostic performance of both imaging modalities. Pathophysiology Autopsy studies, sural nerve biopsy and immunostaining in vitro have tried to provide insight in underlying immunological mechanisms in CIDP and MMN. 20–26 The scarce reports on CIDP describe moderate to severe demyelination and remyelination with onion bulbs without loss of axons. 20–22,27 Some histological studies on MMN describe axonal loss without demyelination, 23–25,28 while others describe de- and remyelination. 29–31 There is an obvious need for additional tools to study the condition of peripheral nerves of patients with a chronic inflammatory neuropathy in vivo . Therefore, quantitative MRI techniques that correlate to histological findings, such as DTI and T2 mapping are promising. Previous DTI studies evaluated the peripheral nerves and the brachial and lumbosacral plexus in small cohorts of patients with CIDP or MMN and healthy controls. 32–40 These smaller studies already showed differences in diffusion parameters and T2 relaxation times between groups which suggests that quantitative MRI techniques could be helpful to explore pathophysiologies further. However, large and systematic studies are currently lacking. Prognosis and treatment Patients with CIDP and MMN both respond to immunomodulatory treatment. For patients with MMN intravenous or subcutaneous immunoglobulins is the only treatment option; patients with CIDP may also respond to treatment with corticosteroids or plasmapheresis. 1,2 Treatment may improve motor and sensory deficits but management of treatment is challenging in current clinical practice. These challenges mainly rely on the fact that treatment response is not easily monitored as it lacks a clear definition. Therefore, it might be difficult to find the right treatment dose in some patients, which could result in over- or undertreatment. In current clinical practice, improvement of muscle strength as measured by MRC scales, myometry or equivalent tests is assumed to be the golden standard of treatment response but strength measurements might be subject to differences between raters. Objective markers that predict course of disease and treatment response are lacking. However, these biomarkers are needed if we want to improve management of CIDP and MMN.