Marieke van Rosmalen

Chapter 8 138 not fulfill the electrodiagnostic criteria for MMN. This patient did not have abnormalities on nerve ultrasound, neither on MRI. Diagnosis in this patient was based on clinical presentation combined with elevated liquor protein and treatment response. We concluded that MRI was of added diagnostic value even in the context of extensive NCS and nerve ultrasound in CIDP, but not in MMN. Recommendations for clinical practice All the above results combined, I would recommend to avoid a qualitative assessment of brachial plexus MRI. Quantitative assessment is reliable and relatively easy to implement in routine practice. Combinations of different measurements are preferred over fixed cut-off points in a quantitative assessment of brachial plexus MRI. Results of brachial plexus MRI could be interpreted using our risk chart ( chapter 4, Figure 4.3 ). Secondly, MRI should only be performed when clinical suspicion remains high despite a normal nerve ultrasound or NCS that does not fulfill the electrodiagnostic criteria in patients with CIDP (but not MMN). If, based on our risk chart, MRI shows abnormalities compatible with CIDP, other possible diagnoses should be excluded with additional laboratory examination. Next, immunomodulatory treatment could be started as trial. It is important that symptoms and treatment response are monitored over time. This strategy prevents that treatment is withheld from patients and might help the clinician with further differentiation in diagnosis. These recommendations for CIDP are summarized in a flow chart ( Figure 8.1 ) that integrates the results of recent nerve ultrasound and MRI studies in the current EFNS/PNS criteria for CIDP. 19 For MMN, MRI could still be a supportive criterion in the diagnostic criteria of MMN, especially when nerve ultrasound is not available ( Figure 8.2 ). Finally, it is important to increase the availability of nerve ultrasound in (non-academic) medical centers. Based on previous studies, nerve ultrasound should be used as a screening tool before NCS is performed. Nerve ultrasound examination should consist of assessment of the median nerve in the forearms and upper arms and of C5 nerve root of the brachial plexus and should be considered abnormal when ≥ 1 measurement site is enlarged. 31,32 When nerve ultrasound is not available in a medical center, I would recommend to perform NCS when a patient is clinically suspected of CIDP or MMN and follow the current diagnostic criteria, with the exception that MRI should always be quantitatively assessed.