Marieke van Rosmalen

Chapter 8 140 Figure 8.2 Proposal of revision of diagnostic criteria for MMN Clinical suspicion of MMN Ultrasound available? Perform ultrasound 1 Perform NCS 3 Yes No No other diagnosis based on additional laboratory findings 2 Start of treatment Definite MMN t+ Perform NCS 3 t- Definite, probable or slowing of conduction Inconclusive Definite MMN Possible MMN Definite Definite MMN Probable Slowing of conduction Inconclusive CSF protein < 1 g/L Probable MMN Elevated anti-GM1 antibodies or abnormal MRI 4 Possible MMN Possible MMN CSF protein < 1 g/L T+ T- T+ Consider alternative diagnosis T- This flow chart summarizes results from recent diagnostic nerve ultrasound and MRI studies on diagnosis of MMN and integrates them in the current diagnostic Utrecht criteria. 24 1 Examination of the median nerve in the forearms (> 10 mm 2 ), upper arms (> 13 mm 2 ) and C5 nerve root (> 8 mm 2 ). Abnormal when ≥ 1 measurement site is enlarged. 2 Additional laboratory examination consists of determination of protein in cerebrospinal fluid, serum anti-GM1 antibodies and exclusion of other (metabolic) causes of neuropathy (e.g. diabetes, hypothyroidism, liver or renal insufficiency, vitamin deficiencies). 3 Results of NCS should be interpreted according to the Utrecht electrodiagnostic criteria. 24 4 Supportive criteria of MMN can be found in Table 8.1 . MRI should be quantitatively assessed. 5 Results of MRI examination should be quantitatively assessed and interpreted using the risk chart in chapter 4, Figure 4.3 Abbreviations: MMN = multifocal motor neuropathy; NCS = nerve conduction studies; CSF = cerebrospinal fluid; MRI = magnetic resonance imaging; T+ = positive result of test; T- = negative result of test; t+ = good treatment response; t- = no treatment response.