Marieke van Rosmalen

Chapter 4 58 disease (ALS and PMA), according to the Brooks criteria. 14 We excluded patients aged < 18 years, patients with motor neuron disease that had a bulbar onset of symptoms and patients who were physically unable to undergo MRI or who met one of the routine contraindications to MRI (e.g. pacemaker, non-MRI approved surgical clips or implants, claustrophobia, a recent prosthetic operation). We obtained demographic and clinical data, including treatment response and results from routine diagnostic work-up, i.e. diagnostic NCS and nerve ultrasound results. Treatment response was evaluated based on the discretion of the treating physician. Written informed consent was obtained from all study participants. Routine diagnostic work-up Nerve conduction studies Diagnostic NCS were performed using a Nicolet Viking IV EMG machine (CareFusion Japan, Tokyo, Japan) following previously described protocols. 10,15 The results were interpreted using the EFNS/PNS criteria for CIDP (definite, probable, possible) and the Utrecht criteria for MMN (definite motor conduction block, probable motor conduction block, slowing of conduction compatible with demyelination). 1,2 Nerve ultrasound Diagnostic nerve ultrasound was performed using a Philips Affinity 70G (Philips Medical Instruments, eL 1-48 MHz linear array transducer) following a previously published protocol. 10 In short, we collected nerve sizes of the median nerves (forearm and upper arm) and brachial plexus trunks bilaterally. We used the ellipse tool to measure cross sectional area (mm 2 ) and we used cut-off values for abnormal nerve size to identify patients with a chronic inflammatory neuropathy (median nerve forearm > 10 mm 2 and upper arm > 13 mm 2 ; plexus trunks > 9 mm 2 ). Nerve ultrasound was considered abnormal if nerve enlargement was present at ≥ 1 measured sites. Equipment and MRI parameters All patients underwent an MRI scan of the brachial plexus and cervical nerve roots on a 3.0 Tesla MRI scanner (Philips Healthcare, Best, the Netherlands) using a 24-channel head neck coil. All participants were positioned in supine position. We performed 3D turbo spin echo spectral presaturation with inversion recovery (SPIR) in a coronal and sagittal slice orientation with the following acquisition parameters: field of view = 336*336*170 mm, matrix size = 224*223, voxel size = 0.75*0.75*1 mm 3 , echo time = 206 ms, repetition time = 2200 ms, turbo spin echo factor = 76, sense factor = 3 (P reduction right/left) and 1.5 (S reduction anterior/posterior), acquisition time = 03:59 minutes. A coronal slab maximum intensity projection (MIP) was created as a post- processing step (slab thickness = 10 mm, number of slabs = 75).