114 CHAPTER 6 previously shown, in a companion cross-sectional comparison to healthy participants, that NA patients with persistent motor dysfunction had decreased activity related to their affected limb in two visuomotor brain regions in the occipito-parietal cortex, especially when biomechanically complex (imagined) movement was involved. 2 In the current study, we focus on these same visuomotor regions of interest (ROIs), to determine whether multidisciplinary rehabilitation (compared to usual care) can lead to increased task-related activity in these regions. Methods This study is part of a randomized controlled trial (RCT) investigating the effect of multidisciplinary rehabilitation on residual complaints and cerebral mechanisms in NA, for which the primary outcome measure is functional capability of the upper extremity (quantified with the Shoulder Rating Questionnaire (SRQ). 124 All MRI-compatible RCT participants were included in this sub-study. In this sub-study, the primary objective was to determine if patients with NA have altered cerebral activity related to motor planning of their affected arm, compared to healthy controls and compared to their nonaffected arm. 124 To this end, we focused on behavioral performance and cerebral activity associated with the hand laterality judgment task. We originally expected to find changes in parietal and occipital brain regions. 124 These a priori regions of interest (ROIs), were further specified to the right extrastriate cortex and bilateral parieto-occipital sulcus, where we recently found reduced imagery-related brain activity in NA patients versus healthy volunteers in the baseline measurement. 2 In addition to these ROI analyses, we performed an exploratory whole-brain search. We also included relevant clinical data collected as part of the RCT to relate cerebral adaptations to changes in symptom severity. The clinical data of the full sample of participants will be published in a parallel study. A previous study compared the baseline task-fMRI of the NA patients to a group of healthy participants. 2 The local medical ethical committee (Medical Ethical Committee region Arnhem-Nijmegen, CMO 2017-3740) approved this study and the study is registered at ClinicalTrials.gov (NCT03441347). Participants The full RCT was powered124 to demonstrate the effect of specialized multidisciplinary rehabilitation compared to usual care on a clinical measure: the functional capability of the upper extremity as measured with the Shoulder Rating Questionnaire Dutch Language Version (SRQ-DLV). 34 We included 47 patients with a right-sided NA of the brachial plexus as part of the RCT. NA was diagnosed by an experienced neurologist (NvA) in patients with a history of acute onset severe, numerical rating scale (NRS) ≥7, upper extremity pain combined with scapular dyskinesia during abduction – anteflexion and muscle paresis of serratus anterior, shoulder exorotation, and long flexor of the thumb. 3 Due to the COVID-19 pandemic and subsequent national measures, inclusion was terminated short of the original goal of fifty patients. Forty-four patients underwent an fMRI scan during the pretreatment baseline assessment. See Figure 1 for an overview of exclusions and drop-out throughout the study. Drop-outs were mostly caused by recurrent NA attacks, COVID-19 related restrictions or personal reasons. The final data set came from 27 patients in this