26 CHAPTER 2 Netherlands. The effect of a rehabilitation programme on functional capability and motor planning of the upper extremity will be compared to that of usual care in this two-arm, single-centre, open-label RCT. The intervention group will receive a specific 17-week multidisciplinary rehabilitation programme at the Radboudumc outpatient clinic, focused on relearning motor control and self-management (see Intervention for more information). The usual care group will first receive usual care for a 17-week period, before entering the rehabilitation programme. Patients in both groups will be assessed in a single session at baseline. At the end of the baseline measurement, patients will be randomised into the intervention or usual care group (see Randomisation for more information). After the first 17 weeks of treatment (i.e. rehabilitation programme or usual care), both groups will be assessed in a second session (at 18 weeks post baseline). After this second assessment, the group that initially received usual care will then follow the specific rehabilitation programme. After completing the 17-week rehabilitation programme, the usual care group will be assessed a third time (at 36 weeks post baseline). All patients will be asked to fill out several questionnaires by e-mail 17 weeks after completing the rehabilitation programme. This follow up will be at either 36 weeks (intervention group) or 54 weeks (usual care group) post baseline. Figure 2 provides a flow chart of the study design. Sub-study The baseline measurements of all patients with NA who are assessed for the randomised controlled trial described in this publication (see Figure 2) will be used for a sub-study. Patients with NA will be compared to 25 age-matched and sex-matched healthy controls in this sub-study. The healthy controls are assessed in a single session. The primary objective of this sub-study will be 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 non-affected arm. This sub-study is important for the interpretation of the secondary objective (the effect of this rehabilitation program on cortical motor planning and representations), to provide information about which cerebral changes from the rehabilitation program are associated with functional impairments in NA. Study population NA is more prevalent in men than in women, with an incidence ratio of 2:1, and can affect people of all ages. NA has an idiopathic form with a median age of onset around 40 years and a hereditary form with a median age of onset of about 28 years. 6, 7 Patients 18 years or older, with either form of NA can participate in the study. Number of participants and sample size calculation In total, 50 patients with NA will be recruited for participation in this study. The required sample size was calculated from the results from the pilot study on the effect of the rehabilitation program. 1 The improvement in functional capability of the upper extremity measured with the Shoulder Rating Questionnaire, Dutch Language Version (SRQ-DLV) was used for this sample size calculation. With a conservative standardised effect size of 0.29 (improvement in SRQ-DLV1), power of 0.90 and two-tailed testing (α = 0.05),