NA-CONTROL: a study protocol for a randomised controlled trial that compares specific outpatient rehabilitation, that targets cerebral mechanisms through relearning motor control and uses self-management strategies to improve functional capability of the upper extremity, to usual care in patients with neuralgic amyotrophy.

Abstract Background: Neuralgic amyotrophy (NA) is a distinct peripheral neurological disorder of the brachial plexus with a yearly incidence of 1/1000, characterised by acute severe upper extremity pain. Weakness of the stabilising shoulder muscles in the acute phase leads to compensatory strategies and abnormal motor control of the shoulder; scapular dyskinesia. Despite peripheral nerve recovery, scapular dyskinesia often persists, leading to debilitating residual complaints including pain and fatigue. Evidence suggests that persistent scapular dyskinesia in NA may result from maladaptive cerebral neuroplasticity, altering motor planning. Currently there is no proven effective causative treatment for the residual symptoms in NA. Moreover, the role cerebral mechanisms may play in persistent scapular dyskinesia remains unclear. Methods: NA-CONTROL is a single-centre randomised controlled trial comparing specific rehabilitation to usual care in NA. The rehabilitation program combines relearning of motor control, targeting cerebral mechanisms, with self-management strategies. Fifty patients need to be included. Patients are recruited through the Radboud university medical center Nijmegen, the Netherlands. Patients with a (suspected) diagnosis of NA, with lateralized symptoms and scapular dyskinesia in the right upper extremity, who are 18 years or older and not in the acute phase can be included. The primary outcome is the Shoulder Rating Questionnaire score, which measures functional capability of the upper extremity. Secondary clinical outcomes include measures of pain, fatigue, participation, reachable workspace, muscle strength and quality of life. In addition, motor planning is assessed with first person motor imagery and functional MRI. In a sub-study the patients are compared to 25 healthy participants, to determine the involvement of cerebral mechanisms. This will enable interpretation of cerebral changes associated with the rehabilitation program and functional impairments in NA. Discussion: NA-CONTROL is the first randomised trial to investigate the effect of specific rehabilitation on residual complaints in NA. It also is the first study into the cerebral mechanisms that might underlie persistent scapular dyskinesia in NA. It thus may aid the further development of mechanism-based interventions for disturbed motor control in NA, as well as other peripheral neurological disorders. Trial Registration: Clinical Trials, NCT03441347. Registered 20 February 2018, https://clinicaltrials.gov/ct2/show/NCT03441347 Keywords: Neuralgic amyotrophy, parsonage turner syndrome, neurorehabilitation, upper extremity, scapular dyskinesia, motor control, peripheral nerve dysfunction, maladaptive neuroplasticity, physical therapy, occupational therapy