Diaphragmatic weakness related to radiotherapy: 2 cases and a review

Post-radiation diaphragmatic weakness have rarely been described. We report two cases of post-radiation diaphragmatic weakness from our center, and review the other published cases, computing clinical, electromyography and magnetic resonance imaging data. Including our two cases, seven cases of post-radiation diaphragmatic weakness have been described. Most occurred after mantle-field radiotherapy for Hodgkin lymphoma (5/7), often in associations with chemotherapy (4/7). Other radiations-induced complications were found (5/7) such as brachial plexopathy, cardiac involvement or hypothyroidy. When studied, phrenic nerve conduction studies revealed different profiles, from clearly abnormal responses to limit amplitudes. Imaging can be a useful diagnostic tool, displaying abnormalities with sharp limits matching the radiation field. Data is limited about long-term evolution. Presentation of post-radiation diaphragmatic weakness seems relatively homogeneous. We propose a diagnosis work-up for post-radiation diaphragmatic weakness, to exclude potentially treatable differential diagnoses.