Diaphragmatic dysfunction in neuromuscular disease, an MRI study

The aim of this exploratory study was to evaluate diaphragmatic function across various neuromuscular diseases using spirometry-controlled MRI. We measured motion of the diaphragm relative to that of the thoracic wall (cranial-caudal ratio vs. anterior posterior ratio; CC-AP ratio), and changes in the diaphragmatic curvature (diaphragm height and area ratio) during inspiration in 12 adults with a neuromuscular disease having signs of respiratory muscle weakness, 18 healthy controls, and 35 adult Pompe patients - a group with prominent diaphragmatic weakness. CC-AP ratio was lower in patients with myopathies (n=7, 1.25 +/- 0.30) and motor neuron diseases (n=5, 1.30 +/- 0.10) than in healthy controls (1.37 +/- 0.14; p=0.001 and p=0.008), but not as abnormal as in Pompe patients (1.12 +/- 0.18; p=0.011 and p=0.024). The mean diaphragm height ratio was 1.17 +/- 0.33 in patients with myopathies, pointing at an insufficient diaphragmatic contraction. This was also seen in patients with Pompe disease (1.28 +/- 0.36), but not in healthy controls (0.82 +/- 0.33) or patients with motor neuron disease (0.82 +/- 0.24). We conclude that spirometry-controlled MRI enables us to investigate respiratory dysfunction across neuromuscular diseases, suggesting that the diaphragm is affected in a different way in myopathies and motor neuron diseases. Whether MRI can also be used to evaluate progression of diaphragmatic dysfunction requires additional studies. (C) 2021 The Authors. Published by Elsevier B.V.