1-A-D-3. An ultrasonography with nerve conduction study on the diaphragm in neuromuscular disorders

An ultrasonography (USG) with nerve conduction study, in addition to a standard pulmonary function test, was performed to evaluate diaphragm function in various neuromuscular disorders. We evaluated 25 neuromuscular patients: 12 amyotrophic lateral sclerosis, 3 myasthenia gravis, 3 myopathy, 3 neuropathy, and 3 central nervous system disorders. USG of the diaphragm was performed in a supine position using a linear probe over the intercostal space at the anterior axillary line. Diaphragm muscle thickness was measured at the end-expiratory period. The amplitude of compound muscle action potentials (CMAP) was obtained by phrenic nerve stimulation with a surface electrode. The recording electrode was placed 5 cm above the xiphoid process, and the reference electrode was placed over the ipsilateral costal margin. There was a significant correlation between diaphragm thickness and forced vital capacity (FVC) (r = .78) and also between CMAP amplitudes and FVC (r = .74). USG of the diaphragm is a novel method for objective evaluation of pulmonary function in neuromuscular disorders without undue patient effort. In addition, USG is easy-to-use at the patient’s bedside and non-invasive, and has the advantage of presuming respiratory function without cooperation of the patients.