Ultrasonographic evaluation of the diaphragm thickness in patients with multiple sclerosis

Background: Diaphragm weakness or dysfunction have been previously reported in multiple sclerosis (MS) patients. The aim of this study was to evaluate diaphragm thickness and thickenning ratio (TR) using ultrasound in MS patients. Methods: This prospective study comprised MS patients and a control group. Ultrasound examination was performed using a linear transducer (6-15 MHz). The diaphragm was seen as a hypoechoic structre between the peritoneum and pleura. End-expirium and end-inspirium measurements were obtained. Change levels and TR (%) were calculated. All participants were assessed using the Expanded Distability Status Scale (EDSS) and Fatigue Severity Scale (FSS). Results: Evaluation was made of 45 MS patients (11 males, 34 females) with a mean age of 37.36 +/- 9.0 years and 36 healthy subjects (3 males, 33 females) with a mean age of 35.19 +/- 9.3 years. The diaphragm thicknesses were similar at end-expirium (1.86 +/- 0.3 vs. 1.83 +/- 0.3 mm) and end-inspirium (3.14 +/- 0.6 vs. 3.46 +/- 0.6 mm). The change level with inspirium (0.90 +/- 0.6 vs. 1.31 +/- 0.7 mm) and TR (49.77 +/- 37.7 vs. 72.30 +/- 40.1%) were significantly higher in the control group compared to the values of MS patients. A weak and negative correlation was determined between EDSS and TR values (r = -0.293, p = 0.008), and no significant correlation was observed between the FSS values and diaphragm thickness (p > 0.05 for all). Conclusion: Although the diaphragm thickness of MS patients seems to be similar to those of healthy subjects, the change level and TR of MS patients seem to be lower. Furthermore, the change level and TR were found to be associated with EDSS.