Ultrasound of the median arcuate ligament syndrome: a new approach to diagnosis

Abstract

Introduction: The currently accepted pathophysiological concept behind median arcuate ligament syndrome (MALS) is vascular compromise by atypically positioned median arcuate ligament. Despite many articles on MALS, only sparse data on the outcome in general and the rather poor outcome after intervention have been reported and this makes at least questionable the current concepts of the underlying disease.

Material and methods: A total of 364 patients with suspected celiac trunk pathology underwent a standardized ultrasound assessment procedure: suspected diagnostic features for MALS such as typically elevated peak flow velocities (PV) in the celiac trunk or atypical celiac trunk deflection-angles (DA) were defined in patients and in 20 matched volunteers.

Results: All the 6 retrospectively clearly diagnosed MALS-patients as well as 40% (8/20) of volunteers presented a DA of over 50°. MALS-patients presented a mean inspiratory PV of 172cm/s (+/- 40.9 cm/s), a mean expiratory PV of 425cm/s (+/-130.1 cm/s) with a PV-amplitude of 249.1% (+/-68.9%). Volunteers presented a mean inspiratory PV of 126.9cm/s (+/-42 cm/s), a mean expiratory PV of 209.9cm/s (+/-80.1 cm/s) with a PV-amplitude of 169.4% (+/-54.3%).

Conclusions: The combination of a maximum expiratory PV of over 350 cm/s and a DA higher than 50° seems to be a most reliable indicator for MALS in this small series of patients. Based on these data we propose that functional ultrasound should be the first line in screening for MALS. However, a clear pathophysiological definition of MALS remains still obscure.