Dural ectasia and conventional radiography in the Marfan lumbosacral spine

Objective. To determine how well conventional radiographic findings can predict the presence of dural ectasia in Marfan patients. Design and patients. Twelve Marfan patients without dural ectasia and 21 Marfan patients with dural ectasia were included in the study. Five radiographic measurements were made of the lumbosacral spine: interpediculate distance, scalloping value, sagittal canal diameter, vertebral body width, and transverse process width. Results. The following measurements were significantly larger in patients with dural ectasia: interpediculate distances at L3-L4 levels (P <0.03); scalloping values at the L1 and L5 levels (P <0.05); sagittal diameters of the vertebral canal at L5-S1 (P <0.03); transverse process to width ratios at L2 (P <0.03). Criteria were developed for diagnosis of dural ectasia in Marfan patients. These included presence of one of the following: interpediculate distance at L4 greater than or equal to 38.0 mm, sagittal diameter at S1 greater than or equal to 18.0 mm, or scalloping value at L5 greater than or equal to5.5 mm. Conclusion. Dural ectasia in Marfan syndrome is commonly associated with several osseous changes that are observable on conventional radiographs of the lumbosacral spine. Conventional radiography can detect dural ectasia in patients with Marfan syndrome with a very high specificity (91.7%) but a low sensitivity (57.1%).