Dallis Clendeninn, Presenter: Nothing to Disclose

Charles F. Lanzieri MD, Abstract Co-Author: Nothing to Disclose

Using T1-and T2-weighted MR imaging modalities, the authors attempt to develop a grading system for the various lesions associated with pediculolysis. 

28 cases (14 male, 14 female, mean age 51.6) were selected on the basis of abnormal signal in either T1-or T2-weighted MRI sequences in the lumbar pedicles. Normal and abnormal pedicles were differentiated by 1) the same marrow signal intensity as parent vertebral body on T1 and T2 weighted sequences, 2) no evidence of a linear defect, 3) uninterrupted cortical margins, and 4) absence of a nidus or vertical trabeculae. Scans which displayed pathology in 3 or more lumbar pedicles, and pathology associated with vertebral body compression fractures were considered normal variants. Abnormal pedicles were categorized and defined as follows: Grade 1a–increased T2 signal intensity involving only the inferior half of the pedicle; Grade 1b–increased T2 signal intensity involving the entire pedicle; Grade 2–increased T2 signal intensity and evidence of a linear defect; Grade 3a–wide area of decreased signal intensity on T1, with normal intensity borders on T2; Grade 3b–same as 3a, with increased T2 signal intensity on the borders; Grade 4a–decreased signal intensity on T1, increased intensity on T2 with thickened cortical margins; Grade 4b–decreased signal intensity on T2.

7 of the initial 28 cases were considered normal variants. Within the remaining 21 cases (9 male, 12 female) there were a total of 33 pedicle stress fractures. Fractures were categorized by the aforementioned criteria and used to develop a grading system (Fig. 1). In all, there were 18 (54.5%) Grade 1 lesions, 6 (18.2%) Grade 2 lesions, 1 (3%) Grade 3 lesions, and 5 (24.2%) Grade 4 lesions. An incidental note was made that the large majority (28, 84.8%) of the lumbar pedicle stress fractures of any grade occurred at L4 and L5 levels, suggesting that these lumbar levels may be most susceptible to the mechanical instability responsible for early stress fractures.

The prevalence and protean nature of mechanical back pain hightlights the need for establishing a useful screening method. An awareness of pediculolysis may be of use when considering management of mechanical back pain.

Understanding the pathophysiology and injury characteristics of pedicular stress fractures using a grading system may lead to improved management of complicated low back pain syndrome.

Clendeninn, D, Lanzieri, C, Pediculolysis: Pedicle to Pars - Stress Fractures of the Lumbar Pedicle.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12020423.html