1. Case of the Month – October 2015 Courtesy of IFEC Paris 41 year old Vietnamese male presented to the IFEC Paris outpatient clinic. He played high-level tennis from ages 18 – 30 without pain. He presents with chronic low back pain and sciatica for 12 years and has stopped all sports. The origin of his pain seems to be carrying a burden. The sciatica appears to be in the S1 distribution on the right.

2. MRIs were done and sent to Prof. Peterson in Zürich to clarify the unusual appearance of L5. What is the Diagnosis for L5 on these coronal slices? What is the clinical significance?

3. ANSWERS What is the Diagnosis for L5? L5 is a nice example of a Butterfly Vertebrae (Sagittal Cleft Vertebrae.) This is not spina bifida as it does not involve the posterior arch but rather the vertebral body itself is in two halves. Note the inferior endplate of L4 is not straight but has changed shape, projecting into the gap between the two halves of the L5 body. This is typical and clearly indicates a congenital anomaly and not an unusual fracture. What is the Clinical Significance? Butterfly vertebrae often slip posteriorly on weight bearing (retrolisthesis) and may compromise the spinal canal size. As with all congenital anomalies of the spine (hemivertebrae, blocked vertebrae, etc.) one much check for related organ anomalies.

4. Sagittal T1 (left) and T2 fat suppressed (right) slices are shown below. Follow L5 from one side to the other. Note that in the mid sagittal area the signal intensity is that of disc material rather than bone. That is because it is disc material.

5. Note the two halves of the L5 body on these axial slices with disc material between. This man also has LBP and right sided radiculopathy of the S1 level. Which abnormal findings on the T2-weighted axial slices below, if any, may be related to his leg pain?

6. ANSWERS Which abnormal findings, if any, may be related to his right leg pain? The left IVFs of L4-5 and L5-S1 are narrow compared to the right side. However, this is the opposite side to his symptoms. The right S1 nerve root on these slices appears normal. However, it would be interesting to see what happens with a weight-bearing MRI scan in this patient considering that he has a butterfly vertebra at L5 which may move posteriorly when upright.