The Ultrasonographic Findings of Trigger Points of Myofascial Pain Syndrome in a Rabbit Model

PURPOSE: Myofascial pain syndrome (MPS) is a common cause of musculoskeletal pain. Myofascial trigger points (MTrPs) have been repeatedly described by numerous authors. However, there have been few studies in which their existence and behavior was supported and their location confirmed. The purpose of this study was to determine whether diagnostic ultrasonography is an objective diagnostic tool which is able to significantly identify or detect the soft tissue changes in the region of clinically identified active MTrPs by using a rabbit experimental model. MATERIALS AND METHODS: Ten MPS model rabbits were used in this study. We made an MPS animal model by causing the rabbits to overuse one leg for 3 weeks by cutting the contralateral L4 spinal nerve root. We compared the ultrasonographic findings of the taut band at pre-OP with those at post-OP during the consecutive three week period. To find the taut bands of the muscle, after skin exposure, the muscles were gently rubbed or pinched with the thumb and index finger on the two opposing surfaces of the muscle across the direction of the fibers. Then, the muscle was held in the same way, but with a 5-8 MHz stick probe being used in place of the thumb. After the palpation of various muscles, we selected the hardest and largest myofascial trigger nodule, in order to observe the ultrasonographic and power Doppler findings of the MPS. The size, shape, echogenecity and vascularity of the MTrPs were observed. RESULTS: The analysis of the results of the ultrasonography revealed that all MTrPs have a hyperechoic area. The mean thickness of the hyperechoic lesion in the biceps was 0.96+/-0.14 cm in the MPS site (at pre-OP?), and 0.49+/-0.12 cm at post-OP 3weeks (p < 0.01). The hyperechoic lesions in all of the studied biceps femoris of the rabbits were observed by high resolution ultrasonography. No definitively decreased vascularity was observed within the hyperechoic area by power Doppler imaging. CONCLUSION: Until now, there has been no objective method for the diagnosis of MPS. However, this study suggests the possibility of using diagnostic ultrasonography as an objective diagnostic tool, by identifying the tissue changes in the region of clinically indicated active MTrPs.

Meniscal Tears of the Knee: Diagnosis with Fast Spin-Echo MR Imaging and Role of Gadolinium-Enhancement

PURPOSE: The usefulness of fast spin-echo MR imaging for the diagnosis of meniscal tear of the knee is amatter of debate. The purpose of this study was to evaluate the accuracy of diagnosis of meniscal tears by fastspin-echo MR imaging and the role of gadolinium enhancement. MATERIALS AND METHODS: Between October 1994 andDecember 1996, 68 consecutive patients with arthroscopically proven meniscal tears participated in this study. AllMR examinations performed on a 1.5-T MR imager with an extremity knee coil. All patients underwent sagittal andcoronal MR imaging, using a fast spin-echo sequence with echo train length(ETL) 8. Sagittal and coronal fatsuppressed T1-weighted MR images were obtained after gadolinium infusion. RESULTS: In 68 cases ofarthroscopically-proven meniscal tears, MR sensitivity to tear was 93% (63/68) for fast spin-echo alone and 96%(65/68) for combined fast spin-echo and fat-suppressed gadolinium enhanced T1-weighted MR images. MR sensitivityto medial meniscus tear was 98% (40/41) for fast spin-echo alone and 98% (40/41) for combined fast spin-echo andfat-suppressed gadolinum-enhanced T1-weighted MR images. MR sensitivity to lateral meniscus tear was 85% (23/27)for fast spin-echo alone and 93% (25/27) for combined fast spin-echo and fat-suppressed gadolinium-enhancedT1-weighted MR images. CONCLUSION: Fast spin-echo MR imaging with adequate imaging parameters is suitable for thediagnosis of meniscal tears, and additional fat-suppressed gadolinium-enhanced T1-weighted MR imaging may increasediagnostic sensitivity to such tears.