Sonographic measures and sensory threshold of the normal sciatic nerve and hamstring muscles.

PURPOSE: The sciatic nerve innervates the hamstring muscles. Occasionally, the sciatic nerve is injured along with a hamstring muscle. Detailed biomechanical and sensory thresholds of these structures are not well-characterized. Therefore, we designed a prospective study that explored high-resolution ultrasound (US) at multiple sites to evaluate properties of the sciatic nerve, including cross-sectional area (CSA) and shear-wave elastography (SWE). We also assessed SWE of each hamstring muscle at multiple sites. Mechanical algometry was obtained from the sciatic nerve and hamstring muscles to assess multi-site pressure pain threshold (PPT). METHODS: Seventy-nine asymptomatic sciatic nerves and 147 hamstring muscles (25 males, 24 females) aged 18-50 years were evaluated. One chiropractic radiologist with 4.5 years of US experience performed the evaluations. Sciatic nerves were sampled along the posterior thigh at four sites obtaining CSA, SWE, and algometry. All three hamstring muscles were sampled at two sites utilizing SWE and algometry. Descriptive statistics, two-way ANOVA, and rater reliability were assessed for data analysis with p ≤ 0.05. RESULTS: A significant decrease in sciatic CSA from proximal to distal was correlated with increasing BMI (p < 0.001). Intra-rater and inter-rater reliability for CSA was moderate and poor, respectively. Elastographic values significantly increased from proximal to distal with significant differences in gender and BMI (p = 0.002). Sciatic PPT significantly decreased between sites 1 and 2, 1 and 3, and 1 and 4. Significant correlation between gender and PPT was noted as well as BMI (p < 0.001). Hamstring muscle elastographic values significantly differed between biceps femoris and semitendinosus (p < 0.001) and biceps femoris and semimembranosus (p < 0.001). All three hamstring muscles demonstrated increased PPT in males compared to females (p < 0.001). In addition, PPT of the biceps femoris correlated with BMI (p = 0.02). CONCLUSION: High-resolution US provided useful metrics of sciatic nerve size and biomechanical properties. PPT for the normal sciatic nerve and hamstring muscles was obtained for future clinical application.

Rectus abdominis muscle tear diagnosed with sonography and its conservative management.

PURPOSE: This is a rare case of a post-traumatic rectus abdominis muscle tear in an adolescent female diagnosed by ultrasonography (US). Conservative management is also described. METHODS: A 14-year-old female presented to a chiropractic clinic with extreme pain and tenderness in the right lower quadrant (RLQ) after post-plyometric power kneel box jumps. Movement aggravated her pain and she demonstrated active abdominal guarding with RLQ palpation. Ultrasonography revealed a subacute Grade 2 right rectus abdominis muscle tear, without evidence of hyperemia or a hematoma. Following the diagnosis of a right rectus abdominis muscle tear, she was treated with spinal manipulation and a course of musculoskeletal rehabilitation directed at truncal stabilization. RESULTS: After treatment, the patient was able to return to play 5 week post-injury without any pain or discomfort. A follow-up US at 3 months provided evidence of muscle healing without complications. CONCLUSION: This case demonstrates the diagnosis of a rare rectus abdominis muscle tear managed conservatively. To our knowledge, less than a dozen cases are reported using US in the evaluation and diagnosis of a rectus abdominis tear.