Localization of the center of the intramuscular nerve dense region of the medial femoral muscles and the significance for blocking spasticity.

[PURPOSE] To identify the body surface position and depth of the center of the intramuscular nerves dense region (CINDR) of the medial femoral muscles.

[METHODS] Utilizing twelve Chinese adult cadavers (six men and six women), with an age range from 35 to 75 (66.5±5.4) years, the body surface curves between the greater trochanter of the femur and the pubic tubercle and lateral femoral epicondyle were designated as horizontal (H) and longitudinal (L) reference lines, respectively. Sihler's staining was performed on one side of the medial femoral muscles to show the intramuscular nerve dense regions, and the contralateral CINDR was labeled with barium sulfate and scanned by computed tomography, and three-dimensional reconstruction was performed. The body surface projection point of CINDR was designated as P. Projection of P in the opposite direction was identified as P'. The intersection of the longitudinal line from P to line H, and that of the horizontal line from P to line L was designated as P and P, respectively. The percentage positions of P and P on the H and L lines and the depth of the CINDRs were determined under the Syngo system.

[RESULTS] The pectineus, gracilis, adductor longus, and adductor brevis muscles each possess one intramuscular nerve dense region; the adductor magnus muscle has two. The P was located at 80.32%, 95.67%, 85.64%, 94.92%, 84.48%, and 88.83% of line H, respectively. P was at 12.76%, 40.68%, 33.26%, 23.39%, 25.57%, and 35.29% of line L, respectively. The depth of CINDRs was at 17.58%, 27.89%, 23.05%, 30.45%, 34.09%, and 29.52% of PP' line, respectively. These percentage values are all means. No statistical difference was observed neither between the left and right sides nor between the male and female cadavers (P>0.05).

[CONCLUSION] These results may help improve the efficiency and efficacy of botulinum toxin A injection in the treatment of medial femoral muscle spasticity.