Effect of lateralization and handedness on the function of the lymphatic system of the upper limbs.

In the upper limbs (UL), lateralization or handedness coincides with functional (and/or anatomical) asymmetries. Scintigraphic techniques were used to investigate the function of the UL lymphatic system and to determine whether significant differences exist between right and left limbs. With limbs at rest, 99mTc-labeled HSA nanosized colloids were injected intradermally into the forearms in 19 volunteers. Activities in the axillary nodes were recorded 1 minute later, then every 20 minutes up to100 minutes later and reported as per ten thousands of injected activity. When comparing right injections to left injections, no significant difference was found using an unpaired statistical test. However, with paired t-tests, axillary node activity (mean +/- SD) was significantly higher when the right limb was injected than when the left limb was injected, both overall (n = 19) (at 100 minutes: 454 +/- 88 versus 299 +/- 45: p = 0.014) and when the 13 right-handed cases were analyzed separately (501 +/- 116 versus 285 +/- 65: p = 0.004). No difference was found for the six left-handed volunteers. Our results demonstrate, at least in the right handed subjects, the functional asymmetry of the superficial lymphatic system of the right and left upper limbs.