Mapping Lymphatic Drainage from the Human Brain to the Head and Neck: Potential Surgical Implications for Dementia.

Background: Lymphatic surgery of the head and neck has been proposed as a potential approach to prevent, delay, or treat Alzheimer's disease (AD). This exploratory anatomical study undertook to map and evaluate potential targets for surgical feasibility studies. Methods: This exploratory anatomical and preliminary laboratory study was supported by fresh cadaver dissection, with indocyanine green (ICG) lymphography to visualize the drainage pathway. Immunohistochemistry was used to confirm the presence of lymphatic tissues and to detect β-amyloid in lymphatic tissues from a cadaver with confirmed dementia. A simulated lymph node-to-vein anastomosis (LNVA) was performed using robotic-assisted supermicrosurgery with the Symani Surgical System (Medical Microinstruments, Inc., Jacksonville, FL, United States). Results: After injection of ICG at the dural meninges, fluorescence progressed toward the skull base to the Level II deep cervical lymph nodes (dCLNs). When injected at the parietal lymphatics, ICG drained past the deep digastric point to the Level II cervical lymph nodes (CLNs). Veins localized adjacent to dCLNs at the deep digastric point and Level II were suggested as candidate surgical targets for LNVA. Histology of lymph nodes from a dementia-confirmed cadaver identified β-amyloid at Level II dCLNs but not at lower levels or in the groin. A robotic-assisted microsurgical LNVA was shown to be feasible. Conclusions: This study found evidence supporting a posterior pathway from human dural meninges to the dCLNs and identified potential surgical candidates for AD intervention. Further research is warranted to build on the feasibility of this approach.