Endoscope-assisted neurovascular decompression of the trigeminal nerve: a cadaveric study

Endoscopes are increasingly used to examine cranial nerves in microvascular decompression (MVD) operations. The superior petrosal vein (SPV) is often purposely sacrificed to gain adequate exposure to the trigeminal nerve (TN) during MVD. Recently, the importance of preserving the SPV has been emphasized due to potential complications associated with its sacrifice. Our focus is to study the ability to operate on the TN with preservation of the SPV by using endoscope-assisted microsurgery. We studied both cerebellopontine angles in seven cadaveric heads which vascular system had been injected with colored silicon material. MVD procedures were simulated using the operative microscope (Moeller-Wedel, Cologne, Germany) and two fixed-angled (0°and 30°) rigid endoscopes (Aesculap, PA, USA). To compare the practical advantages of microscopic MVD (MMVD) and endoscope-assisted MVD (EAMVD), we divided the approaches into four subcategories (microscopic without and with SPV sacrifice and endoscope-assisted without and with SPV sacrifice) and compared the maneuverability associated with each category using a numerical grading system. EAMVD scored significantly better than MMVD both without and with cutting of the SPV (p < 0.001). Only in MMVD did cutting of the SPV improve the maneuverability especially in the superior quadrant of the nerve (p = 0.012). Based on the proposed scoring system, use of the endoscope in an assisted mode facilitates visualization and mobilization of the vascular loop associated with the TN without need to sacrifice the SPV. Sacrifice of the SVP may help maneuverability in the superior quadrant of the nerve in MMVD.