A new and simplified extraoral approach for inferior alveolar nerve block: a cadaveric study and clinical case reports.

Purpose: Inferior alveolar nerve (IAN) and lingual nerve (LN) blocks are commonly performed using the intraoral landmark techniques. However, these methods have a risk of unanticipated nerve and arterial injury or a higher failure rate. We developed a novel extraoral approach for the IAN and LN blocks, the "inferior alveolar nerve block mandibular angle approach (IANB-MA)," using ultrasound guidance. The mechanism of action of this nerve block was examined anatomically, and its clinical feasibility was reported.

Methods: We performed the IANB-MA on four cadavers using different dye volumes (2, 4, 6 and 8 mL). The ultrasound probe was placed on the lower edge of the mandibula of each cadaver, and the needle was advanced to the mandibular inner surface. Blue acrylic paint solution was injected, and its spread was evaluated by dissection.

Results: Our study showed that the medial pterygoid muscle fascia was stained in all cadavers. The dye reached the LN consistently, and the IAN was stained with higher volumes (6 mL and 8 mL). The pterygomandibular space was filled with 6 mL and 8 mL of the dye. The IANB-MA successfully reduced pain in three patients with trigeminal neuralgia, tongue or jaw pain.

Conclusions: The IANB-MA is a novel ultrasound-guided approach to the IAN and the LN. The clinical feasibility and effectiveness of this technique were confirmed in our patients. It may be a good alternative analgesic approach to other conventional approaches.