Content area
Full text
Received Jan 4, 2018; Accepted Mar 15, 2018
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction
A common cause of chronic facial pain syndrome is trigeminal neuralgia, which can be alleviated by injecting the superficial branches of the nerve, such as the supraorbital, infraorbital, and mental nerves, and deep injection of the maxillary nerve in the pterygopalatine fossa and/or the mandibular nerve posterior to the lateral pterygoid plate [1]. Isolated entrapment of the abovementioned nerves is not rare, but treatments using palpation guidance can be challenging because substantial portions of the nerves lie underneath the skull bone. The use of high-resolution ultrasound facilitates real-time visualization of peripheral nerves and adjacent soft tissue structures, such as tendons, ligaments, muscles, vessels, and subcutaneous fat [2]. Ultrasound-guided intervention allows precise targeting of the affected nerves without collateral damage to the nearby vessels and prevents accidental nerve injury, vascular thrombosis, and postinjection hematoma [3–6]. In this review, we aimed to summarize the regional anatomy and ultrasound-guided injection techniques for the commonly affected branches of the trigeminal nerve, including the supraorbital, infraorbital, mental, auriculotemporal, maxillary, and mandibular nerves.
2. Technical Considerations and Regimen for Treatments
All of the sonographic images presented in this review were obtained using MyLab 5 (Esaote Europe B.V., Maastricht, Netherlands). A 10–18 MHz high-frequency linear transducer was used to scan superficial structures. To image deeper structures, such as the lateral pterygoid muscle and plate, a 1–5 MHz curvilinear transducer was used. During the power Doppler examination, the Doppler frequency was set to 6.6 MHz.
To perform the superficial nerve block, 1 to 3 ml of local anesthetic, for example, 0.5% lidocaine, can be injected using a 25-gauge 1.5-inch needle. For deeper nerve blocks, 3 to 5 ml of the anesthetic can be injected using a 22-gauge 3-inch spinal needle. Potential complications include bleeding, hematoma, infection, and hypersensitivity reaction to the injectate. For longer pain relief, the deep injection can be performed using glycerol (100%), alcohol (50–70%), or phenol (5–10%). Because of the serious complications of the abovementioned neurolytic agents, such as permanent sensory deficit, severe allergic reactions, and tissue necrosis, they are gradually replaced by safer and...