Fabrication of a radiofrequency needle bending device and its clinical application

Objective To design and make a radiofrequency needle bending device for individual needs during the radiofrequency thermal lesioning surgery, and observe the convenience of the bent needle passing through the foramen ovale during the radiofrequency Lesion for V2 branch of trigeminal neuralgia guided by CT.MethodsDesigning and making of bending device: the 5 mm thickness stainless steel plate was cut into a semicircle of 90 mm diameter, then divided into two 1/4; one of 1/4 circular was milled to reduce 1.2 mm, and another one of 1/4 circular was also milled to get a groove with a width and depth of the 1.2 mm round the bottom, ARC length scale (0 degrees to 90 degrees, interval 5 degrees) was marked on the device.Methodsof use: the patients with V2 branch of trigeminal nerve pain received 3 mm thick layer semi-coronal CT scan of the foramen ovale area. We selected the appropriate CT images, and use CT software tool ruler pull line around the lateral wall of the maxillary sinus from puncture target to surface of the skin, if meet sphenoid bone, pull another line from the mouth of foramen ovale to the point of puncture at surface of the skin, then measured the α angle between the two lines. The common radiofrequency needle was inserted into the groove of bending device for 5 to 8 mm as needed, and bent it slightly to the side of slope of needle tip until the needle reached theαangle, thus the needle was facing the individual need. Under the guidance of CT, the needle was punctured according to the designed path, when it reached the mouth of the foramen ovale, turned its point to make a anterosuperior direction for the curve of needle, when the needle passed through the mouth of the foramen ovale, then turned its point to make a posterior inferior direction for the curve of needle. Results Among the 215 cases of radiofrequency thermal lesioning for V2 branch of trigeminal neuralgia, 65 cases who met sphenoid block used the bending device to shape the needle for individual need, the bended angle alpha value was from 11° to 32° (18.9°±4.20°). The tip of the curved needle can smoothly reach the target point; radiofrequency thermal lesioning was well finished. V2 pain disappeared completely after radiofrequency, without the injury of V1 and V3. Conclusion When the V2 branch of the trigeminal nerve was punctured through the zygomatic approach, 30.2% of the patients have the obstruction of the sphenoid bone, and the straight needle is difficult to get into the puncture target in the foramen ovale. The individual bent needle by this invented bend device can make the RF tip get to accurate position and guarantee the effect treatment.