Objective: To study the histological effects of different temperatures and durations of radiofrequency on the trigeminal ganglions in rabbits.
Methods: Trigeminal ganglions of 80 rabbits were treated by R-2000B RF thermocoagulation at 60, 70, 80°C respectively and the thermal electrode of 50 mm long and 0.4 mm in diameter. The treaded trigeminal ganglions were removed for HE (hematoxylin & eosin) dying at Days 1, 7, 14 and 28. And the expressions of neurofilament protein (NF200), acetylcholinesterase (ACHE) and muscarinic receptors (M-receptor) were observed after an immunohistochemical detection of HE positive samples.
Results: The positive manifestations of HE were degeneration of trigeminal ganglionic cells, the distribution of nerve fibers and a loss of myelinic membrane. The positive features of immunohistochemistry were as follows: NF200: dark yellow-brown particles within cytoplasm of ganglionic cells and nerve fibers cells; ACHE: deep yellow-brown particles within cytoplasm of ganglion cells and nerve fibers cells; M-receptor: yellow-brown particles within cytoplasm of ganglionic cells and nerve fibers cells. The expressions of NF200, ACHE and M-receptor increased while the temperature and radio frequency time remained constant. There was no significant difference between the expression rates of NF200, ACHE, M receptor at the same temperature for 1 and 3 minutes (P > 0.05). When treated for the same time, the expressions of NF200, ACHE and M receptor decreased more significantly at 70°C versus 60°C (P < 0.05). However, there was no significant difference between 70°C and 80°C (P > 0.05).
Conclusion: 70°C may be a suitable temperature at which radiofrequency causes the greatest harm to trigeminal ganglions so that nerve activity decreases significantly.