Radiofrequency thermocoagulation A percutaneous (requiring a needle inserted through the skin of the cheek) neurosurgical procedure that uses an electrode to damage the Gasserian ganglion and/or pre-ganglionic nerve route. The procedure stops the transmission of pain signals to the brain by selectively damaging the small unmyelinated and small myelinated pain fibres of the trigeminal nerve while ideally sparing the rest of the nerve fibres. This minimally invasive procedure is also known as percutaneous retrogasserian radiofrequency thermocoagulation.