Physics & Application of Radiofrequency for the treatment of chronic pain Erik Speekenbrink Project Manager NeuroTherm

Two different treatments possible with RF Conventional RF (Heat-RF) Pain relief is achieved by effectively breaking the nerve pathway to the brain through the application of heat Pulsed Radiofrequency Pain relief is achieved by the application of an electro-magnetic field onto the nerve through small pulse bursts or radiofrequency energy

Conventional RF A current flows from the active tip of the electrode and heat is generated by the movement of charged ions in the tissue electrolytes The current is returned to the generator through a large area reference plate to prevent heating on this side of the circuit

480 kHz

Golden rules for heat RF Tip temperature and electrode geometry completely characterize the size and shape of equilibrium lesions Lesion size stops growing after 45 seconds because thermal equilibrium is reached The RF current heats the tissue and the tissue heats the electrode Use a tangential approach to the nerve

Temperature

Time dependance

Pulsed RF

Why is Pulsed RF usefull Because it is non-destructive Because it is safe- no reports of morbidity Because you can use it in areas you would not want to heat- e.g. peripheral nerves, DRG, C1 Because it is easier on the patient

Pulsed RF protocol Pulse Amplitude should be set to 45 V If electrode temperature reaches 42 C, reduce the pulse amplitude or pulse width Note: 42C was never an endpoint!! Pulses should be delivered for 2-3 minutes Try to place needle perpendicular to the target, since the electric field is strongest near the tip

Pulsed RF misconceptions The goal is to apply pulsed RF at a level of 45 volts Without exceeding 42 C! It is not necessary to reach 42 C. In fact it is desirable to be between C

What is commonly treated with RF/PRF Facet joints Medial branch neurotomy Dorsal root ganglion Trigeminal neuralgia Cordotomy Inter-vertebral Disc Peripheral nerves

Current developments Multiple output generators More flexible treatment parameters More efficient treatment algorithms Procedure specific electrodes

Simplicity electrode