Physics & Application of Radiofrequency for the treatment
of chronic pain
Erik SpeekenbrinkProject ManagerNeuroTherm
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
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
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 voltsWithout exceeding 42 C!
• It is not necessary to reach 42 C. In fact it is desirable to be between 38-42 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
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