Basics of Basics of Radio Frequency Radio Frequency

techniques in Pain techniques in Pain ManagementManagement

Dr. Ashok Jadon, MD DNBDr. Ashok Jadon, MD DNB

Sr. Consultant & HOD Sr. Consultant & HOD AnaesthesiaAnaesthesia

Tata Motors Hospital, Tata Motors Hospital, JamshedpurJamshedpur

Principle of RF lesion Principle of RF lesion

• RF lessoning involves passage of a RF lessoning involves passage of a very high frequency current (at 300 very high frequency current (at 300 kHz) through a 27 G thermocouple kHz) through a 27 G thermocouple probe.probe.

• When a high frequency alternating When a high frequency alternating current is passed current is passed – To & fro movements of the charged ions To & fro movements of the charged ions – Generation of heat due to this electro-

mechanical friction.

stylet

Exposed tip = 5 mm

RF electrode

Principle of RF (contd.)Principle of RF (contd.)• The electrical field The electrical field

generation and generation and movement of movement of charged particle is charged particle is maximum at its tip maximum at its tip and minimum and minimum around the shaft. around the shaft.

• Therefore the heat Therefore the heat lesion is maximum lesion is maximum around the shaft and around the shaft and minimum at its tip.minimum at its tip.

Conventional vs. Pulsed Conventional vs. Pulsed RFRF

• Heat producing Heat producing lesion. lesion.

• Temp can go up-Temp can go up-to 85 degree C.to 85 degree C.

• In the pulsed RF In the pulsed RF electrical field is electrical field is producing the lesion. producing the lesion.

• Temp. is not raised Temp. is not raised beyond 42 degree Cbeyond 42 degree C

In pulsed RF. Electrical field produces In pulsed RF. Electrical field produces some punch in the capacitor of small some punch in the capacitor of small diameter nociceptive fibers. Thereby diameter nociceptive fibers. Thereby signal transmission is stopped.signal transmission is stopped.

Conventional vs. Pulsed Conventional vs. Pulsed RFRF

• In the conventional In the conventional type the nerves are type the nerves are regenerated in regenerated in future.future.

• Average pain-free Average pain-free period varies for period varies for type of nerve. (3-4) type of nerve. (3-4) years.years.

• In the pulsed RF In the pulsed RF the nerve is the nerve is repaired. repaired.

• Average pain free Average pain free period is 4-24 period is 4-24 months.months.

Lesion characteristicsLesion characteristics

• Temperature Temperature

• Rate of thermal Rate of thermal equilibriumequilibrium

• Local Tissue Local Tissue characteristics-characteristics-ImpedanceImpedance

• Radius of Electrode tip Radius of Electrode tip and Configurationand Configuration

ImpedanceImpedance

• Proximity of electrode Proximity of electrode to the CSF can present to the CSF can present low impedance pathwaylow impedance pathway

• Proximity of large blood Proximity of large blood vessel to electrode can vessel to electrode can deviate the energydeviate the energy

• Proximity to bone can Proximity to bone can cause discontinuity of cause discontinuity of heat due to lower heat due to lower conductivityconductivity

Lesion size versus Lesion Lesion size versus Lesion Time CW: 20V, t= 0 secTime CW: 20V, t= 0 sec

37˚C

40˚C

45˚C

60˚C

55˚C

50˚C

67˚C

COSMAN, MIT

CW: 20V, t=10 secCW: 20V, t=10 sec

37˚C

40˚C

45˚C

60˚C

55˚C

50˚C

67˚C

COSMAN, MIT

CW: 20V, t=20 secCW: 20V, t=20 sec

37˚C

40˚C

45˚C

60˚C

55˚C

50˚C

67˚C

COSMAN, MIT

CW: 20V, t=30 secCW: 20V, t=30 sec

37˚C

40˚C

45˚C

60˚C

55˚C

50˚C

67˚C

COSMAN, MIT

CW: 20V, t=40 secCW: 20V, t=40 sec

37˚C

40˚C

45˚C

60˚C

55˚C

50˚C

67˚C

COSMAN, MIT

CW: 20V, t=50 secCW: 20V, t=50 sec

37˚C

40˚C

45˚C

60˚C

55˚C

50˚C

67˚C

COSMAN, MIT

CW: 20V, t=60 secCW: 20V, t=60 sec

37˚C

40˚C

45˚C

60˚C

55˚C

50˚C

67˚C

COSMAN, MIT

CW: 20V, t=60 secCW: 20V, t=60 sec 50˚C Isotherm

37˚C

40˚C

45˚C

60˚C

55˚C

50˚C

67˚C |E|=2,750 V/m

|E|=17,000 V/m

COSMAN, MIT

Choice Between Choice Between Conventional RF & Pulsed Conventional RF & Pulsed

RFRF

• Special IndicationSpecial Indication• Proximity to Vital StructuresProximity to Vital Structures• Newer ResearchNewer Research

Localization of the Localization of the Target nerveTarget nerve

• Fluoroscopic guidance is mandatoryFluoroscopic guidance is mandatory• Check impedance for the integrity of Check impedance for the integrity of

the circuit (between 200 to 700 the circuit (between 200 to 700 ))• Sensory-Motor DissociationSensory-Motor Dissociation

– Sensory stimulation at X Sensory stimulation at X – No motor stimulation at 2XNo motor stimulation at 2X

Conventional RFConventional RF

• Sensory testing: 0.4-0.6 V at 50 HzSensory testing: 0.4-0.6 V at 50 Hz• Motor testing: 1V at 2HzMotor testing: 1V at 2Hz• Lesion is carried at 80 -85 degree C Lesion is carried at 80 -85 degree C

for for

60 – 90 sec.60 – 90 sec.

ClinicalClinical Indications of Indications of Conventional RFConventional RF

• Gasserian ganglion Gasserian ganglion Trigeminal Trigeminal NeuralgiaNeuralgia

Indications of Conventional Indications of Conventional RF Contd…RF Contd…

Cervical facet joint Cervical facet joint denervationdenervation

Sacro -iliac Joint denervationSacro -iliac Joint denervation

Conventional RF Contd..Conventional RF Contd..

Lumber facet joint Lumber facet joint denervationdenervation

Indication of Pulse RFIndication of Pulse RF

• Stellate Ganglion Stellate Ganglion • Other GanglionOther Ganglion• Brachial Brachial

PlexopathyPlexopathy• SuprascapularSuprascapular• AS ROMANS’ DO• Knee Neuropathic Knee Neuropathic

PainPain

Stellate Ganglion RF

Cervical DRG lesioningCervical DRG lesioning

Lumber DRG lesioningLumber DRG lesioning

Lumber DRG lesioningLumber DRG lesioning

Lumber sympathetic Lumber sympathetic blockblock

ComplicationsComplications• Dysesthesia-5-25%Dysesthesia-5-25%• Anesthesia Anesthesia

dolorosadolorosa• Masticator muscle Masticator muscle

weakness -4%weakness -4%• Facial numbnessFacial numbness• Corneal analgesia-Corneal analgesia-

15%15%• KeratitisKeratitis

• Chemical meningitisChemical meningitis• Carotid-cavernous Carotid-cavernous

fistulafistula• Haematoma –Cheek, Haematoma –Cheek,

RetrobulbarRetrobulbar• Cerebrospinal fluid Cerebrospinal fluid

leakleak• Cranial nerve Cranial nerve

paralysisparalysis

ConclusionConclusion• Radiofrequency AblationRadiofrequency Ablation is a is a

useful minimally invasive useful minimally invasive option for offering option for offering long-termlong-term pain relief, improving quality of pain relief, improving quality of life in a significant proportion life in a significant proportion of chronic pain patients.of chronic pain patients.

• Careful patient selection & Careful patient selection & thorough knowledge about the thorough knowledge about the proposed procedure are proposed procedure are mandatorymandatory

My Sincere My Sincere Thanks to Thanks to

•Dr Gautam DasDr Gautam Das•Dr Krishna PoddarDr Krishna Poddar

Thank YouThank You