Brief history of RF

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RADIOFREQUENCY
NERVE LESIONING
Dr Zbigniew M Kirkor
Pain Clinic, Princess
1 Alexandra Hospital
1
Harlow, Essex, UK
• Brief history of RF
• Physics of RF
• Clinical applications
• Guidelines and protocols
• Evidence for efficacy
2
• Brief history of RF
• Physics of RF
• Clinical applications
• Guidelines
• Evidence for efficacy
3
• Until 1980 - large size probes (14gauge)
•
•
1931 - Gasserian ganglion termolesion,
1975 - RF lesioning of the medial branch for lumbar
facets (Shealy),
•
1977 - RF lesion of dorsal root ganglion (Uematsu),
•
cordotomies.
4
• 1980 - 1995 - introduction of fine probes
•
medial branch (facet joints),
•
dorsal root ganglion,
•
sympathetic chain,
•
1991 - nucleus of the disc.
5
• 1996 to present
•
pulsed RF,
•
cooled RF,
•
era of extensive research and search for evidence,
•
development of computerised generators.
6
• Brief history of RF
• Physics of RF / Pulsed RF
• Clinical applications
• Guidelines
• Evidence for efficacy
7
Radiofrequency
8
Alternating Current and RF
AC frequency (f) is the number of cycles per second
(measured in Hz)

Your household outlet has AC
of 60Hz or 50Hz

Radiofrequency Generator 460kHz = 460,000Hz

A microwave - 500-1000kHz
9
Ionic Heating Using RF Cannula
Insulated
Introducer





RF energy is applied
Ions in surrounding tissue move creating
friction
Friction heats surrounding tissue
Hot tissue heats probe or electrode by
conduction
Probe thermocouple located at the tip,
reads tissue temperature
10
Exposed
Active Tip
Lesion Temperature
Cannula
Insulation
Cannula Active
Tip



80°C
65°C
40°C
Temperature drops as radius from
tip increases
Neurodestruction occurs when
temp reaches > 45ºC
A small zone of reversible
damage surrounds lesion
Clinical implications
• Size matters !!! Larger canniula = larger
area of lesion.
• Temperature between 45 and 80 C.
• Time of lesioning: not less then 60
o
seconds but not more then 90 seconds.
• Tissue impedance: high in dense
tissues, low in liquids (blood, CSF,
disc).
• Probe need to placed parallel (along) to
12
Pulsed RF
13
•
In pulsed RF, the treatment effect is produced by the
electromagnetic field. It is not a thermal lesion.
Electro-magnetic field is maximal at the tip and decreases behind the tip.
14
For Neuropathic Pain

Neuropathic Pain is a
contraindication for Standard RF

Pulsed RF can treat peripheral
nerves without injuring them.

Pulsed RF maximizes voltage whilst
ensuring that temperature does not
exceed 42
15
Standard RF
Pulsed RF
16
• Brief history of RF
• Physics of RF
• Clinical applications
• Guidelines
• Evidence for efficacy
17
RADIOFREQUENCY
• Cervical, thoracic and lumbar facet
joints (medial branch),
• Sacroiliac joints,
• Sympathetic chain.
18
Pulsed RF
• Dorsal root ganglions (nerve roots) cervical, thoracic, lumbar.
• Trigeminal ganglion.
• Peripheral nerves.
19
• Brief history of RF
• Physics of RF
• Clinical applications
• Guidelines
• Evidence for efficacy
20
Published in 2004
Edited by Prof. Nikolai
Bogduk on behalf of the
Standards Committee of ISIS
21
ESTABLISHED PROCEDURES
•
DIAGNOSTIC
•
•
•
Lumbar spinal nerve blocks
Lumbar disc stimulation
Lumbar medial branch blocks
•
•
Cervical disc stimulation
Cervical medial branch blocks
22
ESTABLISHED PROCEDURES
•
THERAPEUTIC
•
•
•
Lumbar transforaminal injection of corticosteroids
Percutaneous radiofrequency lumbar medial
branch neurotomy
Intradiscal electrothermal therapy
•
•
Cervical transforaminal injection of
cortycosteroids
Percutaneous radiofrequency cervical medial
branch neurotomy
23
• “Lumbar
medial branch
blocks are
diagnostic procedures designed to test
if a patient’s pain is mediated by one or
more of the medial branches of the
lumbar dorsal rami.”
• “...
Lumbar medial branch blocks are
used to test if a patient’s pain stems
from a given lumbar zygapophysial
(facet) joint. For that purpose the nerves
that
innervate
the
joint
are
anaesthetized.”
24
• Steroid injection into the facet joint is
NOT a validated method of treatment.
• Diagnostic blocks should be performed
twice, ideally as a double blind
procedure.
• It doesn’t matter what local anaesthetic
is used.
25
• Brief history of RF
• Physics of RF
• Clinical applications
• Guidelines
• Evidence for efficacy
26
• There is very limited number of well
designed Randomized Controlled Trials
for radiofrequency neurotomy.
• There is no RCT for Pulsed RF
neurotomy.
27
28
Pain relief was categorized as at least 80% pain relief from baseline
pain and ability to perform previously painful movements.
For therapeutic interventions, the primary outcome measure was
pain relief with secondary outcome measures of improvement in
functional status, psychological status, return to work, and reduction
in opioid intake.
For therapeutic interventions, short-term pain relief was defined as
relief lasting 6 months or less and long-term relief as longer than 6
months.
29
Conclusion: The evidence for diagnosis of lumbar facet joint pain
with controlled local anesthetic blocks is Level I or II-1.
The indicated level of evidence for therapeutic lumbar facet joint
interventions is Level II- 1 or II-2 for lumbar facet joint nerve blocks,
Level II-2 or II-3 evidence for radiofrequency neurotomy, and
Level III (limited) evidence for intraarticular injections.
30
31
Results: Based on the utilization of controlled comparative local
anesthetic blocks, the evidence for the diagnosis of cervical facet
joint pain is Level I or II-1.
The indicated evidence for therapeutic cervical medial branch
blocks is Level II-1.
The indicated evidence for radio- frequency neurotomy in the
cervical spine is Level II-1 or II-2, whereas the evidence is lacking
for intraarticular injections.
32
www.painphysicianjournal.com
33
Thank you !
34
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