Brian P. Jacob, David C. Chen, Bruce Ramshaw, Shirin Towfigh (eds.) - The SAGES Manual of Groin Pain-Springer International Publishing (2016)

20. Management of Groin Pain…
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on any nerves with a significant motor component as weakness will
occur. Fortunately, the border nerves are primarily sensory, but given the
proximity of DRGs to the spinal nerve, these cannot be safely ablated.
Second, injury to adjacent structures may occur, such as to blood vessels
which may be coagulated by radiofrequency ablation. Finally, neurolysis
can create an area of desensitized skin, which can be bothersome for
certain patients and may progress to anesthesia dolorosa, a feared complication
manifested by pain in the area despite numbness to stimulation.
Nonetheless, these approaches may be of significant benefit in appropriate
cases and after full discussion of risks and benefits with the patient.
Ablation may be performed with injection of a chemical neurolytic such
as phenol or dehydrated alcohol. Radiofrequency ablation creates a thermal
lesion at 80 °C along the active needle tip. Cryoablation creates a
supercooled −70 °C “ice ball” around the neural sheath, which leads to
decreased transmission. Again, case reports have shown promising
results with decreased pain and analgesic requirements [ 22 ].
For patients refractory to percutaneous interventions, peripheral nerve
field stimulation may be attempted. During the trial, stimulating leads are
placed either in proximity to the affected nerve or more subcutaneously
in the painful area. The leads are then sutured at the skin, and the external
lead contacts connected to a patient-controlled pulse generator. The
patient can then vary the stimulation intensity and pattern to produce a
vibratory sensation that overlaps the affected area. After a trial of 3–5
days, the patient reports on any resulting benefit, and if there is evidence
of increased function and decreased need for analgesics, a permanent
device can be placed with an implantable pulse generator. Peripheral
stimulation is based on the gate control theory proposed by Wall and
Melzack, wherein activation of large fibers suppresses painful input from
small fibers. This varies from the traditional use of stimulating leads in
the dorsal column of the spinal cord and is considered an off-label use.
Several case series have shown significant and sustained benefit with
peripheral stimulation, which may hold particular promise long term, as
there is unlikely to be a recurrence of pain after a pain-free interval as can
occur with regeneration of ablated nerves following neurolysis [ 23 –26 ].
Conclusion
Several recent expert reviews have attempted to quantify the effect of
various interventions for chronic postsurgical groin pain [ 16 , 27 ]. Many
promising modalities have been identified, as above; however, differences