Cryoanalgesia for Phantom Limb Pain

Recruiting in Palo Alto (17 mi)

Brian M. Ilfeld, MD - Anesthesiology ...

Overseen byBrian Ilfeld, MD

Age: 18+

Sex: Any

Travel: May Be Covered

Time Reimbursement: Varies

Trial Phase: Academic

Waitlist Available

Sponsor: University of California, San Diego

No Placebo Group

Approved in 1 Jurisdiction

Trial Summary

What is the purpose of this trial?

When a limb is severed, pain perceived in the part of the body that no longer exists often develops and is called "phantom limb" pain. Unfortunately, phantom pain goes away in only 16% of afflicted individuals, and there is currently no reliable definitive treatment. The exact reason that phantom limb pain occurs is unclear, but when a nerve is cut-as happens with an amputation-changes occur in the brain and spinal cord that actually increase with worsening phantom pain. These abnormal changes may often be corrected by putting local anesthetic-called a "nerve block"-on the injured nerve, effectively keeping any "bad signals" from reaching the brain with a simultaneous resolution of the phantom limb pain. However, when the nerve block resolves after a few hours, the phantom pain returns. But, this demonstrates that the brain abnormalities-and phantom pain-that occur with an amputation are not necessarily fixed, and may be dependent upon the "bad" signals being sent from the injured nerve(s), suggesting that a very long peripheral nerve block-lasting many months rather than hours-may permanently reverse the abnormal changes in the brain, and provide definitive relief from phantom pain. A prolonged nerve block lasting a few months may be provided by freezing the nerve using a process called "cryoneurolysis". The ultimate objective of the proposed research study is to determine if cryoanalgesia is an effective treatment for intractable post-amputation phantom limb pain. The proposed pilot study will include subjects with an existing above-knee amputation who experience intractable daily phantom limb pain. A single ultrasound-guided treatment of cryoneurolysis (or sham block-determined randomly like a flip of a coin) will be applied to the major nerves of the thigh. Although not required, each subject may return 4-6 months later for the alternative treatment (if the first treatment is sham, then the second treatment would be cryoneurolysis) so that all participants have the option of receiving the active treatment. Subjects will be followed for a total of 12 months with data collected by telephone.

Research Team

Brian Ilfeld, MD

Principal Investigator

University of California, San Diego

Eligibility Criteria

This trial is for adults over 18 who have had an above-knee amputation at least 12 weeks ago and suffer from moderate to severe phantom limb pain daily. Participants should not change their pain medication or undergo elective surgeries from one month before until four months after the initial treatment.

Inclusion Criteria

I had a leg amputation above the knee more than 12 weeks ago.

I am 18 years old or older.

I experience daily phantom limb pain rated 4 or higher for the last 2 months.

See 1 more

Exclusion Criteria

My BMI is over 40.

You are currently in jail or prison.

Pregnancy

See 3 more

Treatment Details

Interventions

Cryoneurolysis (Procedure)

Trial OverviewThe study tests cryoanalgesia, a prolonged nerve block achieved by freezing nerves, against a sham procedure to see if it can provide long-term relief from phantom limb pain in individuals with above-knee amputations. Each participant may receive both treatments over the course of the study.

Participant Groups

2Treatment groups

Experimental Treatment

Group I: Sham Comparator first, then optional cryoneurolysis treatmentExperimental Treatment2 Interventions

Initial treatment: Sham cryoneurolysis of the major nerves of the thigh in the residual limb: The cryoneurolysis device will be triggered using 1 cycle of 5.5-minute argon activation followed by a 30-60 second defrost period with helium (Varian) or 2 cycles of 2-minute gas activation with a sham probe separated by a 30-60 second defrost (Epimed). However, for sham treatment, the gas is NOT deployed to the probe tip and therefore there is NO drop in temperature with NO resulting cryoneurolysis. Optional active crossover treatment: Cryoneurolysis of the major nerves of the thigh in the residual limb: The cryoneurolysis device will be triggered using 1 cycle of 5.5-minute argon activation followed by a 30-60 second defrost period with helium (Varian) or 2 cycles of 2-minute gas activation with an active probe separated by a 30-60 second defrost (Epimed). For active treatment, the gas will be deployed to the probe tip where a drop in temperature will result in cryoneurolysis.

Group II: Cryoneurolysis first, then optional sham crossover treatmentExperimental Treatment2 Interventions

Initial treatment: Cryoneurolysis of the major nerves of the thigh in the residual limb: The cryoneurolysis device will be triggered using 1 cycle of 5.5-minute argon activation followed by a 30-60 second defrost with helium (Varian) or 2 cycles of 2-minute gas activation with an active probe separated by a 30-60 second defrost (Epimed). For active treatment, the gas will be deployed to the probe tip where a drop in temperature will result in cryoneurolysis. Optional sham crossover treatment: Sham cryoneurolysis of the major nerves of the thigh in the residual limb: The cryoneurolysis device will be triggered using 1 cycle of 5.5-minute argon activation followed by a 30-60 second defrost period with helium (Varian) or 2 cycles of 2-minute gas activation with a sham probe separated by a 30-60 second defrost (Epimed). However, for sham treatment, the gas is NOT deployed to the probe tip and therefore there is NO drop in temperature with NO resulting cryoneurolysis.