Pelvic Pain Treated With MR-guided Cryoanalgesia

Pelvic pain syndromes have a high prevalence of up to 8% in the general population and up to 50% following pelvic trauma and pelvic surgery. While medical management is the initial therapeutic step, it is often ineffective with surgical decompression and resection of the putative nerves being the ultima ratio. Cryoablation can induce long-lasting nerve conduction blocks with resultant pain relief for several months. The objective of this study is to evaluate the effectiveness of magnetic resonance (MR) neurography-guided cryoanalgesia for the treatment of pelvic and associated pain syndromes.

Pelvic pain syndromes including meralgia paresthetica, inguinodynia, and deep gluteal syndrome and others, which are caused by nerves including the the lateral femoral cutaneous nerve (LFCN), genitofemoral nerve (GFN), ilioinguinal nerve (IIN), iliohypogastric nerve (IHN), pudendal nerve (PN), obturator nerve (ON), posterior femoral cutaneous nerve (PFCN), and others, have a high prevalence of up to 8% in the general population and up to 50% following pelvic trauma and pelvic surgery, including episiotomy, orthopedic instrumentation and surgical hernia repair. While medical management is the initial therapeutic step, it is often ineffective with surgical decompression and resection of the putative nerves being the ultima ratio. Cryoablation of sensory nerves at temperatures of approximately 40 degrees Celsius and below (Cryoanalgesia) can induce long-lasting nerve conduction blocks with resultant pain relief for several months, which could be an effective treatment option for a large number of patients in this group before, instead of, and after failed surgical treatment. Cryoablation affords several advantages over other thermal or chemical ablation techniques, including direct visualization of the ablation zone, decreased intraprocedural and postprocedural pain, and the ability to simultaneously use multiple probes in variable configurations to create tailored additive overlapping ablation zones. In contrast to surgical or heat-mediated ablation, cryoablation does not disrupt the acellular epineurium or perineurium, which reduces the risk of neuroma formation and may allow eventual nerve regeneration, after which the cryoanalgesia can be repeated. Interventional MR neurography at 3 Tesla describes the combined use of high-resolution MRI for the visualization of smallest nerves that are located deep inside the pelvis, targeting, placement of needles and probes, and process monitoring, such as growth of the ice ball and relationship to the target nerves. The use of interventional MR neurography is thus ideally suited to perform cryoanalgesia with the highest technical accuracy and safety. The objective of this study is to evaluate the effectiveness of MR neurography-guided cryoanalgesia for the treatment of pelvic and associated pain syndromes.

Eligibility Criteria:
Inclusion Criteria:

* 18 to 100 years
* Chronic pelvic pain for at least 3 months and no adequate pain relief defined as persistent worst pain 4 or above on an 11-point visual analogue scale of 0 (no pain) to 10 (pain as bad as subject can imagine) despite conservative treatments, including but not limited to oral pain medication including NSAIDs and narcotics, physical therapy, and nerve block.
* The 'worst pain' must be reported to be 4 or above on an 11-point visual analogue scale of 0 (no pain) to 10 (pain as bad as subject can imagine)
* Pain must be from a single lumbosacral nerves confirmed with selective nerve blocks providing adequate temporary pain. The selectivity of the nerve block will be confirmed on MR images documenting that the injected local anesthetic immerses the targeted nerve and that there is absence of spread of local anesthetic to adjacent nerves to exclude confounding anesthesia. Adequate pain relief will be defined by pain relief of greater 50% after the nerve block and rest and with aggravating exercise.
* The target nerve is amenable to cryoablation with MRI guidance
* Cryoablation should be performed within 3 months of the nerve block
* No debilitating medical or psychiatric illness that would preclude giving informed consent or receiving optimal treatment and follow-up
* Known coagulopathy or bleeding disorders are controlled

Exclusion Criteria:

* Confounding pain syndromes or conditions.
* Previous nerve surgery
* Currently pregnant, nursing, or wishing to become pregnant during the study
* Serious medical illness, including any of the following: uncontrolled congestive heart failure, uncontrolled angina, myocardial infarction, cerebrovascular event within 6 months prior to the screening visit
* Concurrent participation in other studies that could affect the primary endpoint