Cryoneurolysis for Cutaneous Neuropathic Pain

Study Overview
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Brief Summary
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Feasibility study with 25 patients investigating the effect of cryoneurolysis on persistent cutaneous neuropathic pain after surgery and trauma. All patients receive active treatment (cryoneurolysis). The study design is unblinded, non-randomized, non-controlled.

Official Title
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The Effect of Ultrasound-guided Cryoneurolysis on Persistent Cutaneous Neuropathic Pain After Surgery and Trauma

Conditions
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Neuropathic Pain

Intervention / Treatment
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* Device: Cryoneurolysis


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age > 17 years ASA (American Society of Anesthesiologists) physical status classification system I-III Informed consent Capable of subjective evaluation of pain Capable of reading and understanding Danish and informed written consent Average pain intensity >49/100 on VAS in the primary focal pain area for a minimum of 6 months at the time of inclusion Relevant injury (surgery or trauma) of peripheral nerves Plausible cutaneous location of pain In the area of pain, at least one of the following (1-8): (1) Hypo/anesthesia for touch/brush (2) Hypo/anesthesia for cold (3) Hypo/anesthesia for warmth (4) Hypo/anesthesia for pinprick (5) Allodynia for touch/brush (6) Allodynia for cold (7) Allodynia for warmth (8) Hyperalgesia for pinprick Neuropathic pain score (Douleur Neuropathique en 4 Questions, DN-4) >3/10 Definitive diagnosis of neuropathic pain (Finnerup et al 2016) Exclusion Criteria: Inability to cooperate Inability to understand Danish Allergy to local anesthetic Infection in the area of cryo probe insertion Significant competitive chronic pain Progressive neurologic disease Increased risk at needle insertion and cold exposure (e.g. Raynaud, coagulopathies) Uncontrolled severe systemic disease Implanted electronic devices unless approved by the relevant medical specialist Previous cryoneurolysis with no relevant effect for the same neuropathic pain Previous interventional pain therapy (e.g. spinal cord stimulation) with no relevant effect for the same neuropathic pain Expected duration of life < 2 years Pregnancy Abuse of alcohol, narcotics or medicine Current psychiatric disease Inclusion in other clinical trials Ongoing patient complaint Body mass index < 18.5 or > 34.9 kg/m2 Change of pain therapy within the last 28 days prior to inclusion

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Interventional Model Description: Non-blinded, non-randomized, non-controlled
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Cryoneurolysis<br>All 25 patients will receive cryoneurolysis | Device: Cryoneurolysis<br>* Cryoneurolysis<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Success of cryoneurolysis | Frequency of patients with > 50% reduction of neuropathic pain | 1 hour after cryoneurolysis | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Axonal loss estimated before cryoneurolysis |  | Maximum one year prior to the cryoneurolysis procedure | 
| Hyperalgesia for pinprick | Visual Analogue Scale (VAS) score (0-100) | 1 hour after cryo procedure compared to baseline | 
| Allodynia for brush | VAS score (0-100) | 1 hour after cryo procedure compared to baseline | 
| Frequency of NRS score < 4 | Numeric Rating Scale (NRS) score (0-10) | 1 hour, 2 weeks and 1,2,3,4,5 and 6 months after cryo procedure | 
| Pain score | NRS score (0-10) | 1 hour, 2 weeks and 1,2,3,4,5 and 6 months after cryoneurolysis procedure | 
| Duration of freedom of pain (number of days after the cryoneurolysis procedure) | NRS < 4 | Maximum follow-up until 12 months after cryoneurolysis procedure | 
| Change of neuropathic pain score DN-4 | DN-4 = Douleur Neuropathique en 4 Questions | 1 hour, 2 weeks and 1,2,3,4,5 and 6 months after cryo procedure | 
| Patient satisfaction at completion of cryo procedure | NRS score (0-10) | From skin insertion of cryo probe to withdrawal of cryo probe | 
| Change in muscle strength of relevant muscle groups | Handheld dynamometer | 1 hour after cryoneurolysis compared to baseline | 
| Procedure time for cryoneurolysis |  | From skin insertion of cryo probe to withdrawal of cryo probe | 
| Pain related medication |  | 2 weeks and 1,2,3,4,5 and 6 months after cryo procedure | 
| PGIC | Patient Global Impression of Change | 2 weeks and 1,2,3,4,5 and 6 months after cryo procedure | 
| Adverse events |  | 1 hour, 2 weeks and 1,2,3,4,5 and 6 months after cryo procedure |