Comparative Evaluation of Intraneuroma and Perineuroma Botulinum Toxin Type A Injection Techniques for Chronic Neuroma Pain After Combat-Related Amputation

Chronic neuroma pain is a common and disabling complication following combat-related limb trauma and amputation. Persistent neuroma pain may contribute to residual limb pain, phantom limb pain, impaired prosthesis tolerance, reduced mobility, sleep disturbance, and decreased quality of life. Ultrasound-guided botulinum toxin type A injection has emerged as a promising treatment option because of its potential effects on peripheral nociceptive signaling, neurogenic inflammation, and neuropathic pain modulation.

However, the optimal injection technique for botulinum toxin administration in painful neuromas remains unclear. Two commonly used approaches include direct intraneuroma injection and perineuroma injection surrounding the neuroma. Intraneuroma injection may provide more direct pharmacological modulation of pathological nerve tissue, whereas perineuroma injection may reduce the risk of mechanical nerve injury while still targeting peripheral sensitization mechanisms.

This prospective multicenter study is designed to evaluate the feasibility, safety, and clinical outcomes associated with intraneuroma and perineuroma ultrasound-guided botulinum toxin type A injection techniques in patients with chronic neuroma pain after combat-related amputation.

Patients with ultrasound-confirmed painful neuromas will undergo ultrasound-guided botulinum toxin type A injection using one of the two injection techniques according to local clinical practice and physician decision-making. Clinical follow-up will include assessment of neuroma pain intensity, neuropathic pain characteristics, phantom limb pain, residual limb pain, prosthesis tolerance, analgesic consumption, patient-reported improvement, and adverse events.

The study aims to improve understanding of ultrasound-guided botulinum toxin injection strategies for chronic neuroma pain and to identify potential differences in safety and clinical effectiveness between intraneuroma and perineuroma approaches in patients with combat-related amputations.

• Botulinum toxin type A injection (Drug), also known as Ultrasound-Guided Botulinum Toxin Injection: Ultrasound-guided botulinum toxin type A injection performed for treatment of chronic neuroma pain after combat-related amputation. Two injection techniques will be evaluated: direct intraneuroma injection and perineuroma injection surrounding the neuroma. Procedures will be performed under sterile conditions using high-frequency musculoskeletal ultrasound guidance by clinicians experienced in ultrasound-guided pain interventions.

Primary outcomes

• Change in chronic neuroma pain intensity [Baseline to 12 weeks after injection]: Change in chronic neuroma pain intensity will be assessed using the 11-point Numeric Rating Scale (NRS). Participants will rate their average neuroma-related pain during the previous 7 days on a scale from 0 to 10, where 0 indicates "no pain" and 10 indicates "worst imaginable pain." The change from baseline NRS score will be calculated at each follow-up assessment. Scale Information: Numeric Rating Scale (NRS) Minimum Value: 0 Maximum Value: 10 Interpretation: Higher scores indicate greater chronic neuroma pain intensity and worse clinical outcomes. Negative change from baseline indicates improvement.

Secondary outcomes

• Neuropathic Pain Characteristics Assessed Using the painDETECT Questionnaire (PD-Q) [Baseline to 12 and 24 weeks]: Neuropathic pain characteristics will be assessed using the painDETECT Questionnaire (PD-Q), a validated self-administered questionnaire designed to identify and quantify neuropathic pain symptoms. The questionnaire evaluates sensory descriptors, pain course pattern, and pain radiation. Total scores range from -1 to 38. Scale Information: painDETECT Questionnaire (PD-Q) Minimum Value: -1 Maximum Value: 38 Interpretation: Higher scores indicate more pronounced neuropathic pain characteristics and a greater likelihood of neuropathic pain. Clinical Interpretation: ≤12 = Neuropathic pain unlikely 13-18 = Uncertain neuropathic pain component ≥19 = Neuropathic pain likely
• Residual Limb Pain Intensity [Baseline to 12 and 24 weeks]: Residual limb pain intensity will be assessed using the 11-point Numeric Rating Scale (NRS). Participants will rate their average residual limb pain during the previous 7 days on a scale from 0 ("no pain") to 10 ("worst imaginable pain"). Scale Information: Numeric Rating Scale (NRS) Minimum Value: 0 Maximum Value: 10 Interpretation: Higher scores indicate greater residual limb pain intensity and worse pain outcomes.
• Prosthesis Tolerance Assessed Using Average Daily Prosthesis Wearing Time [Baseline, 3 months, 6 months, and 12 months after amputation or intervention.]: Prosthesis tolerance will be assessed by measuring the average daily duration of prosthesis use reported by the participant. Average daily prosthesis wearing time will be recorded as the total number of hours the prosthesis is worn during a typical day. Measurement: Average daily prosthesis wearing time Unit of Measure: Hours per day (hours/day) Minimum Value: 0 hours/day Maximum Value: 24 hours/day Interpretation: Higher values indicate better prosthesis tolerance, greater comfort during use, and improved adaptation to the prosthesis.

Sex: All, ages: 18 Years to 60 Years

Inclusion Criteria:

* Age ≥18 years
* Combat-related limb amputation
* Chronic neuroma pain lasting ≥3 months
* Ultrasound-confirmed painful neuroma
* Average neuroma pain intensity ≥4/10 on the Numeric Rating Scale
* Ability to undergo ultrasound-guided injection
* Stable analgesic regimen for at least 14 days before enrollment
* Ability to provide written informed consent

Exclusion Criteria:

* Active infection at or near the injection site
* Open wound preventing safe injection
* Previous botulinum toxin injection for neuroma pain within 6 months
* Previous neuroma surgery within 3 months
* Known allergy to botulinum toxin type A
* Coagulopathy or anticoagulation contraindicating injection
* Severe uncontrolled systemic disease
* Inability to complete follow-up assessments

• Results publication: Climent JM, Mondejar-Gomez F, Rodriguez-Ruiz C, Diaz-Llopis I, Gomez-Gallego D, Martin-Medina P. Treatment of Morton neuroma with botulinum toxin A: a pilot study. Clin Drug Investig. 2013 Jul;33(7):497-503. doi: 10.1007/s40261-013-0090-0. PMID 23740337

• Andrii Khomenko, MD, Principal investigator, Feofaniya Clinical Hospital