Silencing Neuroma Pain-Botulinum Toxin Versus Local Anesthetic Injection

Neuroma pain following limb trauma or amputation is characterized by focal neuropathic pain, trigger-point tenderness, and significant functional impairment. Local anesthetic injections are commonly used for diagnostic and therapeutic purposes but typically provide only transient relief. Botulinum toxin type A has demonstrated analgesic properties through inhibition of neurotransmitter release and neurogenic inflammation, potentially offering longer-lasting pain relief.

This multicenter, randomized, double-blind, active-controlled trial will enroll adults with clinically and imaging-confirmed neuroma-related pain persisting for at least 3 months after limb trauma or amputation. Participants will be randomized in a 1:1 ratio to receive either ultrasound-guided botulinum toxin type A injection or ultrasound-guided local anesthetic injection using an identical technique and volume.

Participants will be followed for 24 weeks. Pain intensity will be assessed using a numerical rating scale at predefined intervals. Secondary outcomes include responder rates, neuropathic pain characteristics, pain interference, functional outcomes, analgesic consumption, durability of pain relief, and safety. The study aims to provide high-quality evidence to guide interventional pain management strategies for neuroma-related pain.

• Botulinium toxin type A injection (Drug): A single ultrasound-guided perineural injection of botulinum toxin type A (100 units diluted in 2.0 mL sterile normal saline) administered circumferentially around the imaging-confirmed neuroma using a standardized grid injection technique. The procedure is performed under sterile conditions with real-time ultrasound visualization to ensure accurate perineural placement. No additional corticosteroids or anesthetics are co-administered.
• Local Anesthesia (Drug): A single ultrasound-guided perineural injection of local anesthetic (ropivacaine 0.2%, 2.0 mL or bupivacaine 0.25%, 2.0 mL) administered circumferentially around the imaging-confirmed neuroma using the identical injection technique and volume as the experimental arm. The procedure is performed under sterile conditions with real-time ultrasound guidance. No corticosteroids are administered.

Primary outcomes

• Change in neuroma-related pain intensity from baseline to Week 8 measured using the 0-10 Numeric Rating Scale (NRS) [Baseline (prior to injection) and Week 8 (56 ± 7 days) after injection]: Description Neuroma-related pain intensity will be assessed using an 11-point Numeric Rating Scale (NRS), where 0 indicates no pain and 10 indicates worst imaginable pain. The outcome measure is the mean change in NRS score from baseline (pre-injection assessment) to Week 8 following injection. Higher NRS scores indicate greater pain intensity. Negative values reflect improvement (pain reduction). Between-group differences (botulinum toxin type A versus local anesthetic) will be analyzed.

Sex: All, ages: 18 Years to 50 Years

Inclusion Criteria:

* Age ≥18 years
* History of limb trauma and/or limb amputation at least 3 months prior to enrollment
* Clinical diagnosis of neuroma-related pain with focal tenderness and positive - - Tinel sign
* Imaging confirmation of neuroma by ultrasound or MRI
* Average pain intensity ≥4 on a 0-10 Numerical Rating Scale (NRS) during the week prior to screening
* Stable analgesic regimen for at least 14 days prior to enrollment
* Ability to provide written informed consent

Exclusion Criteria:

* Chronic pain condition unrelated to neuroma that predominates clinical symptoms
* infection at or near the planned injection site
* Known neuromuscular junction disorders (e.g., myasthenia gravis)
* Pregnancy or breastfeeding
* Botulinum toxin treatment within the previous 4-6 months
* Planned surgical neuroma revision during the study period
* allergy or hypersensitivity to botulinum toxin or local anesthetics

• Results publication: Dmytriiev D, Liu W, Barsa M, Khomenko A, Strokan A, Pasquina PF, Cohen SP. Perineuromal hydrodissection for acute postamputation pain? An observational study in a time of war. Reg Anesth Pain Med. 2026 Jul 6;51(7):795-804. doi: 10.1136/rapm-2024-106307. PMID 39971386