1. Radiofrequency Ablation of Amputation Neuromas: A Small Case Series
Physical Medicine & Rehabilitation Service
Department of Rehabilitation
CPT Jennifer Windsor, MD; MAJ Yin-Ting Chen, MD; MAJ Matthew E Miller, MD; CDR Michael B. Jacobs, MD; MAJ David Reece, DO; MAJ William Kroski, DO
Introduction
Case Description
Painful amputation neuroma is a common condition after amputation, and a significant issue facing our Servicemembers. In the modern era, there is a consistent amputation rate of 7-8% during wartime over the past 50 years. Amputation neuromas are a bundle of nerve endings that form via regenerative sprouting after axonal nerve damage during an amputation, with heightened sensitivity to pain to local pressure or palpation, often leading to problems with prosthesis usage and function. Currently, no great definitive option exists. Radiofrequency ablation (RFA) of neuroma is a novel technique for treatment. The technique involves selective destruction of nervous tissue to facilitate pain relief. RFA has wide applications, but is limited in the treatment of neuromas. To the best of our knowledge, there are no reports in the current literature for US-guided continuous RFA for the treatment of neuroma pain in combat amputees.
Case 1: 31 yo AD male injured by an IED with severe ankle injuries leading to elective transtibial amputation (TTA), presented 3 months post amputation with 8-10/10 electric-like radiating pain into the phantom limb in peroneal distribution, inhibiting prosthesis usage and ambulation. US evaluation demonstrated a well-circumscribed hypoechoic spherical mass consistent with peroneal neuroma. US-guided RFA of the left peroneal neuroma was performed 4 weeks following a successful diagnostic injection. At 2- and 9-month follow up, patient rated the pain at 2-3/10, with complete resolution of the electric-like pain and significantly lowered pain medication usage. He was able to ambulate with his prosthesis for more than 7 hours daily.
Case 2: 25yo male status post IED blast with bilateral transfemoral amputations (TFA) 12-months after injury, presented with sharp, radiating pain of left lower residual limb, rated at 10/10, limiting usage of his prosthesis. US evaluation was diagnostic of a symptomatic sciatic neuroma. US-guided RFA of the left sciatic neuroma was performed 1 week following a successful diagnostic injection. Patient reported complete pain cessation on subsequent follow-ups at 2 week, 2 month, and 5 months. He reported decreased medication usage and achieved all day use of his prosthesis.
Figure 1. Example of a neuroma. Longitudinal axis view of a tibial neuroma in the residual limb of a patient with transtibial amputation. The tibial nerve (^) is seen diving deeper into the soleus muscle (S); a gradual thickening and loss of the fibrillar internal architecture is notable before the nerve terminates in the bulbous neuroma (*). Both the gastrocnemius (G) and the soleus muscles are notable for mild atrophy.
US and Treatment Techniques
Neuromas are located through either sonopalpation or anatomical techniques. Sonopalpation is performed by having the patient pinpoint the site of their maximum tenderness that elicits the neuromal pain, and the US transducer is placed directly over this location to identify the neuroma. An alternative method is to trace the intact proximal nerve until reaching the neuroma. Varying the pressure on the neuroma through the transducer can further confirm if the underlying neuroma is the source of pain. Once the neuroma is visualized, a low-volume diagnostic injection of the neuroma is performed under ultrasound guidance; positive response to the diagnostic injection is the prerequisite for RFA.
The NT1100 RF Generator (NeuroTherm, Massachusetts, USA) is used for the RFA. The neuroma is again located using the above technique. 3mL of 2% lidocaine is injected at 2-3 cm proximal to the neuroma to achieve anesthesia, then under ultrasound guidance, the RF needle is guided until entering near the center of neuroma, and the probe is set to 80 degrees Celsius for 90 seconds. The RF probe is then withdrawn and dressings applied.
Conclusion
The use of continuous RFA was helpful in treating the amputation neuroma pain in these two patients; both of them reported marked and long-lasting decreases in pain, decreased medication usage and increased prosthesis usage. Our findings are similar to current literature using pulsed rather than continuous RFA, suggesting there may be no difference between continuous vs. pulsed RFA, demonstrating its potential as a treatment option for neuroma pain refractory to standard treatments. There is little research in RFA and the treatment of neuromas; a larger clinical trial is required to further study the effect of this treatment, the objective impact on function, incidence and types of adverse outcome from the treatment, and to further refine the technique.
Figure 2. Diagnostic injection and pre-RFA anesthetic injection are often performed with the neuroma visualized in short-axis. The needle is seen here guided in an in-plane, lateral-to-medial approach in a peroneal neuroma injection.
Figure 3. After the anesthetic injection, the RFA probe is guided in an in-plane, distal-to-proximal approach until entering the center of the neuroma.
Contact Information: CPT Jennifer Windsor, MD.
The views expressed in this poster are those of the authors and do not reflect the official policy of the Department of Army, Department of Defense, or United States Government.