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The Role of Diagnostic Ultrasound-Guided Selective Common Peroneal Nerve Block in a Patient with Negative Imaging but with Classic Neuropathic Pain After Below Knee Amputation

Saxena, Shashank MD; So, Sokopoleak MD; Williams, Brian A. MD, MBA; Mangione, Michael P. MD

doi: 10.1213/XAA.0000000000000057
Case Reports: Case Report

Below-knee amputation neuromas may be hard to detect radiographically. This case report demonstrates that in a below-knee amputee with negative imaging but with classic neuropathic pain, successful diagnostic ultrasound-guided nerve-selective peripheral nerve block may be performed to diagnose the problem; subsequent resection of the neuroma may relieve severe neuropathic pain.

From the *Department of Anesthesiology, VA Pittsburgh Health Care System; Department of Anesthesiology, University of Pittsburgh Medical Center; and Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.

Accepted for publication February 12, 2014.

Funding: None.

The authors declare no conflicts of interest.

Address correspondence to Shashank Saxena, MD, Department of Anesthesiology, VA Pittsburgh Health Care System, University Drive C, Pittsburgh, PA 15240. Address e-mail to

In this case report, we discuss the management of chronic postamputation neuropathic pain in a below-knee amputee with negative imaging studies. His pain was unresponsive to medical treatment and was ultimately causing significant discomfort.

The patient gave permission for publication of this case report. Approval from our local IRB was also obtained before submission of the manuscript.

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A 45-year-old man with a medical history of coronary artery disease, hypertension, hyperlipidemia, posttraumatic stress disorder, and below-knee amputation (BKA) complained of stump pain rated 8 of 10 for the previous 6 months. His original BKA in August 2008 was complicated by postoperative infection requiring a wound vacuum device. One year later, he developed pain in his residual limb, and a magnetic resonance image (MRI) revealed edema in the tibia and adjoining tissues consistent with chronic osteomyelitis. He subsequently underwent incision and drainage of the stump, along with scar revision. He did well for the next 18 months until he experienced a lancinating, shock-like sensation that radiated from the end of his stump. On physical examination, the tibial stump appeared intact. There was no erythema, fluctuance, or obvious drainage. Plain roentgenograms and MRI showed no apparent pathology. Originally, the patient was treated conservatively with gabapentin, carbamazepine, and hydrocodone. Prosthesis modification was also attempted, without benefit. Medical management was effective initially and helped reduce pain to a 4 out of 10 level; the patient was able to ambulate with his prosthesis with minimal discomfort. However, his neuropathic pain worsened over the next 6 months, and he developed sleep disturbance due to this lancinating pain. He continued to complain of pain, which was localized specifically in the lateral part of the stump with radiation to the posterior part of the thigh, ending distally around the fibular head. On physical examination, the patient had a positive Tinel sign in the common peroneal nerve region. The provisional diagnosis was common peroneal neuropathy with possible neuroma-induced pain. Surgical management was planned due to failure of conservative management to that point.

The orthopedic surgical team requested that the anesthesiologist perform a diagnostic ultrasound procedure to aid in the resection of the possible neuroma. Ultrasound was performed on the day of the procedure; consistent with the previous MRI, we were unable to identify a neuroma-like structure in the stump. Subsequently, the common peroneal and posterior tibial nerves were identified in the popliteal region, and common peroneal nerve diagnostic block was performed with 5 mL of 1.5% mepivacaine. Figures 1 and 2 demonstrate the pre-block and post-block appearance of the common peroneal nerve. The patient reported complete relief of stump pain within 5 minutes after the diagnostic nerve block. We then proceeded with a complete sciatic nerve block at the popliteal fossa for postoperative pain relief with 30 mL of 0.25% bupivacaine, 25 μg clonidine, 300 μg buprenorphine, and 2 mg dexamethasone.1 Spinal anesthesia was also performed with 1.5 mL of 0.75% hyperbaric bupivacaine for pain related to the intraoperative thigh tourniquet.

Figure 1

Figure 1

Figure 2

Figure 2

The common peroneal nerve was released distally, resected as far proximally as allowed by surgical exposure, and then retracted cephalad into the biceps femoris muscle. The resected end of the nerve appeared hyperemic and swollen under direct vision, confirming the diagnosis of common peroneal neuroma.

The patient was followed after the procedure for 9 months and did not report any neuropathic pain in the stump region. He required hydrocodone in the immediate postoperative period for about 4 weeks and did not require any further opioids for pain control. Nine months later, he reported medial stump scar pain, rated 8 of 10, which was treated surgically by scar revision (under sciatic nerve block and spinal anesthesia). He has had no recurrence of his lancinating neuropathic pain in the common peroneal nerve distribution. He has not been using any opioids and has been able to use his prosthesis regularly.

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Clinical treatment of postamputation stump pain can be difficult to manage and frustrating for both patient and physician. Various causes of postamputation stump pain include protruding bone edge, heterotopic calcification, osteomyelitis, tumor recurrence, phantom pain, and neuropathic pain from neuroma formation. Neuroma pain usually starts 2 to 3 months after the initial surgery.2 While the pathophysiology and etiology of neuroma stump pain are unclear, the distal end of a transected nerve likely regenerates abnormally3,4 resulting in a tangled architecture of axons, Schwann cells, endoneurial cells, and perineurial cells within the surrounding scar tissue.3,4 This leads to increased sensitivity to any stimulation from traction on the nerve from scar tissue, compression of the entangled nerve ending, or ischemia of the nerve tissue.

Diagnosis of stump neuroma pain is made clinically, with the classic Tinel sign allowing for localizing it to a single peripheral nerve. Sciatic neuromas are typically easier to detect than those arising from the smaller nerve branches within the thigh.5 MRI is the accepted standard for detection of a neuroma.5 Neuromas have low signal intensity on T1-weighted images and intermediate to high signal intensity on T2-weighted images; they also demonstrate variable enhancement after administration of gadopentetate dimeglumine.5 In patients with above-knee amputation, MRI has been used to detect stump neuromas as heterogeneous masses with intermediate intensity. However, in below-knee amputees, the compactness of musculature, along with fatty atrophy, interferes with the ability of MRI to detect many lesions.6 This was probably the scenario in our patient. It should also be noted that to be radiographically detected, most neuromas need to be 1.0 to 3.5 cm in diameter.6–9

With ultrasound, stump neuromas appear as hypoechoic/anechoic structures, with the surrounding scar tissue appearing hyperechoic. This is in contrast to normal nerves identified as echogenic, cord-like structures with internal linear echoes in longitudinally oriented scans and as an oval-to-round echogenic sections on transverse scans.10 In perioperative settings, ultrasound appears to be more easily available as an alternative to diagnose peripheral neuromas. Ultrasound can also trace the mass to an adjacent nerve, which is helpful in definitive diagnosis.11

Postamputation pain is typically treated conservatively before surgical intervention, but the success rate is mixed.12 Our patient was medically treated for 6 months before seeking surgical cure. Ultrasound guidance has allowed for therapeutic local anesthetic/steroid blocks into neuroma previously localized by MRI,13 but this may require multiple blocks.

To our knowledge, there is no standard guideline on surgical decision making regarding neuroma excision. The incidence of painful neuromas in 1 retrospective study on unilateral traumatic lower limb amputees in Chile was reported to be 12.5%.14 Diagnosis of a suspected neuroma with local anesthetic infiltration under ultrasound guidance could be used before excision, as demonstrated by our case report.

Our case is unique in that the neuroma could not be identified by either MRI or ultrasound. However, we used an ultrasound-guided common peroneal nerve diagnostic block to identify the nerve causing neuropathic pain. This was followed by common peroneal nerve resection and retraction into the biceps femoris, yielding complete relief from the neuropathic pain.

As exemplified in our report, BKA neuromas are difficult to detect by standard diagnostic testing. If the patient receives complete pain relief after ultrasound-guided selective peripheral nerve block, resection of the involved nerve can be undertaken to potentially treat intractable neuropathic pain.

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1. Ibinson JW, Mangione MP, Williams BA. Local anesthetics in diabetic rats (and patients): shifting from a known slippery slope toward a potentially better multimodal perineural paradigm? Reg Anesth Pain Med. 2012;37:574–6
2. Shankar H. Ultrasound-guided sciatic neuroma block for treatment of intractable stump pain. J Clin Anesth. 2008;20:483–4
3. Stokvis A, van der Avoort DJ, van Neck JW, Hovius SE, Coert JH. Surgical management of neuroma pain: a prospective follow-up study. Pain. 2010;151:862–9
4. Rajput K, Reddy S, Shankar H. Painful neuromas. Clin J Pain. 2012;28:639–45
5. Henrot P, Stines J, Walter F, Martinet N, Paysant J, Blum A. Imaging of the painful lower limb stump. Radiographics. 2000;20 Spec No:S219–35
6. Singson RD, Feldman F, Staron R, Fechtner D, Gonzalez E, Stein J. MRI of postamputation neuromas. Skeletal Radiol. 1990;19:259–62
7. Singson RD, Feldman F, Slipman CW, Gonzalez E, Rosenberg ZS, Kiernan H. Postamputation neuromas and other symptomatic stump abnormalities: detection with CT. Radiology. 1987;162:743–5
8. Donnal JF, Blinder RA, Coblentz CL, Moylan JA, Fitzpatrick KP. MR imaging of stump neuroma. J Comput Assist Tomogr. 1990;14:656–7
9. Beggs I. Pictorial review: imaging of peripheral nerve tumours. Clin Radiol. 1997;52:8–17
10. Fornage BD. Peripheral nerves of the extremities: imaging with US. Radiology. 1988;167:179–82
11. Provost N, Bonaldi VM, Sarazin L, Cho KH, Chhem RK. Amputation stump neuroma: ultrasound features. J Clin Ultrasound. 1997;25:85–9
12. Schon LC, Anderson CD, Easley ME, Lam PWC, Trnka HJ, Lumsden DB, Levin G, Shanker J. Surgical treatment of chronic lower extremity neuropathic pain. Clin Orthop Relat Res. 2001;389:156–64
13. Fischler AH, Gross JB. Ultrasound-guided sciatic neuroma block for treatment of intractable stump pain. J Clin Anesth. 2007;19:626–8
14. Rotter K, Sanhueza R, Robles K, Godoy M. A descriptive study of traumatic lower limb amputees from the Hospital Hel Trabajador: clinical evolution from the accident until rehabilitation discharge. Prosthet Orthot Int. 2006;30:81–6
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