Treatment of painful neuroma of amputated phalanx with distal toe transfer: a case report.

Abstract: A painful neuroma in the amputation stump of a finger can be psychologically and physically disabling. Numerous surgical procedures have been attempted to prevent and treat amputation neuromas of the finger, but the results are inconsistent. Microsurgical transfer of the distal second toe to the amputated stump of the finger can provide a pathway and target for the regenerating axons and avoid recurrence of neuromas. In this article, we present the experience of successful treatment of amputation neuromas of an index finger with microsurgical distal toe transfer.

Key Words: neuroma, amputation, phalanx, toe, transplantation

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A painful neuroma in the amputation stump of a finger can be psychologically and physically disabling. Great efforts have so far been made to treat amputation neuromas with various surgical procedures, including ligation, epineurial barriers, implantation into bone, centro-central repair, nerve translocation, electrocautery, and silicone caps. (1-7) However, the results are conflicting and difficult to interpret. Recent research has attempted to prevent and treat amputation neuromas by end-to-side nerve repair and implantation of a nerve ending into a vein graft, (8-13) but the reliability of these methods also needs to be further investigated.

In nerve injury, a successful repair between the proximal and distal segments of the injured nerve allows the axons to reach their target organ and can avoid the formation of a neuroma. (14) Providing a target for deprived axons from the injured nerve may be an ideal way to treat the amputation neuroma. In this article, we report the successful treatment of the amputation neuroma of the distal phalanx with the microsurgical distal second toe transfer.

Case Report

A 51-year-old white male was referred for evaluation and treatment of a painful neuroma of the left amputated distal index finger in July 2004. He had been involved in a work-related accident one year ago, resulting in a crush injury to the left distal index finger and subsequently underwent the left distal phalanx amputation. The wound healed without complications. However, a significant painful left index finger amputation stump developed attributable to neuroma formation. Chronic pain, cold intolerance, and hypersensitivity led to significant disability in typing and inability to perform his usual job duty as a professor, a diving instructor, and as a professional underwater photographer.

Physical examination showed the left index finger amputation stump distal to the distal interphalangeal (DIP) joint. Hypersensitivity was found in the finger stump. A sharp and shocking pain was elicitable with light tapping. The proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints had full ranges of motion. Other fingers of the left hand were within normal limit. X-ray of the left hand showed the left index finger amputation at distal phalanx distal to DIP joint (Fig. 1). Otherwise, the articular, osseous, and soft tissue structures were unremarkable. With strong desire to regain his index finger function and to alleviate painful neuroma, the patient agreed to proceed with resection of neuroma and right 2nd toe to left index finger transplant.

Surgical Procedure

After establishment of general anesthesia, the patient's right hand and left foot were prepped and draped. Under tourniquet control, the left index finger was explored through a fishmouth incision developing volar and dorsal flaps. Two very large neuromas were found imbedded in the dermis in exploration of the volar flap, and then resected. Both digital arteries were then identified through the path of digital nerves and explored back to the proximal portion of the middle phalanx. The ulnar digital artery had excellent pulsatile flow and a dominant vein on the dorsum of the finger appeared to be a suitable recipient when the tourniquet was released.

[FIGURE 1 OMITTED]

In skeletonization of the right second toe, a brisk medial artery signal was identified by the Doppler. The foot was then exsanguinated. An incision was designed to amputate the distal phalanx, as well as raise plantar and dorsal flaps. With elevation of the flaps, the medial and lateral arteries and the associated digital nerves were identified and skeletonized. A dorsal vein was also skeletonized in the SC tissue. With identification of these structures, the distal PIP joint was incised. All structures were then tagged with V clamps and amputated at their proximalmost portion. Both extensor and flexor tendons were divided and the toe was removed to the hand field. The articular surface of the middle phalanx was trimmed back with a rongeur and then a primary closure was done with nylon.

At the hand field, a K-wire was carefully passed through the distal phalanx in the second toe after the articular cartilage had been removed with a rongeur. The distal phalanx was then fixed to the debrided base of the distal phalanx of the index finger (Fig. 2). An end-to-end anastomosis between the medial digital artery of the toe and the ulnar digital artery of the index was performed with 11-0 nylon suture under the operating microscope. With release of clamps there was good pulsatile flow and bleeding in the margins of the toe itself. 10-0 nylon was used to connect both digital nerves. A primary closure was possible on the volar surface with 5-0 nylon. The hand was then turned and an end-to-end anastomosis of the veins was performed with 11-0 nylon suture. There was good flow through the anastomosis at the end of the procedure.

Primarily, closure at the dorsum was found impossible so a split-thickness skin graft was harvested from the posterior calf and tailored to fit the defect with 5-0 chromic suture. At completion of the procedure the toe appeared well perfused and had a good Doppler pulse in the pulp. The finger was dressed and a volar splint fixed in place with a bias. The patient was taken to recovery without complication.

The wound healed and the skin graft survived without complications (Fig. 3). The neuroma was proved by histologic examination (Fig. 4). The physical rehabilitation program began after the K-wire was removed six weeks postoperatively. In four months follow-up, the patient did not have any pain in the operated left index finger. The DIP joint regained the normal range of motion. Sensation to light touch was present on the fingertip, and there were no areas of painful sensation to light touch or tapping. At 10 months postoperatively, the static 2-point discrimination of the fingertip was 3 mm (Fig. 5).

[FIGURES 2 & 3 OMITTED]

Discussion

In the intact peripheral nerve, axons extend from the cell body to the distant target organ. Amputation results in a complete division of the nerve and adjacent tissue and precludes the possibility that regenerating axons will reach appropriate sensory receptors. The regenerating axons may escape and grow into the surrounding tissue and scar, which cause formation of neuroma. The neuroma in the amputated finger has minimal soft tissue padding that can absorb the mechanical energy of normal activity. The pain caused from stimulation can impair the entire function of the hand. (15)

Traditionally, surgical treatment of the painful amputation neuroma of finger includes inhibition of axonal growth and translocation away from noxious stimuli. In the methods of inhibition of axonal growth, ligation of the digital nerve above the neuroma was introduced a century ago. However, this ligature may cause the secondary neuroma formation at the site of ligation as well as at the terminal end. (14,16) Surgical resection of the amputation neuroma of finger is also a century-old procedure. It was thought that the second neuroma after resection of the first would be less troublesome, (17) but this outcome was never reliable. Parenthetically, ineffective procedure may make matters worse because they increase scarring in the bed where the neuroma is located. A longer resection of nerve may also affect sensitivity of the skin of the injured finger.

[FIGURES 4 & 5 OMITTED]

Capping the nerve stump is the procedure in which numerous synthetic materials, such as silicone, have been used to cap the end of nerves to inhibit axonal growth. Many authors reported this methods decades ago. (4,16,18,19) Unfortunately, this technique is not always successful because the terminal ends of nerves are not well sealed. Recently, capping the transected nerve with an extended autologous vein graft has been reported experimentally and clinically with promising results, however, it warrants further investigation. (12,13)

Excision of neuroma with transposition of the proximal nerve into an area with minimal scarring and infrequent contact is a widely practiced surgical remedy. Optional sites for translocation of the neuroma are the dorsal web space and within an intrinsic muscle. (14,15) However, for the neuroma in the amputated distal finger, this translocation is not feasible. Implanting the nerve end in bone has been reported to prevent the nerve end from stimulation. (6,14,20,21) A hole is drilled in the phalanx and the nerve ending is introduced through. However, preventing the nerve ending from moving and the significant potential for a tender nerve ending rubbing against a hard surface is present.

The technique of centro-central nerve union with autologous transplantation has been reported recently for treatment of amputation neuroma. (5,22-24) The theory of centro-central nerve union is based on central axon suppression secondary to the approaching nerves and prevention of the target-derived neurotrophic factors from the nerve endings by sealing of the epineurium. Belcher et al reported a series of clinical cases and showed preliminary results of this technique in treatment of the amputation neuroma of the finger. (22) Centro-central nerve union resulted in more comfortable stumps of the amputated fingers but caused greater loss of sensitivity. End-to-side anastomoses of transected nerves to prevent neuroma formation include coaptations of the nerve endings to the adjacent nerve or back upon itself. (9-11) The theory of end-to-side repair is similar to the technique of centro-central nerve union with axon suppression. Clinical case reports have shown its effectiveness in the treatment of neuromas of superficial radial nerve and ulnar nerve, (9,10) but there have been no reports on the treatment of neuroma in an amputated finger.

From the review of numerous surgical procedures in treatment of painful amputation neuroma of finger, there was no single technique that has been found universally successful. As we mentioned at the beginning of this article, providing a pathway and target can avoid the formation of a neuroma in the repair of a nerve injury. Instead of providing a pathway, these procedures attempt to inhibit axonal growth or translocate the injured nerve away from noxious stimuli. Inconsistent results are predictable. In this case report, we successfully transfer the distal second toe to the amputated distal phalanx with microsurgery technique. The finger regained function without pain.

Microsurgical toe transfer is an established procedure for functional reconstruction of fingers. (25-27) Use of microsurgical toe flap and partial toe transfer for fingertip reconstruction has also been reported. Buncke et al presented six cases of microsurgical toe-to-fingertip neurovascular flap transfers. (28) The dissection technique of the distal toe was well described. Koshima and Hirase also reported a series of cases of finger-tip reconstruction with the microsurgical toetip and toe osteoonychocutaneous flap transfers; all of the transfers had survived. (29,30) These reports provide us the technical support for treatment of the amputation neuroma of the distal phalanx with the microsurgical distal second toe transfer. The success of our case has demonstrated the effectiveness and reliability of this procedure.

In conclusion, the microsurgical transfer of the distal second toe to the amputated stump of the finger can provide a pathway and target for the regenerating axons and avoid formation of a neuroma. Although this procedure requires a skilled microsurgeon, along with measurable risk of operative failure and cost, toe to finger transfer provides an excellent alternative option for treatment of painful neuroma and for functional finger reconstruction.

References

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2. Battista AF, Cravioto HM, Budzilovich GN. Painful neuroma: changes produced in peripheral nerve after fascicle ligation. Neurosurgery 1981;9:589-600.

3. Yuksel F, Kislaoglu E, Durak N, et al. Prevention of painful neuromas by epineural ligatures, flaps and grafts. Br J Plast Surg 1997;50:182-185.

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13. Low CK, Chew SH, Song IC, et al. Implantation of a nerve ending into a vein. Clin Orthop 2000;379:242-246.

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15. Omer GE, Spinner M, Van Beek AL. Management of peripheral nerve problems. Philadephia, W.B. Sauners, 1998.

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18. Robbins TH. Nerve capping in the treatment of troublesome terminal neuromata. Br J Plast Surg 1986;39:239-240.

19. Rahimi F, Muehleman C. Epineurial capping via Surgitron and the reduction of stump neuromas in the rat. J Foot Surg 1992;31:124-128.

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22. Belcher HJ, Pandya AN. Centro-central union for the prevention of neuroma formation after finger amputation. J Hand Surg 2000;25B:154-159.

23. Barbera J, Albert-Pamplo R. Centrocentral anastomosis of the proximal nerve stump in the treatment of painful amputation neuromas of major nerves. J Neurosurg 1993;79:331-334.

24. Lidor C, Hall RL, Nunley JA. Centrocentral anastomosis with autologous nerve graft treatment of foot and ankle neuromas. Foot Ankle Int 1996;17:85-88.

25. Buncke HJ. Toe digital transfer. Clin Plast Surg 1976;3:49-57.

26. O'Brien B, MacLeod AM, Sykes PJ, et al. Microvascular second toe transfer for digital reconstruction. J Hand Surg 1978;3A:123-133.

27. Wei FC, el-Gammal TA. Toe-to-hand transfer. Current concepts, techniques, and research. Clin Plast Surg 1996;23:103-116.

28. Buncke HJ, Rose EH. Free toe-to-fingertip neurovascular flaps. Plast Reconstr Surg 1979;63:607-612.

29. Koshima I, Inagawa K, Urushibara K, et al. Fingertip reconstructions using partial-toe transfers. Plast Reconstr Surg 2000;105:1666-1674.

30. Hirase Y, Kojima T, Matsui M. Aesthetic fingertip reconstruction with a free vascularized nail graft: a review of 60 flaps involving partial toe transfers. Plast Reconstr Surg 1997;99:774-784.</p> <pre> Do not judge men by mere appearances; for the light laughter that bubbles on the lip often mantles over the depths of sadness, and the serious look may be the sober veil that covers a divine peace and joy. --E. H. Chapin </pre> <p>Feng Zhang, MD, PHD, Eric C. Hu, MD, Weijia Chen, MD, PHD, and William C. Lineaweaver, MD

Division of Plastic Surgery University of Mississippi Medical Center Jackson, Mississippi

Reprint requests to Feng Zhang, M.D., Ph.D., Division of Plastic Surgery, University of Mississippi Medical Center, 2500 North State Street, Jackson, MI 39216 E-mail: [e-mail]

Accepted August 26, 2005.

RELATED ARTICLE: Key Points

* In nerve injury, the regenerating axons may escape and grow into the surrounding tissue and scar, which cause formation of neuroma.

* The neuroma in the amputated finger has minimal soft tissue padding that can absorb the mechanical energy of normal activity.

* Traditional surgical treatment of the amputation neuroma of finger includes inhibition of axonal growth and translocation away from noxious stimuli. However, the results are inconsistent.

* Microsurgical transfer of the distal toe to the amputated stump of the finger can provide a pathway and target for the regenerating axons and avoid formation of a neuroma.