A New Modified Approach to Sural Nerve Biopsy: Improving Patient Outcomes
Ivica Ducic, MD, PhD, Justin West, MD.
Georgetown University Hospital, Washington, DC, USA.
BACKGROUND: Peripheral nerve and muscle biopsies ar eoften used to determine the etiology of a neuropathy. The traditional incision for sural nerve biopsy is placed in the distal third of the leg, usually behind the ankle. These biopsies, often performed by plastic surgeons, are relatively simple procedures, but can be associated with significant morbidities, including numbness, pain and/or wound healing issues. The authors reviewed the biopsy techniques described in the literature, and potential complications. A modified approach designed to minimize morbidity and improve patient’s outcome is described.
METHODS: A modified approach for biopsy of the sural nerve and adjacent muscle is done under tourniquet, with patient placed in supine position. A 4cm incision is then marked in the lower pole of the gastrocnemius muscle at the midline, approximately 10-12cm below the popliteal fossa. The medial sural nerve is carefully dissected, and 2-3cm segment submitted to pathology, while the proximal stump of the nerve is implanted into the muscle, thereby minimizing the chance of neuroma formation. If a muscle biopsy is required it is harvested via same access incision. Patient's outcome was evaluated in terms of sensation preservation and complications.
RESULTS: The described modified technique was applied to nine patients with minimum of one year follow up. Of the nine patients, none had wound complication or pain beyond expected incisional post-operative period, no patient developed neuroma and none required additional incision for muscled biopsy. Two patients had diminished to absent sensation over dorsolateral foot, probably due to dominant medial sural nerve branch, while others reported no change in sensation. In comparison, sixteen additional patients evaluated for problems related to either sural nerve pain or a wound complication following the standard, behind/above ankle biopsy. All of these 16 patients were operated by other physicians and all reported absent sensation or numbness over sural nerve innervated dorsolateral foot. Their wounds were treated using standard wound regimens, while patients with neuroma had excision and implantation of nerve to muscle. All sixteen patients who experienced a complication following previous biopsy (done elsewhere) were successfully treated in terms of wound or painful neuroma management.
CONCLUSIONS: The main benefit of this modified technique for biopsy of the sural nerve is that it requires the sacrifice of only one branch of the sural nerve. Whereas the traditional method involved biopsy of the common sural nerve, the present modification results in preservation of sensation as provided by the remaining branch of the sural nerve. Another advantage is the ease in which a surgeon can perform a muscle biopsy with the more proximal incision. This yields faster operative time with potentially less morbidity. The presence of muscle in the same plane also allows the surgeon to bury the cut proximal end of the sural nerve, hopefully resulting in decreased formation of painful neuromas. Finally, a more proximally placed incision may result in a lower incidence of infection and dehiscence given a better blood supply and more supple and mobile soft tissues of the proximal leg relative to the distal leg.