Posterior Interosseous Nerve: An Alternative to Sural Nerve Biopsy

Abstract

Sir: Traditionally, the sural nerve has been the peripheral nerve most often used as a biopsy specimen for work-up of neuropathologic conditions. Drawbacks of sural nerve biopsy include wound infection, dehiscence, neuroma, and permanent sensory loss to the lateral aspect of the foot.1 We are proposing the harvest of the posterior interosseous nerve as an alternative to sural nerve biopsy in diagnosing neuropathologic conditions. The posterior interosseous nerve runs along the floor of the fourth extensor compartment and is exposed through a 3-cm incision (Fig. 1). Two centimeters of the nerve is exposed, the minimum length required by the pathologist. The nerve is preserved in formalin and 2.5% glutaraldehyde. The antebrachial fascia and skin are closed and a light dressing is applied. Use of the hand is allowed immediately.Fig. 1.: The posterior interosseous nerve running through the floor of the fourth extensor compartment.In the first case, a 34-year-old woman with a history of progressive neuromuscular weakness was referred for sural nerve biopsy. Because of progressive difficulty with ambulation, the patient was particularly reticent to accept the loss of sensibility associated with sural nerve biopsy. Microscopy demonstrated large, thinly myelinated fibers and subperineural edema, suggesting chronic inflammatory demyelinating polyradiculoneuropathy (Fig. 2).Fig. 2.: Hematoxylin and eosin staining of posterior interosseous nerve demonstrating demyelination and subperineural edema.In the second case, a 35-year-old woman was referred for sural nerve biopsy. She had a 1-year history of burning pain and progressive atrophy of her buttocks. On microscopy, no inflammatory cells were seen. There was mild subperineural edema, scattered Renault bodies, and a marked decrease in myelinated fibers, consistent with a demyelinating neuropathy. Both patients' wrist incisions healed without difficulty and with acceptable scarring. The surgeon has several goals when performing a diagnostic nerve biopsy: (1) provide adequate specimen, (2) minimize morbidity, and (3) perform the most straightforward procedure. The posterior interosseous nerve is a good option for obtaining these aims. First, the posterior interosseous nerve provides adequate tissue and length (2 cm) for diagnosis. The distal extent of the posterior interosseous nerve is purely sensory, which is often a requirement for nerve biopsy specimens. Second, posterior interosseous nerve harvest has minimal patient morbidity. The posterior interosseous nerve is routinely excised for wrist denervation and is used as a nerve graft for digital nerves.1 Concerns about development of Charcot changes in the joint associated with denervation have not been borne out.2 In contrast, sural nerve harvest leaves a cutaneous deficit on the lateral foot and has been associated with rates of chronic pain, wound dehiscence, and infection as high as 40 percent.3 Even attempts at harvesting proximal branches of the sural nerve to prevent complete loss of lateral foot sensibility are only successful in one-third of cases.4 Posterior interosseous nerve biopsy is a straightforward procedure. The nerve is in a predictable and accessible anatomical location, with a diameter of approximately 1.4 mm. The posterior interosseous nerve is a good alternative if the sural nerve has “burned out.” Thomsen et al. have used the posterior interosseous nerve in diagnosing diabetic neuropathy to avoid the morbidity of sural nerve harvest.5 In summary, we believe that the posterior interosseous nerve should be considered as a source for peripheral nerve biopsy. It is easily accessible, leaves no cutaneous deficit, and is well tolerated. DISCLOSURE The authors have no financial disclosures related to this article. Todd A. Richards, M.D., M.B.A. Catherine M. Curtin, M.D. Division of Plastic and Reconstructive Surgery Stanford University School of Medicine Palo Alto, Calif.