Biopsy of the posterior interosseous nerve: a low morbidity method for assessment of peripheral nerve disorders.

Overview

AIMS: The sural nerve is the commonest peripheral nerve biopsied to help in the diagnosis of peripheral neuropathy of unknown cause. However, associated complications limit its use. The aim was, as an alternative, to asses biopsy of the terminal branch of the posterior interosseous nerve (PIN) in the forearm. METHODS: PIN pathology was morphometrically quantified in 10 male patients with Type 2 diabetes and compared with six PIN biopsy specimens taken post mortem from male cadavers with no history of neuropathy or trauma. RESULTS: The PIN biopsy procedure provides a long (approximately 3 cm) mono- or bifascicular nerve biopsy with generous epineurial tissue and adjacent vessels. Our results show a significantly lower myelinated fibre density in subjects with diabetes [5782 (3332-9060)/mm(2)] compared with autopsy control material [9256 (6593-12,935)/mm(2), P < 0.007]. No postoperative discomfort or complications were encountered. CONCLUSIONS: A reduction in myelinated fibre density has previously been shown to be a clinically meaningful measure of neuropathy in diabetic patients. We demonstrate similar findings using the PIN biopsy. The PIN biopsy procedure fulfils the criteria for nerve biopsy and was well tolerated by the patients. It may be a possible alternative to sural nerve biopsy to allow for diagnosis of neuropathy.