Skin biopsy: a new tool for diagnosing peripheral neuropathy

The prevalence of peripheral neuropathy is about 2% in the general population, but it rises to 12% and 17% in people with one or two recognised risk factors.1 Diabetes is one such risk factor and the most common cause of this disorder—about half of patients who have had diabetes for 25 years have peripheral neuropathy. The early symptoms of diabetic neuropathy and other peripheral neuropathies are due to degeneration of small somatic nerve fibres, which may remain the only nerves involved.2 However, “small fibre neuropathy” may not be detected by traditional physical, neurophysiological, and neuropathological tests. In the past decade, skin biopsy has become a popular method for investigating small nerve fibres.3 It allows general practitioners and non-specialists—such as diabetologists and specialists in orthopaedics—to diagnose neuropathy (thereby avoiding delayed or incorrect diagnosis), to investigate its aetiology, and to focus treatment, in particular for neuropathic pain. We searched the Medline database using combinations of the terms “skin biopsy”, “cutaneous nerve fibres”, “intraepidermal nerve fibres”, “neuropathy”, “painful neuropathy”, and “pain”. We also included evidence provided by the recent guidelines of the European Federation of the Neurological Societies.3 Small fibre neuropathy can be associated with common metabolic disorders (such as diabetes and hyperlipidaemia), immune mediated conditions (such as Sjogren's syndrome, sarcoidosis, and coeliac disease), drug toxicity (such as that caused by antineoplastic drugs and antiretroviral drugs), and viral infections (such as HIV). It can be a feature of hereditary diseases (such as familial amyloidosis and Fabry's disease), or it may be idiopathic. In the absence of known systemic disease, the diagnosis of small fibre neuropathy may not be easy. Pain or burning (or both) in the feet are prominent symptoms, and may be worse at night. Some patients report that contact with warm or cold water elicits discomfort or …