Painful sensory neuropathy - Prospective evaluation using skin biopsy

Objective: In patients presenting with painful, burning feet with minimal s igns of neuropathy, the following questions were addressed: 1) How many of these patients have a peripheral neuropathy? 2) What is the role of skin bi opsy in establishing a diagnosis of neuropathy? 3) What conditions are asso ciated with the neuropathy? and 4) What laboratory studies are useful in th is patient population? Methods: A total of 117 consecutive patients referre d for evaluation:were prospectively studied. All underwent nerve conduction studies (NCS) and a battery of blood tests, including antinerve antibodies . If NCS were normal, a punch biopsy of the skin of the distal leg was perf ormed to ascertain the intraepidermal nerve fiber (IENF) density. In a subs et of 32 patients, the sensitivity of skin biopsy was compared to quantitat ive sudomotor axon test (QSART) and quantitative sensory tests (QST). Resul ts: Three groups emerged. Group 1, with abnormal NCS (n = 60, 34 F/26 M, me an age 60 +/- 14 years), represented 51% of the cohort. The majority had ne uropathies of undetermined cause, but 18 (30%) had associated conditions. G roup 2, with normal NCS and reduced IENF density (n = 44, 29 F/15 M, mean a ge 57 +/- 14 years), represented 38% of the cohort. Three in this group had associated conditions. Group 3, with normal NCS and IENF density (n = 13, 6 F/7 M, mean age 53 +/- 13 years), represented 11% of the cohort; most had no diagnoses but two had MS. In a comparative subset analysis, skin biopsy was more sensitive than QSART or QST in diagnosing a neuropathy. Conclusio ns: Patients presenting with painful feet are heterogeneous, consisting of both large and small fiber sensory neuropathies. In rare cases, a central c ause for pain can be found. Over one-third of patients required a skin biop sy to diagnose a small fiber sensory neuropathy. A limited battery of blood tests facilitated diagnosis, but serum antinerve antibodies were not helpf ul.