Corneal confocal microscopy detects early nerve regeneration after pancreas transplantation in patients with type 1 diabetes

Abstract

OBJECTIVE - Corneal confocal microscopy (CCM) is a rapid, noninvasive, clinical examination technique that quantifies small nerve fiber pathology. We have used it to assess the neurological benefits of pancreas transplantation in type 1 diabetic patients. RESEARCH DESIGN AND METHODS - In 20 patients with type 1 diabetes undergoing simultaneous pancreas and kidney transplantation (SPK) and 15 control subjects, corneal sensitivity was evaluated using noncontact corneal esthesiometry, and small nerve fiber morphology was assessed using CCM. RESULTS - Corneal sensitivity (1.54 ± 0.28 vs. 0.77 ± 0.02, P < 0.0001), nerve fiber density (NFD) (13.8 ± 2.1 vs. 42 ± 3.2, P < 0.0001), nerve branch density (NBD) (4.04 ± 1.5 vs. 26.7 ± 2.5, P < 0.0001), and nerve fiber length (NFL) (2.23 ± 0.2 vs. 9.69 ± 0.7, P < 0.0001) were significantly reduced, and nerve fiber tortuosity (NFT) (15.7 ± 1.02 vs. 19.56 ± 1.34, P = 0.04) was increased in diabetic patients before pancreas transplantation. Six months after SPK, 15 patients underwent a second assessment and showed a significant improvement in NFD (18.04 ± 10.48 vs. 9.25 ± 1.87, P = 0.001) and NFL (3.60 ± 0.33 vs. 1.84 ± 0.33, P = 0.002) with no change in NBD (1.38 ± 0.74 vs. 1.38 ± 1.00, P = 1.0), NFT (15.58 ± 1.20 vs. 16.30 ± 1.19, P = 0.67), or corneal sensitivity (1.23 ± 0.39 vs. 1.54 ± 00.42, P = 0.59). CONCLUSIONS - Despite marked nerve fiber damage in type 1 diabetic patients undergoing pancreas transplantation, small fiber repair can be detected within 6 months of pancreas transplantation using CCM. CCM is a novel noninvasive clinical technique to assess the benefits of therapeutic intervention in human diabetic neuropathy. © 2007 by the American Diabetes Association.