Evaluating neural regeneration after pancreas transplantation with corneal confocal microscopy – early results of an ongoing study

M. Mitu-Pretorian¹, B. Forgacs¹, A. Tavakoli¹, M. Tavakoli², R. Malik², T. Augustine^1
1 Manchester Royal Infirmary, Transplant Unit, Manchester, U.K.; ² Department of Cardiovascular Medicine, University of Manchester, Manchester, U.K.

Objective: After successful pancreas transplantation, there is evidence of repair of diabetic tissue damage. We utilized corneal confocal microscopy as a surrogate test to evaluate neural regeneration after pancreas transplantation.

Materials and methods: 7 Type 1 IDDM patients with diabetes duration of (33 +/- 6yrs) undergoing combined pancreas and kidney transplantation and 7 age matched healthy controls were examined with corneal confocal microscopy, clinical neuropathy evaluation, QST and electrophysiology.

Results: Corneal confocal microscopy demonstrated a significant reduction in NFD (Nerve fibre density) (P<0.0001) and NFL (nerve fibre length) (P<0.0001) at baseline. 12 months after SPK transplantation, HbA1C normalized (5.8+/- 0.5 vs 7.1 +/-0.8, P=0.1) confirming successful transplantation. NDS (P=0.4), Warm (P=0.6) and cold (P=0.7) thresholds, sural NCV (P=0.1), amplitude (P=0.8), peroneal amplitude (P=0.9) and velocity (P=0.3) did not improve. NFD (18.9 +/-3.9 v 15.2+/-1.6 , P=0.3), NBD (49.3+/-12.4 v38.2+/-7.7, P=0.0009) and NFL (16.6+/-3.8 v 11.1+/-1.5, P=0.1) demonstrated improvement which did not reach significance for all parameters due to small numbers and large SEM

Conclusions: Despite marked small nerve fibre damage in Type 1 Diabetics undergoing pancreas transplantation, small fibre repair can be detected within a year after pancreas transplantation. Functional neural improvement is also detected although longer follow-up and larger numbers are required to confirm significance.