Pancreatic Transplantation Improves Diabetic Neuropathy in the Long Term
January 1, 1998
Pancreatic Transplantation Improves Diabetic Neuropathy in the Long Term
ABSTRACT & COMMENTARY
Source: Navarro X, et al. Long-term effects of pancreatic transplantation on diabetic neuropathy. Ann Neurol 1997; 42:727-736.
Tight glycemic control delays, but does not prevent or reverse, the onset and progression of diabetic polyneuropathy (N Engl J Med 1993;329:977-986). Pancreatic transplantation, with or without renal allograft, offers one method of obtaining euglycemia and potentially reversing previously established somatic and autonomic neuropathy. Short-term follow-up (3-4 years) of such patients suggests this to be true (Kennedy WR, et al. N Engl J Med 1990;322:1031-1037; Solders G, et al. Diabetes 1992;41:946-951), but long-term follow-up is wanting.
One hundred fifteen patients with insulin-dependent diabetes mellitus (IDDM) and a functioning pancreatic transplant (PTx), with or without renal allograft, were matched to 92 control patients with IDDM treated with insulin and followed over a 10-year period. The two groups were comparable for age, sex, and duration of diabetes. Complete neurological examinations, motor and sensory nerve conduction studies, autonomic function tests (cardiorespiratory reflexes assessed by heart rate variation during breathing at 6 breaths/min and Valsalva ratio), and pseudomotor nerve function (using evaporimetry and the Silastic mold technique) were performed at baseline pretransplant and at years 1, 2, 3.5, 5, 7, and 10 post-transplant, or baseline, respectively, for the two groups.
At entry, all patients had polyneuropathy. Over the 10-year study period, the neurological examination score improved in the PTx patients at all exam intervals but significantly so only at 3.5 and five years. Significant worsening of the score was seen in the control group at all intervals. Electrodiagnostic studies in PTx patients demonstrated significant improvement in motor and sensory nerve function (average increase in motor and sensory nerve conduction velocity 2-4 m/sec and 1-2 m/sec, respectively) after one year but no significant change in autonomic function tests. Again, control patients deteriorated during the 10-year follow-up at all intervals, with evoked amplitudes falling more markedly than nerve conduction velocity. Autonomic testing showed slight improvement in the PTx group, while deterioration in controls was significant only at one year. Correction of uremia by renal transplantation was found not to play a role in the improvement seen. PTx halts the progression and improves the signs of diabetic polyneuropathy.
COMMENTARY
Diabetics with autonomic neuropathy have a five-fold increase in mortality compared to those without autonomic involvement, so it is discouraging that, of all nerve functions examined, function in this area improved the least. Both motor and sensory nerve conduction velocities improved, but the more sensitive measure of motor fiber loss to distal muscles (i.e., measurement of compound muscle action potential amplitudes) increased only in the more mildly involved nerves. Taken together with the fact that only about half the pancreatic grafts remain functional one year post-transplantation, it remains premature to advocate this operation for diabetics at this time. mr
Compared to those without autonomic involvement, diabetics with autonomic neuropathy have how much of an increase in mortality?
a. Two-fold
b. Three-fold
c. Four-fold
d. Five-fold
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