A PROSPECTIVE QUANTITATIVE STUDY OF SENSORY DEFICITS AFTER WHOLE SURAL NERVE BIOPSIES IN DIABETIC AND NONDIABETIC PATIENTS - SURGICAL APPROACH AND THE ROLE OF COLLATERAL SPROUTING

Background: Sural nerve biopsy (Sbx) has been employed for the diagnos is of peripheral neuropathies and for multicenter trials of therapy in diabetic neuropathy. There is only limited prospective information av ailable about what factors influence the resolution of the sensory def icit (Sdef) after biopsy. Methods: We prospectively studied the surfac e area of skin Sdef after whole human Sbx in diabetic and nondiabetic patients for up to 18 months after the procedure. Sdef was determined by mapping, in two dimensions, the area of loss to pinprick and light touch in the sural distribution using a transparent boot-like device w ith l-square-cm grid markings. At the same time, patients were intervi ewed about biopsy-related symptoms. Results: Overall, the Sdef in all patients declined by an average of 91 +/- 3% at 18 months. The pattern of Sdef decline indicated that collateral sprouting was the mechanism of sensory reinnervation. The extent of Sdef at 6, 12, or 18 months d id not differ between diabetics and nondiabetics. In diabetics, there was a correlation between sensory reinnervation with pre-biopsy sural nerve potential amplitude and HbA(1),C level, but not with age or diab etes duration. Diabetic patients who had nerve resections starting at or below the center of a plane through the lateral malleolus and trave ling proximally for 7 cm or less had a Sdef that was less than patient s with longer and more proximal nerve resections. The majority of pati ents had unpleasant but mild mechanically elicited sensory symptoms at 1 year that had improved in most, but not all patients, by 18 months. Conclusions: Sbx is associated with prolonged sensory symptoms and se nsory loss. Recovery occurs by collateral reinnervation.