Letter To The Editor Reply to Young et al.

Fadel (2) for their interest in our work (1), and their opinions regarding the impracticality of comparing skin sympathetic nerve activity (SSNA) between subjects in different groups. Since single SSNA bursts can include multiple small peaks, they ask, “Does a multiple peak burst represent one or more bursts? ” In our study, such bursts were counted as one by the blinded investigator who analyzed all neurograms, thereby providing uniformity to burst quantification. Second, they correctly point out that the SSNA recordings may represent multiple fiber types and that any given neuro-gram may have varying contributions from each fiber type. They are concerned that in our multiunit recordings, we could miss the fiber type that potentially has elevated activity. Al-though this is true in theory, it is extremely unlikely. The SSNA neurogram is a random sample of total SSNA activity, and it is against the odds that during the 8 (or 16 total SSNA recordings if one includes healthy controls), we always missed the overactive skin fiber type. A more likely explanation for the absence of elevated SSNA in our recordings in end-stage renal disease patients is that it is not present. We invite Drs. Young, Keller, Crandall, and Fadel to review, once again, Fig. 1 in our paper. These representative neuro-grams lay to rest any real question whether SSNA is elevated in ESRD patients compared with healthy controls. In this case, a picture is truly worth a thousand words. REFERENCE