We would like to thank the groups that have responded with letters and inquiries regarding our article.1 It is now clear, based on readers' responses, that complications of GK surgery for PD are not uncommon. Since our report, additional cases have been published.2- 4
Two letters to the editor, one from Young5 and one from De Salles and colleagues (all from Los Angeles, Calif), have attempted to defend the GK procedure based on their own publications, which claim that GK targeting of lesions is precise and predictable. Unfortunately, the evidence fails to support their position. We have already commented on Young's earlier letter; regarding the criticism by De Salles and colleagues that we seriously misrepresented their article, we can only restate the facts as we did in our previous letter.6 The objective of their study was "to show the dose delivery precision of targeting and the geometry and extent of the lesions."7(p990) The data from this study were used by Young to support his argument for the precision of GK therapy. The data on 3 monkeys indicated the following: in monkey 1, the intended STN lesion included the SN at 9 months; in monkey 2, an intended SN lesion showed minimal tissue destruction at 5 months; and in monkey 3, an intended SN lesion showed no tissue destruction at 5 months. Our position in response to the letter by Young was simply that the data from the article by De Salles et al7 were not supportive of his position and that he could not conclude from these data that lesions made with the GK were precise or predictable.