Patients taking SRIs may represent a high-risk group for postoperative neurological events when methylene blue is utilized.

Hypothesis: Equivocal parathyroid technetium Tc 99m sestamibi scan results are likely to demonstrate the correct location for parathyroid adenomas. Design: Patients with primary hyperparathyroidism prospectively consented to participate in an institutional review board-approved study. The parathyroid technetium Tc 99m sestamibi scan results were classified as positive, negative, or equivocal. Setting: A tertiary private hospital in which university faculty practice. Patients: Technetium Tc 99m sestamibi imaging was performed for 464 patients with primary hyperparathyroidism. Eighty-four of these patients had scan results considered equivocal for unilateral adenomas. The algorithm for this group of patients specified that they should receive an injection with technetium Tc 99m sestamibi prior to parathyroidectomy and that an intraoperative parathyroid hormone (iPTH) level decrease of more than 50% be used to define intraoperative success. Seventy-two patients had postoperative calcium levels measured at least 2 weeks after their surgical procedure and defined the study group. The mean follow-up was more than 6 months. Intervention: Parathyroidectomy. Main Outcome Measure: Correlation of equivocal scan interpretation with operative findings and biochemical cure of hyperparathyroidism.

The objective of this study was to determine the value of intra-operative methylene blue (MB) during parathyroid surgery. We did a retrospective study of 473 patients after initial exploration for previously untreated symptomatic primary hyperparathyroidism. Procedural and post procedural data were collected on four groups of patients: minimally invasive parathyroidectomy with MB (n = 147), and without MB (n = 205), bilateral parathyroid exploration with intra-operative parathormone assay with MB (n = 56), and without MB (n = 65). Length of surgery was shorter for patients explored with MB (P = 0.026). For the minimally invasive parathyroidectomy group, the difference between the MB and non-MB groups was seven minutes. Twelve minutes was the difference between the MB and non-MB intra-operative parathormone assay groups. Length of stay, local complications, and correction of hypercalcemia after parathyroidectomy were not significantly affected by the use of MB. Systemic complications were lower in the MB groups. Aside from a statistically significant, but quantitatively minimal decrease in the length of surgery, no consistent benefit was identified with the use of MB for intra-operative parathyroid identification.

The 20 per cent rule proposed by Norman established a guideline using radioactivity in the minimally invasive radioguided parathyroidectomy (MIRP) technique to localize and confirm removal of an abnormal parathyroid gland in patients with primary hyperparathyroidism. If radioactivity in the resected gland was at least 20 per cent of excision site/background radioactivity, the 20 per cent rule was satisfied. Patients meeting these criteria underwent unilateral MIRP without intraoperative parathyroid hormone assay or intraoperative frozen section. The study aim was to independently evaluate the 20 per cent rule in MIRP patients with primary hyperparathyroidism. Using the University of Louisville Parathyroid Database from January 1, 1999 to December 31, 2007, 216 MIRP patients with complete radioguided and postoperative management data were identified. The average percentage of ex vivo parathyroid gland radioactivity compared with excision site/background radioactivity was 107 per cent with a range from 14 to 388 per cent. For 99 per cent (196/198) radioactivity recorded from the excised gland was at least 20 per cent of radioactivity recorded from the excision site. Normocalcemia was documented in 98.5 per cent (195/198) at 12 month follow-up. Our data supports the 20 per cent rule in that in 99 per cent of MIRP patients the resected gland radioactivity was at least 20 per cent of excision site radioactivity allowing localization and confirmation of an overactive gland without intraoperative parathyroid hormone monitoring or tissue analysis.

Routine preoperative PTH and calcium levels are necessary for the biologic diagnosis of hyperparathyroidism, but they do not appear to relate to the outcome of a sestamibi scan and therefore do not complement the radioguided MIRP procedure. Because the size of the affected gland, however, did correlate with a positive sestamibi scan, we conclude that as the volume of the gland increases, so does the likelihood of a successfully chosen minimally invasive surgical approach.