Electrical Impedance Spectroscopy to Aid Parathyroid Identification and Preservation in Central Compartment Neck Surgery: A Proof of Concept in a Rabbit Model.

BACKGROUND: Accurate identification of parathyroid glands during thyroid surgery is crucial to avoid postthyroidectomy hypocalcemia. Electrical impedance spectroscopy has the potential to differentiate between tissues of different morphology. The aim of this study was to determine the electrical impedance patterns of the thyroid, parathyroid, and other soft tissue structures in the rabbit neck. METHODS: The central compartments were exposed in 9 freshly culled New Zealand White rabbits. In situ and ex vivo electrical impedance was measured from thyroid lobes, external parathyroid glands, adipose tissue, and strap muscle using the APX100 device. Specimens of all identified glands were sent for histopathology examination. RESULTS: Histology confirmed correct identification of all excised thyroid and parathyroid glands. The impedance was higher for thyroid tissue at lower frequencies and for parathyroid tissue at higher frequencies. Ex vivo electrical impedance spectra were significantly higher compared with the in situ spectra across all frequencies for thyroid and parathyroid tissues (P < .001). The ratio of low to high frequency in situ impedance of thyroid, parathyroid, and muscle was significantly different (P < .001), allowing for differentiation between these tissues. CONCLUSION: The electrical impedance spectra of rabbit thyroid and parathyroid glands are distinct and different from each other and from skeletal muscle. If these results are replicated in human tissue, they have the potential to improve patient outcomes by achieving early identification and preservation of parathyroid glands.

Near infrared fluorescence imaging of rabbit thyroid and parathyroid glands.

BACKGROUND: Near infrared fluorescence imaging using intravenous methylene blue (MB) is a novel technique that has potential to aid the parathyroid gland (PG) localization during thyroid and parathyroid surgery. The aim of this study was to examine MB fluorescence in the rabbit neck and determine the influence of MB dose and time following administration on fluorescence from thyroid and PGs. METHODS: Thyroid and external PGs were exposed in six New Zealand white rabbits under anesthesia. Varying doses of MB (0.025-3 mg/kg) were injected through the marginal ear vein. Near infrared fluorescence from exposed tissues was recorded at different time intervals (10-74 min) using Fluobeam 700. Specimens of identified glands were then resected for histologic assessment. RESULTS: Histology confirmed accurate identification of all excised thyroid and PGs; these were the only neck structures to demonstrate significant fluorescence. The parathyroid demonstrated lower fluorescence intensities and reduced washout times at all MB doses compared with the thyroid gland. A dose of 0.1 mg/kg MB was adequate to identify fluorescence; this also delineated the blood supply of the external PGs. CONCLUSIONS: The study demonstrates that near infrared fluorescence with intravenous MB helps differentiate between thyroid and PGs in the rabbit. This has potential to improve outcomes in thyroid and parathyroid surgery by increasing the accuracy of parathyroid identification; however, the findings require replication in human surgery. The use of low doses of MB may also avoid the side effects associated with currently used doses in humans (3-7 mg/kg).

Case report: recurrent acute pancreatitis secondary to papillary somatostatinoma--a new association.

Acute pancreatitis may rarely be caused by papillary mass lesions such as adenocarcinomas and neuroendocrine tumours. Occasionally these papillary lesions may cause recurrent episodes of acute pancreatitis and patients presenting in this way require further pancreatic investigation. We believe this to be the first reported case of a duodenal papillary somatostatinoma causing recurrent acute pancreatitis. The patient was investigated with multiple imaging modalities, both at endoscopy and with more traditional radiology, and treated with resection by Whipple's pancreaticoduodenectomy. If diagnosed early in the absence of distant metastases the prognosis of papillary somatostatinoma with tumour resection is excellent.

Refractory bleeding from portal hypertensive gastropathy: a further novel role for thalidomide therapy?

Bleeding from portal hypertensive gastropathy (PHG) can pose a therapeutic challenge. Thalidomide, which selectively inhibits tumour necrosis factor-alpha production by enhancing messenger RNA degradation, has been shown to reduce portal venous pressure in cirrhotic and non-cirrhotic portal hypertension. Thalidomide is also a potent inhibitor of angiogenesis. We describe a case of intractable bleeding from PHG secondary to extrahepatic portal vein obstruction due to malignancy, which was managed successfully by thalidomide, thus obviating the need for major surgery. Although the use of thalidomide for treatment of severe intestinal bleeding has been described previously, this is the first case report, to our knowledge, describing its efficacy in bleeding secondary to PHG. We discuss the possible therapeutic mechanisms for thalidomide in PHG.

Kayser-Fleischer like rings in alcoholic liver disease: a case report.

Kayser-Fleischer rings are brown pigmented rings that run along the periphery of the cornea. Situated in Descemet's membrane and being comprised of granules of deposited copper they have traditionally been thought of as pathognomic of Wilson's disease. However, they can also be seen in other forms of liver disease. We document a case of Kayser-Fleischer like rings occurring in alcoholic liver disease--a previously unreported association.

FK409 inhibits both local and remote organ damage after intestinal ischaemia.

In addition to localized tissue injury, intestinal ischaemia-reperfusion (I/R) leads to remote organ damage, in particular to the lungs. Given that nitric oxide (NO) can attenuate I/R-induced tissue injury in many situations, this study evaluated the effects of the NO donor, FK409, on leukocyte adhesion in the microcirculation of the intestinal villus and also assessed pulmonary tissue damage after intestinal I/R injury. PVG rats were subjected to 30 min intestinal ischaemia and a sub-group of animals received the NO donor FK409 (10 mg/kg; i.v.) both 30 min prior to ischaemia and 30 min post-reperfusion. The intestinal mucosal surface was visualized via an incision made in an exteriorized ileal segment and leukocyte adhesion in the villous microcirculation was determined by in vivo microscopy. Total and differential leukocyte counts from peripheral blood were evaluated. Lungs were removed at the end for histological assessment. Six out of ten untreated I/R animals failed to survive the 2 h reperfusion period, whereas all ten FK409-treated animals survived. I/R induced a significant increase in villous leukocyte adhesion of untreated I/R animals (p<0.001) and this was significantly decreased by FK409 treatment (p<0.001). The total leukocyte count was significantly decreased in untreated I/R animals (p<0.001) and this primarily resulted from a reduction in circulating neutrophil numbers. This effect was not observed in FK409-treated animals. Collapsed alveoli, thickened interstitial walls, and a dense neutrophilic infiltrate were apparent in the lungs of untreated I/R animals, whereas lung histology was normal in FK409-treated animals. In conclusion, FK409 prevented mortality, significantly reduced villous leukocyte adhesion, maintained circulating leukocyte numbers, and prevented pulmonary tissue injury following intestinal I/R. FK409 may therefore be of value in reducing both local and remote tissue damage and improving outcome in situations where intestinal I/R injury is obligatory, such as small bowel transplantation.