Role of thyroid surgery in the obstructive sleep apnea syndrome.

OBJECTIVES: To study the impact of thyroid surgery on obstructive sleep apnea syndrome (OSAS) evaluated by the apnea/hypopnea index (AHI) was studied. Secondary objectives were to evaluate the impact on the positional component of OSAS and to highlight possible predictors of improvement of OSAS after thyroidectomy. METHODS: Twenty-eight patients with OSAS are included in this monocentric study: they underwent total thyroidectomy (n = 26) or left loboisthmectomy. Postoperative assessment involves a nocturnal control polysomnography as of 60 days after surgery. RESULTS: The mean age at the time of surgery is 61.3 years (standard deviation ±7.3) and average body mass index is 29.6 kg/m2 (±7.3). Continuous positive airway pressure (CPAP) treatment is introduced preoperatively in 82% of patients. The statistical analysis shows a significant decrease of 33% in postoperative AHI for the total population (p = 0.001), 77% in patients under CPAP (p = 0.05), and 27% in patients without CPAP (p = 0.02). CPAP therapy could be released in four patients. Given the limited number of subjects studied, the surgery did not impact on the positional component of the OSAS. Statistical analysis failed to link a predictive factor to AHI reduction. CONCLUSIONS: We propose thyroid surgery as an alternative or as a complement to CPAP treatment for the patients with goitre: it allows a significant decrease in postoperative AHI, allowing adaptation of the CPAP treatment downward, or even a release in some cases. These results need to be confirmed on a larger series of patients in a prospective study with standardized criteria for polysomnography and multivariate analysis.

[Scintigraphic study of the lymphatic drainage of the anterior chamber of the mouse eye and its pathophysiological implications]. / Étude scintigraphique du drainage lymphatique de la chambre antérieure de l'œil de la souris et ses implications physiopathologiques.

For many years, the intraocular lymphatic system and particularly the drainage of the aqueous humor by this system have been considered non-existant. Our study is the first to demonstrate, in a dynamic in vivo fashion, the existence of lymphatic drainage in the mouse eye. This has become possible with lymphoscintigraphy with nano-molecules of rhenium sulphide, marked by technetium-99m and injected into the anterior chamber of the mouse eye. Readings were taken using an experimental gamma camera specially built for the small animal. The hypothesis of a "uveolymphatic" drainage pathway within the ciliary body, contributing to aqueous outflow, has recently been highlighted by new improvements in microbiology (discovery of lymphatic endothelial-specific markers) and imaging. This new pathway may lead to many prospects: the development of techniques for visualization and quantification of this in vivo lymphatic flow may help to increase our understanding of the physiopathology and perhaps treatment of chronic glaucoma as well as neoplastic conditions.

Microscopic distribution of iodine radioisotopes in the thyroid of the iodine deficient new-born rat: insight concerning the Chernobyl accident.

UNLABELLED: Thyroid cancer markedly increased in children exposed to iodine radioisotopes following the Chernobyl accident. This increase exceeded predictions based on dose estimates to the whole organ. We sought to investigate whether iodine deficiency may have influenced the pattern of microscopic distribution of radioiodines, which may be important to interpretation of the observed effects. Iodine-deficient new-born rats were injected with iodine-129 (129I) and the microscopic distribution in the thyroid tissue was studied at 24 hr and at one week after administration, using secondary ion mass spectrometry (SIMS). Twenty-four hr after administration, SIMS images showed large differences in 129I uptake among thyroid follicles, with more than a factor ten variation in the local concentration. In addition, the distribution of 129I inside follicles varied with time. At 24 hr, the highest concentration was found at the periphery of the colloid, close to the thyroid cells. There also was enhanced concentration of 129I at one pole of follicles. Distribution inside follicles was homogeneous at 7 days. CONCLUSIONS: 1/Dosimetric models, which assume uniform iodine uptake by thyroid follicles, give an oversimplified picture of radiation dosimetry in cases involving iodine deficiency, which induces patchy tissue irradiation. 2/The dynamic pattern of iodine distribution within thyroid follicles suggests that decay events from short-lived iodines will occur closer to thyroid cells than events resulting from iodine-131.

The perinatal thyroid in iodine deficient regions: risks of radioiodines--hazards of stable iodine overload. A study in the newborn rat.

Administration of large quantities of stable iodine is an effective means of reducing the radiation burden on the thyroid in the event of a nuclear power-plant accident. Such administration may involve countries with low baseline dietary iodine intake. It is questioned whether stable iodine overload is safe, and in particular, what are its effects in newborn infants? Iodine-deficient newborn rats were submitted to a single acute administration of stable iodine (100 microg) on the second day of life. The effects on thyroid structure were studied, after 24 hr and after 7 days, using light microscopy. Compared to controls, the thyroids of animals submitted to stable iodine overload showed, 7 days after treatment, signs of acute toxicity including marked desquamation of epithelial cells and rupture of a large number of thyroid follicles. Our findings in iodine deficient newborn rats suggest that stable iodine overload may have side effects during perinatal life. This prophylactic measure should, therefore, be accompanied by follow-up of thyroid function. Thyroid hormones are critical for brain development, during the first period of life.

Biological consequences of irradiation by low doses of technetium 99m: ultrastructural studies, p53 protein expression and cytogenetic effects.

Few studies concerning the potential genetic effects of diagnostic radionuclides used in nuclear medicine have been reported. The aim of this study was to evaluate the biological and cytogenetic consequences of two technetium 99m-labelled radiopharmaceuticals. Ultrastructural modifications of pulmonary cells were first investigated after injection of 99mTc labelled microspheres in the rat. On the same irradiated cells, nuclear expression of p53 protein was assessed using immunohistochemistry. Despite very high previously calculated doses delivered to pulmonary cells, no morpholological cell damage and no significant increase of nuclear expression of the p53 were noted. There was no correlation between the calculated dose and the ultrastructural biological damage. Secondly, a specific in vitro curve, activity/number of unstable chromosomal aberrations, corresponding to physical characteristics of 99mTc, was established to verify the potentiality of 99mTc to induce such aberrations. In vivo, cytogenetic effects were assessed on blood samples of 5 patients with various arthrosic and periarthrosic diseases obtained after bone scintigraphy. Aberration frequencies of both in vitro and in vivo irradiated lymphocytes were determined using the classical Fluorescence Plus Giemsa technique. No cytogenetic effects appeared with the routinely 99mTc injected activities as predicted by the in vitro curve.