No abstract

Reoperations for persistent or recurrent primary or secondary hyperparathyroidism are demanding tasks mainly when localization of parathyroid tumor(s) was not successful. These procedures may harbor a risk for the patients and therefore need an expert surgeon who is familiar with even the most difficult situation. Important steps before surgery are confirmation of the diagnosis of persistent or recurrent disease and localization of the source of hormone access. Reoperations should be exclusively performed in centers where expert surgeons, radiologists, endocrinologists and nephrologists are available, as well as special technical equipment.

There is a considerable discrepancy in the literature concerning the sensitivity of parathyroid scintigraphy (PS) with 99mTc-MIBI. We therefore analyzed our own data and compared them to the literature in a metaanalysis. All patients who received 99mTc -MIBI scintigraphy and subsequent surgery in our department for the detection of enlarged parathyroid glands in primary (pHPT) or secondary (sHPT) hyperparathyroidism between 1991 and 1999 were included in our retrospective analysis. The results of surgery served as the gold standard. For a true positive result, the scintigraphy had to predict the exact location of parathyroid adenoma (PA) or parathyroid hyperplasia (PH). We then compared these data to the results of a nonstatistical systematic metaanalysis of the literature. Patients (178) underwent PS between 1991 and 1999; 139 were operated on and included in this study. Of these, 109 had pHPT and 30 had sHPT. The sensitivity and specificity of the PS were found to be 45%/94% for pHPT and 39%/40% for sHPT. Fifty-two studies concerning PS were included in the metaanalysis. Sensitivities reported varied from 39% to >90%. Consideration of the different possible techniques used for PS could not explain these discrepancies. Our data show that the sensitivity of PS in clinical routine may be lower than expected from the literature. Our data are consistent with other studies and with partially unpublished clinical observations from other university hospitals. We believe that a well-designed and properly conducted prospective study is necessary to evaluate the reasons for the differences observed.

The volumes of intracranial arachnoid cysts were measured in 136 CT scans of 86 patients. Absolute and relative cyst size was calculated. Left hemisphere and middle cranial fossa location prevailed. A slight negative correlation of relative cyst size with age (r = -0.21, NS) disappeared when analysis was restricted to the adult age group (greater than or equal to 20 years). After the sample was divided into two groups according to relative cyst size (cysts less than mean volume vs cysts greater than mean volume), small AC showed no correlation with age, while large AC correlated positively with age (r = 0.79, P less than 0.05). A subgroup of large AC appears to expand with time, while the majority of small AC remain unchanged.

Aims. To investigate the behavior of non-radial stellar p-modes with high horizontal wave numbers l, a plane layer approximation is sufficient. In the k − ω diagram, the ridges of the p-modes are strongly influenced by the structure of the atmospheric layers. We present a one-layer model the wave equation of which can be solved in closed form. The layer consists of a polytropic convection zone smoothly joined by an envelope with exponentially increasing temperature. We investigate the behavior of p-modes. As the model is convectively unstable there are no g-modes. This shortcoming is not significant as we discuss only p-modes. Methods. The adiabatic wave equation is reduced to Whittaker's equation. As the dispersion relation of the p-modes is a fourth order algebraic equation in ω, the ω(k)-relation can be given in closed form. Results. We discuss the form of the ridges of the diagnostic diagram. It is shown that the modes concentrate at the position of the temperature minimum in the high-frequency limit. A comparision of the ridges with the ridges of a convection zone with an isothermal atmosphere is performed. In the diagnostic diagram, below the f-mode, there is a continuous spectrum. The correspondig waves behave as gravity waves in the range of the exponential temperature increase. It is discussed whether there are resonances in the continuos spectrum. Solutions of the wave equation of vertically propagating waves are presented.