Eyelid squint response to asthenopia-inducing conditions.

PURPOSE: To study the orbicularis oculi muscle response to asthenopia-inducing conditions. METHODS: Twenty subjects (18-36 years) screened for 20/20 vision in each eye participated in the study. Subjects read passages under different asthenopia-inducing conditions. The inducing conditions were glare, low contrast, small font size, refractive error, up gaze, accommodative stress and convergence stress. Surface electromyography (EMG) was used to study the orbicularis oculi response from the right eye. Palpebral fissure height was measured from recorded video images of the right eye. At the end of each condition subjects were asked to rate the severity and type of visual discomfort experienced. RESULTS: Outcome measures for the asthenopia-inducing conditions were compared with their respective nonstress controls. Repeated measures analysis of variance was used to analyze the data. Refractive error (p = 0.0001), glare (p = 0.0001), low contrast (p = 0.007), small font (p = 0.034), and up gaze (p = 0.001) resulted in a significant increase in EMG power. Refractive error (p = 0.0001) and glare (p = 0.0001) also caused significant reduction in aperture size. Reading a low contrast text caused a reduction in blink rate (p = 0.035), whereas refractive error (p = 0.005) and glare (p = 0.01) caused an increase in blink rate. All conditions induced significant visual discomfort (p < 0.001). CONCLUSION: Refractive error and glare, which reduce image quality and benefit from eyelid squint, caused increased EMG power, eyelid squint response and increased blink rate. Low contrast and small font, which reduce image quality but do not benefit from eyelid squint, resulted in increased EMG power without changes in aperture size and reduced blink rate (for low contrast). Accommodative and convergence stress (in subjects with normal accommodative and vergence abilities) did not cause changes in EMG power, aperture size or blink rate. These results suggest that contraction of the orbicularis oculi is a part of the asthenopia mechanism related to compromised image quality.     

Iopamidol and meglumine diatrizoate: comparison of effects on patient discomfort during aortofemoral arteriography

Iopamidol was compared with Renografin-60 (meglumine diatrizoate, Squibb) in a controlled, randomized double-blind study of 40 patients undergoing peripheral arteriography for arteriosclerotic occlusive disease to determine which agent caused less discomfort. Each patient was evaluated for objective signs of discomfort and subjective feelings of pain and heat. Monitoring was achieved by multiple physical examinations, chemical tests, electrocardiograms, and intra-arterial pressure recordings. It is concluded that iopamidol is safe and causes significantly less patient discomfort than Renografin-60.     

Adrenal surgery: Trends during the seventies

Surgical experience with adrenal disease from 1970 to 1979 was reviewed in 315 patients. The pathologic conditions that were encountered were hypercortisolism (74 patients), hyperaldosteronism (46 patients), adrenocortical carcinoma (35 patients), pheochromocytoma (77 patients), and nonfunctioning adenoma (47 patients). In addition, 5 patients with metastatic lesions, 14 with cysts, and 4 with myelolipoma were surgically treated. The accuracy of localizing adrenal lesions increased from about 50 percent to almost 100 percent during the decade studied. The increase was due mainly to the introduction of computerized tomography, the most important advance in the management of adrenal disease. The present study shows that adrenal surgery can be performed with low morbidity and mortality. Operative deaths were confined to patients with malignant disease or increased secretion of cortisol or catecholamines. Only patients with adrenocortical carcinoma (2 year survival probability, 34 percent) or hypercortisolism due to cortical hyperplasia (5 year survival probability, 76 percent) had significantly decreased survival.     

Laboratory and clinical experience with a monoclonal antibody-based radioimmunoassay for serum total thyroxine

The performance characteristics and diagnostic value of a monoclonal antibody-based radioimmunoassay for serum total thyroxine (Mallinckrodt) are described. Between-batch precision (coefficient of variation) was 10.4% at 87 nmol/l and 3.3% at 185 nmol/l. Scatchard analysis revealed a linear plot with a Ka of 5.4 X 10(8) l/mol. Sensitivity was 4.5 nmol/l of thyroxine. An association study showed that the assay reached equilibrium well within the specified incubation time. Cross-reaction of triiodothyronine and reverse triiodothyronine in the assay was 0.6% and 25.0% respectively. Analytical recovery was 91-110%. Linearity was well demonstrated but dilutions of a high concentration of thyroxine in serum did not parallel the standard curve. The correlation coefficient for comparison with a polyclonal antibody assay was 0.95 for 83 patients. The diagnostic accuracy of the monoclonal antibody assay was adequate for most patients with thyroid disease, pregnant women, oral contraceptive users and subjects on thyroxine-replacement therapy. Measurement of total thyroxine by a monoclonal antibody-based method shows no definite advantage over the conventional polyclonal antibody assay.     

Results of reoperation for hyperparathyroidism, with evaluation of preoperative localization studies.

During the past 3 years (June, 1974, to July, 1977), 51 patients underwent reoperation for persistent or recurrent hyperparathyroidism at the Mayo Clinica. The overall success rate for cervical reoperation was 72% and for mediastinal reoperation, was 64%. Arteriography alone provided accurate preoperative localization of missing parathyroid tumors in 11 of 17 patients at a cost per patient benefited of approximately $1,700. Selective thyroid venous sampling with parathormone assay alone correctly lateralized hyperfunctioning glands in only four of nine patients at a cost per patient benefited of approximately $1,900. When used in combination, these studies provided correct localization or lateralization of parathyroid tumors in five of seven patients at a cost per patient benefited of approximately $2,000. Three patients experienced significant neurological complications as a result of thyrocervical arteriography. There were no complications due to venous sampling. In patients who has undergone a less than thorough initial explorations due to venous sampling. In patients who had undergone a less than thorough initial exploration of the neck, the success rate for reoperation was not enhanced by obtaining preoperative tumor localization studies. However, in those patients who had had a thorough and systematic exploration of the neck at their first operations, the success rate for reoperation was almost doubled when preoperative arteriography or venous sampling (or both) was employed.     

Localization of pancreatic insulinoma: comparison of pre- and intraoperative US with CT and angiography

Methods of preoperative radiologic localization of insulinoma were compared in 52 patients, 44 of whom had solitary tumors. Examinations performed in these 44 patients were preoperative ultrasonography (US) in 28, angiography in 26, and computed tomography in 23. Prospective sensitivities were 61%, 54%, and 30%, respectively. Imaging sensitivities were lower for the eight patients with multiple insulinomas. In 28 of the 44 patients, intraoperative US was performed without the examiner being aware of the surgical findings. The sensitivity was 84%. Four insulinomas were not palpable but were visualized sonographically. The combined sensitivity of intraoperative US and surgical palpation for detecting solitary insulinomas was 100%. High-frequency intraoperative US is valuable for detecting occult solitary insulinomas and considerably useful for determining the proximity of insulinomas to the pancreatic and bile ducts.