Carotid occlusion without reconstruction: a safe surgical option in selected patients.

Complete resection of extensive skull base tumors can be difficult when the disease involves or is closely related to the carotid artery. Detachable balloons have been used effectively to permanently occlude the carotid artery prior to anticipated surgical resection, but their use involves risk of significant cerebral complications. To better define the risks and benefits of this procedure, 52 patients who underwent balloon occlusion of the carotid artery followed by surgery with resection of a portion of the carotid artery were retrospectively reviewed. Pathologic findings are presented demonstrating the infiltrative nature of many of these tumors and the difficulty in separating histologically benign tumors from the carotid artery when they are closely related to it. Although vascular reconstruction can be considered whenever carotid occlusion or resection is planned, balloon occlusion without reconstruction can be safely performed in selected patients, avoiding unnecessary and hazardous additional surgery.

Vestibular testing in hearing loss.

The basic electonystagmography battery (saccade, gaze, position, caloric tests, and spontaneous nystagmus) are described along with rotational testing and dynamic posturography. Emphasis is placed on interpretation, relative benefits, and limitations as an aid in diagnosis.

Positional envelope as a response parameter in caloric testing.

Bithermal caloric testing was carried out in 57 normal subjects and 374 patients presenting with subjective complaints of vertigo over a 4-year period from December 1984 to December 1988. Responses were quantitatively assessed using a DEC PDP 11/73 laboratory minicomputer. Patients were classified as normal and abnormal according to caloric responses based on standard methods of calculating unilateral hypoexcitability and directional preponderance using the maximum slow component velocity. Results obtained from the slow component velocity for unilateral hypoexcitability and directional preponderance were compared to the same values obtained from the overall positional envelope calculated by an integration of the slow component velocity vs. time curve. Although duration of nystagmus varies extensively in normal subjects and has not proven clinically useful in identifying abnormalities, the integral of response amplitude over time gives a more complete description of the vestibular response. However, when compared to the maximum slow component velocity in abnormal patients, the positional envelope identified only 94 of the total 119 abnormalities (79%). Therefore, maximum slow component velocity is the more sensitive response parameter in identifying vestibular pathology.

Quantification of the human Sertoli cell population: its distribution, relation to germ cell numbers, and age-related decline.

The human Sertoli cell population was characterized in 14 men by histometric analysis and by direct counts of nuclei in testicular homogenates. Testes obtained at autopsy were perfused with glutaraldehyde and embedded in Epon. Nucleolar and nuclear volumes were determined by the formula of a sphere given the diameter of the nucleoli or average diameter of nuclei measured at the height and width. Nuclear volume was also estimated by adding volumes of nuclear profiles in 0.5-micron serial sections. Sertoli cell number/g was calculated by the product of the percentage nucleoli or nuclei in the parenchyma, parenchymal volume, and histologic correction factor divided by the volume of a single nucleolus or nucleus. Also, Sertoli cell nuclei were counted directly in homogenates of fixed parenchyma. Number of Sertoli cells/g was similar (P greater than 0.05) whether determined by serial sections or in homogenates, but the estimate based on the nucleolar method was higher (P less than 0.01) and the nuclear measurement method was lower (P less than 0.01) than that for serial sections. A group of 37 men aged 20 to 48 yr had significantly (P less than 0.01) more Sertoli cells than did 34 men aged 50 to 85 yr. It is concluded that: 1) the homogenate method is valid for quantification of the Sertoli cell population, 2) Sertoli cells are evenly distributed in different regions of the testis, 3) the average human Sertoli cell supports relatively few germ cells, 4) the human Sertoli cell population declines with age, and 5) there is a significant relationship between sperm production rates and number of Sertoli cells.