The function of the endolymphatic duct--an experimental study using ionic lanthanum as a tracer: a preliminary report.
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Animals↗
Biomedical subjects
H Rask-Andersen
Publications and source records attributed to H Rask-Andersen.
Temporal bone characteristics in Meniere's disease.
The petrous portion of the temporal bone in patients with Meniere's disease differs from that of healthy individuals mainly in its lack of periaqueductal pneumatization and its consequently short and narrow vestibular aqueduct. Diminished pneumatization may have an impact upon the tomographic reproducibility of the aqueduct. A total lack of periaqueductal pneumatization is prevalent in long-standing Meniere's disease. Tomography may serve as a tool by providing a basis for the choice of surgical procedure. Roentgenologic and histologic studies have indicated that the pars rugosa of the endolymphatic sac in normals mainly is housed inside the distal part of the vestibular aqueduct. In patients with Meniere's disease, the sac might be located outside the aqueduct and therefore deprived of the functions of the loose and highly vascular tissue normally surrounding it within the aqueduct. This might influence the total vascular supply of the sac, thereby interfering with its resorptive and immunodefensive functions.
Endolymphatic Sac↗
Lymphocyte-macrophage activity in the endolymphatic sac. An ultrastructural study of the rugose endolymphatic sac in the guinea pig.
The irregular epithelial layer which delimits the intermediate part of the endolymphatic sac, and the surrounding perisaccular tissue, were examined morphologically in the guinea pig by transmission electron microscopy. Specialized areas of the epithelium which have previously been designated as "non-vascularized epithelial processes" (NVP) were constantly observed. These proliferative areas showed a close topographical relation to the free luminal cells and contained an abundance of lymphoid cells. Lymphocytes and macrophages were intimately associated with each other in a manner similar to that seen in these two types of cells in antigen-stimulated lymphoid tissues. There was a marked degeneration and phagocytosis of cells. The richly vascularized perisaccular tissue was rich in plasma cells, monocytes, mast cells and lymphocytes. The latter could be seen to migrate through the endothelial cells in the thin post-capillary venules into the sac tissue. The authors consider that the endolymphatic sac plays a role as an immunological defence organ for the internal ear. A hypothetical model concerning circulation and turnover of certain of the free intraluminal cells in presented.
Animals↗
The vascular supply of the endolymphatic sac.
The vascular anatomy of the endolymphatic sac in guinea pigs was examined following intravascular injection of silicone rubber (Microfil). Methacrylate resin of low viscosity (Mercox) was used to obtain vascular corrosion casts for scanning electron microscopy, which allowed more accurate differentiation between arteries and veins. The extensive vascular system around the sac comprises both arteries and veins, as well as lymphatic vessels. The arterial supply is derived mainly from the posterior meningeal artery in the posterior cranial fossa. In some cases a small artery also leads to the sac from the posterior vestibular artery in the labyrinth (in 7 of the 35 animals investigated). It courses together with the vein of the vestibular aqueduct along the walls of the endolymphatic duct. The blood is drained over the intermediate portion of the endolymphatic sac, which becomes lodged in a rich meshwork of capillaries, venules, veins and a few small arteries. A few venous trunks from both sac walls fuse with the vein of the vestibular aqueduct, which drains blood from the vestibule to the sigmoid sinus. Scanning electron microscopy also revealed numerous anastomosing vessels within bone channels with adjacent bone marrow sinusoids, which also probably contribute to the vascular supply of the endolymphatic sac.
Animals↗
The electrical potential difference and impedance between CSF and blood in unanesthetized man.
The electrical potential difference (PD) between cerebrospinal fluid (CSF) and blood has been studied extensively in animals. To obtain data from man the PD and impedance were recorded from the lumbar subarachnoid space of thirteen unanaesthetized patients with a presumably normal blood--brain barrier. The spontaneous PD ranged from 1 mV to 5 mV, CSF positive to blood. Hyperventilation and CO2-inhalation changed the PD with a mean slope of deltaPD/deltapHa of --4.16 mV/pH. The CSF-blood PD in unanaesthetized man is similar in direction to that found in dogs, goats and rats, but its sensitivity to change in arterial pH may be less.
Adult↗
Tomography in Menière's disease--why and how. Morphological, clinical and radiographic aspects.
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Ear, Inner↗
The surgical anatomy of the endolymphatic sac.
The endolymphatic sac (ELS) and vestibular aqueduct (VA), which play a notable role in the pathogenesis of endolymphatic hydrops and Meniere disease, were identified in all anatomic and tomographic materials. More than 100 temporal bones were used for microdissection, tomography, and plastic molds. Normal subjects and Meniere disease patients were studied tomographically (N = 63) and observed during ELS surgery (N=49). In Meniere disease there is, with increassing duration of diseases, a decrease in the periaqueductal and opercular air cell pneumatization, with a concomitant shorter and straighter VA. This correlates with a decreased ELS luminal patency, and a more inferiorly positioned ELS. These factors help to explain both the difficulties of visualizing the VA by tomography in Meniere disease as well as the occasional difficulties reported by others in satisfactorily identifying the ELS at sac surgery. All observations are made from the surgeon's viewpoint to enhance clinical identification of the ELS.
Adult↗
Urethral pressure profile in prostatic surgery.
Urethral pressure profile measurements were performed in 45 men suffering from micturation disturbances with the aim of evaluating the diagnostic aid of the procedure as compared to conventional urodynamic evaluation. The urethral pressure profile seems to be of value in visualizing the diseases of the prostate and the bladder neck, but it is of no definite aid except for postprostatectomy incontinence.
Humans↗
Dynamics of upper urinary tract. I. An electrophysiologic in vivo study of renal pelvis in pigs: method and normal pattern.
Under halothane anesthesia, peroperative electromyography of the pelvis and ureter together with intrapelvic pressure and urine flow were recorded in 11 pigs; the electromyography was by bipolar extracellular leads. Pressure waves of low amplitude, synchronous with action potentials from leads placed most proximally in the pelvis, preceded action potentials registered by distally placed leads. Transmission of the action potentials from the pelvis to the ureter took place with a constant transmission velocity but the transmission ratio varied from 1:1 to 6:1. Ureteral electric activity was time-related to the urine bolus. The transmission velocity was smaller in the pelvis than in the ureter and seemed to accelerate caudally. Thus, there is electromyographic evidence that the renal pelvis controls ureteric activity and that this pacemaker function is mediated high up, most proximally, in the renal pelvis.
Action Potentials↗
Dynamics of upper urinary tract. II. An electrophysiologic in vivo study of renal pelvis in pigs: analysis of the modality of pelvic activity during normal hydration and diuresis.
Renal pelvic function of Danish Landrace pigs under anesthesia was analyzed during "normal" and forced diuresis. Measurements were made of intrapelvic pressures, electromyogram recordings were taken from the pelvis and ureter, and bolus formation was followed. During constant diuresis, pelvic activity displayed a dominant frequency which varied between individuals. When pressure rose or fell, pelvic activity increased or decreased in proportion to the speed rather than the extent of the pressure change. Thus, after furosemide administration urine flow increased and pelvic pressure rose; and in association with the pressure rise, pelvic activity increased significantly when mean pelvic activity in the phase of steep pressure rise was compared with the mean activity over the last 5 min of the observation period before induction of diuresis. Thereafter, pelvic activity decreased despite maintenance of a higher pressure plateau than that in the initial low diuresis observation period. This mode of function can be explained by reference to the characteristics of smooth muscle. Postulation of a specific pacemaker is unnecessary.
Animals↗
Incomplete ureteral duplication. Electromyographic and manometric investigation.
Studies were made peroperatively in a patient with incomplete ureteral duplication. Bipolar extracellular EMG-leads were taken from both pelvices, both ureteral segments and from the common ureter. Simultaneously pressure measurements were made in the pelvices. Function of the two pelvi-ureteral units were shown to be autonomous. Simultaneous action potentials and pressure waves were observed in each pelvis. Not every pelvic impulse was transmitted to the corresponding ureter, but when transmission did occur, the conduction rate was constant. Impulses from both ureteral branches were conducted distally to the common ureteral trunk, but impulses from the dilated segment had not the same quality (amplitude) as those from the non-dilated segment. Antiperistalsis was not observed. There was a measurable pressure difference between the two segments.
Action Potentials↗
Experimental hydronephrosis. An electrophysiologic investigation before and after release of obstruction.
Pelvi-ureteric function was studied in pigs with experimental urinary tract obstruction, and again, 5 weeks after relief of the obstruction. Study parameters comprised EMG records taken from pelvis and ureter, measurements of intrapelvic pressure and urine flow, and some supplementary studies of renal function. Total obstruction of 5 and 6 weeks duration induced by cuffing the proximal ureter occasioned severe hydronephrosis and renal failure. Pelvic peristaltic activity was of low frequency, and abnormality was clearly more marked after the longer period of obstruction. There was, for example, some preservation of pelvi-ureteric synergism at 5 weeks, but at 6 weeks ureteric activity was wholly autonomous. Pelvic function was similarly isolated, and non productive. Inspection 5 weeks after reconstruction by pelvis resection and neo-anastomosis of the ureter showed continued absence of renal function and no restitution of normal peristaltic patterns. Partial obstruction, effected by implantation of the ureter in the psoas muscle, induced mild pelvic dilatation and impaired renal function, but there were only minor signs of disruption of normal anterograde pelvi-ureteric activity - irregularities, pauses in activity, and double activity complexes. When the ureter was freed functional patterns returned to normal. Both during obstruction and after relief, pelvic pressure increases during forced diuresis were the equivalent of or lower than the pre-determined norm. Cautery at the pelvi-ureteric junction destroyed the musculature and induced a progressive (fibrous stenosis. There was progressive dissociation of pelvi-ureteric activity, total when obstruction was total in which case ureteric activity was only autonomous, and partial when obstruction was partial in which case varying degrees of synergism and autonomous activity were seen. Successful reconstruction (pelvic resection and neo-anastomosis of the ureter) restored an apparent synergism in pelvi-ureteric function.
Animals↗
Dynamics of upper urinary tract in man. Peroperative electrophysiological findings in patients with manifest or suspected hydronephrosis.
In 31 patients undergoing surgery in treatment of hydronephrosis, peroperative pelvic pressure measurements were made. EMG records were taken from pelvis and ureter, and occasional measurements of urine flow were made. In 6 instances these studies were also made in the contralateral "normal" kidney, but in 2 of these patients the diseased kidney was not studied. Pelvic pressure during antidiuresis in these 6 "normal" kidneys was about 5 mmHg, and pelvic activity of frequency 5/min. Pelvi-ureteric impulse transmission was anterograde and conduction times were constant. Conduction ratios varied. During forced diuresis mild pelvic pressure rises were seen together with transient increase in pelvic activity over the period of pressure increase. In the studies of hydronephrotic kidneys no significant differences were seen in pelvic pressure of frequency of pelvic activity compared with the "normal" kidney studies, but impulse transmission was markedly disturbed, manifest by varying conduction times, and, on occasion, total dissociation of activity within the pelvis, and between the pelvis and ureter. The more severe the degree of hydronephrosis, the more marked the disturbance. The findings are similar to those made in experiments with pigs after establishment of varying degrees of urine flow obstruction.
Action Potentials↗
Development of a probe for endoureteral investigation of peristalsis by flow velocity and cross section area measurement.
A probe system for measurement of ureteric flow velocity and ureter cross section area is described. The flow velocity transducer is placed at the tip of a conventional 4-F ureteric catheter. The cross section transducer consists of two circular electrodes at an interval of 4 mm, mounted on the catheter just behind the flow velocity transducer. In vitro calibration established voltage as a function of flow velocity according to Kings law. Stability was excellent (0-point drift less than 1%/hour). Response time for flow rise was 0.02 second, and for flow fall 1.0 second. Variations of the ambient temperature at constant flow showed a margin of error in flow determination of 10 to 15%/1 degrees C temperature variation. In vitro calibration of the cross section transducer established linear correlation between voltage and tube diameter, but limited by the actual interelectrode interval. Probe displacement from tube axis gave an error of up to 10%. In vivo studies were made in anaesthetized pigs. The probe did not affect ureter peristalsis. Flow velocities ranged from 0 to 5 cm/second and ureter cross sectional areas between 0 and 0.2 cm2. Further developments in the measuring system are discussed.
Animals↗
The vestibular aqueduct and the para-vestibular canal. An anatomic and roentgenologic investigation.
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Adolescent↗
Human cochlear aqueduct and its accessory canals.
The anatomy of the adult human cochlear aqueduct and its surrounding structures, and their normal variations at tomography, microdissection and plastic molding are described. The mean length of the aqueduct is 12.9 mm and the mean width of its funnel-shaped external aperture 4.2 mm. The mean width of the narrowest portion is 0.14 mm. No difference in aqueductal width was found between the youngest and oldest age groups. Complete bony obstruction was revealed at microdissection in 3 out of 82 specimens. In the remaining 79 the entire aqueduct was patent. The aqueduct usually runs parallel to the internal auditory canal when seen from above, and the AP projection is therefore most suitable for tomography. At tomography the entire aqueduct was visualized in 60% of the specimens. The isthmic portion was not visible in 40%. Major reasons for nonvisualization of the entire aqueduct are: 1) a luminal width less than 0.1 mm, 2) a high jugular fossa, 3) a posteriorly directed aqueductal convexity (10%), and 4) bony obliteration (4)%). Accessory canals close to and often wider than the aqueduct may complicate tomographic evaluation of the aqueductal patency. Nonvisualization of the aqueduct at tomography does not necessarily indicate nonpatency.
Adult↗
Human endolymphatic duct: possible mechanisms of endolymph outflow.
The ultrastructure of the normal human endolymphatic duct (ED) was observed by transmission electron microscopy. The role of the epithelium, the various regions of the subepithelial space, and vasculature in the resorption of endolymph was morphologically studied in order to generate testable hypotheses of human ED function. These hypothetical mechanisms of endolymph outflow at the level of the ED are a passive transcellular movement of water across the epithelium, driven by an osmotic gradient created by a subepithelial organic matrix; an active transcellular ion exchange with a passive transepithelial outflow of water, which stresses the importance of the dilated lateral intercellular spaces; and an active transcellular vacuolar endolymph outflow, whereby high molecular weight substances are removed by the ED. These mechanisms may be useful in designing experimental studies of the ED and in interpretation of retrospective light microscopic and transmission electron microscopic studies of patients with Meniere's disease.
Adult↗
Human endolymphatic sac: morphologic evidence of immunologic function.
The ultrastructure of ten normal human endolymphatic sacs (ES), fixed immediately after death and obtained at autopsy, was observed by transmission electron microscopy. The roles of the epithelium, subepithelial space, vasculature, and ES leukocytes were morphologically studied to evaluate possible immunologic functions of the human ES. In addition, five intraosseous ES biopsies from patients undergoing translabyrinthine acoustic neuroma resection were studied using the immunoperoxidase technique to identify specific leukocyte subpopulations. Evidence of phagocytic activity included the presence of phagocytic epithelial cells, monocytes, macrophages, and polymorphonuclear leukocytes. Immune surveillance was suggested by intraepithelial and subepithelial T-lymphocytes, numerous fenestrated blood vessels, and the presence of a homogeneously staining substance within the lumina of ES epithelial tubules. No B-lymphocytes were found. The findings support the existence of a local immune system of the normal human inner ear.
Adult↗