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PubMedDate not supplied

[Human vestibular reactions to galvanic stimulation of the labyrinths].

The development of illusionary movements and oscillations of the total body mass center in response to labyrinthine stimulation by ascending and descending current was investigated in 37 healthy test subjects. The stimulation of each labyrinth separately or both labyrinths by the current of opposite direction caused illusionary sensations of tilts, turns and tumbles in various planes. When the test subjects were on the stabilographic platform, their total body mass center shifted toward the anode. Simultaneous stimulation of both labyrinths by the current of one direction produced qualitatively new reactions, such as illusionary movement and displacement of the mass center toward the sagittal plane.

Adolescent↗
PubMed1975

Ultrastructural observations on the maturation of the placental labyrinth of the golden hamster (days 10 to 16 of gestation).

Morphogenesis of the labyrinthine part of the chorioallantoic placenta of the golden hamster between day 10 of gestation and term (day 16) was studied by light and electron microscopy. During this period the labyrinth increases greatly in both size and complexity. Trabeculae of the labyrinth, thin partitions composed of trophoblastic tissue and fetal capillaries which delimit the maternal blood spaces, apparently proliferate both by appositional and interstitial growth. From the time of its formation (day 9 of gestation) until term the labyrinth is hemotrichorial in organization (i.e. three layers of trophoblast separate maternal blood from fetal capillaries). Both the inner and intermediate layers of trophoblast (layers III and II, respectively) are syncytial. The outer trophoblastic layer (III), which is in direct contact with maternal blood, remains cellular, although many of its component cells grow to giant cell dimensions ("labyrinthine giant cells"). Between the tenth and fourteenth days of gestation the anatomical barrier to diffusion between maternal and fetal blood is progressively reduced. This is accomplished both by gradual attenuation of the trophoblastic layers and fetal capillary endothelium and by the formation of discontinuities (gaps) in layer I, and diaphragmed fenestrae in fetal capillary endothelium. The labyrinthine placental barrier is fully developed and probably attains maximal functional efficiency by the fourteenth day of gestation. Late in the fifteenth day of gestation, a few hours before parturition, distinct degenerative changes are apparent in the trophoblastic layers and fetal capillaries of the trabeculae. The factors responsible for initiation these degenerative changes and the onset of parturition are still controversial.

Animals↗
PubMed1993

Variations of the ethmoid labyrinth and sphenoid sinus and CT imaging.

Three hundred macerated and partly isolated postmortem mid-facial bones were studied for the development, variations and dimensions of the structures of the nasal cavity. On 184 axial CT scans of bones (102 male, 82 female) from patients ranging in age from 1 to 90 years old, the dimensions of the ethmoid labyrinth and sphenoid sinus were studied in detail in order to determine which anatomic situation might be unsafe during clinical endoscopic interventions. Six anatomic variations were identified. Most unsafe for surgery seemed to be the following types: type III, in which the anterior diameter of the ethmoid labyrinth was large and the posterior ethmoid and sphenoid diameters were relatively narrow; type V, in which both ethmoid dimensions were large and the sphenoid diameter was narrow: type VI, in which the ethmoid labyrinth had an "hour-glass" shape. Present findings indicate that CT orientation before any endoscopic intervention might help to avoid serious complications.

Adolescent↗
PubMed1981

Immunofluorescent and structural features of cells in the intervascular stroma of the amphibian carotid labyrinth.

The amphibian carotid labyrinth consists of a pars cavernosa, the main chamber of which is in communication with both the base of the external carotid artery, and the vessels of the labyrinthine pars capillaris. On the walls of the main chamber is a network of thick strands of connective tissue and modified smooth muscle cells surrounding the openings into the p. capillaris. These openings lead into wide-diameter atrial vessels, which in turn branch to form the short narrow-diameter vessels. The short vessels form the major component of the labyrinth. A few extremely narrow-diameter vessels are also present. The short vessels open into the roots of the internal carotid artery on the ventral aspect of the carotid labyrinth. The intervascular stroma of the p. capillaris contains numerous stellate and bipolar cells. These cells give a positive response to an immunofluorescent technique specific for smooth muscle myosin and tropomyosin. As the ultrastructural features of these cells are comparable in many respects to smooth muscle, they have been designated as modified smooth muscle cells. It is proposed that these cells act in both an active and passive fashion in maintaining the luminal dimensions of the short vessels relatively constant.

Animals↗
PubMedDate not supplied

Behavioral plasticity of Myrmica rubra ants during learning in a multi-alternative symmetrical labyrinth.

The problem of behavioral plasticity in insects was studied with red ants, Myrmica rubra, by altering a habit developed in a multi-alternative labyrinth with care for offspring as motivation. In altering the habit, location of reinforcement was changed: in the first series, the brood was transferred from the target areas to relatively symmetrical areas of the transverse axis of the labyrinth; in the second, reinforcement was left on one area that had not been preferred during learning of the target area. In both situations, the ants displayed the ability to alter labyrinth habits. The first alteration was the more complex, and 62.5% of the ants were able to manage it while 87.5% managed the second. Such indices as the first correct solution, the average number of movements in the cycle, and total number of correct cycles were also poorer for the first alteration. Development of a new motor habit was accompanied by a change (intensification) of the initial spatial-motor asymmetry. Individual variability in ant behavior were more evident in alterations. The animals not able to manage alterations exhibited definite preneurotic traits. It is suggested that ants have high plasticity and ability to successfully modify their behavior to correspond to change in the experimental situation.

Animals↗
PubMed2000

High-resolution magnetic resonance and volume rendering of the labyrinth.

Our aim was to verify the feasibility of volume rendering (VR) of high-resolution magnetic resonance (HR-MR) data sets of the labyrinth. We retrospectively reviewed the HR-MR data sets of 16 consecutive patients with no MR evidence of labyrinthine pathology. High-resolution MR data sets were obtained by means of a 3D T2-weighted FSE sequence with the use of a 3-in. circular surface coil for signal reception, and processed with a high-end workstation. Two reviewers performed separately VR of the labyrinth by selecting the signal intensity interval for attribution of opacity and transparency. Concerning the time taken for definition of the volume of interest, the two observers needed, respectively, 28.9 and 33.1 min (SD +/- 8.7-9.5 min), whereas the time taken for VR was respectively, 26 and 33.2 min (SD +/- 8.8-8.9 min). Concerning the selection of the signal intensity interval, the two observers had, respectively, 86.4 and 88.7 mean lower threshold (SD +/- 34.5-33.5), 488.9 and 495.4 mean upper threshold (SD +/- 56.3-53.8). In our experience, we have found VR of HR-MR to offer a reliable and reproducible technique for producing 3D representations of the labyrinth. The VR algorithms use all data within the imaging volume and optimize the dynamic range ascribed to the object being visualized.

Adolescent↗
PubMed2003

Conservative (labyrinth-preserving) transpetrosal approach to the clivus and petroclival region--indications, complications, results and lessons learned.

OBJECTIVE: Tumours or vascular lesions of the clivus and juxtaclival region present a unique challenge to neurosurgeons and a variety of techniques, with a wide spectrum of complexity, have been advocated. This report presents the use of a conservative transpetrosal approach which combines partial removal of the postero-lateral petrous bone with preservation of the labyrinth, with particular focus on efficacy and the reduction of complications. PATIENTS AND METHODS: Over 9 years, 52 patients underwent a conservative combined supra-infratentorial, labyrinth-preserving transpetrosal approach. There were 32 women and 20 men; 33 had tumour lesions including 22 patients with a clival or petroclival meningioma. Among the 19 patients with a vascular lesion, 12 patients had a basilar artery trunk aneurysm, including one giant midbasilar aneurysm. 3 Patients had vertebro-basilar junction aneurysms, and 4 patients had a pontine cavernoma. Data on the clinical features, investigations and operative techniques were extracted from the patient's case records. Outcome was assessed by serial examinations of the patients or by telephone interview with the treating physician, and in survivors graded as excellent, good or poor. RESULTS: 52 patients, 23 patients (44%) had an excellent outcome, in 21 patients (41%) the outcome was good and in 7 patients (13%) the outcome was poor. One patient with a complex fusiform basilar trunk aneurysm, operated upon as an emergency, died in the postoperative period. Total resection was achieved, as demonstrated by follow-up MRI in 20 of 33 patients with a tumour, including 15 of 22 patients with clival or petro-clival meningiomas. All vascular lesions were treated effectively and in 14 patients with a basilar or vertebro-basilar junction aneurysm, clipping of the aneurysm was achieved. In one patient, a giant calcified vertebro-basilar junction aneurysm was resected. New cranial nerve deficits or an accentuation of a pre-existing deficit, occurred in 8 patients with a tumour and 4 patients with a vascular lesion. Complications included: temporary conductive hearing deficit in 4 patients, a minor laceration of the sigmoid/transverse sinus in 4 and transient post-operative CSF leakage in 12 patients. Temporary lumbar drainage resulted in sealing of the CSF leak in 8 patients, but in 3 patients a permanent ventriculo-peritoneal shunt had to be implanted. CONCLUSION: When based on adequate experience in skull base surgery, the combined supra-infratentorial, conservative transpetrosal approach, with preservation of the labyrinth, allows direct and wide exposure of a large variety of tumour and vascular lesions located along the supra- and infratentorial juxta-clival area; little or almost no retraction of neurovascular structures is needed and with adherence to important principles, complications related to the approach can be minimised.

Adult↗
PubMed1984

The participation of forelimb flexors in labyrinth and neck reflexes in the decerebrate cat.

The reflex behaviour of triceps and biceps brachii was assessed by EMG recordings during natural labyrinth or neck stimulation. Labyrinth reflexes resulting from changes in head position are antagonistic to those resulting from changes in neck position. Reflexes recorded from biceps were reciprocal to those recorded in ipsilateral triceps and symmetrical to those from contralateral triceps. A scheme of labyrinth and neck reflexes involving forelimb flexors is presented.

Animals↗
PubMed1992

Permeability changes of the blood-labyrinth barrier measured in vivo during experimental treatments.

The communication between blood and cochlear perilymph was investigated using the tracer ion trimethylphenylammonium (TMPA). TMPA can be detected in micromolar concentrations by ion-selective microelectrodes, allowing it to be used as an almost ideal marker to study intercommunication between fluid compartments. TMPA-sensitive electrodes were sealed into the cochlear scalae, using procedures which avoided the artifactual displacement of perilymph by cerebrospinal fluid (CSF). TMPA was infused intravenously at a low rate to produce a plasma concentration of approximately 0.5, mM. The time course of entry into perilymph of scala tympani (ST), scala vestibuli (SV) and into CSF were compared. After 90 min infusion, the mean CSF concentration reached 14.3% of that measured in plasma. The TMPA concentrations measured in ST and SV perilymph were significantly lower than those recorded in CSF, only reaching an average of 6.5% and 3.7% of the plasma concentration respectively after 90 min. The slow entry of TMPA confirms the existence of a tight blood-labyrinth barrier, equivalent to the blood-brain or blood-CSF barriers. The rate of TMPA entry into perilymph was increased by epinephrine-induced hypertension or by simultaneous administration of histamine and prostaglandin E2. These treatments are presumed to increase the permeability of the blood-labyrinth barrier. Characterization and manipulation of blood-labyrinth barrier permeability could be important to our understanding cochlear pathology.

Animals↗
PubMed2006

Hepatocyte growth factor activator inhibitor-1 (HAI-1) is essential for the integrity of basement membranes in the developing placental labyrinth.

Hepatocyte growth factor activator inhibitor-1 (HAI-1) is a membrane-associated Kunitz-type serine protease inhibitor that regulates cell surface and extracellular serine proteases involved in tissue remodeling and tumorigenesis, such as HGFA, matriptase, prostasin and hepsin. We generated HAI-1 deficient mice, which died in utero due to placental defects. The HAI-1(-/-) placental labyrinth exhibited a complete failure of vascularization and a compact morphology of the trophoblast layer. Immunofluorescent staining of collagen IV and laminin and electron microscopy analysis revealed that this aberrant labyrinth architecture was associated with disrupted basement membranes located at the interface of chorionic trophoblasts and allantoic mesoderm. Unlike the placental labyrinth, basement membranes and vasculogenesis were normal in embryo and yolk sac. Therefore, basement membrane defects appear to be the underlying cause for the greatly impaired vascularization and trophoblast branching in HAI-1(-/-) placentas. In wild-type placentas, the expression of matriptase and prostasin co-localized with their physiological inhibitor HAI-1 to the labyrinthine trophoblast cells in proximity to basement membranes. In HAI-1(-/-) placentas, both the localization and expression of the two proteases remained unchanged, implying uncontrolled proteolytic activities of the two enzymes. Our study demonstrates the important role of HAI-1 in maintaining the integrity of basement membrane most likely by regulating extracellular proteolytic activities during placental development.

Animals↗
PubMed1999

Development of blood-labyrinth barrier in the semicircular canal ampulla of the rat.

Cationic polyethyleneimine (PEI) administered intravenously was transported to anionic sites on the capillary and subepithelial basal laminae (BL) in the vestibular labyrinth. Therefore, changes in the PEI distribution on the BL reflect changes in the transport system in the vestibular labyrinth. A 0.1% PEI solution was administered intravenously (7.5 ml/kg) to developing (1, 4, 7, 14 days after birth) and adult rats in order to investigate the development of the macromolecular transport in the ampulla of the semicircular canal as a function of age. After 1 h, the bony labyrinth was removed and embedded in Epoxy resin. Ultrathin sections of the ampulla were then examined with a transmission electron microscope. In the subepithelial BL in the dark cell area and capillary BL in the crista ampullaris, the PEI distribution in both 1- and 4-day-old rats was markedly increased compared to that in either 7-, 14-day or adult rats. In the sensory cells in 1-, 4-day or 7-day-old rats, PEI density and area was significantly greater than in the adult rats. These findings suggest that the macromolecular transport system in the developing rat ampulla becomes mature by 14 days after birth and that the maturation of its transport system in the ampulla is strongly associated with that in the stria vascularis.

Animals↗
PubMed2000

Effect of violation of the labyrinth on the sensory epithelium in the chick cochlea.

Models in which a single large systemic dose of gentamicin is used to cause near-synchronous hair cell (HC) loss in the basal end of the chick cochlea have proven increasingly useful in the study of HC regeneration. We quantified the amount of HC death, as a percentage of the length of the basilar papilla, following single doses of 200 mg/kg and 300 mg/kg of gentamicin in 23-day-old chicks. Following 200 mg/kg of gentamicin, there was total HC loss in the basal 18.0% of the sensory epithelium and partial HC loss in the basal 26.3%. Following 300 mg/kg of gentamicin, there was total HC loss in the basal 30.5% of the epithelium and partial HC loss in the basal 40.9%. The second goal of this study was to determine whether cannula implantation in the inner ear, and infusion of bromodeoxyuridine causes HC damage. We found that creation of a fistula in the labyrinth is not associated with HC damage, but that cannula implantation can cause HC death, and can also cause potentiation of gentamicin-induced HC death. Revision of the cannula and surgical technique to ensure minimal penetration into the labyrinth almost entirely eliminated these effects. We conclude that surgical technique is critical in experimental models in which the labyrinth is violated.

Animals↗
PubMed2001

An experimental study on radiation streaming through a labyrinth in a proton accelerator facility of intermediate energy.

A radiation streaming experiment has been carried out at the Takasaki Ion Accelerator Facility for Advanced Radiation Application at the Japan Atomic Energy Research Institute in a room housing a Cu target irradiated with 68 MeV protons and in a labyrinth of three-legs having a total length of 29 m. In the experiment, neutron and gamma ray energy spectra, neutron reaction rates, and neutron and gamma ray dose equivalent rates were measured using various counters and dosimeters. The experimental data show the applicability of some empirical formulas for estimating the thermal neutron flux in a room and neutrons streaming in a labyrinth designed for a proton accelerator operating in the intermediate energy region. The data suggest that it is mandatory to estimate the gamma ray dose equivalent rate in a labyrinth, which is dominated by the secondary gamma rays due to the neutron capture reaction.

Academies and Institutes↗
PubMed2005

Fistula of the cochlear labyrinth in noncholesteatomatous chronic otitis media.

OBJECTIVE: To discuss the clinical aspects and management of promontory fistula of the cochlear labyrinth. STUDY DESIGN: Case report and review of the literature. SETTING: University hospital, tertiary referral center. PATIENT, INTERVENTION, AND RESULTS: The authors describe an unusual case of cochlear fistula localized to the promontory discovered during tympanoplasty for noncholesteatomatous chronic otitis media in a 59-year-old woman. Bone conduction was slightly impaired after operation and hearing improved after a revision myringoplasty performed for reperforation. CONCLUSION: Erosion of the bone of the labyrinth can also be observed in noncholesteatomatous otitis media. The presence of a fistula is not always associated with profound hearing loss. Overlying pathologic tissue can be removed without damaging the membranous labyrinth.

Audiometry, Pure-Tone↗
PubMed1997

Klein's archaic Oedipus complex and its possible relationship to the myth of the labyrinth: notes on the origin of courage.

The ancient Greek myth linking the images of the labyrinth and the Minotaur provides an allegory for Melanie Klein's conception of the archaic Oedipus complex as well as a vivid illustration of Winnicott's notions of object usage and the 'subjective object'. The labyrinth is suggestive of mother's body as the first area for an infant's exploration and putative sadistic conquest. The Minotaur, in turn, suggests the infant's unconscious phantasies about the content of mother's body, namely such projective identifications onto that body as the paternal penis and the 'internal babies'. Further, the heroic dynamic personified by Theseus in the myth of the labyrinth metaphorically signifies what is here proposed as a developmental line that involves the courage to do a number of things, including to become, to create, to seek, to explore, to do, to challenge, to undertake risks, to accept, to rescue, to initiate, to think, to know and to realize. The Minotaur can thus be thought to serve as a universal subjective signifier for an 'Object of Challenge', which, if not successfully dealt with by the ego-development of the infant, transforms that default into the 'Object of Nemesis'. Ultimately, this myth of mastery speaks to the psychoanalytic process itself as well as casting light on the transformative aspects of sexual intercourse as a personal healing ritual.

Ego↗
PubMed1980

Responses of lateral reticular neurons to sinusoidal stimulation of labyrinth receptors in decerebrate cat.

1. The electrical activity of 106 individual neurons located in the precerebellar lateral reticular nucleus (NRL) and the surrounding medullary reticular formation (RF) has been recorded in precollicular decerebrate cats during sinusoidal tilt around the longitudinal axis of the whole animal leading to stimulation of labyrinth receptors. 2. Among these lateral reticular neurons tested, 48 of 712 (67.6%) NRL neurons and 11 of 35 (31.4%) RF neurons responded to slow rotation of the animal at the standard frequency of 0.026 Hz and at the peak amplitude of displacement of 5-10 degrees. 3. All the responsive units showed a periodic modulation of firing rate during the sinusoidal stimulus. In particular, 35 of 57 units (i.e., 61.4%) were excited during side-up and depressed during side-down tilt of the whole animal; on the other hand, 14 of 57 units (i.e., 24.6%) showed the opposite behavior. In both instances, the peak of the responses occurred with an average phase lead of about 16 degrees with respect to the extreme side-up or side-down position of the animal. The remaining eight units (i.e., 14%) showed a phase shift of the peak of their response of about 90 degrees with respect to the animal position. 4. The sensitivity of the responses, expressed in percentage change of the average firing rate per degree of displacement, did not change by increasing the peak amplitude of tilt from 5 to 15 degrees at the frequency of 0.026 Hz. This finding indicates that the system was relatively linear with respect to the amplitude of stimulation. The sensitivity of the units, however, slightly increased but the phase angle of the responses did not change by increasing the frequency of tilting from 0.015 to 0.15 Hz at the peak amplitude of 5 or 10 degrees. These findings indicate that the responses depended on stimulation of macular labyrinth receptors. 5. Most of the lateral reticular units affected by tilt received also a bilateral convergent input from the hindlimbs. 6. These observations are related to the results of previous studies in which the responses of macular afferents, vestibular nuclei neurons, and corticocerebellar Purkinje (P) cells to sinusoidal tilt of the whole animal have been investigated. A possible role of lateral reticular neurons in the labyrinth control of posture in decerebrate cat is also discussed.

Afferent Pathways↗
PubMedDate not supplied

Labyrinth anesthesia--a forgotten but practical treatment option in Ménière's disease.

The aim of this study was to determine the efficiency of labyrinth anesthesia - the intratympanic instillation of lidocaine--in the treatment of Ménière's disease and to recall a forgotten method. Twenty-four patients (15 male, 9 female), aged from 19.7 to 80.6 years (mean: 47.8 years) with the clinical diagnosis of unilateral Ménière's disease who underwent labyrinth anesthesia in our department were included in this retrospective study. After local anesthesia of the tympanic membrane, a solution of 4% lidocaine and furfuryladenine (Kinetin) was instilled into the tympanic cavity. Patient records, a questionnaire and a physical examination were used to evaluate vertigo control, hearing loss, tinnitus, and quality of life according to the AAO-HNS criteria before and after surgery. Postoperatively, 87.5% of patients reported at least a noticeable decrease of vestibular symptoms, 66.7% of these patients were free of attacks for an average of 26.5 months. Postoperative hearing was the same or even improved in 87.5% of our patients. Tinnitus was not affected in any individual. Based on the findings presented herein, we consider labyrinth anesthesia a practicable and, due to its safety, highly recommendable therapeutic option for patients suffering from Ménière's disease.

Adenine↗
PubMed2006

Exploring the effects of walking the labyrinth.

PURPOSE: This pilot study examines the effects of walking a labyrinth. METHOD: A convenience sample of 25 community members participated in a four-group, repeated measures study to gather information about vital signs and affect before and after labyrinth walks. Because of the small sample size, results were inspected for effect size (ES) differences in pre-to postcomparisons. Mean postwalk scores were also compared to control group scores. FINDINGS: Systolic and diastolic blood pressures showed essentially no ES differences pre to postwalk. The remaining ES comparisons showed .14 ES for pulse differences, .37 ES for respirations, and .22 and .56 ES differences for positive and negative affect measures, respectively. CONCLUSIONS: Comparisons of postwalk scores for walkers to nonwalkers showed mixed results in significance of differences. IMPLICATIONS: This pilot study shows the feasibility of the procedures for assessing the effects of labyrinth walking on basic parameters of health.

Adult↗