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PubMed2006

Is there a role for atrial peptides in the labyrinthine "disease"?

The important role of atrial natriuretic peptides (ANP) in regulating blood pressure and changing vascular permeability has been widely studied and assessed during the last ten years. Considering the characteristics of this mechanism, which is responsible for a hypotensive and hypovolemic effect, and the possible role of hypotension associated with a default of autoregulatory sympathetic reactions in inner ear unexplained disorders, it seems reasonable to hypothesize a possible involvement of ANP system in the genesis of such disorders. As a matter of fact, the presence of specific receptors for ANP in the inner ear has been widely reported in studies concerning both rat and human inner ear, although their precise role in the labyrinthine homeostasis has not been satisfactory explained until now. Some aspects concerning vascular and fluid regulation of the inner ear under different conditions still remain not totally clear, and consequently a detailed explanation to the possible mechanism causing inner ear disorders of functional origin is lacking; from this point of view, an investigation on the serum level of ANP in subjects with labyrinthine affections of uncertain origin could be of some utility in contributing to assess the role of this system in the inner ear fluid regulation and in the inner ear perfusion and to investigate on the possible influence of an abnormal ANP release in some kind of inner ear damage.

Atrial Natriuretic Factor↗
PubMed1996

Hormonal modulation of inner ear fluids.

In the cochlea, hormones such as antidiuretic hormone and adrenocorticosteroid hormones are supposed to modulate the endolymph osmolality acting on the labyrinthine water permeability, on the one hand, and on the Na+, K(+)-ATPase, on the other hand. To test the hypothesis that these hormones are involved in the inner ear fluids homeostasis, the electrochemical composition of cochlear fluids was studied in control Long Evans rats, Brattleboro rats that are genetically deprived of antidiuretic hormone, and in adrenalectomized Long Evans rats. The results demonstrated that: i) in Brattleboro rats, the endocochlear K gradient was absent whereas the endocochlear potential and the Cl concentration gradients were maintained; the K gradient was restored by the dDAVP administration; ii) in adrenalectomized rats, no modification of the electrochemical composition of endolymph occurred; the injection of bumetanide (10 mg/kg) induced a larger decrease of the endocochlear potential in adrenalectomized rats than in control animals. These results suggest that the cellular transport systems involved in the endolymph secretion may be altered by different hormones such as antidiuretic hormone and/or adrenocorticosteroid hormones. Nevertheless, the hormonal modulation of the inner ear fluid homeostasis remains to be further documented.

Adrenal Cortex Hormones↗
PubMed1991

Effects of renal insufficiency on the cochlear absorptive-secretory areas. A morphological study in the Mongolian gerbil.

In order to evaluate the effects of experimental renal insufficiency (RI) on the labyrinthine absorptive-secretory areas (ASA), 54 adult Mongolian gerbils were submitted to bilateral nephrectomy or to sham procedure. At different intervals (3, 6, 9, 12, 15, 18, 21, 24 hours) after the surgical procedures, or during the terminal stage (28 h) the animals were decapitated and both temporal bones were dissected to obtain selected specimens of the cochlear ASA. The specimens were processed and analysed by light and electron microscopy. Structurally, RI induced progressive thickening of the epithelial components (stria, prominentia, sulcus); separation by fluid accumulation between stria and mesodermal layer; and frequent dilatation of intraepithelial vessels. Ultrastructurally, diverse signs were observed parallel to the evolution of the RI. After 12 h a progressive enlargement of the intercellular spaces, which was particularly evident in the stria surrounding the vessels and in the other sulcus, was observed. Its latest expression was a marked widening of the basolateral spaces containing a granular substance. After 12 h the formation of large cytoplasmic perinuclear spaces containing small rounded vesicles, probably secondary to fluid accumulation, could be observed in the marginal cells. After 24 h diverse signs of organellar damage became evident (schedule: mitochondrial swelling, lysosome like figures, myelin like figures). In the terminal stage, a general homogenization of the cytosol was common. The findings suggest a definite re-distribution of fluids in the inner ear. A close relationship between renal dysfunction and labyrinthine microhomeostasis is therefore proposed.

Animals↗
PubMed1992

Distribution of intraventricularly injected horseradish peroxidase in cerebrospinal fluid compartments of the rat spinal cord.

The circulation of the cerebrospinal fluid along the central canal and its access to the parenchyma of the spinal cord of the rat have been analyzed by injection of horseradish peroxidase (HRP) into the lateral ventricle. Peroxidase was found throughout the central canal 13 min after injection, suggesting a rapid circulation of cerebrospinal fluid along the central canal of the rat spinal cord. It was cleared from the central canal within 2 h, in contrast with the situation in the brain tissue, where it remained in the periventricular areas for 4 h. In the central canal, HRP bound to Reissner's fiber and the luminal surface of the ependymal cells; it penetrated through the intercellular space of the ependymal lining, reached the subependymal neuropil, the basement membrane of local capillaries, and appeared in the lumen of endothelial pinocytotic vesicles. Furthermore, it accumulated in the labyrinths of the basement membrane contacting the basolateral aspect of the ependymal cells. In ependymocytes, HRP was found in single pinocytotic vesicles. The blood vessels supplying the spinal cord were classified into two types. Type-A vessels penetrated the spinal cord laterally and dorsally and displayed the tracer along their external wall as far as the gray matter. Type-B vessels intruded into the spinal cord from the medial ventral sulcus and occupied the anterior commissure of the gray matter, approaching the central canal. They represented the only vessels marked by HRP along their course through the gray matter. HRP spread from the wall of type-B vessels, labeling the labyrinths, the intercellular space of the ependymal lining, and the lumen of the central canal. This suggests a communication between the central canal and the outer cerebrospinal fluid space, at the level of the medial ventral sulcus, via the intercellular spaces, the perivascular basement membrane and its labyrinthine extensions.

Animals↗
PubMed1984

Free-floating cells in the endolymphatic sac after surgical utricular nerve section.

Free-floating cells (FFC) in endolymphatic sac (ES) were microscopically examined, counted, and statistically studied in 8 squirrel monkeys after the unilateral section of the utricular nerve (UNS). After the operation these monkeys were kept for 17-38 days until the acquisition of functional (locomotor balance) compensation was completed. The result showed twice more FFC in the ES on the operated side, than those on the nonoperated side. The result showed a significant increase (p less than 0.05) of FFC in the ES under the pathological condition with autogenous debris in the endolymphatic space, and proved the existence of some reactive role of the ES to the labyrinthine insult.

Animals↗
PubMed1979

[Acoustic neurinomas. Trans-labyrinthine approach (author's transl)].

The authors, supporters of a tight oto-neuro-surgical collaboration, show their tactical evolution in front of acoustic neurinomas which they operated at first in two stages, trans-labyrinthine then sub-occipital, and now they approach only by trans-labyrinthine way. They report their experience and their results to the point of a first serie of 30 cases : 10 combined approaches in two stages, and 20 trans-labyrinthine approaches. The mortality (3 cases-10%) for this first serie is still raised. One patient, after a softening of the pons, maintained important sequelles. On the other hand, among the remaining 26 patients, 13 kept a normal facial motricity and 5 recovered but with syncinesis. These first results are still perfectible : among the 20 last cases only trans-labyrinthine approached the facial nerve preservation was realised in 72% of the cases. The most frequent surgical complication is a cerebro-spinal fluid leak (7 cases) which fortunately the most often spontaneously dry up (6 cases) but which justify a very attentive closure technic. The authors show the arguments which convinced them of the interest of the trans-labyrinthine approach such it is done by W. House.

Adult↗
PubMedDate not supplied

Pathogenesis of vocal cord polyps.

Polyps of the vocal cords are a separate entity occurring nowhere else in the larynx or in the human body. Gelatinous and telangiectatic, but mainly transitional types of polyps can be discriminated. Histological, histochemical and electron microscopic investigations on a series of polyps show that an alteration of the permeability of blood vessels may be of importance, allowing the extravasation of edema fluid, fibrin or erythrocytes. Following this, reactive processes develop with the formation of labyrinthine vascular spaces. This process is very similar to the organization of a thrombus. Since polyps occur mainly in people who use their voices very intensively, and develop at the site of maximum muscular and aerodynamic forces exerted during phonation, vocal cord polyps are considered a sequela of a phonotrauma.

Humans↗
PubMed1980

Cerebrospinal fluid otorrhea.

Cerebrospinal fluid (CSF) otorrhea is a dangerous and potentially life threatening occurrence for which the otolaryngologist is often consulted. CSF otorrhea occurs on the basis of skull fracture, tumor, infections, congenital anomalies, and operative trauma. Forty-three patients with CSF otorrhea of varied etiology are reviewed in this paper. Eight cases are of congenital or labyrinthine origin confirming at surgery the probable connection between the subarachnoid and perilymphatic spaces. Eleven cases had spinal fluid otorrhea due to infection. All cases presented with symptoms of chronic infection: 4 cases had a history of previous surgery for chronic ear disease; 7 cases had temporal lobe abscess; 1 case had a cerebellar abscess; 8 had tegmen defects secondary to cholesteatoma; in 1 case the tegmen defect was due to previous surgery for chronic infection. Nine of 11 cases have serviceable hearing postoperatively. Fourteen cases of spinal fluid otorrhea resulted from trauma: 1 case was due to traumatic stapes footplate fracture in a congenitally malformed ear; 4 were due to transverse temporal bone fracture; and 9 were due to longitudinal temporal bone fractures. All transverse fractures resulted in nonhearing ears. Three cases were due to a combination of temporal bone fracture and infection. In 2 of these cases chronic infection preceded the fracture; in 1 case the fracture led to chronic ear disease with spinal fluid leakage. One patient required 1 surgical procedure for closure of the otorrhea, 1 patient 2 procedures, and 1 patient 3 procedures. Ten cases are due to translabyrinthine acoustic neuroma removal: 7 cases had resolution of the spinal fluid leakage after conservative nonsurgical treatment; and 3 required surgical intervention using muscle, fat and fascia obliteration of the spinal fluid pathway.

Adolescent↗
PubMed1999

Spontaneous cerebrospinal fluid otorrhea from a tegmen defect: transmastoid repair with minicraniotomy.

Spontaneous cerebrospinal fluid (CSF) otorrhea is a rare condition that presents in 2 clinical categories. In congenital labyrinthine malformations, it leads to bouts of meningitis in a hearing-impaired child. In the adult age group, a spontaneous CSF leak almost always results from a dural and bony defect in the tegmen area. Possible pathogenic mechanisms include progressive sagging and rupture of dura through a congenital tegmen dehiscence and progressive bone erosion by aberrant arachnoid granulations. These patients usually present with a middle ear effusion, resulting in clear discharge after myringotomy with tube insertion. Based on 4 patients with a CSF leak from a tegmen defect, this report reviews the clinical findings and diagnostic approach. The surgical management by a 5-layer closure using a transmastoid approach with minicraniotomy is outlined. This procedure offers a relatively simple and reliable method for repair without the inherent risks of a middle fossa craniotomy.

Age of Onset↗
PubMed2002

Spontaneous cerebrospinal fluid otorrhoea: case report and literature review.

Cerebrospinal fluid otorrhoea may occur through the temporal bone both in children and adults. In children it is generally associated with labyrinthine malformations and usually presents with hearing loss in a child with recurrent meningitis. In adults it is sequel to direct head injury, otologic or neurotologic surgery or infection. More rarely this pathology is described as being "spontaneous", occurring without any history of trauma, surgery or infection. Spontaneous cerebrospinal fluid otorrhoea in adults may present with dull symptoms such as a blocked ear or short term conductive hearing-loss. The anatomic site of this fistula is the tegmen tympani which may have a microscopic or macroscopic bone deficiency or sometimes even a "silent" meningoencephalic herniation. The authors describe a case of spontaneous cerebrospinal fluid otorrhoea occurring in an adult patient with bilateral absence of the tegmen tympani and review the literature regarding this specific. They suggest that its actual occurrence may be underestimated. Special attention should be given to adult patients with recurrent or persistent middle ear effusion. Any suspicion should be followed by meticulous imaging and surgical exploration since this may be a lifethreatnening situation.

Cerebrospinal Fluid Otorrhea↗
PubMed1992

Transcranial magnetic stimulation of the facial nerve: intraoperative study on the effect of stimulus parameters on the excitation site in man.

Magnetic stimulation (magStim) of the intracranial facial nerve is performed in clinical and research settings, but the activation site is a matter of controversy. Latencies of nasalis muscle responses to magStim were, therefore, compared with those obtained by direct electrical stimulation of the facial nerve (a) at the root exit zone (REZ); (b) at the porus of the facial canal; and (c) in the stylomastoid fossa during microvascular decompression operations in the cerebellopontine angle (CPA). Measurements of latencies of the nasalis muscle response, obtained while the stimulating coil was placed over the parieto-occipital area of the scalp, indicated that it was the labryinthine segment of the facial canal, 5 to 16 mm distal to the CPA, that was activated. This would be in agreement with studies of physical models reported in the literature that showed (a) the strength of the electrical current generated by a magnetic field is particularly high close to a nerve foramen; and (b) excitation to magStim is most likely to occur where the induced electrical field changes rapidly over distance, i.e., at anatomical boundaries between media of high and low specific resistance. These characteristics are found at the end of the labyrinthine segment of the facial canal, where the facial nerve leaves the low-resistance cerebrospinal fluid and enters the high-resistance petrous bone. The site of neural excitation is robust and unaffected by stimulus intensity and current direction within a wide range, or by large changes in location of the coil.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1998

Polychlorinated biphenyl (PCB) exposure produces placental vascular and trophoblastic lesions in the mink (Mustela vison): a light and electron microscopic study.

Polychlorinated biphenyls (PCBs) cross the placenta and cause fetal death in mink. No indications of impaired implantation have been reported. To study the effects of PCB on mink placental morphology, 2 groups each of 10 animals were orally exposed to Clophen A50 at 0.65 mg (low dose) and 1.3 mg (high dose) per day for 54 days, starting before mating, with 10 control animals. Placentae from mid to late gestation were examined by light and electron microscopy. In the controls, 11% of placentae were degenerate compared to 31% (low dose) and 64% (high dose) in PCB-exposed mink. All control animals exhibited implantation sites, while one animal in the low dose and four in the high-dose group exhibited none. However, there was no difference between PCB-exposed and control animals in the number of placentation sites in implanted animals. Fetal death was markedly increased in PCB-exposed mink, with only four animals (low dose) having all viable fetuses and eight (low and high dose) having a mixture of viable and dead fetuses. Nine exposed animals displayed maternal vascular lesions in the placental labyrinthine zones of viable fetuses, comprising loss and degeneration of endothelial cells, thrombi and haemorrhages. Extracellular fluid was present between the interstitial layer of maternal vessels and the syncytiotrophoblast, and there was focal degeneration of the trophoblast and fetal vasculature. It appears, therefore, that exposure of the mink placenta to PCBs affects maternal vasculature and produces degenerative changes in the trophoblast and fetal vessels, leading to fetal growth retardation or death.

Animals↗
PubMed1995

[An atraumatic needle for continuous epidural and plexus anesthesia].

The needle type introduced by Edward Tuphy for continuous spinal anaesthesia in 1944 is still used as the standard instrument for epidural anaesthesia up to the present day. Puncture of the dura and severance of the epidural catheter are the typical, though fare, complications of this procedure, giving rise to most of the actions brought for damage suffered during obstetric anaesthesia. The cerebral spinal fluid loss caused by thick needles can have serious consequences, including subdural and intracranial haematoma, cranial nerve pareses, labyrinthine hearing impairments and pneumocephalus. Special Sprotte needle for catheter introduction. In spinal anaesthesia and lumbar puncture the Sprotte needle has proven a very suitable instrument for the CSF loss syndrome and, to a large degree, post-spinal headaches. To adapt the atraumatic properties of this needle point for epidural anaesthesia the needle has been equipped with a plastic ramp to direct catheter insertion, and the opening geometry has been slightly modified for epidural application (see Fig. 1). The lateral catheter channel projects into the base of the needle point, which is thus shortened, and the edges of the needle opening are rounded so that the catheters cannot be severed. This needle bears the type designated "Special Sprotte needle" (EP no. 271715, USP no. 4842585). Needle diameter and application fields. The 1.1-mm (19.5 G) needle with 23-G catheter was introduced for epidural anaesthesia and continuous plexus anaesthesia at the Würzburg University Hospital and has proven itself in routine clinical practice. A 20-G version is being tested with a 25-G catheter for continuous spinal anaesthesia at several centers in USA, because finer spinal catheters are not permitted there by the FDA. For continuous spinal anaesthesia this needle has been available without the modified opening geometry since 1989 in sizes 22 G and 24 G and is wide by used in Europe. CSE technique with special and standard Sprotte needles. Spinal analgesia or anaesthesia) can be performed with the special needle and 123-mm-long 27 G or 29 G standard Sprotte needles before placement of the peridural catheter.

Anesthesia↗
PubMed2002

Theoretical study of the field-induced pattern formation in magnetic liquids.

When a thin layer of magnetic fluid confined with an immiscible nonmagnetic liquid is subjected to a perpendicular field, the formation of hexagonal and labyrinthine patterns is observed experimentally. To develop a coherent theoretical description of this phenomenon, the free energy functionals of both types of magnetic structures are derived. Both energy functionals have the same form, which explains that the theoretical results found in this paper for hexagonal and labyrinthlike striped patterns are analogous. The size of the patterns is determined by minimizing the free energy. The influence of the method for computing the magnetic energy on the theoretical results is studied. An accurate computation of the magnetic energy proves important in predicting the experimental pattern size as a function of external field and of layer height. How the results change, when a constant magnetization is assumed during the pattern formation is also investigated. The transition between hexagonal and striped structures is studied by a comparison of their free energies. The ratio of the magnetic to the nonmagnetic liquid is found to be an important factor for the relative stability of the patterns. In agreement with experiments, striped structures are observed at large phase ratios, whereas at small phase ratios hexagonal patterns predominate.

Journal Article↗
PubMed1985

Pneumocephalus following treatment of a stapes gusher.

A case history is presented of a patient who underwent stapedectomy complicated by a cerebrospinal fluid (CSF) gusher. A persistent postoperative CSF leak was controlled by elevation of the head and spinal drainage. Retrograde passage of air through a labyrinthine fistula, however, resulted in pneumocephalus and transient neurologic deficit. This is a rare but serious complication of treatment of a stapes gusher which demonstrates the potential for entry of air intracranially in the presence of a perilymph fistula.

Adult↗
PubMed1991

Transcranial magnetic stimulation excites the labyrinthine segment of the facial nerve: an intraoperative electrophysiological study in man.

The site where transcranial magnetic stimulation (magStim) depolarizes the facial nerve was investigated in 6 patients who underwent surgery of the cerebellopontine angle (CPA). The facial nerve was stimulated (1) magnetically prior to craniotomy, (2) electrically near the brainstem (elREZ), (3) at the exit from the CPA into the facial canal (elPorus), and (4) in the stylomastoid fossa (elStylo). The range of latency differences (delta) of compound muscle action potentials (CMAPs) recorded from the ipsilateral mentalis muscle were as follows: delta elREZ-magStim: +0.5 to +1.1 ms (P less than or equal to 0.03, Wilcoxon test); delta elPorus-magStim: +0.2 to +0.5 ms (P less than or equal to 0.03); delta elStylo-magStim: +0.8 to +1.0 ms (P less than or equal to 0.03). On the basis of anatomical data and a facial nerve conduction velocity of 33-46 m/s in these patients, it was concluded that transcranial magnetic stimuli depolarized the facial nerve at a location 10-15 mm distal to its entrance into the facial canal. This corresponds to the end of the labyrinthine segment of the facial nerve, i.e. the transit zone where the nerve ceases to be surrounded by cerebrospinal fluid (CSF) with its high electrical conductivity and enters the high-resistance tissue of the petrous bone.

Action Potentials↗
PubMedDate not supplied

Diving injuries to the inner ear.

Most of the previous literature concerning otologic problems in compressed gas environments has emphasized middle ear barotrauma. With recent increases in commercial, military, and sport diving to deeper depths, inner ear disturbances during these exposures have been noted more frequently. Studies of inner ear physiology and pathology during diving indicate that the causes and treatment of these problems differ depending upon the phase and type of diving. Humans exposed to simulated depths of up to 305 meters without barotrauma or decompression sickness develop transient, conductive hearing losses with no audiometric evidence of cochlear dysfunction. Transient vertigo and nystagmus during diving have been noted with caloric stimulation, resulting from the unequal entry of cold water into the external auditory canals, and with asymmetric middle ear pressure equilibration during ascent and descent (alternobaric vertigo). Equilibrium disturbances noted with nitrogen narcosis, oxygen toxicity, hypercarbia, or hypoxia appear primarily related to the effects of these conditions upon the central nervous system and not to specific vestibular end-organ dysfunction. Compression of humans in helium-oxygen at depths greater than 152.4 meters results in transient symptoms of tremor, dizziness, and nausea plus decrements in postural equilibrium and psychomotor performance, the high pressure nervous syndrome. Vestibular function studies during these conditions indicate that these problems are due to central dysfunction and not to vestibular end-organ dysfunction. Persistent inner ear injuries have been noted during several phases of diving: 1) Such injuries during compression (inner ear barotrauma) have been related to round window ruptures occurring with straining, or a Valsalva's maneuver during inadequate middle ear pressure equilibration. Divers who develop cochlear and/or vestibular symptoms during shallow diving in which decompression sickness is unlikely or during compression in deeper diving, should be placed on bed rest with head elevation and avoidance of maneuvers which result in increased cerebrospinal fluid and intralabyrinthine pressure. With no improvement in symptoms after 48 hours, exploratory tympanotomy and repair of a possible labyrinthine window fistula should be considered. Recompression therapy is contraindicated in these cases...

Action Potentials↗
PubMed1990

Ultrastructural studies on the placentae of streptozotocin induced maternal diabetes in the rat.

Following induction of diabetes by a single injection of (IP) streptozotocin (STZ) to pregnant Wistar rats on days 2, 4 and 6 to 12 of gestation, fetuses and placentae were collected on day 20. The controls were either untreated or vehicle treated; alternatively following STZ injection, 2-6 IU of insulin was administered (sc) daily until term. The placentae were fixed in a glutaraldehyde and paraformaldehyde mixture and ultrathin sections were examined under the electron microscope. The structure of the vehicle treated control resembled that of the untreated control. The insulin control group had pathological changes similar to those of the diabetic group but with considerably less frequency. The giant cells in the basal zone of STZ group were numerous; they had abundant dilated cisternae of rough endoplasmic reticulum, intracytoplasmic fibrinoid and nuclear inclusions. The trophospongial cells presented numerous clear vacuoles, lysosomes and myelin bodies. Enlarged vacuoles often impinged deeply on the nucleus. The glycogen cells disintegrated resulting in cyst formation. In the labyrinthine zone, layer I trophoblast revealed increased number of large pores through which layer II trophoblast projected into the maternal sinusoid. Layer II had abundant glycogen, lipid droplets and lysosomes. Layer III had imbibed much fluid and appeared foamy with swollen organelles. Fibrinoid substance was produced by the giant cells, basophils and the trophoblast bordering the maternal sinusoids. Cyst development was preceded by degeneration of glycogen cells in the basal zone and of the trophoblast in the labyrinthine zone. Pronounced development of gonadotropin/somatotropin granule-like 'secretory granules' and smooth endoplasmic reticulum associated lipid droplets also characterised the labyrinthine trophoblast. The observed placental pathology appears to correlate well with the intrauterine growth retardation and fetal malformations recorded in this animal model.

Animals↗