Asymptomatic fibrous dysplasia of the temporal bone.

INTRODUCTION: Fibrous dysplasia is a bone disorder of unknown origin in which normal bone is replaced with fibrotic tissue and disorganised bone trabeculae. The temporal bone is rarely affected. Because of the slowly progressive course of the disease, many mild cases may never be recognised and are found incidentally. We present a patient with fibrous dysplasia of the right temporal bone, who had few complaints. OBJECTIVE: A 62-year-old man was incidentally found to have fibrous dysplasia of the temporal bone on routine computed tomography scan. METHOD: One case report. RESULTS: Computed tomography showed a thickening of the right temporal bone with a ground-glass appearance. The 62-year-old man opted for watchful waiting. CONCLUSION: We have presented an asymptomatic fibrous dysplasia of the temporal bone. Mild cases may never be recognised and are found incidentally because of their slow progression.

Membrane current possessing the properties of a mechano-electric transducer current in inner hair cells of guinea-pig cochlea.

We measured the membrane current possessing the properties of a mechano-electric transducer current in isolated inner hair cells of guinea-pig cochlea. In a free-standing hair bundle, depolarization to +80 mV evoked a stable outward current attributable to the opening of transducer channels, and repolarization to -80 mV evoked a transient inward current indicating adaptation. The time constant of adaptation increased as the membrane potential depolarized. Dihydrostreptomycin diminished both the outward and inward currents.

Idiopathic hypereosinophilic syndrome involving the middle ear: clinical case report and discussion.

Multiple organ system involvement is seen in the idiopathic hypereosinophilic syndrome (HES). Cardiovascular, lung and upper airway, liver, spleen, skin and nervous systems are frequently involved. In this article, we describe two cases of HES involving the middle ear and lung. In both cases, the histological pictures showed an increase of eosinophils in the tissue of the tympanic cavity.

Correlation between MRI findings and second-Look operation in cholesteatoma surgery.

Two-staged intact canal wall tympanoplasty is a common operation for treatment of middle ear cholesteatoma. MRI provides better tissue differentiation of the middle ear and/or mastoid, which often become occupied with soft density tissue after the first operation. If MRI was able to detect the presence of a recurrent or residual cholesteatoma with sufficient sensitivity and specificity, this may facilitate a decrease in the number of second-look procedures. This study compared MRI findings to surgical findings at second-look surgery and calculated the correlation rates between the two sets of findings. Thirty ears having undergone intact canal wall tympanoplasty for cholesteatoma at the initial operation were examined by MRI prior to the second look. Otoscopic findings of the tympanic membrane were nonsuspect in all cases. The true positive rate was 11/30 (37%) and the true negative rate was 10/30 (33%), leading to a radiosurgical correlation of 70%, whereas the false positive rate was 6/30 (20%) and the false negative rate was 3/30 (10%). This indicates that 30% of the MRI findings were incorrect. Therefore, at the present time, MRI does not appear as a likely replacement for second-look surgery in cases of intact canal wall tympanoplasty.

Regulation of inner ear fluid in the guinea pig cochlea after the application of saturated NaCl solution to the round window membrane.

The regulation of K+ and Na+ in the inner ear fluid of the guinea pig was studied after the application of saturated NaCl solution to the round window membrane. K+ and Na+ activities in the scala tympani increased rapidly and then decreased. K+ activity in the scala media increased immediately, but Na+ activity continued to increase during the period of observation. K+ activity in the scala vestibuli continued to increase in the observation period. Na+ activity in the scala vestibuli increased and then decreased. The endocochlear potential decreased immediately to approximately 20% of its initial level. Total activities of K+ and Na+ increased immediately and then decreased in both the scala tympani and scala media. The total activity of K+ and Na+ increased slowly and showed no regulatory decrease in the scala vestibuli. Thus, changing patterns in the total activity of K+ and Na+ were similar for the scala tympani and scala media, but not for the scala media and the scala vestibuli. Different patterns of K+ and Na+ activities among the three scalae indicate that their mechanisms for regulating inner ear fluid differ.

Ramsay-Hunt syndrome in a 4-year-old child.

The Ramsay-Hunt syndrome mostly affects adults, but a small number of children with herpes zoster oticus have been reported. We describe a case of Ramsay Hunt syndrome in a healthy 4-year-old boy. He developed varicella at 7 months of age. At the age of 4 years, he complained of pain in his right ear, and herpes zoster vesicles were noted on his right pinna. Three days later, he developed right facial paralysis. He was treated with intravenous acyclovir and methylprednisolone. One month later, his facial paralysis had fully resolved.

Congenital malformation of the inner ear associated with recurrent meningitis.

Congenital deformities of the labyrinth of the inner ear can be associated with meningitis and varying degrees of hearing loss or deafness. A recurrence of meningitis is due to the development of a fistulous communication between the subarachnoid space and the middle ear cavity, and can prove lethal. An illustrative case of a 4-year-old Japanese girl with bilateral severe hearing loss, recurrent meningitis and malformations of the inner ear and stapes footplate is presented. Removal of the stapes during tympanotomy provoked a gush of cerebrospinal fluid. The defect was repaired successfully, and there has been no further episodes of meningitis to date.

Huge hamartoma with inverted papilloma in the nasal cavity.

We report clinical experience in managing a 46-year-old Japanese man with long-standing nasal obstruction resulting from a huge left nasal mass. Computed tomography, magnetic resonance imaging and biopsy were used to make a provisional diagnosis of inverted papilloma. The mass was resected via a frontal approach combined with rhinotomy. Histopathologic examination of the resected specimen was consistent with a hamartoma that included an inverted papilloma on a portion of its surface. In addition to being rare tumors in the nasal cavity, we believe that our patient's tumor the largest nasal hamartoma ever reported.

Recording of mechano-electrical transduction currents by a nystatin perforated-patch method.

Mechano-electrical transduction (MET) currents in isolated cochlear hair cells of chicks were recorded by use of a nystatin perforated-patch method. The membrane of a cell-attached patch was permeabilized by nystatin in the patch pipette, thus providing electrical continuity between the pipette and the cytoplasm of the cell without loss of cytoplasmic compounds. The current-voltage relationship was linear for the inward-going MET current at negative membrane potentials, but outward currents were reduced at positive membrane potentials, evidence of inward-going rectification. Elevation of the intracellular concentration of calcium at positive membrane potential, mediated via a voltage-dependent Ca2+ channel, may suppress the outward-going MET current by acting from within the cell.

Intracellular calcium suppresses mechano-electrical transduction current in chick cochlear hair cells.

Intracellular calcium concentration ([Ca2+]i) was elevated by photolysis of the caged calcium compound, Nitr-5, and by use of the intrapipette perfusion technique in hair cells dissociated from the chick cochlea. An increase in [Ca2+]i induced an outward-going current at a membrane potential of -40 mV, as recorded with an intracellular medium of 160 mM KCl. This current was carried by the Ca2+-activated K+ current. In contrast, an increase of [Ca2+]i induced an inward-going current at -50 mV with a 160 mM CsCl-based intracellular medium. This inward-going current was carried by the Ca2+-activated non-selective cation current. The amplitude of the mechano-electrical transduction current was suppressed by the increase of [Ca2+]i, achieved both by photolysis and by use of the intrapipette perfusion method.

Elevation of intracellular calcium induced by the intrapipette perfusion technique modifies membrane ion currents in the chick cochlear hair cell.

The concentration of intracellular calcium ion ([Ca2+]i) was altered in the same hair cell dissociated from a chick cochlea by the intrapipette perfusion technique. At a membrane potential of -40 mV, the elevation of [Ca2+]i generated outward-going currents within 60 sec when the intrapipette solution was based on KCl. In controls, at membrane potentials more positive than -50 mV, outward K+ currents were observed and at large positive potentials, the outward K+ current decreased, showing an N-shaped I-V relationship. This outward K+ current was increased by elevation of [Ca2+]i and was partially suppressed by a TEA-containing extracellular solution. We suggest that the Ca2+ increased by the intrapipette perfusion technique operates directly inside the cell membrane and activates Ca(2+)-activated K+ currents.

Gadolinium blocks mechano-electric transducer current in chick cochlear hair cells.

We investigated the effects of gadolinium ion (Gd3+) on the mechano-electrical transduction (MET) current using a whole-cell patch electrode voltage clamp technique in dissociated cochlear hair cells of chicks. Gd3+ blocked the MET channel in a concentration- and voltage-dependent manner. At -50 mV, Gd3+ blocked the MET channel, with a Hill coefficient of 1.14 and a dissociation constant (KD) of 1.01 x 10(-5) M. Adaptation of the MET current disappeared after the introduction of Gd3+, a change that may be due to a decrease in inward going MET currents, specifically the Ca2+ component.

Voltage-dependent Ca2+ channels in the spiral ganglion cells of guinea pig cochlea.

Voltage-dependent Ca2+ channels in spiral ganglion cells (SGCs) isolated from guinea pig cochlea were investigated using the patch-clamp technique in a whole-cell recording mode. The voltage-dependent Na+ and K+ currents were blocked by adding tetrodotoxin, 4-aminopyridine, and tetraethylammonium to the external solution and by using choline or Cs+ in the external and internal solutions instead of Na+ or K+, respectively. The depolarizing voltage steps evoked inward currents with slow current decay. The maximum amplitude of the inward current increased in a hyperbolic manner with increasing extracellular Ca2+ concentration, indicating that the inward current was a voltage-dependent Ca2+ current (ICa). In 5 mM Ca2+ external solution, the ICa activated from a membrane potential around -60 mV and reached full activation at about -10 mV. The ICa inactivated from about -60 mV and became fully inactivated at about O mV, consistent with the high-voltage-activated Ca2+ channel subtype. Ionic selectivities for Ca2+ channels in SGCs were as follows: Ca2+ > Ba2+ > Sr2+. Effects of both inorganic and organic Ca2+ antagonists also were examined. The inhibitory strength was as follows: La3+ > Cd2+ > Ni2+ > or = Co2+ for inorganic Ca2+ antagonists, and flunarizine > nicardipine > methoxyverapamil > diltiazem for organic ones.

Disturbance of regulation of sodium by cis-diamminedichloroplatinum in perilymph of the guinea pig cochlea.

We studied the acute effects of cis-diamminedichloroplatinum (CDDP) on the cochlear partition and inner ear fluid in the guinea pig. At 48 hours after the administration of a single intramuscular injection of CDDP, 12.5 mg/kg of body weight, the endocochlear resting potential (EP) was significantly decreased to 32.1 +/- 1.8 mV in the treated animals, versus 80.6 +/- 1.0 mV in the control animals. There was a significant rise in potassium (K+), sodium (Na+), and chlorine (Cl-) in the endolymph of the animals treated with CDDP as compared with the control animals. Only Na+ was found to increase significantly in the perilymph, reaching more than twice the level of the control animals; both K+ and Cl- remained within the normal range. Serum electrolytes also remained within the normal range. Evaluation of modified ionic permeabilities across the endolymph-perilymph barrier showed an apparent increase in Na+ permeability and a normal range of K+ and Cl- permeabilities. Histopathologic examination of the cochlea showed a moderate collapse of the endolymphatic space, with atrophy of the stria vascularis and destruction of the outer hair cells. The findings suggest that the acute changes produced in the cochlea by administration of CDDP were attributable to a breakdown in the regulation of Na+ metabolism in the perilymph.

Single channel recordings of calcium currents in chick cochlear hair cells.

Single Ca2+ channel currents were recorded from chick cochlear hair cells by using cell-attached patches. The elementary current was about -2 pA at 70 mV positive to the resting potential (R.P.+ 70 mV); the slope conductance over a 40 mV voltage range was 24 pS. The open time histogram was reasonably well expressed by a single exponential function, while the closed time histogram was expressed by a sum of two exponential functions. The Ca2+ channel was activated around R.P.+ 60 mV and the average ensemble current did not decay during 130 ms depolarization, suggesting that the Ca2+ channel in chick cochlear hair cells is the L-type. The Ca2+ channel has three modes of gating behaviour, expressed as current records with brief openings (mode I), no openings (mode 0), or long-lasting openings and very brief closings (mode 2).

The effects of ototoxic drugs on mechano-electric transduction channels in chick cochlear hair cells.

The effects of ototoxic drugs on mechano-electrical transduction (MET) currents were investigated in dissociated cochlear hair cells of the chick, using a whole-cell patch-electrode voltage-clamp technique. Dihydrostreptomycin (DHSM) and cisplatin (cis-dichlorodiammine platinum II, CDDP) blocked the MET channel in a dose- and voltage-dependent manner. In contrast, acetyl salicylate did not suppress the MET current. At -50 mV, DHSM and CDDP blocked the MET channel with a Hill coefficient of 0.93 and 2.1, respectively. These findings suggest that a single DHSM molecule or more than one CDDP molecule binds to a single MET channel.

Potassium circulation in the perilymph of guinea pig cochlea.

To determine whether any differences exist in potassium circulation between the scala vestibuli and scala tympani, we recorded the change in K+ activity in both scalae of the guinea pig cochlea at the basal and third turns, using a double-barrelled, K(+)-sensitive microelectrode after perfusion with artificial perilymph containing 20 mM KCl and 130 mM NaCl. K+ activity increased immediately after the start of perfusion and decreased after its completion. The rates of decrease of K+ activities were approximately 1.0 mEq/l per min in the scala vestibuli of the basal and third turns, also 1.0 mEq/l per min in the scala tympani of the basal turn, and approximately 0.5 mEq/l per min in the scala tympani of the third turn. The rate of decrease of K+ activity in the scala tympani was significantly slower in the third turn than in the basal turn. Blockage of the cochlear aqueduct depressed the rate of decrease of K+ activity in the scala tympani more in the basal turn than in the third turn. These results suggest that there is a difference in potassium circulation between the scala vestibuli and scala tympani, and that the cochlear aqueduct plays an important role in potassium circulation in the perilymph of the scala tympani.

Profiles of resting potentials across the stria vascularis in kanamycin-deafened guinea pigs.

The resting potentials of the marginal cells in the stria vascularis of the guinea pig were determined from changes in the combined electrode-tissue resistance of the electrode. The resistance of the electrode was 45.5 +/- 16.0 M omega (n = 20) before penetration of the stria vascularis and 46.7 +/- 17.3 M omega (n = 20) after penetration. The resistance drops across the luminal membrane of the marginal cells were 46.0 +/- 22.6 M omega (n = 12) in kanamycin-deafened guinea pigs and 54.5 +/- 33.1 M omega (n = 9) in normal guinea pigs. The endocochlear potential (EP) and resting potentials in the marginal cells were 90.1 +/- 6.0 mV (n = 14) and 70.4 +/- 11.3 mV (n = 14) in kanamycin-deafened guinea pigs and 84.8 + 5.1 mV (n = 29) and 74.7 +/- 11.7 mV (n = 29) in normal guinea pigs. The resting potentials in the marginal cells decreased gradually and were approximately 0 mV around 20 min after anoxia in both kanamycin-deafened and normal guinea pigs. These changes were comparable to those of EP in kanamycin-deafened guinea pigs during anoxia. The mechanism of the EP in kanamycin-deafened guinea pigs is discussed.

Cisplatin blocks mechano-electric transducer current in chick cochlear hair cells.

The effects of cisplatin (cis-dichlorodiammine platinum II, CDDP) on the mechano-electrical transduction (MET) current were investigated with a whole-cell patch-electrode voltage clamp technique in dissociated cochlear hair cells of chicks. CDDP blocked the MET channel in a dose- and voltage-dependent manner. At -50 mV, CDDP blocked the MET channel with a Hill coefficient of approximately 2 and a dissociation constant (KD) of 1.5 x 10(-3) M. The kinetics of CDDP blockade consist of a voltage-independent and a voltage-dependent component.

Mechanism of lack of development of negative endocochlear potential in guinea pigs with hair cell loss.

The endocochlear potential (EP), and the concentration of K+, Na+ and Cl- were measured simultaneously in endolymph of guinea pigs. The EP was 85.6 +/- 0.8 mV in normal guinea pigs, 90.7 +/- 0.8 mV in the kanamycin-treated animals, and 91.6 +/- 1.2 mV in those treated with nitrogen mustard-N-oxide (NMNO). Thirty minutes after the onset of anoxia, the EP (negative EP) was -29.3 +/- 1.0 mV in the normal group, -0.2 +/- 1.0 mV in the kanamycin-treated group, and -1.9 +/- 1.3 mV in the NMNO-treated group. The permeability coefficients of K+ (Pk), Na+ (Pna) and Cl- (Pcl) across the endolymph-perilymph barrier during the period of 20-30 min after the onset of anoxia in the normal group were (341.6 +/- 38.2) x 10(-9) cm3 sec-1, (53.0 +/- 8.1) x 10(-9) cm3 sec-1 and (111.8 +/- 27.2) x 10(-9) cm3 sec-1, respectively. Pk was decreased in the kanamycin- and NMNO-treated groups. Pna did not differ between the normal and treated groups. Pcl was increased in the kanamycin- and NMNO-treated groups. The K+:Na+:Cl- permeability ratio was 1:0.16:0.32 in the normal group, 1:1.12:11.6 in the kanamycin-treated group, and 1:0.44:5.60 in the NMNO-treated group. The results indicate that the lack of development of a negative EP in the kanamycin- and NMNO-treated guinea pigs was attributable to the increased Pcl and the decreased Pk across the endolymph-perilymph barrier, probably the organ of Corti, during anoxia.