Clarence Angelborg

Supporting elements in the organ of Corti. I. Fibrillar structures in the supporting cells of the organ of Corti of mammals.

Supporting elements in the organ of Corti : I. Fibrillar structures in the supporting cells of the organ of Corti of mammals

Cochlear blood flow increases after systemic hemodilution: Comparison of simultaneous laser doppler flowmetry and radioactive microsphere measurements

Guinea pig cochlear blood flow was measured before and after systemic normovolemic hemodilution with high molecular weight dextran. Absolute determinations of blood flow (in the cochlea, brain, kidney and lung) were accomplished by use of radioactive-labeled (85Sr or 141Ce) microspheres. Relative measurements of the cochlear blood flow changes were made simultaneously by the use of a laser Doppler flowmeter. The flowmeter probe was placed on the first cochlear turn. Hemodilution to an average systemic hematocrit of 20% increased cochlear blood flow by 250% as measured with microspheres. The laser Doppler instrument significantly underestimated the actual flow increase giving an indication of 148%. Furthermore, the data, when analyzed on an individual trial basis, showed a very poor correlation between the two methods. The theoretical basis for these findings in relation to the use of the laser Doppler instrument is discussed.

THE CALORIC RESPONSE IN MENIBRE'S DISEASE DURING SPONTANEOUS AND GLYCERIN-INDUCED CHANGES OF THE HEARING LOSS

In patients with Menieres disease the caloric response from the diseased labyrinth may vary during the course of the disease. Fluctuations in caloric response and fluctuations in hearing may occur independently. After the consumption of glycerin by patients with Menieres disease, the caloric response from the diseased ear may be reduced, reinforced or unaffected. Variations in caloric response and hearing have been compared; no distinct individual pattern has been noted. Possible reasons for the lack of agreement in the reaction pattern in the acoustic and non-acoustic labyrinth, both during the course of the disease and after glycerin consumption, are discussed. After glycerin consumption, the caloric response was reduced on one side in one out of seven normal subjects, while the hearing remained unaffected. Glycerin may provoke direction-changing positional nystagmus in normal subjects as well as in patients with Menieres disease.

The Effect of Glycerol on Cochlear Blood Flow

Cochlear and cerebral blood flows were measured in albino rabbits by the microsphere method before and 15 min after intravenous administration of glycerol. Both cochlear and cerebral blood flow were significantly increased. The increase in cochlear blood circulation is interpreted as a contributory factor in producing the improvements in hearing threshold seen in the positive glycerol test in Ménières disease.

Serum osmolality in patients with Meniére's disease.

Hyperosmolality in serum was found in 19 of 56 patients with Menieres disease. The cause of the moderately elevated serum osmolality has not yet been identified. The serum sodium and potassium concentrations were within normal limits. The hyperosmolality may indicate that Menieres disease is a disorder afflicting the entire organism. Hyperosmolality alternating with normal osmolality was seen in several patients, a phenomenon which may be in accordance with the general fluctuating character of the disease. The elevation of serum osmolality after the peroral consumption of glycerin in patients with Menieres disease was studied and related to the hearing loss, and no correlation was found.

An Ultrastructural and Functional Study of the Inner Ear after Administration of Hyaluronan into the Middle Ear of the Guinea Pig

A single dose of hyaluronan, 19 mg/ml was administered into the right middle ear cavity of guinea pigs. The auditory function of the right ear was tested by recording the gross neural action potential (N1) before, directly after, and 28 days after the administration of hyaluronan. In a control group the right ear was sham-operated and the gross neural action potential (N1) was recorded twice; on the day of the sham operation and 28 days later. All animals were killed 28 days after the operation. All treated as well as sham-operated ears and every second intact ear were studied by scanning electron microscopy (SEM.) No ear had signs of hearing deterioration. Macroscopically, most of the hyaluronan was eliminated from the middle ear after 28 days. In the histological examination, pathological stereocilia were found in the apical turn of the cochlea in the ears to which hyaluronan was administered, the sham operated and the intact ears.

Cochlear Blood Flow in Endolymphatic Hydrops

There is no animal model for Menieres disease but by obliteration of the endolymphatic duct, endolymphatic hydrops may be achieved in several animal species. In order to measure the cochlear blood flow in ears with endolymphatic hydrops the endolymphatic duct was obliterated in 9 guinea pigs. The blood flow was measured with the microsphere method and the cochlear histology was studied. The regional and total blood flow was determined in the serially sectioned cochleas 2, 4 and 8 months after obliteration of the endolymphatic duct. No change in regional or total cochlear blood flow was observed in the hydropic ears.

THE EFFECT OF UREA AND MANNITOL ON COCHLEAR BLOOD FLOW

The cochlear and cerebral blood flows were investigated in albino rabbits with the microsphere method, both before and after intravenous injection of hyper-osmotic solutions of urea or mannitol. A significant increase in blood flow was recorded in both the inner ear and the brain. The discrepancies in the effects on blood flow and on hearing in patients with Menieres disease provided by urea and mannitol are discussed.

The Microsphere Method for Studies of Inner Ear Blood Flow

The microsphere method was adapted in 1974 for studies of cochlear blood flow. Since then it has been used in Uppsala, Sweden, at the Department of Otolaryngology, University Hospital, for investigations of the blood flow circulation in the inner ear. The experience with the technique, the subjects, the actual projects and the results are presented and discussed.

Distribution of Macromolecular Tracer Particles (Thorotrast(R)) in the Cochlea. An Electron Microscopic Study in Guinea Pig: Part I. The organ of Corti, the basilar membrane and the tympanic covering layer.

Thorotrast(R) containing thorium dioxide particles with diameters of around 100 Å was introduced in perilymph or endolymph using various methods and concentrations. The location of the tracer particles in the cochleas was determined using the transmission electron microscope. Injection of tracer into the cerebrospinal fluid (CSF) was considered to be the least unphysiological way to bring the tracer to the cochlea, and therefore most of the experiments were performed in that way. The distribution of tracer was very dependent on the mode of injection and the concentration of tracer in the cochlea. With very high concentrations it appeared that every kind of cell had a capacity of phagocytizing. No significant tracer uptake was noted in the cells of the organ of Corti after direct injection of small amounts of tracer in the cochlear duct. After tracer administration in the cerebrospinal fluid, the tracer rapidly reached the scala tympani. The tympanic border cells contained large numbers of tracer particles, while lesser amounts were found in the homogenous parts of the basilar membrane. No tracer was seen in the cells of the organ of Corti. After perfusion of the cochlear perilymph, some tracer was seen in the cells of the organ of Corti. The limited passage of tracer to the organ of Corti was not regarded as proof of free communication between perilymph and cortilymph. Glycerol administration to the animals did not change the propagation of tracer in the cochlea. After injection of tracer into dead animals, tracer inclusions could be seen in the tympanic border cells, indicating the possibility of a cell phagocytizing ability, also some time after death.