Jan Stahle

Immunodefence of the Inner Ear?: Lymphocyte-Macrophage Interaction in the Endolymphatic Sac

Owing to their proximity to areas exposed to infection, the sensory organs of the inner ear are probably dependent on an efficient antimicrobial defence. The longitudinal flow of endolymph to the endolymphatic sac may be of major importance in this context. Substances entering the ear can be automatically carried to the distal part of the endolymphatic duct, where lymphoid cells are present and endolymphatic phagocytosis occurs. In the intermediate part of the epithelium of the sac morphological signs marking the incoming substances are present. A vigorous interaction between lymphocytes and macrophages, similar to that observed in antigen-activated lymphoid tissue, may be seen. The sac is here surrounded by a rich network of lymphatic capillaries and blood vessels.

The Natural Course of Meniere's Disease

A retrospective study of 161 Meniere patients followed up for 9 years or more is presented. The development with respect to hearing, caloric response, vertigo and ability to work was analysed. The main functional loss was found to take place early in the course of the disease. There was an increase in bilaterality with time.

Long-term progression of Meniére's disease.

A retrospective study of 161 Meniére patients followed up for 9 years or more is presented. The development with respect to hearing, caloric response, vertigo and ability to work was analysed. The main functional loss was found to take place early in the course of the disease. There was an increase in bilaterality with time. Spontaneous relief in vertigo over the years has been noticed.

The Temporal Bone in Patients with Meniere's Disease

Sixty-three patients with Menieres disease were compared with a group of healthy individuals with respect to findings at tomography and plain radiography. The temporal bone in patients differed in many respects from that in the healthy controls. Characteristic features in patients were a lack of periaqueductal pneumatization, a lack of pneumatization medial to the arcuate eminence, a short vestibular aqueduct, a narrow external aperture of the vestibular aqueduct, and a reduction in size of the mastoid air cell system. The mean mastoid area in the diseased ear in patients was 7.93 cm2 and in controls 11.59 cm2. The vestibular aqueduct was visible in its full length on tomograms in 81% of the healthy controls and in 65% of the diseased ears in patients. The mean volume of the mastoid air cell system in Meniere patients, determined at operation, was 5.3 ml.

The Laser as a Tool in Inner-Ear Surgery

Minute and reproducible inner-ear lesions were produced in surviving guinea pigs by using an argon laser. Preselected areas, mainly in the cochlea, were irradiated for 0.5-30 seconds at power densities at the focal spot of around 1 to 2 kW/cm2. the laser beam did not perforate the otic capsule but produced superficial changes. Beneath the impact point in the bone, a rounded lesion was observed in the vascular stria. Damage to the organ of Corti of varying extent occurred, depending on the energy dosage delivered. the organ of Corti in the impact area was characterized by either a complete loss or a reduced number of lipid granules in the Hensen cells. Hair-cell changes covering about one-third of a coil were frequently noted. Variations in the appearance of the cilia after irradiation are presented. Expansions of the tips of the cilia on the outer hair cells are described. the outer hair cells proved to be more affected by the laser irradiation than the inner hair cells. Scanning electron microscopy and p...

Melanin Capacity to Accumulate Drugs in the Internal Ear: A Study on Lidocaine, Bupivacaine and Chlorpromazine

The distribution and retention of labelled lidocaine, bupivacaine, and chlorpromazine to melanin in the internal ear after intravenous and intraperitoneal injection were examined by whole-body autoradiography. Both young pigmented hooded rats and albino rats were studied. In the pigmented rats chlorpromazine showed the greatest accumulation, which was more pronounced in the cochlea than in the vestibular portion. The other two substances were evenly distributed in the internal ear. After a single injection of chlorpromazine and of bupivacaine these substances were still bound to the melanin of the internal ear after 14 days, which was the longest survival time. Lidocaine, on the other hand, had disappeared after only 4 days. Strong uptake and retention of the three substances were observed in the eyes of pigmented animals. In albino animals there was very weak, transient uptake in the internal ear of chlorpromazine and bupivacaine, but not of lidocaine. In studies in vitro on isolated bovine eye melanin there was considerably greater adsorption of chlorpromazine than of lidocaine and bupivacaine. An uptake was noted in the human eye in experiments in vitro. Clinical tests revealed no acute or late damage to hearing or sight after large doses of lidocaine. The participation of melanin in different basal labyrinthine functions such as the energy transfer mechanism and the sound protective mechanism is discussed in the light of the results obtained. Further, the theory is put forward that the melanin affinity of certain substances can be of both therapeutic and ototoxic importance.

Accumulation of 14C-Lidocaine in the Inner Ear Preliminary Clinical Experience utilizing Intravenous Lidocaine in the Treatment of Severe Tinnitus

Clinical experience has demonstrated that intravenously administered local anaesthetics have a mitigating effect on severe tinnitus. In an attempt to gain some insight into the mechanism of this effect, autoradiography of the inner ear of young pigmented rats was performed after intravenous injection of 14C-lidocaine. Some accumulation of lidocaine was found in the modiolus, but almost none in the stria vascularis. A large accumulation was observed in other melanincontaining tissues, such as the hair follicles and uvea. The in vitro accumulation of 14C-labelled lidocaine adsorbed on melanin granules was low (12%) as compared with that of other drugs, such as kanamycin (89%) and chloroquine (85%). These autoradiographic results indicate that lidocaine has an effect upon the inner ear, in addition to its previously demonstrated effect on the CNS.

Laser and the Labyrinth: Some Preliminary Experiments on Pigeons

The inner cars of pigeons have been irradiated by means of a Q-switched ruby laser with an output pulse energy of about 0.3 joule. Atrophy of the epithelium and changes in the bony and membranous labyrinth have been observed. The ability of the laser beam to penetrate thin slices of bone has been tested. The biological effect of the laser beam seems to be mainly thermal, but ultrasonic waves created in the focal spot may contribute.

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.

Macula Utriculi in Four Cases With Meniere's Disease

Four patients suffering from Menieres disease were labyrinthectomized. Maculae utriculi were removed and studied by electron microscopy. The neuro-epithelia from all four patients appeared fairly normal, considering the age of the patients. However, two types of degenerative change, which could be related to the inner ear disorder, could be distinguished. One was vacuolation of the sensory cell cytoplasm, followed by pycnosis of the nucleus and cell death. The other was cystic degeneration. This started with localized separations between the sensory cell and the nerve chalice. These separations developed into a single cystic cavity. A few large intra-epithelial cysts were found, probably representing the final stage of the cystic degenerative process.