Safety assessment of trans-tympanic photobiomodulation.

We evaluated functional and morphological changes after trans-tympanic laser application using several different powers of photobiomodulation (PBM). The left (L) ears of 17 rats were irradiated for 30 min daily over 14 days using a power density of 909.1 (group A, 5040 J), 1136.4 (group B, 6300 J), and 1363.6 (group C, 7560 J) mW/cm(2). The right (N) ears served as controls. The safety of PBM was determined by endoscopic findings, auditory brainstem response (ABR) thresholds, and histological images of hair cells using confocal microscopy, and light microscopic images of the external auditory canal (EAC) and tympanic membrane (TM). Endoscopic findings revealed severe inflammation in the TM of C group; no other group showed damage in the TM. No significant difference in ABR threshold was found in the PBM-treated groups (excluding the group with TM damage). Confocal microscopy showed no histological difference between the AL and AN, or BL and BN groups. However, light microscopy showed more prominent edema, inflammation, and vascular congestion in the TM of BL ears. This study found a dose-response relationship between laser power parameters and TM changes. These results will be useful for defining future allowance criteria for trans-tympanic laser therapies.

Computer simulation study of the penetration of pulsed 30, 60 and 90 GHz radiation into the human ear.

There is increasing interest in applications which use the 30 to 90 GHz frequency range, including automotive radar, 5 G cellular networks and wireless local area links. This study investigated pulsed 30-90 GHz radiation penetration into the human ear canal and tympanic membrane using computational phantoms. Modelling involved 100 ps and 20 ps pulsed excitation at three angles: direct (orthogonal), 30° anterior, and 45° superior to the ear canal. The incident power flux density (PD) estimation was normalised to the International Commission on Non-Ionizing Radiation Protection (1998) standard for general population exposure of 10 Wm-2 and occupational exposure of 50 Wm-2. The PD, specific absorption rate (SAR) and temperature rise within the tympanic membrane was highly dependent on the incident angle of the radiation and frequency. Using a 30 GHz pulse directed orthogonally into the ear canal, the PD in the tympanic membrane was 0.2% of the original maximal signal intensity. The corresponding PD at 90 GHz was 13.8%. A temperature rise of 0.032° C (+20%, -50%) was noted within the tympanic membrane using the equivalent of an occupational standard exposure at 90 GHz. The central area of the tympanic membrane is exposed in a preferential way and local effects on small regions cannot be excluded. The authors strongly advocate further research into the effects of radiation above 60 GHz on the structures of the ear to assist the process of setting standards.

Laser-induced tissue remodeling within the tympanic membrane.

The tympanic membrane (TM) separates the outer ear from the tympanic cavity. Repeated pathologies can permanently decrease its tension, inducing conductive hearing loss and adhesive processes up to cholesteatoma. The current main therapy is its surgical reconstruction. Even though lasers have been proposed to tighten atrophic TMs, details of this effect, specifically histological analyses, are missing. We therefore used laser pulses to induce TM collagen remodeling in an animal model to compare the histological and electrophysiological effects of different applied laser intensities before entering clinical studies. We irradiated Fuchsin-stained areas of the TM in anesthetized mice with 532-nm laser-pulses of 10 mW for 30 s (0.3 J), 25 mW for 30 s (0.75 J) or 50 mW for 30 s (1.5 J) monitoring hearing with auditory brainstem responses (ABRs). The mice were sacrificed after 2 to 8 weeks and histologically analyzed. An increase in the TM thickness within the defined, stained, and irradiated areas could be observed after 4 weeks. Polarized light microscopy and transmission electron microscopy demonstrated the tissue volume increase majorly due to new collagen-fibrils. Directly after irradiation, ABR thresholds did not increase. We herein demonstrate a controlled laser-induced collagen remodeling within defined areas of the TM. This method might be the prophylactic solution for chronic inflammatory ear pathologies related to decreased TM tension.

Tympanic membrane breakdown after intratympanic injection of steroids in irradiated ears.

OBJECTIVE: To describe a rare complication of intratympanic injection of steroids in susceptible ears. PATIENTS: We present two patients with a history of irradiation involving the injected ear. INTERVENTION: Therapeutic. MAIN OUTCOME MEASURE: Tympanic membrane condition after intratympanic injection of steroids. RESULTS: Total or near-total breakdown of the irradiated tympanic membrane. CONCLUSION: Tympanic membranes with an impaired wound-healing ability, together with exposure to intratympanic steroids, may be at risk for total or near-total breakdown.

Effects of Intratympanic Dexamethasone on High-Dose Radiation Ototoxicity In Vivo.

BACKGROUND: Stereotactic radiosurgery for lateral skull base tumors can cause hearing loss when the cochleae are exposed to high doses of single-fraction radiation. Currently, there are no known nondosimetric preventative treatments for radiation-induced ototoxicity. HYPOTHESIS: Intratympanic (IT) dexamethasone (DXM), a synthetic steroid, protects against radiation-induced auditory hair cell (HC) and hearing losses in rats in vivo. METHODS: Seven rats received radiation (12 Gy) to both cochleae. In irradiated rats and six nonirradiated rats, IT DXM was randomized to one ear, while tympanic puncture without DXM was performed on the contralateral ear. Baseline and 4-week postradiation auditory-evoked potential tests were performed. The cochleae were processed for HC viability. RESULTS: Cochleae exposed to radiation demonstrated more outer HC (OHC) loss in all turns than nonirradiated ears (p <0.05). OHCs were more susceptible to radiation injury than inner HCs in the middle and basal turns (p <0.05). In irradiated cochleae, there was a nonsignificant trend for less OHC loss with IT DXM in the basal turn when compared with placebo. IT DXM did not improve radiation-induced hearing threshold shifts; however, a high rate of tympanic membrane perforations occurred with irradiated ears which may contribute to this finding. CONCLUSION: Radiation induced loss of OHCs in all turns of the cochlea. IT DXM reduced OHC loss in the basal turn of irradiated ears; however, this finding did not achieve statistical significance. Although IT DXM did not affect radiation-induced hearing threshold shifts in adult rats in vivo, this may be due to a high rate of tympanic membrane perforations.

Thermal damage threshold at 633 nm of tympanic membrane of pig.

Doppler vibrometers are used by many research groups to monitor the motion of the tympanic membrane (TM) and of middle ear ossicles for in vivo and in vitro studies. Power densities in these applications reach 80 W/cm(2). To determine the safe limit of exposure, a cw dye laser at a wavelength of 633 nm was used to investigate the threshold of thermal damage of TM of pigs under exposure times of 60 s. To determine the applied power density accurately, the spot size of the laser beam was monitored by an objective lens and a CCD camera. Twenty-six laser exposed samples of TM were stained by haematoxylin and eosin stain and the semi-thin sections were examined microscopically. In none of the sections was any laser induced damage observed with power densities below 7.1 kW/cm(2), whereas serious damage occurred showing coagulation, carbonisation and perforation in all cases with laser powers above 8.2 kW/cm(2). The threshold for damage and the conical shape of the damage zone is explained by photon propagation and absorption in the tissue especially by the increase of the scattering factor at higher tissue temperature. The thermal damage threshold of 8 kW/cm(2) is compared to the maximum permissible exposure given in laser safety standards for skin.

Expression of sialic acids in the developing murine tubotympanum.

Sialoglycoconjugates in the developing murine tubotympanum were characterized using lectin histochemistry with wheat germ agglutinin (WGA), Limax flavus agglutinin (LFA), Sambucus nigra agglutinin (SNA), Maackia amurensis agglutinin (MAA), peanut agglutinin (PNA), and neuraminidase treatment. WGA, LFA, MAA, and neuraminidase-PNA labeled epithelial goblet cells, glandular mucous cells, and cell surfaces of adult and newborn murine tubotympanum. SNA did not label any secretory components. PNA labeled secretory cells and cell surfaces of the fetal tubotympanum without neuraminidase treatment. After birth, these secretory cells and cell surfaces were labeled with PNA only after neuraminidase treatment. These results revealed that: Sialoglycoconjugates are produced from glandular mucous cells and epithelial goblet cells and are present on cell surfaces and within the mucous blanket; their terminal tri-saccharide linkage appears to be the sequence Neu5Ac(alpha 2-3)Gal(beta 1-3)GalNAc; sialic acids appear before birth and gradually increase; terminal galactose residues are masked by sialic acids after birth.

Early changes of auditory brain stem evoked response after radiotherapy for nasopharyngeal carcinoma--a prospective study.

A prospective study of the effect of radiotherapy for nasopharyngeal carcinoma on hearing was carried out on 49 patients who had pure tone, impedance audiometry and auditory brain stem evoked response (ABR) recordings before, immediately, three, six and 12 months after radiotherapy. Fourteen patients complained of intermittent tinnitus after radiotherapy. We found that 11 initially normal ears of nine patients developed a middle ear effusion, three to six months after radiotherapy. There was mixed sensorineural and conductive hearing impairment after radiotherapy. Persistent impairment of ABR was detected immediately after completion of radiotherapy. The waves I-III and I-V interpeak latency intervals were significantly prolonged one year after radiotherapy. The study shows that radiotherapy for nasopharyngeal carcinoma impairs hearing by acting on the middle ear, the cochlea and the brain stem auditory pathway.

[The treatment of glomus tympanicum tumors in the years 1962-1992 in the Krakow Otolaryngological Clinic]. / Guzy klebków bebenkowych w materiale Kliniki Otolaryngologii AM w Krakowie w latach 1962-1992.

Between the years 1962-1992 25 woman were treated surgically with glomus tympanicum tumors. All those patients were irradiated postoperatively and 80% of 5 years survival were achieved. According to our experience and data of the literature the method of choice in treatment those tumors should consist of surgery and radiation therapy postoperatively.

[Efficacy of noninvasive hemolaserotherapy in patients with bronchial asthma and concomitant rhinosinusitis]. / Effektivnost' neinvazivnoi gemolazeroterapii u bol'nykh bronkhial'noi astmoi s soputstvuiushchim rinosinusitom.

AIM: To study efficacy of low-intensive infrared laser radiation impact on the tympanic membrane in patients with bronchial asthma (BA) and concomitant rhinosinusitis (RS). MATERIAL AND METHODS: 78 patients with moderate BA of a mixed type and concomitant chronic RS were divided into 3 groups: group 1 patients received medication plus infrared laser radiation of the tympanic membrane and paranasal sinuses; group 2 patients were exposed to supravenous laser radiation (0.63 mcm); group 3 received pharmacotherapy alone. The effect of the treatment was assessed by spirometry, peakflowmetry and paranasal sinuses findings. RESULTS: The highest response was achieved in group 1 which manifested with positive changes in clinical, device and spirometric data on BA and x-ray data on RS courses. The least effective treatment was observed in group 3. CONCLUSION: Use of infrared laser radiation of the tympanic membrane and paranasal sinuses projection in the treatment of BA patients with RS is effective, nontoxic and easy to use both in hospitals and outpatient departments.

[YAG-Nd laser: effects of radiation on acoustic analyser function in experimental animals]. / Vliianie izlucheniia IAG-ND lazera na funktsional'noe sostoianie slukhovogo analizatora éksperimental'nykh zhivotnykh.

Effects of laser radiation on the function of the internal ear receptors were studied using short-latent acoustic evoked potentials (SLAEP) of rabbit truncus cerebri. Contact laser impact in the area of the medial wall of the tympanic cavity in one of the ear was made after registration of baseline SLAEP. The other ear served control. It was found that YAG-Nd laser radiation had the receptor damage threshold within 7-8 W. Assessment of laser energy reaching receptors of the animals' labyrinth was carried out by the thickness of the bone of tympanic medial wall in the rabbit middle ear. Differences in the above thickness in humans and rabbits and calculated transmission factors for laser radiation of the bone tissues indicate that radiation power 14-16 W may appear critical in manipulations on human middle ear.

[Response of spiral organ cells on laser radiation to the region of tympanic graft (experimental study]. / Reaktsiia kletok spiral'nogo organa na lazernoe vozdeistvie v oblasti timpanal'nogo loskuta (éksperimental'noe issledovanie).

Spiral organ cells ultrastructure was studied electron microscopically after exposure to high-energy NIAG-Nd-laser radiation in contactless impulse regimen (1.06 microns, 20-40 W, 100 microseconds) in experimental tympanoplasty. The above laser radiation did not entail gross destruction in receptor and pillar cells in the peripheral compartment of the organ of hearing. Irrespective of the radiation power 3 days after the exposure some irradiated receptor cells showed insignificant changes: mitochondrial vacuolization, altered cuticular plate. 7 days after the exposure a positive response was registered in the majority of the receptor cells and in some pillar cells. This reflects activization of intracelluler biosynthetic processes.

Effect of local irradiation with 630 and 860 nm low-level lasers on tympanic membrane perforation repair in guinea pigs.

OBJECTIVE: In this study, we evaluated the effect of low-level lasers on the healing of tympanic membrane perforation, one of the most common otological pathologies. METHODS AND MATERIALS: Twenty-four guinea pigs were randomly assigned to either the experimental or control group. One day after the induction of a 2 mm diameter, centred myringotomy in all animals, the tympanic membranes in the experimental group were irradiated with 630 and 860 nm lasers for 10 days. Two weeks later, histological changes in the membranes were evaluated. RESULTS: Tympanic membrane thickening and inflammatory cell infiltration in the tympanic membranes and surrounding tissues were significantly less in the experimental group (p < 0.001). The distance from the external auditory canal wall to the malleus tip did not differ significantly between the two groups (p = 0.42). CONCLUSION: The results show that the combined application of 630 and 860 nm lasers had a significant effect on the healing of tympanic membrane perforation, and on the prevention of thick fibrotic or atelectatic neomembrane formation.

Effect of low-level laser treatment on cochlea hair-cell recovery after ototoxic hearing loss.

The primary cause of hearing loss includes damage to cochlear hair cells. Low-level laser therapy (LLLT) has become a popular treatment for damaged nervous systems. Based on the idea that cochlea hair cells and neural cells are from same developmental origin, the effect of LLLT on hearing loss in animal models is evaluated. Hearing loss animal models were established, and the animals were irradiated by 830-nm diode laser once a day for 10 days. Power density of the laser treatment was 900 mW/cm(2), and the fluence was 162 to 194 J. The tympanic membrane was evaluated after LLLT. Thresholds of auditory brainstem responses were evaluated before treatment, after gentamicin, and after 10 days of LLLT. Quantitative scanning electron microscopic (SEM) observations were done by counting remaining hair cells. Tympanic membranes were intact at the end of the experiment. No adverse tissue reaction was found. On SEM images, LLLT significantly increased the number of hair cells in middle and basal turns. Hearing was significantly improved by laser irradiation. After LLLT treatment, both the hearing threshold and hair-cell count significantly improved.

Changes in tympanic temperature during the exposure to electromagnetic fields emitted by mobile phone.

OBJECTIVE: Mobile phones generate microwave radiation which is absorbed by exposed tissue and converted into heat. It may cause detrimental health effects. The aim of the experiment was to check if exposure to EMF emitted by mobile phone influenced the tympanic temperature. MATERIAL AND METHODS: Human volunteer study was performed on ten healthy young men, aged 22.1±4.7 years, examined three times: 1. on a day with 2×60 min of no exposure (sham day), 2. on a day with continuous, 60 min exposure and 60 min of no exposure, 3. on a day with intermittent exposure (4×15 min "on" and 4×15 min "off"). Exposure was generated by mobile phone (frequency 900 MHz, SAR 1.23 W/kg). The study was double-blind, performed under controlled conditions (at 24°C and 70% humidity). The tympanic temperature (T(ty)) was monitored every 10 sec by a thermistor probe placed close to the aural canal membrane in the ear opposite the one in contact with mobile phone (contralateral position). Multivariate repeated-measures analysis of variance was used to calculate the results. RESULTS: The mean T(ty) in the whole group during continuous exposure was significantly higher than during sham exposure (p = 0.0001). During intermittent exposure the temperature was lower than during sham day (difference was up to 0.11°C). Within an hour after continuous exposure, T(ty) was higher by 0.03°C and after intermittent exposure T(ty) was lower by 0.18°C in comparison with sham day. Two hours after exposure T(ty) was significantly lower (p = 0.0001) than after sham exposure (0.06°C and 0.26°C respectively). The trends in T(ty) during experiment differed significantly in relation to exposure conditions (p < 0.05). CONCLUSIONS: The results of this analysis indicate that the physiological response to EMF exposure from mobile phone was mostly related to type of exposure (continuous or intermittent).

Structural changes in the middle ear tissues of the rat after fractionated irradiation.

Chronic suppurative otitis media often ensues in patients treated with irradiation against a head and neck tumor. In an experimental study, rats were exposed to irradiation to evaluate the sensitivity of the middle ear to an accumulated irradiation dose of 20-45 Gy. Observed otomicroscopically, all animals appeared to have normal tympanic membranes and no fluid developed in the middle ear space. Ten days after the irradiation, minor structural changes had occurred in the pars flaccida. The keratinizing epithelium had thickened and mitoses were seen histologically. The lamina propria was edematous and contained polymorphonuclear cells and macrophages. The middle ear mucosa from all other tissue sites appeared normal. Six months after irradiation only minor changes in the pars flaccida were evident: the lamina propria was thin and inelastic and macrophages were present in the stroma. It is inferred from this study that the middle ear of the rat is relatively resistant to irradiation.