Laser Scanning Microscopy of the Human Larynx Mucosa: A Preliminary, Ex Vivo Study

OBJECTIVE

Laser scanning microscopy (LSM) supplies in vivo information from epithelia up to depths between 0.1 to 0.5 mm. The aim of this ex vivo prospective pilot study was to investigate the potential use of LSM for the diagnosis of laryngeal cancer and its precursors.

METHODS

Forty-three larynx specimens of 26 patients (age 35-61 years, mean age 51.9+/-9.5 years; 7 women and 19 men) with laryngeal lesions were investigated with LSM. The LSM findings were compared with histopathologic sections. The following criteria were used for characterization of cancerous lesions: enlarged nuclei, enlarged cells with variable shapes, cluster of cells, increased nucleus/cytoplasm ratio, irregular cell architecture, and loss of cellular junctions characterized by lack of visualization of the cell membrane.

RESULTS

LSM enables the visualization of epithelium up to the basement membrane, Reincke space, the subepithelial vessels, and the fibers of the subepithelial space. In contrast to the squamous epithelium, the respiratory epithelium bears kinocilia. The beat of the cilia and the directed mucous transport can be observed ex vivo. With the use of the presented malignancy criteria, a sensitivity of 72.7% and a specificity of 82.9% for differentiation of dysplasia and benign laryngeal lesions from cancer were reached.

CONCLUSIONS

LSM in an ex vivo manner supplies microscopic images up to the subepithelial space. LSM could represent a new technology in laryngology to visualize larynx epithelia. In the next step, in vivo LSM will be applied to evaluate laryngeal lesion in vivo.

Contact Endoscopic Comparison of Morphology of Human Fungiform Papillae of Healthy Subjects and Patients with Transected Chorda Tympani Nerve

BACKGROUND

The chorda tympani nerve (CTN) carries gustatory fibers from taste buds of fungiform papillae (fPap) of the anterior portion of the tongue. Accordingly, middle ear surgery with transection of the CTN may result in gustatory impairment. With use of contact endoscopy, the present study aimed to compare number and shape of fPap and subepithelial vessel formation in patients after CTN transection with that of healthy controls.

MATERIAL AND METHODS

The number of fPap per square centimeter was obtained in addition to measures of gustatory sensitivity using electrogustometry and intensity ratings of natural taste stimuli. Data from 32 healthy subjects (mean age 40 yr; 16 female, 16 male) were compared with those from 14 patients whose CTN had been cut and partly resected during middle ear surgery because of cholesteatoma (mean age 38 yr; 7 female, 7 male). Middle ear surgery was performed by two of the authors.

RESULTS

In healthy subjects, a higher fPap density was found on the tongue's tip compared with its edge; younger subjects had higher densities than older subjects. No sex-related differences were observed. Patients with transected CTN exhibited a significant decrease of taste function as measured with both natural and electric stimuli. In patients, we found significantly fewer and flatter fPap on the side of the tongue where surgery had been performed in comparison with the contralateral side. In addition, fPap density at the ipsilateral side was significantly lower compared with fPap density on the respective side in healthy controls.

CONCLUSION

As established through contact endoscopy, the number of fPap decreases in relation to deafferentation and also in relation to the subjects' age, both of which are accompanied by a decreased gustatory sensitivity.

Implementation of monoclonal antibody fluorescence on the Abbott CELL-DYN Sapphire haematology analyser: evaluation of lymphoid, myeloid and platelet markers

Apart from qualitative flags, that are typically inefficient and uninformative, haematology instruments provide little meaningful information about lymphocyte populations or the lineage of atypical or immature elements, The CELL-DYN Sapphire haematology analyser uses integrated optical and fluorescence (488 nm) measurements, with FL1 (FITC) and FL2 (PE) detectors being configured for fluorescent analysis. As monoclonal antibodies (Mab) are widely used as cellular probes, and are likely to constitute the future basis for immunodifferentials, we explored the feasibility of implementing immunofluorescence on this routine haematology analyser. An extensive series of Mab (CD2, CD3, CD4, CD8, CD11b, CD13, CD14, CD16, CD19, CD22, CD33, CD34, CD41, CD42b, CD45, CD56, CD61, CD64, CD235a and HLA-DR) were tested singly or in FITC/PE combinations. Analyser processing and data acquisition was achieved using CD-Sapphire automated CD61 immunoplatelet or CD3/4/8 assay procedures and, apart from mixing EDTA-blood and antibody, no further sample manipulation was required. Downloaded raw files were processed with cytometry software, and all evaluated reagents showed population discrimination analogous to flow cytometry. Practical procedures were straightforward and required minimal operator training. Extended information that can be obtained from monoclonal antibodies with a routine haematology analyser has the potential to extend haematology laboratory practices and positively impact laboratory and clinical efficiency.

Differential proteome analysis of tonsils from children with chronic tonsillitis or with hyperplasia reveals disease-associated protein expression differences

A proteomic approach has been used to establish a proteome map and differentiate between the protein composition of tonsils from patients with chronic tonsillitis (CT) and that of tonsils with hyperplasia (HPL). Two-dimensional gel analysis was performed with material from four patients with HPL and five patients with CT. An average of approximately 600 spots were detected in each gel. A total of 127 different proteins were identified in 158 spots analyzed by mass spectrometry. Our study revealed disease-associated differences between protein abundance for two protein spots, an HSP27 isoform and UMP-CMP kinase. Both protein spots were more abundant in the CT group. HSP27 ELISA was performed for 32 patients, 12 belonging to the HPL group and 20 to the CT group. ELISA could not be used to differentiate HSP27 isoforms nor to distinguish CT from HPL. HSP27 was found to migrate to two further protein spots in the 2D gels. The differently expressed HSP27 isoform migrated as the most acidic of all the HSP27 isoforms detected, indicating the highest degree of phosphorylation. The sum of all three HSP27 abundances in the gels from the CT group was not different from that of the HPL group, consistent with the ELISA results. Our results suggest that phosphorylation differences caused the observed migration differences of HSP27. Together with the UMP-CMP kinase abundance differences, we conclude that kinase and/or phosphatase activity are different in CT and HPL.

Paraneoplastic changes of oropharyngeal mucosa in breast cancer

BACKGROUND

Paraneoplasias in the oral cavity are uncommon and have been rarely described so far. A woman with isolated papillomatosis and keratosis of oropharyngeal epithelia is reported.

CASE REPORT

In a 43-year-old woman suffering from breast cancer, extensive changes of oropharyngeal epithelia were apparent 2.5 years after primary surgery and combined radiochemotherapy (RCT) as well as relapse therapy with RCT. At that time, radiologic investigations showed no locoregional or distant metastases. Nevertheless, after removal of the upper lip changes and skin resurfacing of the upper lip, progression of the oropharyngeal and labial changes was registered. Subsequent restaging showed advanced liver metastases. After treatment of the liver metastases, a regression of the extensive oropharyngeal changes became apparent.

CONCLUSION

The appearance of untypical changes of oropharyngeal epithelia is suspective of paraneoplasia. In order to diagnose tumor recurrence, a restaging should be performed.

Confocal microscopy of the peripheral gustatory system: comparison between healthy subjects and patients suffering from taste disorders during radiochemotherapy

OBJECTIVES

Laser-scanning microscopy (LSM) was used to compare taste buds and epithelia of fungiform papillae of healthy subjects with those of patients suffering from taste disorders during/after radiochemotherapy (RCT). Aim of the study was to investigate effects responsible for taste loss at a microscopic level.

STUDY DESIGN

Prospective study.

METHODS

Data from 12 healthy subjects (mean age 52.4, SD 9.5 years) were compared with those of 12 patients (mean age 54.7, SD 8.5 years) with head and neck cancer suffering from taste disorders during RCT. Four parameters from LSM were selected for analysis: 1) distance between the pore of the taste buds of fungiform papillae and the crest of the papillary vessels; 2) epithelial cells of each taste bud at 34 mum; 3), cell density, and 4) area of the taste pore at 4 mum. These data were correlated to measures of gustatory sensitivity obtained with both the validated "taste strips" test kit and electrogustometry.

RESULTS

Patients complaining from taste disorders during RCT exhibited a significant decrease of taste function assessed with both natural and electric stimuli. In these patients, we found thicker epithelia and smaller areas of the taste pores compared with healthy subjects. In 30% of those patients, no taste pores were detectable; in deeper sections, however, normal taste buds were present.

CONCLUSIONS

In conclusion, in RCT patients with taste disorders, LSM indicates changes of epithelia of fungiform papilla but no changes of the taste bud structure. Damage of the chorda tympani nerve by scattered rays, direct or indirect mucotoxic effects of chemotherapeutic agents, and covering of taste pores by epithelial cells are likely reasons for taste loss during RCT.

Fixation of the Stapes Footplate in Children: A Clinical and Temporal Bone Histopathologic Study

OBJECTIVE

To clarify the anatomic characteristics, cause, and surgical outcomes relating to fixation of the stapes footplate in children.

STUDY DESIGN

Retrospective case review and four-center histopathologic study of temporal bones.

SETTING

Tertiary referral center.

PATIENTS

We reviewed charts and histologic specimens from 12 children, aged 7 to 13 years, who underwent surgery for footplate fixation. We also studied stapes footplates in 288 temporal bones from 181 children ranging from newborn (20-44 weeks of gestation) to 13 years of age.

MAIN OUTCOME MEASURE

Anomalies of the stapes footplate in children.

RESULTS

The average age of diagnosis of hearing loss was 6.6 years. Criteria for a diagnosis of otosclerosis were progression of a conductive hearing loss and an intraoperative finding of fixation of the anterior stapediovestibular joint in five patients. In contrast, a nonhomogeneous, thickened, fixed footplate and the absence of an annular ligament were indicators of congenital fixation in six children. In one child, there was neither new bone from the otic capsule nor any obvious otosclerotic foci. In the temporal bone study, 17 of 181 (9.4%) children had anomalies of the stapes footplates, with ankylosis in 4 (2.2%). In two subjects (1.1%), there was an otosclerotic focus not in contact with the stapes footplate.

CONCLUSION

Children younger than 6 years with various congenital anomalies are more likely to have congenital footplate fixation, which will present intraoperatively as a thickened footplate with a partial or absent annular ligament. Children older than 6 years with progressive conductive hearing loss are more likely to have otosclerosis, which presents as fixation of the anterior stapediovestibular joint. The difference in surgical outcomes is probably related to different degrees of footplate abnormality.

In vivo observation of papillae of the human tongue using confocal laser scanning microscopy

The aim of this investigation was to visualize the epithelial structures of the tongue using confocal laser scanning microscopy (LSM). The human tongue epithelium of 28 healthy subjects, aged 21-67 years, mean age 38 years, 14 women and 14 men, was examined in vivo by LSM. Using LSM, a combination of the Heidelberg Retina Tomograph HRT II and the Rostock Cornea Module, up to 800-fold magnifications were obtained. On the tongue surface both filiform and fungiform papillae and their taste pores were easily identified. The epithelium of the tongue with its subcellular structures could be observed up to a depth of 50 microm, cellular structures up to 150 microm and subepithelial vessels up to 300 microm. Additionally the papillary crests and blood flow were visible. Confocal LSM seems suitable for noninvasive in vivo examination of the tongue. The hydraulic z scan, the manual start setting and the measurement of the depth allow a clear classification of the observed structures.

An “Endosteal Electrode” for Cochlear Implantation in Cases with Residual Hearing? Feasibility Study: Preliminary Temporal Bone Experiments

BACKGROUND

Over the years, an increasing number of patients with some degree of residual hearing have received cochlear implants. In these cases, the marginal benefit provided by hearing aids alone is not sufficient; however, as experience has already shown, when hearing aids are used in combination with a cochlear implant, more benefit may be obtained. As a prerequisite, this requires that residual hair cell function must remain intact postoperatively. One of the European pioneers of cochlear implants, Ernst Lehnhardt, questioned whether residual hearing might better be preserved if the implanted electrode permits the fluid-filled inner ear space to remain intact. Subsequently, he proposed insertion of a very flat electrode array design into the extraluminal space between the spiral ligament and the bony cochlear wall (endosteum).

OBJECTIVE

Our study aimed to determine whether it is feasible to insert an endosteal electrode model intracochlearly but extraluminarily, anatomically, and ultimately surgically and to determine the impact on surrounding intracochlear structures.

METHODS

Insertion of two silicon models of an endosteal electrode were carried out in 15 human temporal bones. Histologic examination of the temporal bones after electrode insertion was performed on both fresh and fixed specimens to determine whether the desired anatomic site of insertion was achieved. In combination with light reflected and electron microscopic techniques, the extent to which the surrounding structures were impacted was also examined.

RESULTS

Successful insertion of the prototype silicon endosteal electrodes was performed intracochlearly and extraluminarly in 11 of the 15 temporal bone specimens, confirming the anatomic feasibility of insertion into the crevice between the spiral ligament and endosteum.

CONCLUSIONS

On the basis of the anatomy of the human temporal bone, insertion of an "endosteal electrode" is feasible. Subsequently, in vivo animal studies are needed to determine the physical effects of insertion of an endosteal electrode design prototype upon the functionality of the surrounding intracochlear structures and in particularly the ability to preserve hearing function.

Konzept eines „endostealen” Cochlear Implant-Elektrodenträgers für Patienten mit Restgehör und Machbarkeitsstudie aus anatomischer Sicht

BACKGROUND

Many patients with severe hearing loss could benefit from a bimodal stimulation unilaterally: acoustically in the apical region of the cochlea with some residual low frequency hearing and electrically via a cochlear implant in the basal turn with lost high hearing in the high frequency range. As a new concept we introduce the idea of an "endosteal electrode" - to be inserted between spiral ligament and endosteum of the bony wall without opening the fluid-filled inner ear. In this paper the feasibility from the anatomical point of view is to be proven.

MATERIALS AND METHODS

In 10 human temporal bone specimens the bone covering the membraneous inner ear is carefully removed in the site of a typical cochleostomy. It should by proven whether or not the soft tissue layer covering the inner ear could be left intact and, furthermore, whether a "dummy-electrode array" could be inserted "endosteally".

RESULTS

In 10 of the 10 specimen the preparation could be carried out in the desired way, leaving the spiral ligament intact. The regular site of the "electrode" was morphologically proven after embedding the specimens for histological evaluation.

CONCLUSIONS

From the anatomical point of view, an "endosteal cochlear implantation" seems feasible. Further experiments including animal studies must show, whether this concept might succeed functionally.

[Effects of systemic or topical administration of corticosteroids and vitamin B in patients with olfactory loss]

BACKGROUND

Aim of the present, unblinded, multicentric, open trial was to compare effects of 3 treatments in patients with olfactory dysfunction.

METHODS

Treatments included administration of systemic corticosteroids (oral prednisolone), local corticosteroids (mometasone nasal spray), and systemic vitamin B, respectively. A total of 192 patients participated (95 women, 97 men; mean age 56 years). Duration of the smell loss ranged from 1 to 288 months (average 45 months). Olfactory dysfunction was due to infections of the upper respiratory tract (n = 72), sinunasal disease (n = 19), and posttraumatic olfactory loss (n = 10); the largest portion was classified as idiopathic (n = 85); other causes were rare (n = 6).

RESULTS

Following systemic administration of corticosteroids improvement of olfactory function was observed (p < 0.001). Similarly, improvement of the sense of smell was found 2 (p = 0.03) and 6 months (p = 0.001) after local administration of mometasone, respectively. In contrast, after administration of vitamin B no significant change of olfactory function was seen after 2 months, while improvement was present after 6 months (p = 0.001). Duration of olfactory dysfunction had no effect on changes of smell function.

CONCLUSIONS

These results indicate that improvement of olfactory function is found in olfactory dysfunction of different causes. Adequately controlled, blinded studies are needed to further explore potential effects of the various treatments.

Stapesfixation bei Kindern

BACKGROUND AND OBJECTIVE

The audiometric results after stapes surgery in children with isolated stapes footplate fixation were reason enough to analyze intraoperative findings and surgical procedures.

PATIENTS/METHODS

A total of 438 stapes surgeries were performed in the years 1985-2000, and a retrospective analysis was made of the anamnestic data, intraoperative findings and audiometric data from 12 children with isolated fixation of the stapes footplate. The average age of the children when operated was 10.2 years (the youngest was 7 and the eldest 13). A loss of hearing had set in 5 years earlier.

RESULTS

Taking the anamnestic data and the intraoperative into account, otosclerosis was found in 5 children. One child had a narrow oval window niche, in a further six children a congenital fixation of the stapes footplate was evident. Only 58% (n=7) of the 12 children operated showed acceptable postoperative hearing results. The best hearing results were found in children with juvenile otosclerosis. In three of six children with congenital stapes fixation, a worsening of both bone and air conduction was evident. The average conductive hearing loss was 30 dB at 1, 2 and 4 kHz.

CONCLUSIONS

When explorative tympanotomy is indicated, a thin-layer CT scan of the temporal bone should be made to assess the risk of a liquor pressure labyrinth developing.

Riechst�rungen

The present manuscript is the result of a collaborative effort within the framework of the Working Group of Olfactology and Gustology of the German Society for ENT, Head and Neck Surgery. It provides a comprehensive overview about the current views on the epidemiology, terminology, diagnostics, and therapy of olfactory dysfunction, and aims to offer a framework for the standardized procedures for the diagnosis and therapy of olfactory disorders.

[Testing the sense of taste using validated procedures]

Psychophysical tests related to the sense of taste are usually less complex than those of the sense of smell. In addition to global tests a regional examination of the sense of taste might be indicated to search for nerve lesions. There are numerous validated psychophysical tests available based on the administration of liquid or solid substrates. The use of electrical currents (electrogustometry) is especially feasible for a rapid regional testing. The registration of gustatory event-related potentials to objectify results from psychophysical examination is possible although limited to a few centers world-wide.

[Testing the sense of smell using validated procedures]

There is a growing interest into the investigation of smell disorders in both research and clinical practice. For psychophysical ("subjective") investigations related to the sense of smell a variety of test kits are available, namely the various "Sniffin' Sticks" kits, the UPSIT (University of Pennsylvania Smell Identification Test) or the CCSIT (Cross-Cultural Smell Identification Test). Recording of olfactory evoked potentials (OEPs) and respiration olfactometry can be used for diagnosing smell dysfunctions in a more objective way.

Konfokale Laser-Scanning-Mikroskopie zur Beurteilung des Zungenepithels

BACKGROUND

Superficial changes of the epithelium of the tongue are diagnosed by biopsy. The aim of this in-vivo study was to show the normal epithelium, the subepithelial structures and the subepithelial vessels of the tongue using confocal microscopy.

METHODS

A digital confocal Laser-Scanning Microscope (LSM), a combination of the Heidelberg Retina Tomograph HRT II and the Rostock Cornea Module (Heidelberg Engineering GmbH) was used. This digital microscope makes computer-based external hydraulic z-scan possible and the automatic collection of patient-based video sequences and the 3D reconstruction of the structures of the fungiform papilla. 800-fold magnifications are possible using a water immersion lens (Zeiss, 63-fold). A parabolic plexiglass disc with holes and a video camera were used to stabilize the tongue and to control the contact between the tongue surface and the contact element of the lens.

PATIENTS

Confocal microscopy was performed on 17 healthy test volunteers aged 21 to 56.

RESULTS

First findings with confocal LSM as a contact procedure show that a precise identification of the fungiform and filiform papillae and 3D reconstruction of the pores is possible. Furthermore, different cell layers of the tongue epithelium, subcellular structures of the epithelium and the subepithelial vessels to depth of 50 microm can be visualized by the erythrocytic flow and a max. 800-fold magnification.

CONCLUSIONS

The confocal LSM is a nondestructive contact procedure and allows the in-vivo analysis of the tongue epithelium.

[Contact endoscopic quantification of fungiform papillae--correlation to taste ability?]

BACKGROUND

Besides anamnestic data and taste test, the clarification of epithelial taste disorders makes macroscopic evaluation of the surface of the tongue necessary.

METHODS

In this article the contact endoscopy is evaluated for examination of the tongue epithelium and for quantification of the fungiforme papillae. These results are related to the results of the spatial taste test (1. chemical taste test with sodium chloride in 2 different suprathreshold concentrations and sucrose in also 2 different suprathreshold concentrations; 2. electrogustometry with a bipolar electrode).

PATIENTS

In a prospective study we performed contact endoscopy in 16 healthy volunteers from ages 7 to 68 years. The subjects were divided into 2 age groups (< or = 45 years and > 45 years) and 2 papillae density groups. In 34 patients with either taste disorders of unknown cause or in patients with macroscopic changes at the tongue surface, the spatial and whole mouth taste tests and contact endoscopy were used to clarify the cause of the complaints.

RESULTS

Density and shape of the fungiform papillae as well as the shape of the subepithelial vessels of the papillae vary among the investigated human subjects in the different age groups. No correlation between intensity ratings, papillae density und age was found after stimulation with 40 % sucrose at the tongue tip in the younger age group. Stimulation of the tongue edge with 15 % sodium chloride, however, showed a relationship between the two different density groups and the different age groups.

CONCLUSIONS

The contact endoscopy allows the evaluation of the epithelium in the oral cavity. It is a nondestructive method and is additionally easy to handle, but the evaluation of the observed epithelia needs interdisciplinary co-operation with pathologists. No relevant informations are supplied in diagnostics of taste disorders.

[Taste disorders and recovery of the taste function after middle ear surgery]

BACKGROUND

The incidence and the scale of recovery of the taste function after middle ear surgery is usually determined by the use of anamnestic data and electrogustometry.

METHODS

Taste tests (regional chemical taste test, electrogustometry and subjective evaluation) were performed preoperatively, 2 to 3 weeks and 6 to 9 months after middle ear surgery. These results were evaluated by taking the scale of chorda tympani nerve (CTN) manipulation into consideration. Three groups were chosen: group 1: no or small CTN manipulation, n = 54; group 2: strong CTN manipulation, n = 14; group 3: severed CTN, n = 50.

PATIENTS

In a prospective study 118 patients were examined after middle ear surgery in the ENT-Department of the University of Rostock between 2001 and 2002. 61 females and 57 males, age from 7 - 81 years, were included.

RESULTS

Complaints were observed in all three groups, mainly in groups 2 and 3. These included taste disorders, taste phenomenon and numbness of the tongue. Using regional chemical taste tests, the taste loss of group 3 could be proven for those patients with complaints in 64 % and for those patients without complaints in 27 %. The electrogustometry is more sensitive than chemical taste test. All patients had pathological thresholds after chorda cutting (78 % no thresholds; 22 % elevated thresholds). 68 out of 118 patients (58 %) had a second follow-up after 6 to 9 months after middle ear surgery. The complaints are declining in all groups. In groups 2 and 3 a recovery of taste function could be observed. Even if the number of patients with severed chorda, who suffer from taste disorders, diminishes, a recovery of the taste function could only be observed in 30 %.

CONCLUSIONS

The scale of chorda manipulation is important for the recovery of the taste function after middle ear surgery. The CTN should be preserved intraoperatively, especially when an operation of the contralateral ear is planned as well.

Replication timing of human telomeric DNA and other repetitive sequences analyzed by fluorescence in situ hybridization and flow cytometry

The replication timing of telomeres seems to differ between species. Yeast telomeres are late replicating, whereas limited data from very few human cell lines have indicated telomere replication throughout S phase. In the present study a series of permanent cell lines and patient samples was investigated using a flow cytometric approach for telomere length determination based on in situ hybridization using peptide nucleic acid probes and DNA staining. This method permits selective analysis of cells in specific phases of the cell cycle without perturbation of the cell cycle machinery. The timing of replication of telomeric C(3)TA(2) and T(2)AG(3) repeats was found to differ between individual samples and could precede or be concomitant with the replication of bulk DNA. Replication of the T(2)AG(3) strand seemed to occur somewhat later than that of the C(3)TA(2) strand in some samples. (GTG)(n) and other repetitive sequences generally showed a replication pattern similar to that of the bulk of DNA with slightly individual differences, whereas centromeric DNA repeats consistently replicated within a short time frame in late S phase. The apparent variability in replication timing seen for telomeric DNA might suggest individual differences in firing of replication origins.

Heat radiation during caloric vestibular test: thermographic demonstration in temporal bone experiments

Since Barany's descriptions in 1906, cold and warm irrigations of the external ear canal have been used for unilaterally testing vestibular excitability. The fluid kinetics within the endolymph have been studied thoroughly, whereas relatively few published articles deal with the mechanisms of heat transfer from the external to the internal ear. Even though heat conduction via the bone seemed to be well established in the textbooks, Feldmann and co-workers found heat radiation to be a very important factor. Using a rather uncommon method, we tried to make this heat radiation more apparent: in temporal bone experiments, temperature distribution was followed by thermography. Temporal bone specimens were prepared in such a way that heat distributions became visible after experimental caloric irrigations of the external ear canal. Temperature changes could well be verified by changes in coloration of the 2-dimensional thermograms. Conclusions were drawn from registrations performed in 2 projections, 90 degrees to each other, allowing cautious statements about 3-dimensional distribution. The velocity of heat transfer at the very onset of the reaction can only be explained by radiation, whereas later, other mechanisms, such as conduction via the bone or convection via the middle ear gas, may have some influence. Our results support Feldmann's findings and underline the significance of radiation in the heat transfer mechanism.