Individual models for virtual bone drilling in mastoid surgery

Segmented training cases for virtual simulation of bone-drilling interventions in middle ear surgery have proven to be helpful in learning about surgical anatomy of the temporal bone. The anatomy of the mastoid shows a high degree of variability, however, and the aim of this study was to evaluate whether individual virtual models could be created within an affordable timeframe, and to what extend they reflected natural individual anatomy during virtual mastoid surgery. Automatic segmentation schemes were used, and these reduced the time required to create individual models on the basis of DICOM CT scans to less than 5 minutes. Models based on CT data with a slice distance of 0.4 mm or better were found to provide excellent handling, an acceptable depiction of mastoidal organs, and a helpful impression of the individual surgical situation. Although landmarks are still more easily detected in real mastoids, virtual drilling of individual models makes the 3D estimation of specific anatomy more effective than estimations based on interpretation of CT scans alone.

Restoration of hearing by hearing aids: conventional hearing aids - implantable hearing aids - cochlear implants - auditory brainstem implants

Aim of this report is to explain the current concept of hearing restoration using hearing aids. At present the main issues of conventional hearing aids are the relative benefits of analogue versus digital devices and different strategies for the improvement of hearing in noise. Implantable hearing aids provide a better sound quality and less distortion. The lack of directional microphones is the major disadvantage of the partially implantable hearing aids commercially available. Two different clinical studies about fully implantable hearing aids have been started in 2004. One of the most-promising developments seems to be the electric-acoustic stimulation.

[G-DRG System 2005. Analysis and evaluation of significant changes from the viewpoint of HNO medical science]

With the release of the new Global Case Agreement by Self Administration in Public Health on the 16 September 2004, the adjustment of the G-DRG System for the year 2005 was completed. Otorhinolaryngology, and head and neck surgery face several changes in the fields of diagnosis and procedural coding (ICD-10-GM 2005, OPS-301 2005), G-DRG case allocation, and extra reimbursements for special interventions. Despite some considerable improvements, substantial problems remain unsolved. This paper presents and comments on the key points of the G-DRG System for 2005 for otorhinolaryngology, and head and neck surgery.

[Histomorphological study of experimentally induced canalolithiasis]

Free otoconia in the posterior semicircular canal (pSCC) are regarded as the main reason for benign paroxysmal positional vertigo. We investigated the distribution of otoconia in the membranous labyrinth of guinea pigs (n = 34) after a defined rotatory/angular kinetic acceleration. The angular kinetic energy of the rotatory experiment produced a dislocation of the otoconia and sometimes of the complete gelatinous otolithic membrane of the utricular and saccular macula. The otoconia could be observed in all three semicircular canals but predominated in the dark cell areas of the utricular side of the lateral SCC. A total obstruction of the semicircular canal could never be seen. Close to the lateral crista, perilymphatic hemorrhage could frequently be observed. The saccular otoconia were located in the amalgamation between endolymphatic membrane and saccule. The results of this histological study can form the basis for different theories about the genesis of canalolithiasis and cupulolithiasis and the vertigo which accompanies them.

Beeinflussung muskul�rer Gesichtsschmerzen durch Botulinumtoxin�A

OBJECTIVE

Can chronic pain of the masticatory muscles be positively affected by low dose injection of botulinum toxin (BTX-A)?

METHODS

Twenty patients suffering chronic myofacial pain were questioned and examined after injection of 25-50 U Dysport into the affected muscles over a period of 8 weeks.

RESULTS

Four weeks after injection of BTX-A patients reported a significant reduction of pain (p <0.001, paired t-test. Power of performed test with alpha 0.050:1.000). Then the pain remained constant over the next 4 weeks. Concurrently a significant increase of mandubular range of movement was observed (p <0,05, Wilcoxon signed rank test).

CONCLUSIONS

Even though lacking placebo control the findings suggest that patients suffering chronic myofacial pain may benefit from injection of low dose BTX-A into the affected muscles.

[Oropharyngeal vocal tract space during singing--comparison of tactile-kinesthetic and auditory perception with objective endoscopic findings]

BACKGROUND

In this study we compared the perceived diameter of the vocal tract's oropharyngeal part with the diameter that was determined endoscopically.

METHODS

28 singers (13 male, 15 female) were examined with transnasal fiberscopic pharyngoscopy while singing the vowels /a/, /i/ and /u/ in 4 different timbres (normal, opened, covered, dumpled) and 3 different pitches (chest/modal register, subjective comfortable pitch for singing, head/falsetto register). The tactile-kinesthetic and auditive rating of the singers, the auditive rating of a singing teacher and the visual-endoscopic analysis of three laryngologists were compared.

RESULTS

The tactile-kinesthetic and auditory self-perception of the singers was quite different from the auditive perception of a singing teacher and visual endoscopic findings of the laryngologists. The singers had the impression that the different singing timbres (normal, opened, covered, dumpled) influence oropharyngeal vocal tract space during singing. They judged the vowel itself and the pitch as having very little influence. Based on his auditory perception, the singing teacher also rated that the timbre plays an important role for the oropharyngeal vocal tract space but he found vowels to be the parameter with the greatest impact. Via visual endoscopic examination we found that, among the three parameters (vowel, timbre, pitch), the different vowels are most influential on the oropharyngeal vocal tract space. Analysis of video sequences revealed that pitch and timbre are less important.

CONCLUSION

Subjective tactile-kinesthetic and auditory perception of the singers differs from auditory perception of the singing teacher as well as from endoscopic findings. The endoscopically determined oropharyngeal vocal tract space during singing the vowels /i/ or /u/ tends to be larger compared to the oropharyngeal vocal tract space while singing the vowel /a/.

[Sonography of the larynx--an alternative to laryngoscopy?]

PROBLEM

The aim of this study was to determine whether the pictorial results obtained from B-mode ultrasonography duplicate those of laryngeal endoscopy and whether there are any additional advantages when using ultrasonography.

PATIENTS AND METHODS

A total of 22 patients with various diseases of the larynx were examined ultrasonically with the ultrasound plusing a Sonoline Elegra as well as with a '7.5 L40' and a 'VF 13/5' linear array. In order to compare both methods directly, reference data were prepared and contrasted.

RESULTS

All of the laryngeal lesions recognised in the endoscopic investigation were also demonstrable by the use of ultrasound, although minor changes were difficult to detect. In one case, ultrasonography suggested the presence of an infiltration of the thyroid cartilage, otherwise no additional information was available using this method.

CONCLUSIONS

Using ultrasonography, the image quality of the larynx is worse than that of the soft tissue of the neck, which is determined by the air-mucous membrane boundary as well as the (ossified) cartilaginous skeleton. Thus, ultrasonography is useful in cases of larger laryngeal lesions, while there is no advantage in the detection of small processes.

[Preliminary results for superficial parotidectomy using the ultrasonically activated scalpel (Ultracision Harmonic Scalpel)]

BACKGROUND

The high density of blood vessels in the parotid gland, the direct vicinity to the facial nerve and the narrow surgical situs require efficient intra- and postoperative hemostasis. The ultrasonic scalpel (US) accomplishes both tissue dissection and vessel coagulation simultaneously by an ultrasonically activated shear movement of 55 500 Hz. The combination of hemostasis and tissue dissection particularly qualifies US for use in surgery of the parotid gland. Until now, there have been no published studies about application of US in surgery of the parotid gland.

METHOD

20 patients with benign parotid tumors treated with a conventional technique of superficial parotidectomy and 20 patients with a superficial parotidectomy using the ultrasonically activated scalpel were examined in regard to intra- and postoperative hemostasis, wound healing and postoperative pain. Also, the quality of the histopathological specimen obtained by US was evaluated.

RESULTS

In 85 % (17/20) of superficial parotidectomy efficient intraoperative hemostasis did not require electrocoagulation. In 15 % (3/20) of parotid tumors additional bipolar electrocoagulation were required because of venous bleeding from vessels exceeding 2.0 mm in diameter. Postoperative bleeding did not occur at all. Wound healing was uneventful in all cases. Surgery-related postoperative pain was not intensified. Time of operation was shortened. Histopathological evaluation, especially in the margin area, was not impaired.

CONCLUSION

The US offers tissue dissection with effective intra- and postoperative hemostasis. The combination of simultaneous tissue dissection and hemostasis enables a good overall view and control of the surgical site. In addition, based on the mechanical function the US has only a minimal thermal effect on neighboring tissues and enables controlled tumor resection without damaging the facial nerve.

[New aspects of the mechanics of the auditory tube]

The aim of the present article is to describe the mechanical components of the auditory tube and the role of these components in auditory tube function. Particular attention will be given to those aspects which have not been sufficiently dealt with in the past, such as the role of the isthmus region, the function of the lateral mucosal folds, the significance of the of the surfactant proteins and the pathophysiology of the patulous auditory tube. Special attention is given to the tensor veli palatini muscle and its physiology. Because of its isometric contraction, the function of this muscle depends on so-called hypomochlia changing the direction of its force. In the context of this article, the three hypomochlia involved are the pterygoid hamulus, Ostmann's fatty tissue and the medial pterygoid muscle. The so-called "Eppendorf-maneuver" is depicted for the first time.

[Postoperative nausea and vomiting--pathophysiology, prophylaxis and treatment]

Postoperative nausea and vomiting (PONV) are among the most common complications in operative medicine. Especially patients undergoing middle ear surgery or adenotonsillectomy are frequently associated with PONV (70 %). Furthermore, emesis carries the risk of severe postoperative complications and is associated with additional costs and distress in patient management. If the patient carries a high risk for postoperative emesis, the patient should receive a prophylactic antiemetic therapy. 5-HT 3 receptor antagonists are highly effective in prevention and management of PONV. This review will discuss pathophysiology, prophylaxis and treatment of postoperative nausea and vomiting after E.N.T. surgery.

[The "Costen Syndrome" - Which Symptoms Suggest that the Patient may Benefit from Dental Therapy?]

INTRODUCTION

Since the thirties the hypothesis of a direct connection between temporomandibular disorders (TMD) and tinnitus/otalgia has been discussed. The thesis of this possible connection is often named after one of the earliest and most vehement supporters as "Costen Syndrome". This review is aimed to elucidate the present state of the discussion from the Dentist's point of view.

DIAGNOSIS/EPIDEMIOLOGY/THERAPY OF TMD

Diagnostic research criteria which define TMD are not standardized. Despite high prevalence and strong demand for treatment of TMD there is still a lack of a commonly accepted standard therapy and the potential benefit from a therapeutic point of view is still controversial. TMD AND TINNITUS/OTALGIA:: Concurrence of TMD and tinnitus by a common underlying cause is still unproven. By contrast a causal link between certain forms of TMD and otalgia is obvious.

CONCLUSION

A lack of clear definitions and standards for the diagnosis of TMD is the main hinderance to prove a causal relationship especially between TMD otalgia. However patients seeking care for otalgia with no identifiable otologic cause may benefit from dental therapy. Therefore future studies should focus on well defined subgroups of TMD to investigate a link between otalgia/tinnitus and TMD.

[Use and results of universal newborn hearing screening with ALGO portable device]

BACKGROUND

Congenital hearing disorder, which has an occurrence of 1 in 1000 newborn babies, is a health problem that should be taken seriously. Once it has been discovered too late, it leads to lifelong language, intellectual, emotional and social problems. The aim of this project was the critical evaluation of a universal, ABR-based newborn hearing screening, looking at the specificity and the success of the method used as well as the organisational requirements and costs involved with this method.

METHODS

From August 1999 until March 2000, 464 newborn babies, born at the University Hospital Eppendorf in Hamburg, were examined with the Algo portable. Another 31 children, all younger than 6 months, were also examined with the Algo portable, because of suspected hearing loss. When a child got a refer twice by the Algo portable, the child was examined again, using the conventional ERA-machine (Evoselect) to confirm the suspected hearing loss and to assess its grade.

RESULTS

98% of the newborns at our hospital were examined. Up to now, out of 13 conspicuous children, the majority of which belonged to the risk group, 6 have been identified as unambiguously bilateral and 2 as unilateral hard of hearing. After an introductory period of two months, the average costs per examination could be set at 38.65 DM and app. 3200 DM per bilateral hearing loss discovered.

CONCLUSION

A Universal Newborn Hearing Screening is necessary and can be executed with calculable effort with concern to personnel, time and finance.

[Stereoscopic simulation of ear surgery intervention with a novel 3D computer models]

INTRODUCTION

The presentation of the surgical anatomy of the temporal bone by standard anatomical figures is not suitable for otosurgical training. For the comprehension of its complex morphology temporal bone drilling is inalienable. Aim of the present cooperation was to gain an interactive real-3D program for the simulation of specific laterobasal surgical approaches.

METHODS

The program was derived from a standard horizontal section of a human temporal bone using a Siemens Somatom Plus 4 Tomograph. The slice thickness was 1 mm, the image matrix was 512. The Voxel-Man-system was used to built up the application for unix workstations.

RESULTS

Each step of a surgical approach to the temporal bone can be performed by the present computer model. Calculation in a stereo mode even allows spatial 3D-perception when using red/green glasses.

CONCLUSIONS

This program is a novel tool to simulate critical aspects of otosurgical procedures on a computer. Up to now the lack of tactile and kinesthetic information does not allow to renounce individual temporal bone drilling.

[Topographic diagnosis in the area of the head-neck: initial experiences comparing ultrasound panorama images with CT and MRI]

PURPOSE

Due to the restricted width of the ultrasound array, documentation of topographical correlations in B-scan-echography is still difficult. By means of Color SieScape it is possible to produce successive images of the regions of interest by lateral movement of the ultrasound array. Aim of the present study was to evaluate this new method in comparison to CT and MRI.

METHOD

18 patients with tumors in different areas of the head and neck region were examined by CT or MRI and by sonography. Color SieScape was used for documentation. A Sonoline Elegra ultrasound platform with 7.5 MHz linear array was used for the investigations.

RESULTS

Because of claustrophoby no MRI-investigation could be done in 4 of the patients. Sonography and Color SieScape documentation was possible in all cases. In addition to the panorama-information of SieScape technique in every investigation by Color SieScape large and very small vessels could be documented in colour.

CONCLUSION

By the use of Color SieScape the identification of the topographical correlations is improved. The spatial resolution is comparable to MRI and better than in CT. Investigation of patients who suffer from claustrophobia is much easier by Color SieScape. The imaging of parapharyngical structures could not be improved by Color SieScape. Nevertheless it is the only technique for the coloured documentation of even small vessels and topographic relations. Color SieScape investigations are faster and less expensive than CT or MRI.

[Clinical relevance of developmental changes of the endolymphatic sac]

BACKGROUND

Outcome of endolymphatic sac shunt surgery crucially depends on endolymphatic sac morphology. The intraoperative finding of a fibrotic sac, e.g., will lead to therapy-failure. Aim of the present study was to determine possible developmental changes in endolymphatic sac morphology which could imply, that a shunt operation should not be undertaken in older age.

METHOD

46 histological temporal bone serial sections were examined. All sections were taken from the "Wittmaack Temporal Bone Collection". All specimens were obtained from patients with morphologically healthy ears, especially without a history of Menière's disease or other kinds of vertigo.

RESULTS

During the fetal period the endolymphatic sac is a wide cavity that is surrounded by immature embryonal connective tissue. In older age this cavity gradually shrinks, leading to stenosis in about 80% of the cases. The endolymphatic duct, however, remains open.

CONCLUSION

The increasing fibrosis of the endolymphatic sac is part of the natural involution of the inner ear. It constitutes a natural limitation for the outcome of endolymphatic sac shunt surgery in the elderly.

Planning and rehearsal of surgical interventions in the volume model

Visualization of 3D medical data is routinely used in a wide range of applications. However, for the planning and rehearsal of surgical interventions more sophisticated techniques for interaction have to be developed. The realistic specification and visualization of free form cuts is needed to allow the 'look and feel' close to a real dissection. The problem here is, since these cuts are not represented by intensity changes, that the gray-level-gradient-method can not be used for the estimation of surface normals. In addition, the interactive repositioning of dissected fragments has to be simulated. We have developed an extended ray-casting algorithm for visualization of object motion in the volume model. We implemented new methods for the representation, modeling and high quality rendering (subvoxel resolution) of arbitrarily shaped cut regions within the volume model. The representation is done using a dynamic data structure. This way, all operations can easily be reversed and the original object information is preserved. The modeling of cut surfaces is done in an independent data volume where the partial-volume-effect, which is the prerequisite for the gray-level-gradient method, is calculated as it would be generated by an imaging system. This way, the localization of cut surfaces at subvoxel resolution and an accurate estimation of the surface normals is achieved. The key point here is to detect if a cut surface really truncates an object or if the object has not been affected by a cutting operation. We will present an new method, called adaptive sampling which allows to determine the situation by the generation of additional sample points (when necessary) during the ray casting process. The described techniques provides the basis for simulation of surgical interventions in the voxel-model which could not be achieved with any surface-based method. We present a system for simulation and rehearsal of otosurgical approaches, where we implemented a drill-like tool with which the student lays off the route to the operating area. The key point is to not injure structures of risk such as the facial nerve. For applications like the simulation of craniofacial surgery we developed a gradual cutting tool ("virtual scalpel").

[Anatomy of the valve system of the internal jugular vein]

BACKGROUND

Central venous catheters (CVC) in the internal jugular vein have become an important adjunct to the overall management of intensive care patients, but their use is associated with frequent neck complications. In a review of the literature anatomical variation in size, form and function of the valve system of the internal vein was found.

PURPOSE

This study macroscopically and microscopically investigates the anatomical variety of the vein valves of the inferior internal jugular vein.

MATERIAL AND METHODS

100 cadavers from legal autopsies were investigated. We selected 45 patients with an acute myocardial infarction death and a control group (55 patients) formed by different causes of death. The veins were prepared for light microscopic study, the specimens were serially sectioned (ca. 30 sections) and stained with hematoxylin and eosin.

RESULTS

Anatomical variety was observed predominantly unilateral on the right side of the internal jugular vein. The valves were often bicuspid at the right side (92%) and tricuspid on the left side (64%) and mostly located ca. 2 cm above the subclavia-jugularis bifurcation. In the histological study, a variability of the net of collagen and elastin fibres in the tunica intima and media was observed. The structure of the adventitia was constant. 18 patients with a jugular valve vein incompetence (age over 60) appeared to have thickening of the tuberculum in the sinus of the valve. The cups of the valves were found rudimentary in these patients with advanced stages of tricuspid incompetence.

CONCLUSION

The present study demonstrates the variety of the valves of the jugular vein. They play an important role to impede the retrograde flow during cardiopulmonary resuscitation as well as in jugular vein cannulation.

[Evidence-based medicine--a critical overview]

BACKGROUND

Evidence-based medicine (EBM) is a strategy for the standardization of medical decision-making. The purpose of this review was to demonstrate the most important tools of EBM and to critically appraise them.

METHODS

The current literature concerning the subject is reviewed. A clinical example for the systematic use of EBM in diagnostic tests is explained in detail.

RESULTS

The risk of an increasing bureaucratic hindrance of medical procedures by EBM is weighed against the advantages of a systematic strategy for the valid assessment of medical information. According to the clinical example EBM proves to be a valuable tool in the quantitative estimation of residual risk and reliability of diagnostic tests in everyday clinical practice.

CONCLUSION

The critical use of the systematic tools of EBM for clinical decision-making is recommended.

[Removal of a cochlea implant with chronic granulation labyrinthitis and foreign body reaction]

BACKGROUND

Cochlea Implantation is an accepted treatment for children and adults with profound sensorineural deafness. In rare cases postoperative complications may occur so that removal of the implant is unavoidable.

CASE REPORT

In a particular case we present and discuss the case of a 69-year-old patient.

CONCLUSION

After removal of a cochlear implant, the electronic array is frequently left in the cochlea as a temporary replacement. This is a common practice, but whether it is advisable should be verified according to the specific intraoperative situation.

[Muscular compliance of the auditory tube]

BACKGROUND

The simultaneous electromyographical assessment of innervation patterns of the mylohyoid and the tensor veli palatini muscle is introduced as a new technique for the examination of the auditory tube function.

PATIENTS AND METHODS

Clinical studies were performed on 30 healthy volunteers and 50 patients suffering from chronic tubotympanic mucositis and cholesteatoma. Concentric needle electrodes were advanced into the tensor veli palatini muscle through the palate. The mylohyoid muscle was examined using surface electrodes.

RESULTS

Innervation patterns of the tensor veli palatini muscle in volunteers were limited to the time interval of the mylohyoid innervation pattern only, i.e., the oral and pharyngeal phases of swallowing. In 14 of the chronic otitis patients these tensor muscle innervation patterns were found outside this interval.

CONCLUSION

This observation provides a new pathophysiological explanation for the clinical concept of a relative closing failure of the auditory tube. These results emphasize the significance of coordination in muscular compliance of the tube.

[A new aspect on the development of chronic middle ear diseases in patients with cleft palate]

BACKGROUND

The prevalence of chronic middle ear disease in patients after surgery for cleft palate is about 50%. Aim of the present study was to analyse its morphological and physiological causes to prevent chronic atelectatic otitis media or cholesteatoma.

METHODS

15 adult patients with cleft palate were examined using middle ear microscopy, pure tone audiometry, EMG of the tensor veli palatini muscle and MRI of the Eustachian tube.

RESULTS

8 of 15 patients had chronic middle ear disease. With 13 of 15 patients single motor unit action potentials could be recorded from the tensor veli palatini muscle. MRI of the Eustachian tube revealed two decisive observations in patients with chronic middle ear disease: in 4 patients the pterygoid hamulus could not be detected, in all otitis patients the continuity of tensor veli palatini muscle was interrupted or disturbed by medial or lateral fixation.

CONCLUSION

Chronic middle ear disease with cleft palate patients is basically caused by impaired muscular compliance of the Eustachian tube. Thus integrity of hamulus as well as tensor veli palatini muscle must become of crucial interest in cleft palate surgery.

[Complications with permanent damage in endonasal paranasal sinus operations--more frequent in experienced surgeons?]

BACKGROUND

The rate of serious complications in endonasal sinus surgery has not gone down although optical aids are widely used nowadays. Are serious complications caused more often by unexperienced or experienced surgeons using a microscope and/or endoscope?

METHODS

We defined serious complications as follows: death, persistent neurological deficits or permanent loss of vision, and injury to the internal carotid artery. Two different studies were made: the first consecutive 300 interventions of 6 sinus surgeons were evaluated. Sixteen malpractice cases were analysed regarding the experience of the surgeon.

RESULTS

In 9 out of 16 malpractice cases serious complications were attributable to experienced surgeons, five to moderately experienced surgeons, and only two to an inexperienced surgeon (although he had extensive experience in external sinus surgery). There were 6 deaths, 6 neurologic defects, 2 visual disorders, and 2 injuries to the internal carotid artery without any sequelae. In 9 cases the serious complications were related to injury of the internal carotid artery, in five cases to perforation of the skull base. Twice the orbital wall was penetrated. In 1800 procedures performed by 6 surgeons, no serious complications were encountered. There were only lesions of the periorbit (n = 33) or CSF leaks (n = 8) without any permanent damage to the patient.

CONCLUSIONS

Even an experienced surgeon must always keep in mind that serious complications can occur in sinus surgery. One must constantly be alert to the possibility of anatomical variants or specific pathologic findings.

[Value of duplex ultrasound in diagnosis of parotid tumors]

BACKGROUND

The sensitivity of diagnostic imaging of processes in the parotid gland has been increased by improved spatial resolution, yet specificity remains unchanged. The purpose of this study was to determine whether the low-flow color duplex technique alters the specificity of B-mode ultrasonography.

PATIENTS AND METHODS

Forty-one patients with tumors of the parotid gland were examined by color duplex echography as well as histologically. Twenty-eight of the 41 patients had benign tumors and 13 had malignant disease. In 17 of 41 patients, color duplex ultrasonography failed to detect any vascularization within the tumor. Histopathological examination showed that 3 of these 17 tumors were malignant and 14 of 17 were benign. Intranodal vascularization was detected in 24 cases. Ten of these patients were found to have malignant tumors of the parotid gland; 14 had benign parotid tumors.

RESULTS

Our present findings show that marked intratumoral vascularization especially appears in malignant tumors. In contrast to lymph nodes, the location and texture of intranodal blood vessels do not provide information about the nature of the neoplasm.

CONCLUSIONS

Low flow duplex ultrasonography does not increase the specificity of preoperative examination in tumors of the parotid gland.

[Microlight-guided spectrophotometry of the cochlea]

BACKGROUND

Intraoperative measurements of local intracapillary hemoglobin oxygenation of the human cochlea via the round window membrane have been shown to be possible using the Erlangen microlight-guided spectrophotometer. The aim of the present study was to develop a new microlight guide suitable for measurements in the round window niche and to evaluate electrophysiologically the possible impact of the procedure on the cochlea.

METHODS

Measurements were made for wavelengths of 450 to 900 nm at a total power of 5.3 mW. The exit diameter of the light guide was 200 microns and the angle used was 20 degrees. The recording depth was about 250 microns. The atraumatic character of the spectrophotometry was demonstrated by monitoring the compound action potential (CAP) threshold tuning curve from 1 to 34 kHz in ketanest-anesthetized guinea pigs.

RESULTS

CAP thresholds remained constant (0.3 +/- 3.9 dB SPL) during 3 to 30 min of exposure to the light.

CONCLUSIONS

These results suggest that the spectrophotometry may be useful as a new technique for intraoperative monitoring of intracapillary hemoglobin without causing physiological deterioration of the cochlea.

[What is the value of color-coded duplex ultrasound in diagnosis of head-neck tumors]

BACKGROUND

The aim of the present study is to demonstrate the rating of low flow color duplex echography as a new technique in the preoperative staging of head and neck cancer.

METHODS

Forty-four patients with squamous cell carcinomas of the oral cavity, oropharynx, and hypopharynx were examined. Gray scale imaging as well as color duplex scan with doppler spectrum quantification were performed on each patient using a Siemens Quantum 2000 duplex scan with 7.5 MHz linear array.

RESULTS

Squamous cell carcinomas of the upper aerodigestive tract as well as their metastases are poorly vascularized but show irregular vascular patterns. In comparison to gray scale echography estimation of tumor borderline is improved by imaging of peripheral tumor vessels. Furthermore, imaging of irregular central tumor vessels in metastatic lymphatic nodes renders important information for N-staging.

CONCLUSION

Thus color duplex echography should be recommended for routine application in preoperative head and neck tumor staging.

[Diseases of the petrous bone--demands made on radiologic diagnosis from the otosurgical point of view]

Advances in microsurgical techniques in otosurgery as well as further developments in imaging methods enable the surgeon to perform procedures at the petrous bone that are as radical as they can contribute to retaining the function. The present study aims at explaining by means of case reports the specific otosurgical problems in typical diseases of the otobase and at presenting the ranking of the individual imaging methods from the surgeon's point of view. For example, special features in the preoperative diagnosis of glomus tumours, acoustic neurinomas, Ménière's disease, cholesteatomas and so-called petrous bone tip processes are pointed out. A special aspect of radiological and surgical collaboration is seen in highly vascularised tumours of the otobase in respect of the possibilities offered by interventional angiography. The importance of MR-tomography in preoperative diagnostics is assessed with some reservation because this does not show up surgically relevant landmarks.