Biomedical subjects

G Eggers

Publications and source records attributed to G Eggers.

At least 19 recordsLinked to original sources

PubMed2006

Piezosurgery--a new safe technique in cranial osteoplasty?

All surgical interventions on the neurocranium bear the risk of injury of the dura mater and development of a cerebrospinal fluid fistula. Therefore, despite careful preparation, damage to the dura mater cannot always be omitted. Especially after surgery and in patients with increased intracranial pressure (craniosynostoses) there is a high risk of perforating the dura. In this article a new surgical technique for osteotomy (Piezosurgery) that avoids perforation of the dura is presented. Ultrasonic microvibrations allow a selective cut of only mineralized structures without damage to the soft tissue. Even in case of accidental contact the dura remains undamaged. This advantage is also useful for bone splitting, to separate the tabula externa from the tabula interna in situ, without any risk of dura perforation even in case of the very thin bones in an infantile skull. The present work shows the applicability of piezoelectric surgery in high-risk patients after osteotomy, avoiding perforation of the dura mater.

Brain Injuries↗

PubMed2006

Image-to-patient registration techniques in head surgery.

Frame-based stereotaxy was developed in neurosurgery at the beginning of the last century, evolving from atlas-based stereotaxy to stereotaxy based on the individual patient's image data. This established method is still in use in neurosurgery and radiotherapy. There have since been two main developments based on this concept: frameless stereotaxy and markerless registration. Frameless stereotactic systems ('navigation systems') replaced the cumbersome stereotactic frame by mechanically and later also optically or magnetically tracked instruments. Stereotaxy based on the individual patient's image data introduced the problem of patient-to-image data registration. The development of navigation systems based on frameless stereotaxy has dramatically increased its use in surgical disciplines other than neurosurgery, but image-guided surgery based on fiducial marker registration needs dedicated imaging for registration purposes, in addition to the diagnostic imaging that might have been performed. Markerless registration techniques can overcome the resulting additional cost and effort, and result in more widespread use of image-guided surgery techniques. In this review paper, the developments that led to today's navigation systems are outlined, and the applications and possibilities of these methods in the field of maxillofacial surgery are presented.

Cephalometry↗

PubMed2005

Ultrasound guided lithotripsy of salivary calculi using an electromagnetic lithotriptor.

Sialolithiasis is a common disease of the major salivary glands. A supplement to the traditional therapies is extracorporeal shock wave lithotripsy of the calculus. This method has been adopted from the therapy of renal or bladder calculi. Patients with a solitary calculus of parotid or submandibular gland were treated with a specially designed lithotriptor. In a retrospective study the results of this therapy were analysed. The success rate was far better for parotid gland calculi than for submandibular calculi. We could not find better results than those published in literature with other devices. In our therapeutic concept, sialolithotripsy is the therapy of first choice for single parotid gland calculi. For submandibular gland calculus this method is advisable in selected cases only.

Electromagnetic Phenomena↗

PubMed2005

[Markerless patient registration. A new technique for image-guided surgery of the lateral base of the skull].

BACKGROUND: Markerless patient registration is a new procedure that may reduce logistical efforts and possibly also the radiation load on the patients prior to a computer-assisted intervention. Congruent surfaces, such as bone surfaces or skin surfaces, represented in a data set and in the surgical site, can be overlapped with the help of surface matching. Hitherto, these techniques were performed by using the periorbital and frontal skin of the face. The present clinical study assessed the usability of the auricle as a skin structure for markerless patient registration in lateral skull base surgery. PATIENTS AND METHODS: The periauricular precision of the navigation system SSN was investigated clinically in ten patients. Radiopaque registration markers in the periauricular region served as a target in order to evaluate the markerless registration method. RESULTS: Exact patient registration failed in five cases due to temporary deformation of the auricle caused by the head support during CT imaging. An excellent patient registration (mean target registration error = 0.9+/-0.2 mm) was found as long as the auricles had not been temporarily deformed during CT imaging. CONCLUSION: Laser-scan registration of the auricle reduces logistics in image-guided lateral skull base surgery. The problem of temporary deformation of the auricle during CT imaging might be solved by an appropriate opening in the head support at the level of the auricles.

Humans↗

PubMed2005

Image-guided removal of foreign bodies.

Foreign bodies are common in the head and face. We investigated the use of image-guided navigation systems for the removal of foreign bodies in 10 patients between 1998 and 2004. In all cases foreign bodies were retrieved. There were no major complications. Image-guided removal of foreign bodies is safe and valuable.

Adolescent↗

PubMed2005

An augmented reality system for image-guided surgery.

The introduced new developed navigation system is a High Intensity Approach Light System for augmented reality in image-guided surgery. The surgeon follows the projected approach lights with his ordinary surgical instruments. Thus, tracked instruments are not necessary with this system.

Humans↗

PubMed2005

Laser surface registration for lateral skull base surgery.

OBJECTIVE: Logistics in the run-up to computer-assisted lateral skull base intervention can be reduced by markerless registration methods. So far, only the facial skin surface but not the skin surface that was near to the lateral skull base was used for markerless patient registration. The present study was designed to evaluate whether the auricles may serve as an accurate spatial reference for markerless patient registration in image-guided lateral skull base surgery. STUDY DESIGN: In a prospective clinical study, the precision of markerless patient registration was checked by using periauricular evaluation markers and additional distant oral evaluation markers that served as targets for the infrared pointer of a navigation system. Ten patients with cranial tumors, bony malformations, or foreign bodies who were planned for image-guided surgery were selected. Markerless patient registration was performed by laser-scanning with the SSN++ navigation system. RESULTS: Based on the auricle, a high accuracy (mean target detection error tde = 0.9 mm +/- s = 0.3 mm) was achieved in markerless patient registration as long as the auricle was not deformed during CT imaging or during laser scanning. However, the conventional CT acquisition with a head support caused temporary auricular deformations in half of the patients, which made a precise laser-scan registration impossible. CONCLUSIONS: Automated laser registration of the auricle reduces the logistical input in connection with computer-assisted lateral skull base surgery, ensuring the accuracy that has been achieved up to now with marker-based methods. Constantly good results can be achieved if the head support of the computer tomograph has an appropriate opening at the level of the auricles in order to avoid auricular deformations during CT acquisition.

Adult↗

PubMed2005

Robot-assisted craniotomy.

In the Special Research Centre 414 of the German Research Funding (DFG, Bonn) a system for robot-assisted cranial surgery was developed. It is designed for the accurate and safe execution of craniotomies and repositioning of bone pieces. The system is intended for use in the surgical therapy of craniosynostosis. Preoperatively, CT imaging is performed. In a computerized planning system the position and shape of the intended craniotomy is intuitively planned on a virtual model of the patient's skull. Intraoperatively, after conventional removal of the covering soft tissue, the robot performs the craniotomy autonomously. Extensive testing in phantom studies and animal tests confirmed the reliability and accuracy of the system. A thorough risk analysis of the system was performed. In this paper, the first clinical use of the system on a patient is described and the clinical importance is discussed.

Bone Cysts↗

PubMed2005

Detection of foreign bodies of the head with digital volume tomography.

OBJECTIVES: Foreign bodies occur as a sequela of trauma or therapeutic interventions. If the risks are not too high, therapy of choice is the removal of the foreign body. This is only possible if the existence of a foreign body is detected and it is localized accurately. METHODS: The suitability of digital volume tomography (DVT) for the detection and localization of foreign bodies was investigated. Samples of various materials that are typically found as foreign bodies in the head and neck region were used. RESULTS: All materials investigated are principally detectable with DVT. Highly radiopaque material was detectable down to small sizes. The detectability of less radiopaque substances like wood and resins was poor when located in soft tissue. CONCLUSION: DVT is an appropriate tool for the detection of radiopaque foreign bodies. However, foreign bodies made of wood and resin, although detectable by DVT, can be missed when located in muscular tissue. The detectability decreases further when the foreign body is located adjacent to a highly radiopaque tissue like bone. This has to be taken into consideration when using DVT for foreign body detection.

Contrast Media↗

PubMed2005

Geometric accuracy of magnetic resonance imaging of the mandibular nerve.

OBJECTIVES: Magnetic resonance imaging (MRI) is not routinely used for dental implant planning. A prerequisite for dental implant planning is the accurate imaging of risk structures like the mandibular nerve. The geometric accuracy of the imaging of the mandibular nerve was investigated. METHODS: Two human cadaver heads were scanned using MRI. Computed tomography (CT) scans of the same heads were used as a benchmark. Using a stereotactic frame, corresponding images of MRI and CT were superimposed and the concordance of the images of the mandibular nerve in MRI with those of the mandibular canal in CT was assessed. RESULTS: The geometric accuracy of the mandibular nerve in MRI was as good as that of the mandibular canal in CT imaging. CONCLUSIONS: MRI of the mandibular nerve is sufficiently accurate for the use of this imaging method in dental implant planning.

Artifacts↗

PubMed2003

[New concepts in image assisted surgery: automated patient registration based on the jaw and external ear].

OBJECTIVE: Automatic and marker less patient registration based on natural anatomical interfaces may considerably reduce the radiation load and logistical input prior to computer-assisted surgical interventions, as it is not necessary to place and measure reference markers. The present study was to find out if, apart from the facial skin, also auricles as well as the upper and lower jaw can be used as anatomical interfaces for the intraoperative registration of the patient's position. MATERIAL AND METHOD: Prior to surgical intervention the positions of 20 patients were registered by a high-resolution 3D laser scan and correlated with the preoperative CT data set. Tumors, skeletal malformations, and foreign bodies were indications for surgical intervention. Auricles as well as the upper and lower jaw were used to register the patient's positions. The accuracy of this basically marker less method was clinically evaluated through the additionally placed conventional registration markers. RESULTS AND CONCLUSION: The marker less patient registration based on natural anatomical interfaces was successful in the upper jaw (deviation: 0.8+/-0.3 mm). The tongue and mobile floor of the mouth led to geometric incongruence and inadequate laser registration in the lower jaw. As far as the auricles were concerned, high accuracy could only be achieved as long as the auricles had not been deformed during CT imaging (deviation: 1.9+/-0.9 mm). The usual CT acquisition with a conventional head support, however, led to temporary auricular deformations in more than half of the patients, which made an exact laser scan registration impossible.

Artifacts↗

PubMed2003

[Primary renal manifestation in malignant lymphomas and leukemia].

Primary manifestation of malignant lymphoma and/or leukaemia rarely occurs in the kidney. It can be the cause of a hitherto unexplained acute renal failure or it is incidentally detected as shown in the three cases under report.1.A 68-year-old man was operated on because of a symptomatic tumour in his right kidney. At nephrectomy, a conventional (clear cell) renal cell carcinoma was found simultaneously with an occult mantle cell lymphoma infiltrating the adjacent renal and extrarenal tissue. Clinical follow-up uncovered nodal and bone marrow involvement, so that a primary renal manifestation of mantle cell lymphoma was apparent.2.A 69-year-old man with suspected vertebral metastasis underwent partial renal resection because of a mass in his left kidney. Histologically and immunohistochemically, the renal infiltration was diagnosed as a precursor B-lymphoblastic lymphoma. After chemotherapy and irradiation, leukaemic blood cell counts with 50% lymphoblasts proved a primary renal manifestation of precursor B-lymphoblastic leukaemia/lymphoma.3.A 13-year-old boy presented clinically with renal failure, enlarged kidneys, and normal urinalysis. Renal biopsy showed a diffuse interstitial infiltration with atypical T-lymphoblasts compressing tubules and surrounding preserved glomeruli. Subsequent clinical bone marrow smears presented 60% T-lymphoblasts, so that the final diagnosis of a primary renal manifestation of acute T-lymphoblastic leukaemia of mature thymic cortex type was made. Immediate chemotherapy resulted in total recovery of renal function and bone marrow findings.

Adenocarcinoma, Clear Cell↗

PubMed2003

Second malignant neoplasms after treatment of childhood cancer.

The aim of this study was to determine therapy-related risk factors for the development of second malignant neoplasm (SMN) after childhood cancer. The German Childhood Cancer Registry (GCCR) registers all childhood malignancies since 1980 including SMN. A nested case-control study with 238 SMN cases and 450 controls was conducted. A confirmatory, as well as an explorative, analysis was performed. Radiotherapy showed a small effect on the risk of SMN for doses >or=65 Gy. Regarding the chemotherapeutical agents, we saw increased Odds Ratios (OR) for high doses of cyclophosphamide (CP >8000 mg/m(2) OR=6.3 (95% Confidence Interval (CI): 1.3-30.2)), cisplatinum (DDP >435 mg/m(2) OR=2.8 (95% CI: 1.1-6.7)) and mercaptopurine (MP >5000 mg/m(2) OR=4.5 (95% CI: 1.1-18.9)). Patients jointly receiving high doses of MP (>5000 mg/m(2)) and dexamethasone (DEXA >or=1200 mg/m(2)) had an OR=6.9 (95% CI: 1.2-40.3). Our results could be added to those of other investigations to give indications for modifying future therapeutic strategies for childhood cancer.

Adolescent↗

PubMed1998

Polyamine modulation of mitochondrial calcium transport. I. Stimulatory and inhibitory effects of aliphatic polyamines, aminoglucosides and other polyamine analogues on mitochondrial calcium uptake.

In this study, the regulation of mitochondrial Ca2+ transport by polyamines structurally related to spermine and by analogous polycationic compounds was characterized. Similar to spermine, a number of amino groups containing cationic compounds exerted a dual effect on Ca2+ transport of isolated rat liver mitochondria: a decrease in Ca2+ uptake velocity and an enhancement of Ca2+ accumulation. In contrast to the effects of spermine and other aliphatic polyamines, however, the accumulation-enhancing effect of aminoglucosides, basic polypeptides, and metal-amine complexes turned into an inhibition of Ca2+ accumulation at higher concentrations. Within groups of structurally related compounds, the potency to decrease Ca2+ uptake velocity and to enhance Ca2+ accumulation correlated with the number of cationic charges. The presence of multiple, distributed cationic charges was a necessary, but not sufficient criterion for effects on mitochondrial Ca2+ transport, because cationic polyamines and basic oligopeptides which did not enhance mitochondrial Ca2+ accumulation could be identified. Spermine was not able to antagonize the blocking of Ca2+ uptake by ruthenium red, but rather showed an apparent synergism, which can be explained as a displacement of membrane-bound Ca2+ by spermine. The aminoglucosides, gentamicin and neomycin, but not the inactive polyamine bis(hexamethylene)-triamine, inhibited the binding of spermine to intact mitochondria. Apparently, the binding of spermine, gentamicin, and a number of polyamine analogues to low-affinity binding sites at mitochondria, which have low, but distinct structural requirements and which may correspond to phospholipid headgroups, indirectly influences the activity state of the mitochondrial Ca2+ uniporter. The ability of aminoglucosides to displace spermine from the mitochondria and to inhibit mitochondrial Ca2+ accumulation may contribute to the mitochondrial lesions, which are known to occur early in the course of aminoglucoside-induced nephrotoxicity.

Aminoglycosides↗

PubMed1998

Comparison of olfactory function in patients with seasonal and perennial allergic rhinitis.

Hyposmia is a common symptom in allergic rhinitis. However, little is known about differences in the olfactory function of patients with seasonal or perennial allergy. A prospective controlled study was performed on 28 patients with allergic rhinitis to grass pollen and on 47 patients with allergic rhinitis to mites. Sixty-six healthy volunteers served as a control. Olfactory function was evaluated by a modified Connecticut Chemosensory Clinical Research Center testing procedure for threshold, identification, and discrimination. The grass pollen-allergic patients were tested preseasonally and after 3 weeks of intraseasonal grass pollen exposure; the mite-allergic patients and the volunteers were tested once. In the mite allergics, olfactory threshold, identification, and discrimination tests were significantly worse than in the volunteers (all P < 0.0001). In the grass pollen allergics, the results in olfactory identification and discrimination tests were not different from the controls if tested out of the season (both P > 0.05). However, in threshold testing (P = 0.0139), the results were worse. Intraseasonally, the grass pollen allergics showed a significant decrease in threshold, identification (both P < 0.0001), and discrimination testing (P = 0.0029). If the intraseasonal pollen allergics were compared to the mite allergics, they showed better results in identification (P = 0.0087) and threshold (P < 0.0001) tests, but worse results in discrimination testing (P = 0.0002). Therefore, the different kind of allergen exposure seems to result in a different pattern of allergic olfactory dysfunction.

Adolescent↗

PubMed1998

[Comparison of the effects of digoxin or enalapril in the treatment of heart failure due to mitral insufficiency].

BACKGROUND: There is not much evidence about the usefulness of digoxin or enalapril in the treatment of heart failure due to mitral insufficiency. AIM: To compare digoxin and enalapril in the treatment of heart failure due to mitral insufficiency. PATIENTS AND METHODS: Patients with mitral insufficiency, in sinus rhythm, with a heart failure grade II or III and with echocardiographic left ventricular dilatation were eligible for the study. They received sequentially, during 12 weeks each, digoxin 0.25 mg/day or enalapril in doses up to 20 mg/day, with a washout in-between period of 2 weeks. The order of the sequence was determined randomly. At the start and end of treatment, functional class according to NYHA and maximal exercise tolerance in the treadmill were assessed and a color Doppler echocardiogram was done to measure ventricular dimensions, function and degree of mitral insufficiency. RESULTS: Nine patients on enalapril and 12 on digoxin improved their functional capacity. Digoxin improved exercise time in 76 +/- 168 sec (p = 0.022), whereas this change was not significant with enalapril (38 +/- 158 sec; p = 0.2). With enalapril treatment, ventricular diastolic dimension decreased from 59.3 +/- 8.1 to 58 +/- 9.3 mm and the area of mitral insufficiency decreased from 8.1 +/- 3.5 to 6.6 +/- 3.1 cm2. Digoxin did not induce any significant echocardiographic change. CONCLUSIONS: In these patients, digoxin and enalapril improved functional class. Digoxin improved exercise time and enalapril reduced ventricular dimensions and mitral insufficiency.

Adult↗

PubMed1997

Olfactory dysfunction in allergic rhinitis is related to nasal eosinophilic inflammation.

BACKGROUND: Olfactory dysfunction is a common finding in patients suffering from allergic rhinitis. However, little is known about the pathophysiology underlying this phenomenon and about the time course of hyposmia in seasonal allergy. METHODS: A prospective controlled study was performed on 17 patients with allergic rhinitis to grass pollen in order to evaluate olfactory function in correlation to the duration of allergen exposition, symptoms, eosinophil cationic protein (ECP) in nasal secretions, and nasal volume flow (NVF). Olfactory function was evaluated preseasonally and on days 3, 7, 14, and 21 of the season using a modified Connecticut Chemosensory Clinical Research Center testing procedure for threshold, identification, and discrimination. Twelve volunteers without allergy served as controls. RESULTS: Preseasonally, patients and controls performed equally in discrimination and identification testing, but not in threshold testing. No changes were found in the controls, but a significant decrease in threshold and identification from the 7th day of the season in patients with allergy was noted that was better correlated to ECP than to NVF. NVF was already maximally decreased from the 3rd intraseasonal day with no further changes. ECP increase became significant at day 14. CONCLUSION: Patients with grass pollen allergy develop olfactory dysfunction during natural allergen exposure that might be related to allergic inflammatory mechanisms.

Adult↗

PubMed1993

Effect of spermine on mitochondrial matrix calcium in relation to its enhancement of mitochondrial calcium uptake.

The mechanism of spermine-induced enhancement of mitochondrial Ca2+ uptake was explored using the fluorescent Ca2+ indicator Fluo-3/AM to measure the free matrix Ca2+ concentration. Simultaneously, the extramitochondrial Ca2+ concentration was registered by a Ca(2+)-ion selective electrode. Spermine lowered the extramitochondrial steady state Ca2+ concentration and at the same time induced a decrease of the intramitochondrial Ca2+ concentration. However, there is a concentration-dependent reversal of the stimulatory action of spermine, which may be explained by the existence of a second, low-affinity binding site for spermine which mediates an inhibition of uptake in spite of the existence of an inwardly directed Ca2+ gradient.

Aniline Compounds↗