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Biomedical subjects

T Lenarz

Publications and source records attributed to T Lenarz.

At least 199 records · Page 11Linked to original sources
PubMed1991

Ototoxicity of vancomycin: an experimental study in guinea pigs.

Vancomycin (V)-a polypeptide antibiotic-is the drug of choice in severe infections with multiresistant staphylococcus spp. Due to the multimorbidity of the patients receiving V, the interactions with known ototoxic agents and the lack of an audiometric documentation, earlier clinical reports of V-associated hearing loss must be carefully interpreted. To elucidate this topic, a controlled animal study considering nonspecific effects was performed. 40 albino guinea pigs with positive Preyer's reflex and normal hearing were used. The hearing function was controlled by means of brainstem auditory evoked potentials before and after intraperitoneal administration of V (75, 150, 300 mg/kg b.w. for 11-17 days), gentamicin (60 mg/kg b.w. for 26 days), neomycin (100 mg/kg b.w. for 17 days) and sodium chloride solution. The cochleas were dissected for hair cell counting by the surface preparation technique. Additionally, the serum concentrations of V were measured. As a result there was no significant difference in hearing loss between the controls and the animals treated with 75 and 150 mg V; toxic doses of 300 mg V led to a certain threshold elevation after click stimuli, but not after trapezoid stimuli of 1, 4 and 8 kHz. On the other hand, the aminoglycosides as a positive control caused an obvious hearing loss after click and trapezoid stimuli, which was correlated to the amount of outer hair cell loss. Renal damage could be excluded by histological examination of the kidneys and estimation of creatinine in serum. Therefore, treatment with moderate doses of V comparable to clinical conditions does not exhibit a specific ototoxicity as compared to the aminoglycosides.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Allergic reaction form of middle ear mucosa. An animal experiment study].

The middle ear is not a body site at which anaphylactic reactions (type I in the classification of Coombs and Gell) predominate. Non-IgE-mediated reactions preferentially occur in response to an allergen. Out of 64 guinea pigs, 48 were sensitized and provoked with an allergen (p-toluene-diamine, hair dye). Sixteen nonsensitized animals were treated in order to rule out toxic reactions. A mainly lymphomonocytic infiltration (without eosinophilia) is proof of allergic origin. In addition there is a more or less pronounced edema. This may also be absent, as the present study shows. A differential diagnosis of inflammatory reactions is not feasible with conventional histologic techniques alone. This is doubtless due to the fact that immune mechanisms (tuberculin reaction type) are also present in chronic infections. In the animal experimental model, a definitive separation between toxic and allergic reactions is possible. Sporadic clinical observations of this allergic reaction form of the middle-ear mucosa are thus confirmed.

Animals↗
PubMed1989

[Detection and assessment of cervical lymph node metastases in head-neck tumors. A comparison of methods].

From 1984 to 1987, seventy-two patients with squamous cell carcinomas involving oropharynx, hypopharynx, larynx and cervical lymph nodes, who underwent surgery, were examined to determine the value of computed tomography (CT), magnetic resonance (MR), high-resolution real-time sonography (US) and palpation in preoperative staging of cervical nodal metastases. The clinical staging was compared with the microscopic findings in the neck specimens and with operative reports. For the identification and description of cervical lymph node metastases, US and CT are more valuable than MR and palpation. In comparison to CT, however, US has advantages in most cervical areas as a dynamic method with variable representation of interesting regions. False positive errors are related to confusion with inflammatory nodes in all examinations. Metastatic infiltration of surrounding tissue especially of neck vessels, are best recognised by means of US and MR. However, the high rates of sensitivity and low rates of specificity of all methods point to the possibility of a great number of false positive errors in demonstrating tissue infiltration.

Angiography↗
PubMed1989

[Detection of muscle, vein and artery infiltrations of cervical lymphatic metastases].

In a prospective study, 15 patients with squamous cell carcinomas of head and neck and clinical fixed cervical lymph node metastases were examined to determine the value of computed tomography, magnetic resonance imaging and high resolution real time ultrasonography in preoperative recognition of muscle and vessel infiltration. The preoperative findings were compared with the microscopic results of neck specimens and the operative reports. For each diagnostic method sensitivity, specificity, and effectivity were calculated. Ultrasonography, magnetic resonance imaging and computed tomography can assess muscle infiltrations as well. Metastatic infiltrations of carotid arteries are best recognised by ultrasonography and magnetic resonance imaging. Both methods are more valuable than computed tomography. All methods are unsuccessful in detecting infiltrations of the jugular vein. In conclusion, metastatic infiltrations of surrounding tissue, as described by imaging methods, are rarely confirmed by histological results.

Carcinoma, Squamous Cell↗
PubMed1989

[Treatment of sudden deafness with the calcium antagonist nimodipine. Results of a comparative study].

In a prospective randomised clinical study on 80 patients with idiopathic sudden hearing loss the therapeutic value of nimodipine was evaluated. Nimodipine is a 4-5-dihydropyridine calcium antagonist with selective spasmolytic and vasodilatory properties on cerebral vessels. The mean improvement of hearing (250, 500, 1000, 2000, 4000 Hz) amounted to 16.5 +/- 11.3 dB as compared with 18.6 +/- 10.2 dB achieved by standard treatment with hydroxyethyl starch (HAES) and naftidrofuryl. The difference is not significant (p greater than 0.2). These results together with the low rate of side effects indicate nimodipine as a therapeutic alternative in cases of hypertension, cardiac failure and allergic predisposition. The possible role of spontaneous recovery on one side and of specific parameters such as rheologic abnormalities or type of audiogram are discussed. They are important for a more sophisticated therapeutic approach towards sudden hearing loss.

Adult↗
PubMed1989

[Fine structure analysis of the petrous bone using high-resolution thin-layer computed tomography. 2: Place and success of CT in comparison with conventional x-ray diagnosis of petrous bone fractures].

Thirty patients with suspected petrous fractures following trauma were examined by high resolution CT and by conventional radiography. CT proved the most sensitive method for demonstrating petrous fractures and their complications. CT increased the rate of diagnosis by 17%. All fractures seen on CT could be classified, but accurate classification on the basis of conventional radiographs was only possible in 52% of cases. High resolution CT is superior in demonstrating damage to the labyrinth and the ossicles. Indications for conventional tomography are confined to atypical fractures with a course unsuitable for CT.

Humans↗
PubMed1989

Radiological evaluation of temporal bone disease: high-resolution computed tomography versus conventional X-ray diagnosis.

Sixty-two patients with different temporal bone lesions were prospectively examined by high-resolution computed tomography (CT) and conventional plain radiography, including pluridirectional tomography. High-resolution CT enabled a clear diagnosis in 80% of cases, conventional radiology in 63%; 1.6-times more bone information was recorded by high-resolution CT which is clearly superior for imaging cholesteatomas, metastases and inflammatory processes and for evaluating osseous destruction. With regard to pathological soft tissue or effusions filling the tympanic cavities, conventional radiology shows poor sensitivity (0.61). High-resolution CT is the most sensitive method for the imaging and classification of temporal bone fractures, including labyrinthine damage and ossicular chain injuries. Only in cases of atypical fractures with an unfavourable relationship to the CT planes, can carefully directed tomography be more effective. In most cases high-resolution CT replaces conventional radiology and should be the method of choice for comprehensive radiological examination of the temporal bone.

Bone Diseases↗
PubMed1989

[Sonographic diagnosis of head and neck tumors in association with therapy].

Basing on the experience with 558 patients suffering from tumours or suspicious lesions in the head and neck region, sonographic pointers that have been inadequately noted so far, are pointed out to improve diagnosis, follow-up, and post-therapeutic care. Among the possibilities offered by sonography are: to confirm or exclude bony involvement of the mandible in tumours of the oral cavity and the oropharynx, to objectify the results of antineoplastic chemotherapy, to offer possibilities to optimize radiotherapy, as well as to show criteria for the early detection of a relapse under consideration of the primary therapy.

Adolescent↗
PubMed1989

[Diagnosis of acoustic neuroma].

Modern diagnostic procedures have enabled very early diagnosis of acoustic neuromas, making previously unattainable operative successes feasible. This change, which has taken place over the past decade, is demonstrated using data on 64 patients collected from 1970 to 1987. Over this period the case history shortened to a third, tumour size shrank to less than half and symptoms became more circumscribed and less severe. Operative results are impressive with regard to improvement or preservation of hearing and survival of the facial nerve. Technical diagnostic procedures can be reduced to a minimum of non-invasive methods. As very small intracanalicular neuromas can now be detected, there arises the question of the management strategy of choice, which would in selected cases include a period of watchful waiting.

Adult↗
PubMed1988

Auditory evoked potentials and total sleep deprivation in depressed patients.

Cortical auditory evoked potentials (latencies N1 and P2, N1-P2 amplitude, and amplitude/stimulus intensity function) were studied before and after 1 night's total sleep deprivation in 20 drug-free depressed inpatients. Responders to sleep deprivation showed an augmenting pattern on the non-dominant hemisphere and a reducing pattern on the dominant hemisphere. The interhemispheric difference in auditory cortex was also apparent in the group of patients who failed to respond to sleep deprivation, but with values pointing in the opposite direction. The augmenting pattern shown by responders in the nondominant hemisphere may be a predictor of therapeutic response to sleep deprivation and to subsequent treatment with drugs influencing serotonergic pathways.

Adult↗
PubMed1988

[Electric response audiometry in retrocochlear hearing disorders].

The intensive clinical use of Electric Response Audiometry (ERA) has recently improved the diagnosis of sensorineural hearing loss. The Auditory Evoked Potentials (AEP) allow a precise topodiagnosis of the whole auditory system. However, specific limitations of the different potentials (cochlear, neural, brainstem, thalamic, cortical) have to be considered to avoid an overestimation of ERA. Based on the author's own material of more than 3500 recordings, most cases of a retrocochlear hearing loss are located at the auditory nerve and the brainstem. Therefore, brainstem electric response audiometry (BERA) and electrocochleography (ECoG) are the two most important methods of ERA. Typical Brainstem AEP (BAEP) features of retrocochlear disorders are shown. They are of different diagnostic value. A prolongation of the central conduction time or a break down of the later BAEP, both unequivocal signs of a retrocochlear lesion, were found in only 62 per cent of 100 cases of acoustic neuroma. However, diagnostic sensitivity can be improved to 96 per cent by additional use of ECoG and electrical promontory testing of the excitability of the auditory nerve. This value cannot be attained by any other audiometric test. These results show that BERA and ECoG are essential screening methods of high sensitivity in the differential diagnosis of sensorineural hearing loss. Additional values for diagnostic specificity and efficacy are also given in comparison with a group of patients initially suspected of having a cerebellopontine angle tumour. These values exceed those of conventional audiometric tests by far. Therefore, BERA and ECoG are reliable predictors of a retrocochlear lesion and can be judged as the best indicators for a CT scan or magnetic resonance imaging at present.

Audiometry, Evoked Response↗
PubMed1987

[Detailed structural analysis of the petrous bone using high-resolution thin-layer computerized tomography. 1. Sensitivity of substructural demonstration using a standardized study technic].

High-resolution CT, using fine sections, is a valuable method for radiological examination of the petrous bone. A standardized method of examination using the orbitomeatal and coronary plane is adequate for detailed screening of the petrous bone and shows almost all structures with high accuracy. The sensitivity of the method for showing 35 sub-structures of the inner and middle ear was investigated by examining 40 petrous bones which were normal clinically and radiologically, using the orbito-meatal and coronary planes. The radiation dose to the lens is less than from pluri-directional tomography. For special problems and for demonstrating very small structures, cuts may have to be performed in other planes, suitable for the required topography.

Ear, Middle↗
PubMed1987

[Value of various radiological study results in the follow-up of Camurati-Engelmann disease].

Camurati-Engelmann disease is a rare progressive bone dysplasia; involvement of the skull base can lead to deafness, vestibular disturbances, facial paralysis and damage to the optic nerves. Treatment with corticosteroids, calcitonin and diphosphonates promises only very limited success. Conservative treatment of compression of the cranial nerves is almost ineffective, but the aim of surgical treatment is decompression of involved nerves. The differential diagnosis depends on radiological findings and clinical symptoms. Follow-up depends on radiographic examination and skeletal scintigraphy for showing the extent of the disease. CT may help in demonstrating compression of cranial nerves and define the indications for surgical decompression.

Adult↗
PubMed1987

Chemotherapy of otitis media with ofloxacin.

This study evaluated the therapeutic role of ofloxacin in different forms of otitis media. After identifying the infecting bacteria in 250 patients with acute otitis media, or chronic otitis media, the clinical efficacy of orally administered ofloxacin 200mg twice daily was assessed in 45 patients from each of these groups. The clinical results were comparable with those obtained after conventional local and oral antibiotic therapy. Microbiological examination of the ear secretions revealed Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae and Haemophilus influenzae to be the main pathogens in acute otitis media, whereas in chronic otitis media P. aeruginosa and Proteus sp. were detected in most of the cases. Ofloxacin concentrations in secretions and mucosa specimens of the middle ear exceeded serum concentrations by more than 2-fold. On the basis of these preliminary results, ofloxacin appears to be an effective orally administered agent, without ototoxicity, which is effective against S. aureus and P. aeruginosa, 2 important pathogens in middle ear infections. Ofloxacin should be considered as an alternative for the therapy of otitis media, especially the chronic forms.

Anti-Bacterial Agents↗
PubMed1987

[Iatrogenic thrombosis of the jugular vein. A case report].

We report on a 52-year-old female patient who developed a thrombophlebitis with consecutive thrombosis of the internal jugular vein 14 days after hemicolectomy and prolonged central venous catheterisation. The tip of the polyethylene catheter was placed in the internal jugular vein. The pathophysiology of the thrombotic inflammation can be related to local alterations of the vessel wall due to mechanical irritation as well as hyperosmotic solutions on one side and bacterial infection on the other. The life threatening complications such as septicaemia, diffuse embolisation of other organs and the development of superior vena cava syndrome can be prevented only by instantaneous surgical removal of the jugular vein. Additionally, antibiotic and highdose heparine therapy are necessary. A review of the literature supports our experience.

Catheters, Indwelling↗
PubMed1986

[Ofloxacin in the conservative therapy of acute and chronic otitis media--a preliminary clinical report of experiences].

After ascertaining the bacterial spectrum in 105 patients with Otitis media acutissima, Otitis media chronica mesotympanalis and Otitis media chronica epitympanalis, the efficacy of oral therapy with ofloxacin in five patients from each of these groups was assessed. The results are comparable with those following conventional local and intravenous antibiotic therapy. On the basis of these preliminary results, ofloxacin can be considered as a highly efficient oral substance which is effective against Staphylococcus aureus and Pseudomonas aeruginosa, two important pathogens in inflammatory ear infections.

Acute Disease↗