Search PubMed⌕ Search

Biomedical subjects

T Lenarz

Publications and source records attributed to T Lenarz.

At least 73 records · Page 4Linked to original sources
PubMed2000

Auditory brainstem implant in auditory rehabilitation of patients with neurofibromatosis type 2: Hannover programme.

An auditory brainstem implant (ABI) is indicated for patients suffering from bilateral neural deafness. The most affected patients are those with neurofibromatosis type 2 (NF2). An implantation is possible either at the same time as, or after, surgical removal of an acoustic neuroma. This paper demonstrates the results of eight out of 11 patients with NF2, seven of whom received an ABI after tumour removal. Pre-operatively, all of them were deaf. Post-operatively, the first fitting served to determine the individual stimulation parameters for each electrode. The stimulation-dependent side-effects were eliminated by reducing the stimulus intensity without causing negative effects on the hearing with the ABI. Only in one case was an open set understanding achieved within the first year. However, all patients had a better speech understanding when they combined their hearing with the ABI and their lip-reading abilities. There is no correlation between the performance with ABI and the tumour size or the duration of deafness.

Adolescent↗
PubMed1999

Sensorineural hearing loss in children.

Sensorineural hearing loss in children, either congenital or acquired, has an incidence of 2-4 per million. Molecular diagnosis of early childhood deafness became available for some types of syndromal and non-syndromal forms and will offer different treatment modalities in the future. Severe to profound sensorineural hearing loss can be effectively treated with cochlear implants. There is evidence of cerebral auditory plasticity under electrical stimulation of the auditory nerve with better performance in early implanted children. Other predicting factors are related to the type of schooling, family support and residual hearing. In the long-term, prelingually deafened children will develop considerable speech perception and production. Children with marginal benefit from hearing aid amplification show significant improvements in speech perception following implantation. Implantation is also possible in cases of cochlear malformation. However, special attention has to be given to the facial nerve, a possible CSF leak and electrode misplacement. Apart from hearing improvement cochlear implants have a positive impact on the family situation, schooling and personal well-being.

Adolescent↗
PubMed1999

[Temporal bone fracture after head trauma causing rhinoliquorrhea and meningitis].

We report our experience in managing a temporal bone fracture after head trauma that had no apparent clinical signs. Recurrent CSF rhinorrhea and meningitis lead to extensive diagnostic procedures. Operative exploration of the temporal bone demonstrated a fracture line along the horizontal part of the carotid artery. The location of the fracture did not cause such typical symptoms as hearing impairment, facial paralysis, vertigo or tinnitus. Only CSF liquorrhea through the Eustachian tube indicated a fracture at the lateral skull base.

Cerebrospinal Fluid Rhinorrhea↗
PubMed1999

Complications in pediatric cochlear implant surgery.

In a retrospective analysis we evaluated the intra and postoperative complications in children who underwent cochlear implantation between 1984 and 1993 at the Medizinische Hochschule Hannover. The data and records of 366 children were collected and analyzed. Relevant parameters were major complications such as significant infection, intraoperative bleeding, facial nerve injury, implant loss and device failure, as well as lesser complications, including delayed wound healing, chronic pain and vertigo. Late complications such as cholesteatoma or electrode dislocations were also registered. Cases of acute otitis media were managed with conservative treatment. Data presented indicate that cochlear implant surgery in children is a reliable and safe procedure with a low percentage of severe complications. Problems related to ear surgery can occur and should be manageable with standard procedures. Careful operative techniques and sufficient personal experience can help avoid severe post-operative problems.

Adolescent↗
PubMed1999

[Complications of cochlear implant surgery in children and adults].

BACKGROUND: In a retrospective analysis we evaluated the complication rate in 697 patients after cochlear implantation between 1985 and 1995 (366 children, 331 adults; 604 Nucleus, 50 Clarion and 42 other implants). RESULTS: Intraoperatively in 74 cases (10.6%) total or partial cochlear obliteration was found, a CSF gusher occurred in 7 cases. Minor complications such as seroma (8 adults), wound infections (14 patients), emphysema, and swelling were successfully treated with conservative methods and drugs. Seven (2.1%) adults showed facial nerve palsy postoperatively with incomplete recovery only in 2 of them (0.6%). No permanent facial nerve palsy was observed in children. Cholesteatoma developed in 18 adults (5.4%), which was treated by revision surgery. CONCLUSIONS: In conclusion, cochlear implant surgery is a safe procedure with a low complication rate. However, Cochlear implantation should be performed by well experienced ear surgeons who can properly handle intraoperative and postoperative problems. The patients should be informed about the typical risks of ear surgery including implant removal due to infection or technical defects, facial nerve palsy, vertigo and, especially in adults, increased tinnitus.

Adolescent↗
PubMed1999

[Sonographic diagnosis of metastatic renal cell carcinoma to the head and neck region].

In the area of the head and neck metastases from distant primary tumours are rare in comparison to the common squamous cell carcinomas of the upper respiratory and digestive tract. Thus correct preoperative diagnosis may be difficult. Two cases with distant metastases of renal cell carcinoma to the head and neck region are presented in this report. In a 60-year-old male patient, diagnostic evaluation of unilateral epistaxis revealed a radioopacity of the maxillary sinus, six months after removal of a renal cell carcinoma. In the second case a slowly progressive indolent swelling of the left neck developed in a 56-year-old man six years after resection of a renal cell carcinoma and two years after surgical treatment of a pancreatic carcinoma. Following clinical examination, modern imaging techniques with special emphasis on colour Doppler sonography with a Siemens Quantum 2000 were used for diagnostic evaluation in both patients. Sonography of metastatic renal cell carcinoma to the maxillary sinus revealed complete opacity of the antrum. The cervical mass proved to the inhomogeneous and hypoechogenic and was difficult to distinguish from the lower parotid lobe and the vessel sheath. A common feature of both tumours was a high degree of perfusion which could be confirmed by superselective angiography. The histological examination of the surgical specimen showed an isolated metastasis of a renal cell carcinoma in both cases. In patients with a history of renal cell carcinoma the possibility of distant spread to the head and neck region should be taken into account even after a long period of complete remission. Colour Doppler sonography facilitates the distinction between the normally well perfused secondary tumours and squamous cell carcinomas which usually only have a minimal blood supply. Because of the high risk of profuse bleeding a biopsy should only be performed in the operating theatre.

Carcinoma, Renal Cell↗
PubMed1999

[Ultrasound evaluation of characteristics of cervical lymph nodes with special reference to color Doppler ultrasound. A contribution to differentiating reactive from metastatic lymph node involvement in the neck].

BACKGROUND: Cervical mass due to lymphadenopathy is a common cause for consultation of an ENT specialist by patients. In many cases exact differentiation without biopsy between reactive and metastatic lymphnodes is difficult but crucial and necessary for each patient. Ultrasound is the imaging system with the highest sensitivity for the evaluation of pathological lymph nodes. However, differentiating benign and malignant lesions remains a problem. PATIENTS: In a prospective study, 138 cervical lymph nodes of 62 patients were evaluated according to conventional ultrasound criteria such as size, shape, brightness, demarcation, etc., and according to parameters of color doppler sonography such as intensity and localization of perfusion. The so called Pourcelot or resistance index, an objective parameter, was measured in order to examine a possible improvement of specificity in differential diagnosis of both entities. All lymph nodes were surgically removed and histologically examined after ultrasonography. RESULTS: 133 lymph nodes were evaluated in the study. Lymphadenitis was demonstrated in 72 cases, whereas 61 of the lumps showed metastases of squamous cell carcinoma of the head and neck region. Three patients with primary malignant lymphoma were excluded from the study. The conventional ultrasound parameters such as size, homogenity, shape and brightness did not reveal any substantial difference between the two groups. However, lymph node metastases significantly showed higher Doppler signals than the reactive ones. Most of the metastases were perfused in the periphery or had a diffuse spread of blood flow. The most valuable parameter from the prognostical point of view proved to be the Pourcelot Index with a threshold value less than 0.6 for metastases, which increased the specificity to 92% with a probability of p = 0.001. CONCLUSIONS: The results of this study demonstrate an increase of the ultrasound specificity in differentiation of pathological cervical lymph nodes using color flow imaging. Unfortunately, this method does not enable the physician to correctly diagnose the findings in all patients. Therefore histological evaluation is mandatory in all doubtful cases.

Adolescent↗
PubMed1999

[The Nucleus Double Array Cochlear Implant: a new concept in obliterated cochlea].

AIM: In order to increase the number of intracochlear electrodes to be inserted into a totally obliterated cochlea a special implant has been developed in collaboration with Cochlear Ltd. The implant features two separate electrode carriers containing 11 and 10 active electrodes, respectively, and a reference electrode on the receiver stimulator package. The potential stimulation modes include monopolar and bipolar stimulation as well as stimulation between both arrays. SURGICAL TECHNIQUE: A cochleostomy at the round window provides access to the scala tympani. Newly formed bone is removed as far as the anterior portion of the basal turn. Care is taken to identify and preserve the osseous border of the cochlea. A second cochleostomy is performed immediately caudal to the cochleariform process after removal of the incus. New tissue can be removed here in the same way. The two electrode carriers are then placed into the first and the second turn respectively. The remaining procedure corresponds to the procedure for cochlear implantation in cases in which the cochlea is not obliterated. PATIENTS: For the purpose of a clinical study n = 10 patients aged between 32-66 years with an obliterated cochlea were fitted with a double array cochlear implant. All patients showed signs of total obliteration of the basal turn either in preoperative imaging or during surgery. Intraoperative inspection revealed that the second turn was not obliterated in 4 of 10 patients. POSTOPERATIVE RESULTS: Postoperatively, a standard test battery was used to determine auditory performance over a period of time. All patients achieved significantly better speech understanding due to the additional apical electrode array. No complications occurred. CONCLUSION: In cases involving an obliterated cochlea, the number of intracochlear electrodes can be increased with the double array implant. As a result, the patients achieve significantly better auditory results.

Adult↗
PubMed1999

Adenoid cystic carcinoma of the skull base.

Adenoid cystic carcinoma (ACC) is a slowly growing tumor with a particular tendency to infiltrate the surrounding tissue by perineural spread. The clinical diagnosis may prove difficult due to the submucons extension of the tumor, especially at the skull base. This article outlines the clinical characteristics, diagnostics, and treatment modalities in a series of 56 patients with an ACC in the head and neck diagnosed between 1970 and 1998 in 32 females and 24 males. The youngest patient was aged 24 years, the oldest 77 years. The average age was 54 years. In 16 patients the tumor originated in the paranasal sinuses or the nasopharynx and involved the skull base. As a rule, several months passed between the manifestation of the first symptoms such as pain, blocked nose, epistaxis, or diplopia and the initial clinical diagnosis. All patients received surgical treatment, however, complete microscopical resection could only be achieved in approximately one third of the cases. Therefore, nine patients were postoperatively treated with radiotherapy. The average survival rates of the patients with an ACC of the skull base were only 99 months as compared to 144 months in the patients without skull base involvement.

Journal Article↗
PubMed1999

Expression pattern of the plasminogen activator-plasmin system in human cholesteatoma.

The plasminogen activator-plasmin system plays a pivotal role in the delicately regulated process of extracellular matrix remodeling. Recent studies have shown that an imbalance of proteolytic enzymes over specific inhibitors in this system may lead to an aggressive, expanding, and infiltrating cellular phenotype. As cholesteatoma resembles a tumor in many ways, we investigated the pattern of expression for members of the plasminogen activator-plasmin system in 12 human cholesteatomas, using immunohistochemistry. As controls, 3 tympanic membranes and 4 ear canal skin specimens were used. In contrast to the tympanic membranes, all cholesteatoma specimens showed a strong expression of plasminogen at the basal epithelial cell layers. In ear canal skin, only the basal surface of the most basal epithelia stained discretely positive. The urokinase-type plasminogen activator (uPA) could be detected in the basal stratum of the cholesteatoma matrix and in the surrounding granulation tissue, while tissue-type plasminogen activator (tPA) was not detectable at all. Plasminogen activator inhibitor-1 (PAI-1) was expressed in both the granulation tissue and the granular cell layer of the matrix, but not in the basal epithelial cells; PAI-2 showed a pericellular expression pattern in the subbasal and granular cell layers. Neither uPA, tPA, nor the PAIs could be detected in tympanic membrane controls; ear canal skin showed the same staining pattern as cholesteatoma only for PAI-2. Our data demonstrate that there is a clear imbalance in favor of proteolytic activity in the basal epithelial layers of the cholesteatoma matrix, which might at least partly account for the aggressive behavior of this tumorlike lesion. Further, the pattern of expression resembles the pattern described for several epithelial malignancies.

Cholesteatoma, Middle Ear↗
PubMed1999

Clinical results of the CLARION magnetless cochlear implant.

This paper reports initial results for the CLARION Multi-Strategy Cochlear Implant, presently under investigational study in Europe. A magnetless implantable cochlear stimulator (ICS) with an ear-mold-supported headpiece was designed in response to an increasing demand for a magnetic resonance imaging (MRI)-compatible cochlear implant. Surgical technique, accompanying magnetless headpiece, and MRI compatibility were evaluated in 11 deaf patients (ages 6 to 62 years) who were implanted with a magnetless Clarion implant. Because of the headset mechanics, the ICS was implanted closer behind the ear than a magnet-containing ICS. The ICS-MRI compatibility was investigated with 1.5- and 0.3-T MRI. Results showed that the surgery was relatively safe and easy to learn. The headset was stable and reliable. The MRI compatibility tests indicate that the ICS poses no contraindication for patients needing MRI. Overall, the results suggest that the Clarion magnetless cochlear implant is relatively safe and easy to implant, is MRI-compatible, and functions well with the ear-mold-supported headpiece.

Adult↗
PubMed1999

Simultaneous Analog Stimulation (SAS)--Continuous Interleaved Sampler (CIS) pilot comparison study in Europe.

The recent availability of the enhanced bipolar electrode array in the CLARION Multi-Strategy Cochlear Implant has permitted clinicians to fit patients successfully with the Simultaneous Analog Stimulation (SAS) strategy by means of bipolar coupling. Out of 22 consecutively implanted subjects, 20 subjects could be fitted with both Continuous Interleaved Sampler (CIS) and SAS strategies. Their performance was evaluated up to 3 months postoperatively. Speech perception results, as well as the patient's preference for either CIS or SAS, were examined. It was found that half of the subjects selected SAS as their preferred strategy and that the use of a preferred strategy resulted in higher overall patient performance. Further analyses showed that those subjects preferring SAS had higher electrode impedance values and lower threshold and most comfortable loudness levels than subjects preferring CIS. We presume that these psychophysical findings are, in part, related to the position of the intracochlear electrode array. Specifically, SAS users may have a more modiolus-hugging electrode array position.

Cochlear Implantation↗
PubMed1999

Speech perception results for children implanted with the CLARION cochlear implant at the Medical University of Hannover.

The perception of speech of 167 children implanted with a CLARION Multi-Strategy Cochlear Implant (1.2 device) was evaluated preimplantation and at 3, 6, 12, 18, and 24 months postimplantation. The children were between 15 months and 15 years of age. The test materials consisted of 8 tests involving syllable structure, single- and 2-syllable words, differentiation of word pairs, and sentences. Two difficulty levels were used, depending on developmental age (<7, and 7 to 15 years). There was an improvement in test scores over time for both age groups. The younger children (particularly those under age 4) improved steadily over the first 2 years, while the older children tended to plateau between 12 and 18 months after implantation. These findings demonstrate that deaf children up to 15 years old benefit from cochlear implants. Children under 4 years of age may even have the ability to compensate for delays in speech development before they reach school age.

Adolescent↗
PubMed1999

Cochlear implantation in children under the age of two: the MHH experience with the CLARION cochlear implant. Medizinische Hochschule Hannover.

This paper examines reports on the selection criteria, the surgical procedure, and the postoperative performance for children under the age of 2 implanted with the CLARION Multi-Strategy Cochlear Implant (1.2 device). Eighteen children have been implanted since 1996 with a mean age at implantation of 18 months (range 11 to 23 months). All children were selected by means of a standardized preoperative diagnostic protocol. The surgical procedure used in older children was modified depending on the head and mastoid size, skull thickness, and recurrent otitis media. Auditory perception was tested prior to as well as 3, 6, 12, and 18 months following implantation by means of a standardized age-adapted test protocol. The electrode array was inserted without difficulty in all cases, with no complications to date. On average, auditory performance improved over time up to 18 months after implantation. Closed-set test scores increased by 25% to 55% in 18 months. Open-set test scores began to show improvement between 6 and 12 months postoperatively. Overall, our experience indicates that cochlear implantation in children under the age of 2 is relatively safe and reliable. The Clarion 1.2 device surgery can be performed without complications. Auditory performance results support the effectiveness of early implantation.

Cochlear Implantation↗
PubMed1999

The influence of ionizing radiation on the CLARION 1.2 cochlear implant during radiation therapy.

OBJECTIVE: This study aimed to determine the maximum dose of radiation the CLARION 1.2 cochlear implant can withstand safely. INTRODUCTION: Cochlear implants restore functional hearing to patients with sensorineural deafness. Because some patients may need radiation therapy, it is important to investigate the influence of ionizing radiation on cochlear implant function. METHODS: This study tested the function of four CLARION 1.2 implants (Advanced Bionics, Sylmar, CA, U.S.A.) after varying radiation treatments with gamma rays. The first implant received a cumulative dosage of 69 Gy over nine treatments (single doses between 0.1-30 Gy). The second was irradiated with a total of 90 Gy, receiving three treatments of 30 Gy each. The third and fourth received doses more typical of patient therapy (i.e., 2 Gy) approximately 30 times, for a cumulative dosage of approximately 60 Gy. Implant function was tested after every treatment; the CLARION implant incorporates a back-telemetry system, allowing impedance and current output testing. RESULTS: Despite the type of treatment, the results were quite consistent: difficulties in function occurred when the cumulative dosage inside the implant was approximately 60 Gy. The first implant recovered completely and the second recovered partially. DISCUSSION: The CLARION 1.2 cochlear implant seems to safely withstand approximately 60 Gy of radiation before experiencing functional difficulties. In a clinical situation, the implant would not likely be in the target volume irradiated, and thus the patient's therapeutic cumulative dosage might be higher.

Cochlear Implants↗
PubMed1998

[Tullio phenomenon after cochlear implantation].

The Tullio phenomenon is defined as an acoustically inducible vestibular disorder that was first described in 1929. In an animal experiment Tullio provoked acoustic oscillations at the labyrinth followed by signs of imbalance. In the literature this phenomenon can be found in healthy but sensitive persons as well as in patients with Meniere's disease and patients with lesions between the stapes, footplate and the membranous labyrinth caused by fractures, stapes dislocations, labyrinthitis or perilymphatic fistulas. In this case report a patient complained about vertigo after cochlear implantation provoked by acoustical stimulation at a sound pressure level above 90 dB independent of the cochlear implant (CI). During tympanoscopy we found scar tissue surrounding the ossicles after CI. After disconnecting the ossicular chain no vertigo or nystagmus could be provoked. After CI regular ENT examinations and appropriate explorations of postoperative complaints are necessary. Vertigo especially requires very careful diagnostic procedures.

Acoustic Stimulation↗
PubMed1998

[Neonatal hearing screening with the Echosensor automated device for otoacoustic emissions. A comparative study].

Following the recommendations of the United States National Institutes of Health Consensus Conference in 1993, otoacoustic emissions (OAE) are now used internationally for hearing screening. The use of recording systems as well as the interpretation of results requires specially trained personnel although measurements are easier to perform than other recording methods available. To date, no objective method for general hearing screening, has been introduced in Germany, for neonates or children at risk, even though it would be desirable to detect and rehabilitate children with congenital hearing loss as early as possible (incidence, 1-6 per 1000). The Echosensor provides the means for carrying out OAE recordings within a short period of time and includes an automatic evaluation of results. Recordings can also be made by trained personnel. As a comparison test, audiologically trained staff recorded otoacoustic emissions in 111 new-born children in order to compare the results of the Echosensor with the results of a conventional OAE measurements device (the ILO88). The aim of this pilot study was to determine the reliability and validity of the recordings in comparison with available standards in brainstem audiometry. Our study showed that the results of the Echosensor corresponded well with the ILO88 results. Consequently, an OAE measuring method is now available is also provides high sensitivity and specificity and is easy to use. Our findings show that the Echosensor can meet the demands of systematic hearing screening in Germany.

Acoustic Impedance Tests↗