PubMed Health⌕ Search

Biomedical subjects

R Laszig

Publications and source records attributed to R Laszig.

At least 55 records · Page 3Linked to original sources
PubMed1999

Auditory brainstem: development and plasticity of GAP-43 mRNA expression in the rat.

Expression of the growth and plasticity associated protein GAP-43 is closely related to synaptogenesis and synaptic remodeling in the developing as well as in the mature nervous system. We have studied the postnatal development of GAP-43 mRNA expression in the auditory brainstem and determined the time course of its reexpression following deafening through cochlear ablation using a digoxigenin-coupled mRNA probe. By the first postnatal day, GAP-43 mRNA was expressed at high levels in all auditory brainstem nuclei. But whereas GAP-43 mRNA is almost entirely lost in most of these nuclei in the adult animal, significant levels of this molecule are retained in the inferior colliculus and, most notably, in the lateral and medial superior olivary nucleus. As a consequence of unilateral cochleotomy, GAP-43 mRNA rose dramatically in some neurons of the ipsilateral lateral superior olive, whereas the hybridization signal decreased in others. Using double staining protocols, we found that those olivary neurons that increase their level of GAP-43 mRNA appear to be identical with the cells developing strong GAP-43 immunoreactivity after cochleotomy. By combining axonal tracing with in situ hybridization, we proved that at least some of the cells with increased levels of GAP-43 mRNA and protein are the cells of origin of olivocochlear projections. A substantial decrease of the level of GAP-43 mRNA took place in the inferior colliculus contralateral to the lesioned cochlea. Our results led us to suggest that neurons in the superior olivary complex may play a crucial role in orchestrating auditory brainstem plasticity.

Aging↗
PubMed1999

[Extended indications for cochlear implantation. The Freiburg results in patients with residual hearing].

The usual indication for a cochlear implant (CI) is acquired deafness in patients for whom conventional hearing aids are of no benefit. The question is whether CI is superior to the best conventional hearing aids for patients with some residual hearing, but who achieve only minimal speech recognition (< 30% in the Freiburg monosyllable word test at 70 dB (I) SPL) with optimal hearing aids. We report our experience with five patients with residual hearing who underwent cochlear implantation (Nucleus Mini 22 and 24) on the worse side. The patients were examined preoperatively and at 1, 6 and 12 months following activation of the implant. The Freiburg monosyllabic word test, the Göttingen sentence test and consonant recognition were used to assess postoperative results. All patients benefitted from CI when test scores were compared with preoperative ones. All patients achieved a score in the Freiburg monosyllabic word test of more than 60% at 70 dB (I) SPL 12 months post switch-on. Four patients achieved a score of more than 85% in the Göttingen sentence test. These results and the progress made in cochlear implant technology are an impetus to continue discussions of various considerations of criteria for cochlear implants and possibly extend these for patients with severe hearing impairment.

Adult↗
PubMed1999

Paraganglioma as a systemic syndrome: pitfalls and strategies.

Tumours of the neuroendocrine system in the head and neck region are mostly paragangliomas of the glomus tympanicum or jugulare, or of the carotid body. The majority of these tumours are benign, and the coexistence of multiple paragangliomas seems to be rare. Pre-operative embolization and surgery are regarded as primary therapy for these tumours. The treatment regimen in any patient depends on age, general health, hearing status and the function of the lower cranial nerves. Several presentations are possible in which paragangliomas occur as systemic disease. 1. Paragangliomas may occur bilaterally, or, in rare cases, in multiple areas. Pre-operative bilateral angiography is of utmost importance. In case of multicentricity, it might be necessary to proceed without, or just with, unilateral surgery for preservation of adjacent structures. In surgery of jugular vein paraganglioma, we usually perform a modified transmastoidal and transcervical approach with preservation of middle-ear structures and the ossicles. As an alternative or supplement to surgery, radiotherapy or definitive embolization may be used in the treatment of paragangliomas. 2. Paragangliomas may occur as multiple endocrine neoplasia (MEN) syndrome combined with medullary thyroid gland carcinoma, and, facultatively, pheochromocytoma. In these cases, endocrinological examination and magnetic resonance imaging (MRI) of the adrenal region, the thorax and the neck are required for an adequate therapeutic strategy. As MEN may be inherited, family history should be evaluated. 3. Paragangliomas can became malignant and metastasize. Thus, cervical lymph node metastases or distant metastases may occur. We recommend the removal of all ipsilateral lymph nodes and their histological examination.

Adult↗
PubMed1999

Cochlear implants and electrical brainstem stimulation in sensorineural hearing loss.

Cochlear implants and multichannel auditory brainstem implants enable patients with bilateral total or profound hearing loss to receive at least acoustic information. Both types of prosthesis are based on electrical stimulation of the auditory pathway. Different speech coding strategies and the number of electrodes used may influence the postoperative results. The preoperative evaluation of patients is of utmost importance. The cochlear implant is suitable for patients with hearing loss due to inner ear disorders, but who have functioning hearing nerve. Patients with a defect of the hearing nerve can be provided with an auditory brainstem implant.

Brain Stem↗
PubMed1999

Central electrical stimulation of the auditory pathway in neurofibromatosis type 2.

The auditory brainstem implant (ABI) is a viable treatment option for patients with neurofibromatosis type 2 (NF2) whom either vestibular schwannomas or the surgery used to remove them has rendered totally deaf. This device stimulates the central auditory pathways in a manner similar to the cochlear implant in individuals with a total hearing loss. A multichannel model with transcutaneous signal transmission is in use experimentally in both the United States and Europe. Of 14 patients implanted with the ABI in a European pilot study, 13 received auditory sensations at initial tuning. Surgical implantation of the ABI is generally, but not always, performed at the same time as tumor removal, with the preferred route being the transmastoid-translabyrinthine approach. After insertion, monitoring of the device is required to optimize the location of its electrode on the cochlear nucleus complex.

Electric Stimulation↗
PubMed1999

[Ear surgery].

Explore the source record for details and available documents.

Cochlear Implantation↗
PubMed1998

[Cochlear implants. Prosthetic management of deafness at the turn of the century].

In recent years the cochlear implant has become an established method for rehabilitation of bilateral sensory deafness in adults and children. Intracochlear multichannel stimulation with sophisticated speech coding strategies has proved to be reliable and safe enough for use in adults as well as young children; thus, a few cochlear implant systems with different specifications are currently available. The differences in their hardware and software are discussed. Furthermore, the current indications for cochlear implants in patients whose hearing is severely impaired and important aspects of the preoperative evaluation are presented with special emphasis on difficult cases such as deformities, multihandicapped subjects and very young children. Our results after 12 years of experience and more than 700 implantations suggest that the most important prognostic factor is the duration of deafness.

Adult↗
PubMed1998

[Complications of endonasal paranasal sinus surgery--diagnostic and therapeutic consequences].

BACKGROUND: Functional endoscopic sinus surgery has been proven the therapeutic method of choice in surgical therapy of chronic sinusitis. On the other hand, endonasal sinus surgery may cause severe complications even when performed by a skilled surgeon. This is easily explained by the close vicinity of many functionally important structures to the operative site. CASE REPORTS: Three histories are reported that involve possible complications even in apparently simple cases. Diagnostic and therapeutic consequences are discussed. In a case previously diagnosed histologically as chronic unspecific sinusitis, an endonasal biopsy resulted in endocranial bleeding requiring neurosurgical intervention. Midline granuloma was found to be the correct diagnosis. Another patient was seen with a normal X-ray of the sinuses and solitary polypoid structure in his left nose. Polypectomy was planned and a CT scan was performed, which demonstrated a meningocele. Transfacial surgery was then performed to remove the meningocele. Another patient presented with a traumatic impression of the frontal sinus, and open reposition by transfacial surgery of the frontal and ethmoid sinus was planned. When CT scans revealed an uncovered optic nerve in the sphenoid sinus of the fractured side, we abandoned ethmodectomy and performed reposition of the frontal sinus as the only surgical procedure. RESULTS AND CONCLUSIONS: In this paper, we show typical complications of endonasal sinus surgery and strategies for avoiding them. If any complication occur, prompt treatment is required. Three groups of complications can be defined: perforation of frontobasal dura resulting in cerebrospinal fluid (CSF) fistula, severe bleeding, and orbital or optic nerve injury. When the surgeon discovers an intraoperative complication, possible consequences must be considered immediately to minimize side effects for the patient. A CSF fistula should be closed in the same procedure, and transfacial surgery may be necessary. Hemorrhage resulting from an ethmoidal artery may require frontoorbital surgery and ligation of this vessel. If retrobulbar hemorrhage caused by retraction of an ethmoid artery occurs, immediate intervention is necessary. Usually a transfacial approach, resection of the medial orbital wall and retrobulbar decompression are performed. In some cases lateral canthotomy may be the best way to drain haematoma and decompress the optic nerve. Subsequently, orbital revision and ligation of the retracted artery must be performed. Any delay can result in persistent visual loss. We conclude that the extranasal frontoorbital approach should be part of the residency training program in ENT departments. Any surgeon performing endonasal sinus surgery must be trained in transfacial emergency procedures, which should be part of anatomic preparations in teaching courses, thus avoiding severe damage in case of intraoperative complication.

Aged↗
PubMed1998

Tinnitus in Cochlear Implant Users: The Freiburg Experience.

Cochlear implantation is a well-accepted method of aural rehabilitation in deaf or severely hearing-impaired adults and children. A majority of patients not only suffer from hearing impairment but from tinnitus. The high rate of preoperative tinnitus in adults (68.1%) stands in contrast to assumed lower rates in children. Unknown are such factors as how tinnitus develops in children, how they realize what tinnitus is, and whether the mechanism of development of tinnitus differs from that in adults, respectively. Electrical stimulation of the auditory pathway is followed by loss, or at least reduction, of tinnitus in most cases (75%). Also, the insertional trauma alone is able to stop tinnitus in some patients. Attention must be paid to the low risk of developing tinnitus postoperatively. No reports are available regarding tinnitus in children. Though younger children may not be able to report, some adolescent patients report preoperative or postoperative tinnitus (or both) that is reduced by electrical stimulation at the rates seen in adults. Further investigations are needed to define the mechanism of tinnitus development in children and to define optimal stimulation modes and rates for tinnitus reduction with best auditory performance.

Journal Article↗
PubMed1998

Cochlear implants for adults obtaining marginal benefit from acoustic amplification: a European study.

OBJECTIVE: This study aimed to examine the application of a speech recognition score of 30% on open-set word materials as the upper limit for preoperative performance in determining cochlear implant (CI) candidacy for European non-English-speaking hearing-impaired persons. This study also aimed to determine the effect of implantation on residual pure-tone hearing thresholds and to determine the incidence and benefit of a contralateral hearing aid postimplant. STUDY DESIGN: The single-subject design study, involving 20 postlinguistically deafened subjects, compares preoperative performance with hearing aids to postoperative performance with a CI at 6 months after surgery. Subjects were implanted with either the Nucleus Mini 22 or the Nucleus 24 CI systems implementing the MPEAK and SPEAK coding strategies. Fourteen subjects meeting the selection criteria were accrued consecutively specifically for inclusion in the study, whereas the remaining 6 retrospectively implanted subjects were identified for inclusion via patient records. PATIENTS: The investigation included 8 clinics over 3 countries (France, Germany, and Spain) and involved 20 postlinguistically deafened subjects who obtained marginal benefit from acoustic amplification before surgery. Nineteen subjects were older than 18 years of age with 1 subject being 14 years old included in the data report as well. MAIN OUTCOME MEASURES: Open-set speech recognition was evaluated before and after surgery using recorded word lists and sentence lists in the subject's native language to determine benefit from the treatment. Baseline audiograms were obtained before surgery for frequencies of 0.25-8.0 kHz for both ears and compared to pure-tone hearing thresholds measured at 1 month after surgery to determine the effect of the implantation on residual hearing. Additionally, a questionnaire was administered to determine the incidence and benefit of continued hearing aid use in the contralateral ear postimplant. RESULTS: Nineteen of the 20 study subjects displayed a significant benefit after surgery at 6 months after switch-on for open-set speech recognition. The remaining subject displayed no significant change in performance on objective testing. The implantation resulted in a significant downward shift in hearing thresholds for the implant ear in the majority of subjects. However, 50% of subjects displayed conservation of some residual hearing. For the majority of subjects, hearing aid use in the contralateral ear was discontinued because of lack of perceived benefit after surgery. CONCLUSIONS: The Nucleus Multichannel CI provides a significant benefit for postlinguistically deafened adults who display marginal benefit from acoustic amplification. Therefore, in French-, German-, and Spanish-speaking clinics, a speech recognition score of 30% on open-set word materials is considered an appropriate upper limit for preoperative performance in determining CI candidacy. In view of a significant downward shift in pure-tone thresholds in the implant ear for the majority of subjects, in cases of asymmetry, it is recommended that the poorer ear be implanted. After surgery, the majority of subjects did not perceive an added benefit from continued use of their contralateral hearing aid.

Adolescent↗
PubMed1997

Plasticity of the auditory brainstem: effects of cochlear ablation on GAP-43 immunoreactivity in the rat.

In the adult brain, expression of the growth associated protein GAP-43 may serve as an indicator of synaptic remodeling. We have studied localization and time course of the re-expression of GAP-43 following deafening through cochlear ablation. As a consequence of unilateral cochlear lesioning, a substantial increase in the expression of GAP-43 was observed in the neuropil of all subnuclei of the ipsilateral cochlear nuclear complex. This expression of GAP-43 occurred in well-defined fibers and boutons. In the ventral cochlear nuclei, boutons immunoreactive for GAP-43 were often localized on cell bodies. However, they were found only on selected subpopulations of cochlear nucleus neurons, i.e., on cell bodies containing glutamate or calretinin immunoreactivity, but apparently not on GABAergic neurons. Olivocochlear neurons must have been axotomized by the operation. Following cochlear ablation, a dramatic re-expression of GAP-43 occurred in cell bodies of the ipsilateral lateral superior olive but not in the ventral nucleus of the trapezoid body. Position and number of these cells suggested that most, if not all, of them serve the lateral olivocochlear bundle. However, although axon collaterals are given off by certain types of olivocochlear neurons, a direct involvement of the immunoreactive cell bodies in the emergence of GAP-43 in the cochlear nucleus is not obvious. A transient rise of GAP-43 immunoreactivity that could not be attributed to axotomized neurons was observed in the contralateral dorsal cochlear nucleus and in the ipsilateral inferior colliculus. Given the functional significance attributed to GAP-43, we conclude that the sudden loss of spiral ganglion cells leads to a reactive synaptogenesis in complex patterns across several auditory brainstem nuclei.

Aging↗
PubMed1997

[Early and long-term results of rehabilitation of cochlear implant patients]].

BACKGROUND: Cochlear implantation is nowadays a reliable and well-accepted method of auditory rehabilitation in selected adults and children. METHODS: We present rehabilitation data on 21 adult patients provided with the Nucleus CI22 M cochlear implant using the SPEAK strategy. RESULTS: Results of first tune-up show an open set speech understanding in approximately 50% of patients. Long-term results also reveal further improvement in patients who had no open set speech understanding. Our data seem to indicate similar results in comparison to other groups using the CIS strategy. CONCLUSIONS: In adults, open set speech understanding can be achieved even at the first tune-up. Results of early rehabilitation seem to be influenced by duration and etiology of deafness, experience with hearing aids, and other factors.

Adult↗