PubMed Health⌕ Search

Biomedical subjects

R Quester

Publications and source records attributed to R Quester.

10 recordsLinked to original sources
PubMed2004

[Optimization of microsurgical operation technique to insert auditory brainstem implants, taking into account the results of a morphometric study].

STATE OF THE ART: The surgical placement of auditory brainstem implants to stimulate the cochlear nuclear region in patients with acquired bilateral retrocochlear deafness allows limited restitution of hearing. However, there have been few studies on the topographical relations in the target region, particularly the floor of the IVth ventricle. TOPIC OF THE STUDY: Is it possible to obtain more precise anatomical data in order to improve the surgical approaches and techniques for the placement of auditory brainstem implants? AIMS. To obtain a more precise topo- anatomical orientation in the target region for microsurgical lateral and midline approaches or a stereotactic operative strategy. METHODS AND RESULTS: Landmarks for the placement of an auditory brainstem implant via the IVth ventricle were examined and measured in a series of formalin-fixed human brainstems ( n=28). These data, and knowledge of their variability, allow a more precise surgical lateral approach. It is essential to precisely localise the target region, as it can only be partly discerned under the microscope during an operation. For this reason, to date its precise localisation has been determined only electrophysiologically. CONCLUSION: Exact target localisation improves safety. From an anatomical point of view the midline approach gives the chance to enlarge the indication spectrum for an implant. The anatomical data obtained here could also be integrated into a stereotactic surgical strategy.

Adult↗
PubMed2003

[Diagnosis, treatment and progress after frontal lobe injury].

The comprehensive assessment of a frontal lobe injury is one of the most complex problems in diagnosis and treatment due to the variability of nature, extent and effect of various disorders of higher cerebral functions, i. e. impairment of the ability to act systematically, attention, motivation and emotionality. This brings about considerable differences in assessing and judging the effects of frontal lobe syndromes. Impairments of initiation, planning and carrying out of actions, of impulse control, attention, memory and self-perception often manifest in disorganised and dissocial behaviour which brings about serious effects in many fields of social adaptability. Deeper neurological insights in nature and effects of these deficiencies and improved diagnostical methods and concepts of intensive-care treatment as well as the improved understanding in the necessity of a longterm rehabilitation program have led to the development of specific strategies concerning the dealing with the patient, the counseling of the social environment, especially of the relatives, and the treatment of the patient's symptoms. In the course of acute and rehabilitative treatment the patient normally has to develop strategies of habituation and adaptation to his social environment, furthermore techniques of compensation as well as an improvement of personal resources including attention, memory and planning of actions. The ability of self-control ought to be improved by training of behavioural strategies leading to an increased independence. The success of treatment varies distinctly from individual to individual. As a rule, basic capabilities in the scope of higher brain functions as well as executive and behavioural abilities can be improved. However, a restitutio ad integrum of all dysfunctions is very rare.

Brain Injuries↗
PubMed1999

Topographic anatomy of the cochlear nuclear region at the floor of the fourth ventricle in humans.

OBJECT: The development of appropriate methods to stimulate the dorsal and ventral cochlear nucleus by means of an auditory brainstem implant in patients with acquired bilateral anacusis requires a detailed topoanatomical knowledge both of the location and extension of the nuclear surface in the fourth ventricle and lateral recess and of its variability. The goal of this study was to provide that information. Anatomically, it is possible to use a midline surgical approach to the fourth ventricle rather than the translabyrinthine and suboccipital routes of access used hitherto. This is especially useful if severe scarring, which occurs as a result of tumor removal in the cerebellopontine angle, make the orientation and placement of an auditory brainstem implant via a lateral surgical approach difficult. There have been only a few studies, involving single cases and small series of patients, in which the focus was the exact extension of the cochlear nuclei, whose microsurgically relevant position in relation to the surface structures is not known in detail. METHODS: Landmarks that are important for the placement of an auditory brainstem implant through the fourth ventricle were examined and measured in a large series of 28 formalin-fixed human brainstems. In all cases, these examinations were supplemented by addition of a histological section series. For the first time values of unfixed fresh brainstem tissue were determined. Anatomical features are discussed with regard to their possible neurosurgical relevance, taking into account inter- and intraindividual variability. CONCLUSIONS: The midline approach would provide an opportunity to stimulate the whole area of the dorsal as well as the ventral cochlear nucleus with an auditory brainstem implant.

Adult↗
PubMed1997

The shrinkage of the human brain stem during formalin fixation and embedding in paraffin.

On the basis of measurements on fresh human brains (n = 33), changes in size of the brain stem which occurred as a result of formalin fixation and embedding in paraffin were quantified and converted into linear correction factors. In contrast to the known changes in the cerebrum, the formalin fixation did not result in a 'positive formalin effect', but left transverse values unchanged and led to decreases in longitudinal distances of 1-8% (correction factors: 1.01-1.09). Further embedding resulted in a linear shrinkage of 11-12% (correction factors: 1.12-1.13) transversely and 17% (correction factor: 1.21) longitudinally, which was smaller than the shrinkage in the cerebrum of 11-25% (correction factors: 1.13-1.34) reported in the literature. The examinations revealed changes in the brain stem caused by the total fixation and embedding process different from those of the cerebrum.

Adolescent↗
PubMed1997

[Early stimulation, a component of an early rehabilitation treatment concept on the neurosurgical intensive care unit].

Restitution or improvement of impaired brain function following severe head trauma essentially depends on immediate and systematic application of adequate rehabilitation measures. In an collaborative study of the University of Cologne Rehabilitation Centre and Clinic for Neurosurgery, the question is investigated whether early-onset stimulation therapy might have a favourable effect on the course of recuperation, including possible acceleration in regaining consciousness. For 60 minutes at least twice a day, auditory, tactile, olfactory, visual, gustatory and kinesthetic stimulation is administered to the patient, under medical supervision and with the help of nursing personnel, physiotherapists and the patient's family. In order to record the patient's reactions to these stimuli, heart rate, frequency of respiration, skin resistance, and muscle activity are measured and the patient's behaviour is observed using standardized assessment instruments.

Adult↗
PubMed1996

Electromyographic facial nerve monitoring during resection for acoustic neurinoma under moderate to profound levels of peripheral neuromuscular blockade.

The facial nerve is monitored intra-operatively using electromyography to identify and prevent damage during the excision of an acoustic neurinoma. In order to determine whether a profound level of peripheral neuromuscular blockade could be achieved without compromising facial electromyographic monitoring, 11 patients undergoing resection of acoustic neurinoma were studied. After induction of anaesthesia, an infusion of atracurium was administered to reduce the integrated electrically evoked muscle potential (EEMP) of the hypothenar eminence by 70-100%. The facial nerve was directly stimulated in the surgical field and the facial evoked muscle potentials (EMPs) were recorded. Even under complete peripheral neuromuscular blockade (i.e. no electrically evoked muscle potential measurable over the hypothenar eminence, no palpable hypothenar muscle response) it was possible to evoke facial muscle electromyographic responses by stimulation of the facial nerve.

Adult↗
PubMed1993

Radical removal of a large glossopharyngeal neurinoma with preservation of cranial nerve functions.

A 51-year-old man is reported who was suffering from an extensive right-sided glossopharyngeal neurinoma (4.6 x 3.4 cm). The patient was admitted with a history of headache for six to seven years and vomiting for two years accompanied by a progressive hearing loss, tinnitus and dizziness during the last year. Audiometry indicated a perceptive deafness in the whole frequency range up to 70 dB HL, while electronystagmography (ENG) showed a loss of vestibular function of the right side, but there were no signs of a jugular foramen syndrome. Magnetic resonance imaging (MRI) revealed a large tumor portion in the right cerebello-pontine angle with only a small part in the jugular foramen. The neurinoma was completely removed by microsurgery through a suboccipital approach with preservation of nerves VII-XII. The postoperative course was uneventful and normal function of facial and caudal cranial nerves (Nn IX-XII) were proven by electromyography and magnetic stimulation, with exception of a transitory hypesthesia in the palatine region which completely normalized within a few months. The right-sided hearing loss was unchanged, but vertigo improved. In comparison with literature review the lack of temporary or permanent postoperative dysfunctions of caudal cranial nerves as well as of the facial nerve was extraordinary in the reported case.

Audiometry, Pure-Tone↗
PubMedDate not supplied

Vypro II mesh in hernia repair: impact of polyglactin on long-term incorporation in rats.

BACKGROUND: To the Vypro II mesh, a large-pore-sized multifilamentous polypropylene mesh for hernia repair, supplementary polyglactin 910 multifilaments were added to improve intraoperative handling. As it has been suggested that polyglactin induces fibroplastic reactions and wound complications, this study was designed to evaluate the long-term tissue reaction to polyglactin in the Vypro II mesh. MATERIALS AND METHODS: Two mesh materials, the Vypro II composite mesh (PP + PG) and the pure polypropylene variant (PP), were compared after inlay implantation in a standardized rodent animal model. After 14, 28, 42, 56, 84 and 112 days of implantation, histological analysis of the inflammatory response was performed: material absorption, inflammatory tissue reaction, fibrosis and granuloma formation were investigated. RESULTS: Total absorption of polyglactin filaments of the Vypro II mesh occurred between 56 and 84 days of implantation. Both the inflammatory and the fibrotic reaction were initially increased in the PP + PG mesh group. These differences disappeared in the following implantation period. After 112 days, inflammation was even less pronounced in the PP + PG mesh group. CONCLUSION: The present data confirm a short-term polyglactin-induced increase in inflammation and fibrosis around implanted Vypro II meshes in rats. With regard to the long-term tissue response, even an anti-inflammatory property of polyglactin multifilaments in low-weight and large-pored polypropylene meshes cannot be ruled out.

Absorption↗