Biomedical subjects

Peter K Plinkert

Publications and source records attributed to Peter K Plinkert.

At least 19 recordsLinked to original sources

PubMed2007

Prevalence of ocular manifestations in hereditary hemorrhagic telangiectasia.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is a systemic disorder of the fibrovascular tissue. Few data have been published on the frequency of ophthalmologic manifestations. The aim of this study was to assess this frequency. METHODS: A prospective observational cross-sectional study was conducted in a multitude of clinical practices and in a tertiary referral center. The main outcome measure was the number of vascular malformations detected by an ophthalmologic inspection of the retina and the conjunctivae in both eyes in a random sample of patients with HHT. RESULTS: No retinal telangiectases were observed in any of the 75 patients (150 eyes) examined. Conjunctival telangiectases were detected in 28 of 74 patients (47 of 148 eyes). CONCLUSIONS: The prevalence of retinal telangiectases seems to be lower than 1/75 (< 1.3%). This data does not justify screening procedures to detect retinal telangiectases. Ophthalmologists should be aware of the symptoms of HHT and its systemic character.

Adult↗

PubMed2006

Benefit from tonsillectomy in adult patients with chronic tonsillitis.

The objective of this study was to determine the benefits of tonsillectomy in adult patients with chronic tonsillitis with special emphasis on the influence of age and gender. Cross-sectional survey analysis of patients at least 1 year after undergoing adult tonsillectomy at a university department. We used the Glasgow Benefit Inventory and a specifically constructed illness inventory (Specific Benefits from Tonsillectomy Inventory). One hundred and nine patients completed the survey. Significant improvements were demonstrated in three out of four GBI scores ['total score' (+16.9), 'general health' (+12.9), 'physical functioning' (+46.6), all P<0.0001] and in all SBTI scores ['symptom change' (+58.3), 'reduced use of resources' (+70.9), 'general benefit' (+52.1), all P<0.0001]. Gender did not play a significant role in benefit evaluation whereby younger patients evaluated the surgery as more beneficial than older patients. Adult patients with chronic tonsillitis definitely benefit significantly from tonsillectomy. Younger adult patients perceived greater surgical benefits than older adult patients. Patient gender did not significantly influence tonsillectomy benefit evaluation.

Adult↗

PubMed2006

Contact endoscopic findings in hereditary hemorrhagic telangiectasia.

BACKGROUND: Hereditary hemorrhagic telangiectasia is characterized by angiodysplastic lesions. So far, knowledge is limited on the vascular architecture and rate of occult manifestation of telangiectases. Contact endoscopy has not been used for this task before. METHODS: Eleven patients with hereditary hemorrhagic telangiectasia were examined with contact endoscopy to identify occult telangiectases. Sixty enoral telangiectases were studied in detail to characterize their architecture. RESULTS: No occult telangiectases could be detected. In most cases, telangiectases consisting of a simple dilated loop were small. In contrast, most of the complex telangiectases were larger. CONCLUSIONS: Visually normal areas in patients with hereditary hemorrhagic telangiectasia did not seem to have abnormal vascularization. Simple dilated capillary loops might be precursors of telangiectases with a more complex structure. Contact endoscopy seems to be a promising tool for the in vivo monitoring of therapies and the natural course of vascular disorders in humans and in animal models.

Adult↗

PubMed2006

Alternobaric vertigo--really a hazard?

OBJECTIVE: To determine the prevalence of alternobaric vertigo (AV) in sport divers and to find out whether AV led to dangerous situations underwater. Furthermore, to examine whether objective neurootologic tests are associated with the manifestation of AV. DESIGN: Retrospective cohort study. PARTICIPANTS: Sixty-three sport divers with an average diving experience of 10 years and 650 dives were questioned regarding their medical and diving history and the manifestation of vertigo during diving. METHODS: Microscopic otoscopy, tympanometry, stapedius reflexes, hearing threshold for air and bone conduction, caloric video-oculography including analysis of the slow-phase velocity of the nystagmus, acoustic brain stem responses, and magnetic resonance imaging were performed to find possible differences between divers with and without AV. RESULTS: We found 17 divers with AV (27%). There was no significant difference in all measured parameters apart from sex and history of middle ear equalization difficulty in divers with AV. Ten (59%) of 17 female divers and 7 (15%) of 46 male divers experienced AV, representing a significant sex difference (p < 0.001). Correlation with our divers' outpatient clinic revealed that female divers had a significantly higher incidence of middle ear equalization disorders which could be an explanation for the predominance of female divers with symptoms of AV. None of the divers reported any dangerous or life-threatening situations following AV. Whether AV leads to dangerous situations underwater remains unclear, but this hypothesis is not supported by our data. CONCLUSION: Alternobaric vertigo is a common finding in divers. In our study group, female divers had a four-time higher risk to suffer AV. Our data do not support the thesis that AV is a life-threatening condition.

Acoustic Impedance Tests↗

PubMed2006

Polydimethylsiloxane particles for permanent injection laryngoplasty.

OBJECTIVES: Polydimethylsiloxane (PDMS) particles are a nonresorbable material that allows for permanent vocal fold augmentation. This study investigated morbidity and voice quality in patients treated for unilateral vocal fold paralysis by injection of PDMS particles. METHODS: Fourteen patients who had neurogenic unilateral vocal fold paralysis of different causes were included in this prospective study. Each patient underwent videostroboscopic assessment before and after operation. Friedrich's dysphonia index (DI), a score system combining subjective and objective parameters, was used to describe voice quality. A DI of 0 reflects a normal voice, and a DI of 3 stands for complete aphonia. The PDMS particles were injected into the paraglottic space by microlaryngoscopy under general anesthesia. RESULTS: The median follow-up was 4.1 months. There was no complication attributable to the injection of PDMS particles. The mean DI was 2.8 before operation. After the operation, voice quality improved significantly in each patient, as reflected by a mean postinjection DI of 1.4. CONCLUSIONS: Particles of PDMS provide a relatively safe and minimally invasive option for permanent vocal fold augmentation. The functional results in terms of voice improvement are comparable to those obtained with other techniques, including thyroplasty. In the European Community, PDMS particles are officially approved for use in the human larynx.

Adult↗

PubMed2006

Does the timing of tracheal intubation based on neuromuscular monitoring decrease laryngeal injury? A randomized, prospective, controlled trial.

Vocal cord injuries (VCI) and postoperative hoarseness (PH) are common complications after general anesthesia. Poor muscle relaxation at the moment of tracheal intubation may result in VCI. There is a large interindividual variation in neuromuscular depression after administration of neuromuscular blocking drugs. Therefore, the optimal individual timing of tracheal intubation based on neuromuscular monitoring (monitoring) may decrease VCI. In this prospective trial, 60 patients were randomized into 2 groups: Monitoring group: tracheal intubation at maximum block based on monitoring after atracurium 0.5 mg/kg and 2-min group: tracheal intubation 2 min after injection of atracurium 0.5 mg/kg. Intubating conditions were evaluated with the Copenhagen score. VCI were examined by stroboscopy before and 24 and 72 h after surgery. PH was assessed at 24, 48, and 72 h after surgery by a standardized interview. Excellent intubating conditions were significantly increased in the monitoring group compared with the 2-min group: 8 versus 2 patients, respectively (P = 0.036). The incidence of PH between the study groups was comparable: 7 (monitoring) versus 8 patients (2-min) (P = 0.860). Similar findings were observed for VCI: 9 versus 5 patients; respectively (P = 0.268); type of VCI: thickening of the vocal cords: 8 (monitoring) versus 5 (2-min) patients (P = 0.423), hematomas: 2 patients in each group (not significant). The present study demonstrated that neuromuscular monitoring improved endotracheal intubating conditions. However, tracheal intubation at maximum intensity of neuromuscular block was not associated with a decrease in vocal cord injuries.

Adult↗

PubMed2004

Analysis and detection of binaural interaction in auditory evoked brainstem responses by time-scale representations.

The beta-wave of the binaural interaction component (BIC) in auditory evoked brainstem responses has been shown to be an objective measure of binaural interaction. However, a reliable and automated detection of this component capable of clinical use still remains a challenge. In this study, wavelet based time-scale representations of auditory evoked brainstem responses were investigated for the analysis of binaural interaction and for an automated detection of the beta-wave. Twenty normal hearing subjects with verified normal directional hearing and speech intelligibility in noise were included in our study. In all of these subjects, the BICs exhibited a characteristic concentration of energy in the time-scale domain which allowed for an automated detection of the beta-wave. Moreover, our study provides an explanation why the beta-wave is hard to detect for larger interaural time delays using time-scale entropy based arguments. It is concluded that time-scale representations of auditory brainstem responses are well suited for the analysis of binaural interaction and allow for an automated detection of the beta-wave.

Acoustic Stimulation↗

PubMed2004

Phase III results with a totally implantable piezoelectric middle ear implant: speech audiometry, spatial hearing and psychosocial adjustment.

OBJECTIVE: To evaluate the treatment efficacy of an electromechanical middle ear amplifier implant (AI) in patients with chronic moderate-to-severe sensorineural hearing loss (SNHL). The AI is a piezoelectric system with a sound processor and a rechargeable battery within a hermetically sealed titanium canister. Its titanium-sealed microphone is placed in the bony region of the ear canal. The incus-coupled transducer (actuator), which is also inside a titanium casing, is fastened to the adjacent bone. MATERIAL AND METHODS: This was a phase III study comprising 20 intention-to-treat patients. Telemetrical adjustments followed electromechanical amplifier implantations. We used a word recognition test as our primary efficacy measure (Freiburg Speech Recognition Test: DIN 45621). Secondary efficacy measures were the sentence comprehension test (Goettinger Satztest, 1996) for auditory orientation within noisy and quiet environments and a psychosocial adjustment test (Gothenburg Profile Test, 1998). The 6-month follow-up comprised a complete medical examination. Nineteen patients completed the study (per-protocol patients; 100% reference). RESULTS: Seventeen patients (89%) demonstrated improved binaural recognition of phonetically balanced monosyllables. Fourteen postoperative patients (74%) attained a perfect score (100%) on this test, compared to only 3 preoperative patients (16%). Thirteen patients (68%) reached the sentence recognition threshold at a 2:1 dB signal-to-noise ratio during noisy trials. Correct identification of the noise source direction in the horizontal plane occurred in 89% of the trials. The Gothenburg Profile Test scores showed that the subjective evaluation of hearing, orientation, social behavior and self-confidence increased from 48% to 88%. Three patients did not benefit from the implant. CONCLUSION: Treatment of SNHL with a totally implantable hearing system can be an efficient method for those patients unable to wear hearing aids. However, in order to avoid implantation in non-responders, there is a need for more specific audiological indication criteria.

Audiometry, Pure-Tone↗

PubMed2004

Objective detection of the central auditory processing disorder: a new machine learning approach.

The objective detection of binaural interaction is of diagnostic interest for the evaluation of the central auditory processing disorder (CAPD). The beta-wave of the binaural interaction component in auditory brainstem responses has been suggested as an objective measure of binaural interaction and has been shown to be of diagnostic value in the CAPD diagnosis. However, a reliable and automated detection of the beta-wave capable of clinical use still remains a challenge. We propose a new machine learning approach to the detection of the CAPD that is based on adapted tight frame decompositions which are tailored for support vector machines with radial kernels. Using shift-invariant scale and morphological features of the binaurally evoked brainstem potentials, our approach provides at least comparable results to the beta-wave detection in view of the discrimination of subjects being at risk for CAPD and subjects being not at risk for CAPD. Furthermore, as no information from the monaurally evoked potentials is necessary, the measurement cost is reduced by two-thirds compared to the computation of the binaural interaction component. We conclude that a machine learning approach in the form of a hybrid tight frame-support vector classification is effective in the objective detection of the CAPD.

Artificial Intelligence↗

PubMed2004

[Minimally invasive surgery of the paranasal sinuses].

Surgery of the paranasal sinuses for chronic sinusitis or nasal polyposis has changed profoundly over the last decades. Today, minimally invasive surgery through the nostrils is the standard of care throughout the world. Classic procedures using an extranasal approach have been abandoned almost completely. This development was mainly driven by the introduction of rigid telescopes providing an angled view of the operation field. In addition, new pathophysiological findings have suggested less radical procedures. Functional endoscopic sinus surgery (FESS) shows high success rates, complications are rare, but potentially serious. Computer-assisted surgery systems for intraoperative navigation are at the threshold of being used on a routine basis. However, at the present time their use must not be considered as mandatory for the vast majority of cases. Postsurgical treatment using nasal irrigations with normal saline solution and topical application of steroids is of great importance to provide long-term success following surgical interventions.

Humans↗

PubMed2003

Laryngeal morbidity and quality of tracheal intubation: a randomized controlled trial.

BACKGROUND: Vocal cord sequelae and postoperative hoarseness during general anesthesia are a significant source of morbidity for patients and a source of liability for anesthesiologists. Several risk factors leading to laryngeal injury have been identified in the past. However, whether the quality of tracheal intubation affects their incidence or severity is still unclear. METHODS: Eighty patients were randomized in two groups (n = 40 for each) to receive a propofol-fentanyl induction regimen with or without atracurium. Intubation conditions were evaluated with the Copenhagen Score; postoperative hoarseness was assessed at 24, 48, and 72 h by a standardized interview; and vocal cords were examined by stroboscopy before and 24 and 72 h after surgery. If postoperative hoarseness or vocal cord sequelae persisted, follow-up examination was performed until complete restitution. RESULTS: Without atracurium, postoperative hoarseness occurred more often (16 vs. 6 patients; P = 0.02). The number of days with postoperative hoarseness was higher when atracurium was omitted (25 vs. 6 patients; P < 0.001). Similar findings were observed for vocal cord sequelae (incidence of vocal cord sequelae: 15 vs. 3 patients, respectively, P = 0.002; days with vocal cord sequelae: 50 vs. 5 patients, respectively, P < 0.001). Excellent intubating conditions were less frequently associated with postoperative hoarseness compared to good or poor conditions (11, 29, and 57% of patients, respectively; excellent vs. poor: P = 0.008). Similar findings were observed for vocal cord sequelae (11, 22, and 50% of patients, respectively; excellent vs. poor: P = 0.02). CONCLUSIONS: The quality of tracheal intubation contributes to laryngeal morbidity, and excellent conditions are less frequently associated with postoperative hoarseness and vocal cord sequelae. Adding atracurium to a propofol-fentanyl induction regimen significantly improved the quality of tracheal intubation and decreased postoperative hoarseness and vocal cord sequelae.

Adolescent↗

PubMed2003

Development of the first force-controlled robot for otoneurosurgery.

OBJECTIVE: In some surgical specialties (eg, orthopedics), robots are already used in the operating room for bony milling work. Otological surgery and otoneurosurgery may also greatly benefit from the enhanced precision of robotics. STUDY DESIGN: Experimental study on robotic milling of oak wood and human temporal bone specimen. METHODS: A standard industrial robot with a six-degrees-of-freedom serial kinematics was used, with force feedback to proportionally control the robot speed. Different milling modes and characteristic path parameters were evaluated to generate milling paths based on computer-aided design (CAD) geometry data of a cochlear implant and an implantable hearing system. RESULTS: The best-suited strategy proved to be the spiral horizontal milling mode with the burr held perpendicular to the temporal bone surface. To reduce groove height, the distance between paths should equal half the radius of the cutting burr head. Because of the vibration of the robot's own motors, a high oscillation of the SD of forces was encountered. This oscillation dropped drastically to nearly 0 Newton (N) when the burr head made contact with the dura mater, because of its damping characteristics. The cutting burr could be kept in contact with the dura mater for an extended period without damaging it, because of the burr's blunt head form. The robot moved the burr smoothly according to the encountered resistances. CONCLUSION: The study reports the first development of a functional robotic milling procedure for otoneurosurgery with force-based speed control. Future plans include implementation of ultrasound-based local navigation and performance of robotic mastoidectomy.

Equipment Design↗

PubMed2003

Noise in magnetic resonance imaging: no risk for sensorineural function but increased amplitude variability of otoacoustic emissions.

OBJECTIVES: Objectives were to perform exact measurements of the noise exposure in a magnetic resonance imager and to investigate the effects of magnetic resonance imaging (MRI) noise on hearing sensitivity, which are still controversial, in a large number of patients. STUDY DESIGN: Prospective trial. METHODS: Acoustic noise during seven different MRI sequences was measured using a custom-made microphone containing no ferromagnetic parts. In 244 ears of 126 patients, pure-tone audiometry was performed once before and once after MRI noise, and distortion product otoacoustic emissions were measured once before and three times after MRI. RESULTS: The sound pressure level (SPL) at the patient's ear (with consideration of the sound-damping effect of the head support) ranged from 79.5 to 86.5 dB (A), depending on the MRI sequence, with brief sound pressure peaks up to 120 dB SPL. No significant incidence of temporary threshold shift and no reduction of mean distortion product otoacoustic emission amplitude were apparent. However, a significant increase in distortion product otoacoustic emission amplitude variability after noise exposure with equal distribution of increased and decreased amplitudes was observed. This variability showed a maximum at 15 minutes after noise, as demonstrated by continuous measurements. CONCLUSIONS: First, MRI noise does not impose a risk to hearing function under the measurement condition of a sound-damping head support or ear protectors. Second, a subtle effect is demonstrated by increased distortion product otoacoustic emission amplitude variability. Third, the increased otoacoustic emission amplitude variability is an audiometric parameter that is extremely sensitive to effects of acoustic stimulation, indicating more discrete changes in cochlear activity than pure-tone audiometry or otoacoustic emission amplitude reduction. A shift of the operation point (OP) of the outer hair cell (OHC) between basilar membrane and tectorial membrane is suggested as underlying cause.

Audiometry, Pure-Tone↗

PubMed2003

Dural cell culture. A new approach to study duraplasty.

Fistulas of the cerebrospinal fluid are often repaired by insertion of grafts of various kinds. However, current knowledge of wound healing after graft insertion is limited, and only a few animal studies are available. The objective of this study is to test whether an in vitro model is suited to analyze cellular healing aspects after duraplasty and to assess dura substitutes in such conditions in regard to their surface attractiveness for cellular migration from the dura margins. Harvested dura pieces from minipigs were perforated to mimic central dura lesions, placed on various coated surfaces (collagen, laminin, poly-L-lysine) or grafts, and investigated in a cell culture for cellular closure of the perforation. Cellular migration from the dura into the central perforation was noted on collagen-coated surfaces and when defects were filled with collagen gels, but there was no cell growth on surfaces with poly-L-lysine or laminin coating. Immunocytochemistry identified the migrating cells mainly as fibroblasts with some intermingled epithelial cells. Scanning electron microscopy proved cellular closure of defects after dura placement on allogenic non-crosslinked collagen transplants. Less cellular migration was observed on poly-P-dioxanon sheets, while no cells migrated into the central dura perforation after placement on a cartilage substitute. Cell counting indicated enhanced cellular closure of the dura opening after introduction of insulin or fibroblast growth factor (sign test for both: 0.031). Our study succeeded in establishing a cell culture model for duraplasty and indicated cellular migration from the dura borders at the site of the defect during the wound healing process. The cell culture model presented in this report shows that collagen grafts are best suited for duraplasty. In accordance with the immunocytological finding of fibroblast migration from the dura borders additional application of fibroblast-stimulating growth factors accelerated cellular defect closure.

Animals↗

PubMed2003

Experimental robotic milling in skull-base surgery.

OBJECTIVE: In the field of otorhinolaryngology, a variety of skull implants have been developed to assist hearing-impaired or even deaf patients. The first step in the implantation procedure, and also in lateral skull-base surgery, is to drill the calvarian or mastoid bone. We intended to investigate the hitherto unknown parameters for performing this procedure and to establish the first set-up for robotic milling of the lateral skull base. MATERIALS AND METHODS: Experimental milling of the skull base was conducted on two human specimens using a hexapod robot. RESULTS: Optimized parameters were determined with a drill speed of 30,000 revolutions/min and a form feed rate of 5 mm/s for the calvarium and 1 mm/s for mastoid bone, respectively, in a spiral-path fashion. While using a cutting burr, mean force levels were 4.81 N for calvarian bone and 6.12 N for mastoid bone, respectively--well below our empirical limit of 10 N. However, maximum levels easily surpassed these limits, reaching 27.7 N. CONCLUSION: The prerequisites for robotic skull-base surgery were fulfilled. With further work to implement feedback of sensory input, robots may increase precision for various tasks in skull-base surgery.

Humans↗

PubMed2003

The binaural interaction component (BIC) in children with central auditory processing disorders (CAPD).

The detection of binaural interaction is of diagnostic interest in patients with central auditory processing disorders (CAPDs), as binaural hearing tasks are frequently affected in these patients. Owing to the comorbidity associated with disorders such as an attention-deficit hyperactivity disorder, pathological results in subjective tests often show extra-auditory factors such as reduced attention rather than impaired central auditory function. Therefore, objective measures for auditory processing disorders are essential. The binaural interaction component (BIC), which is the arithmetical difference between the sum of the monaurally evoked auditory potentials of each ear and the binaurally evoked brainstem potentials, has been used as an objective measure of binaural interaction in humans. BIC measurements can therefore be considered as a possible diagnostic tool in CAPD patients. One aim of the present study was to examine whether and to what extent BIC measurements are capable of differentiating between normal children and children 'at risk for CAPD'. BIC measurements were performed on 17 children at risk for CAPD and in a group of 25 children with normal results in the central audiometric tests used. Using the presence or absence of clearly demonstrable BIC waveforms as an indication of whether a CAPD is present or not, a sensitivity and specificity of 76% could be achieved. We conclude that BIC measurements might be of some diagnostic value in CAPD patients.

Child↗

PubMed2002

Recurrent giant cell reparative granuloma of the skull base and the paranasal sinuses presenting with acute one-sided blindness.

The etiology, pathogenesis, histopathologic diagnosis, prognosis, and treatment of giant cell reparative granulomas of the skull are controversial. We report a 14-year-old girl with an advanced recurrent giant cell reparative granuloma of the skull base and paranasal sinuses whose only clinical manifestation was a loss of vision. After undergoing endovascular catheter embolization, the patient underwent repeated surgical resections of the mass via a combined frontobasal and modified infratemporal approach followed by radiation therapy. Histopathologic examination confirmed the diagnosis of giant cell reparative granuloma. A traumatic event in the patient's history-a fossa canina abscess followed by tooth extraction 14 months before admission-supports the theory of a reactive reparative process as a pathogenetic mechanism for this disease. Histopathologic criteria and clinical aggressiveness must be considered to achieve adequate treatment of giant cell lesions of the skull.

Case Reports↗

PubMed2002

Transtympanic endoscopy for drug delivery to the inner ear using a new microendoscope.

Anatomic variations of the round window (RW) niche found in approximately 33% of human temporal bones may account for some ofthe problems associated with local drug delivery to the inner car. A microendoscope with a total outer diameter of 1.2 mm was developed in particular for easy visualization and of drug delivery to the RW niche. It incorporated a thin fiber optic, a working/laser channel (0.3 mm) and an irrigation/suction channel (0.27 mm). When compared to a common 30 degree lens optic, with the microendoscope a greater area of the round window niche could be overseen. In addition, the endoscope could be advanced directly upon the surface of the RW membrane (RWM). The microendoscope may be used for evaluation of the anatomy of the RW niche prior to the placement of local drug delivery systems, for application of drugs directly onto the surface of the RWM or to verify the correct placement of inner ear drug delivery systems.

Administration, Topical↗