Biomedical subjects

K Tschopp

Publications and source records attributed to K Tschopp.

At least 19 recordsLinked to original sources

PubMed2004

[Sinonasal hemangiopericytoma].

Hemangiopericytomas are rare perivascular tumors. The nasal cavity and paranasal sinuses are most often involved in the head and neck region. A case of hemangiopericytoma in a 63 year old patient is presented. The initial symptom was recurrent bleeding from the nose. The patient had a history of radiotherapy for a pituitary adenoma 30 years previously. Computed tomography and magnetic resonance imaging showed a polypoid opacification of the ethmoid, sphenoid and basal aspects of the frontal sinus on the right side. Histological diagnosis was obtained from nasal biopsy. Preoperatively, arteriography and tumor embolisation were performed. The tumor was completely excised using a combined endonasal and external approach as an osteoplastic revision of the frontal sinus via bicoronal incision. There was no recurrence at follow-up 1 year later.

Biopsy↗

PubMed2004

[Influence of intraoperatively applied current of coagulation on the postoperative course in tonsillectomy].

BACKGROUND AND METHODS: Postoperative pain after tonsillectomy is greater using diathermy compared to the use of ligatures for hemostasis. In the present paper, the influence of coagulation current on the postoperative course is assessed quantitatively. The applied coagulation current was registered in Watt per second (Ws) in 63 patients. Intraoperative blood loss, operation time, experience of the surgeon, postoperative pain and the consumption of analgesics were registered. RESULTS: The mean intraoperative blood loss was correlated to the amount of applied coagulation current. Operation time was reduced with increased coagulation current. The energy of the applied coagulation current correlated significantly with pain in the late postoperative period. There was no influence in the amount of coagulation current on the consumption of analgesics or postoperative hemorrhage. Blood loss was less and operation time was shorter with more experienced surgeons. Six secondary postoperative hemorrhages were observed. Hemorrhage occurred more often with inexperienced surgeons. The applied coagulation current was, however, not dependent on the surgeon's experience but on his individual technique for intraoperative control of hemostasis. CONCLUSIONS: Pain following tonsillectomy is related to the amount of intraoperatively applied coagulation current, especially in the late postoperative course (days 10 - 14). This may be explained by tissue damage and increased eschar due to coagulation. Careful and reserved use of intraoperative coagulation will reduce postoperative pain.

Adenoids↗

PubMed2001

Evaluation of persistent torticollis following adenoidectomy.

Post-operative neck complaints are not an uncommon finding following adenotonsillectomy. However, non-traumatic subluxation of the atlantoaxial joint (Grisel's syndrome) should be considered in cases of persistent neck pain and stiffness. An early diagnosis and adequate treatment of this rare condition is mandatory to prevent potentially serious complications. We describe three cases with persistent torticollis in the post-operative period, discuss the pathogenesis and evaluate the clinical management of these patients.

Adenoidectomy↗

PubMed2000

[Detection of central auditory compensation in unilateral deafness with functional magnetic resonance tomography].

BACKGROUND: Functional magnetic resonance imaging (fMRI) is a noninvasive method to detect focal brain activity at high spatial resolution. Acoustic stimulation induces an increase of regional cerebral blood flow in the primary auditory cortex. This entails an increased concentration of diamagnetic oxyhemoglobin in the capillaries and the venous system. The resulting decrease of the local magnetic susceptibility was detected as a signal increase in T2*-weighted images. The central auditory pathways predominantly cross to the contralateral hemisphere in normally hearing subjects. The aim of the present study was to investigate the primary auditory cortex after acoustic stimulation in unilateral deaf patients using fMRI. METHODS: Magnetic resonance images were acquired on a 1.5 T Siemens Vision scanner. For fMRI, a single shot gradient recalled, echo planar imaging (EPI) sequence with decreasing excitation order was used, allowing the aquisition of 9 slices within 1.8 s. The 9 slices covered a slab of 3.6 cm in cranio-caudal extension in the region of the temporal lobes. For statistical processing of the raw image data the SPM96 software package was used. A p-value of p < 0.01 was applied to differentiate between activated and non-activated. The resulting functional activation maps were superimposed onto the EPI scan. The number of activated pixels was used to quantitate the cortical response upon acoustic stimulation. Stimulation consisted of a 1000-Hz sine tone (100 dB SPL at the distal end of the head phone, pulsed at 6 Hz) to which the patients were asked to listen passively. A piezoelectric loudspeaker was mounted on the subject table and connected to a plastic tube system leading to a combination of bilateral ear- and headphones. Auditory paradigms require disentangling experimental excitation from the scanner noise that approximates 90 dB. Headphones suppress noise by approximately 30 dB. To decrease the acoustic background-to-stimulation ratio and to keep background noise constant during stimulation and resting, we employed short scanning (1.8 s) and long resting periods (10.2 s; TR = 12 s). This acquisition mode allows sufficient recovery during off-periods and sufficient excitation during on-periods. 14 unilateral deaf patients were examined. The mean duration of deafness was 22.5 years. RESULTS: Acoustic stimulation of the deaf ear revealed only weak cortical activation which could be explained by sound transmission via bone conduction to the other ear. A significant increase of BOLD (blood oxygen level dependent)-activation in the primary auditory cortex could be demonstrated in all patients after stimulation of the hearing ear. However, remarkable individual differences were noticed concerning the absolute number of activated pixels. The lateralization ratio was calculated by the number of activated pixels on the hearing side divided by the number of activated pixels on the deaf side. A mean lateralization ratio of 0.9 (Stdv +/- 0.6) was found. The mean lateralization ratio for patients with a right deaf ear (n = 8) and those with a left deaf ear (n = 5) was 1.1 (Stdv +/- 0.7) and 0.6 (Stdv +/- 0.3) respectively. However, the difference was not significant (Wilcoxon test: p = 0.08). CONCLUSIONS: Central-auditory compensation by bilateral cortical activation was demonstrated in unilateral deaf patients. Moreover, a tendency towards a dominance of the left primary auditory cortex was found, although the difference between both hemispheres was not significant. The lateralization ratio in unilateral deaf patients is similar to findings after binaural stimulation in normally hearing subjects.

Acoustic Stimulation↗

PubMed2000

[Experiences with the treatment of vascular malformations using the Nd-YAG laser].

Lasers have been used for about 15 years in the treatment of vascular malformations and haemangiomas in the head and neck area. The physical properties of the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser system make it particularly suitable for this purpose. We review our first experience with the treatment of vascular malformations using the Nd-YAG-laser. 9 Patients with 10 vascular malformations were treated. A complete remission was achieved with 9 of the 10 vascular malformations and a partial remission with the remaining case. No complications were observed. The neodymium:yttrium-aluminum-garnet (Nd:YAG) laser therapy has proven itself as simple to use, being highly effective and having a low complication rate.

Adolescent↗

PubMed2000

Choanal atresia in premature dizygotic twins--a transnasal approach with Holmium:YAG-laser.

Twins born prematurely presented with choanal atresia and were successfully treated using a transnasal, endoscopically and microscopically controlled Ho:YAG-Laser assisted technique. One twin, who had bilateral choanal atresia was operated immediately, the other one, with unilateral choanal atresia, received surgery 8 months after birth. The rare feature of twins both suffering from choanal atresia and a technique for definitive treatment of this disease in premature neonates are presented and discussed. This report of dizygotic twins with nonsyndromal choanal atresia suggests the possibility of an autosomal recessive inheritance with various penetration or an undefined teratogenic etiologic factor.

Choanal Atresia↗

PubMed1998

Tonotopic organization of the human auditory cortex as detected by BOLD-FMRI.

Functional magnetic resonance imaging is a noninvasive and nonradioactive method for the detection of focal brain activity. In the present study the auditory cortex was investigated in nine normal subjects who were binaurally stimulated using pulsed sine tones of 500 Hz and 4000 Hz. The BOLD (blood oxygenation level dependent) signal change coincided with the stimulation paradigm and was detected in the plane of the superior temporal gyrus. The comparison of the spatial distribution of activated areas revealed a different behavior for the two frequencies. The present findings underline the existence of a frequency specific organization in the medio-lateral, fronto-occipital and cranio-caudal extension in both hemispheres of the auditory cortex in human. The activated areas for the high tone were found more frontally and medially orientated than the low tone stimulated areas. Furthermore, a slight cranio-caudal shift was observed for the higher frequency, more pronounced in the right than in the left temporal lobe. Finally, for most of the subjects investigated the BOLD activation area of the 500 Hz sine tone was larger than that of the 4000 Hz stimulation. Both frequencies showed a lateralization of signal response to the left temporal lobe.

Acoustic Stimulation↗

PubMed1998

[Visualization of central auditory processes with functional magnetic resonance tomography].

BACKGROUND: Central auditory processes can be visualized using functional MRI in a non-invasive manner and at high spatial resolution. Acoustic stimulation leads to an increase of blood flow of activated areas in the plane of the superior temporal gyrus. Radiologically, this may be visualized based on the long T2-relaxation time of oxyhemoglobin. PATIENTS: Ten normal-hearing subjects with ages between 28 and 38 years took part in the investigations. They received binaural, monaural right, and monaural left stimulation with pulsed sine tones of 1000 Hz at a pulse rate of 6 Hz and a sound pressure level of 100 dB SPL. Tonotopic organization of the auditory cortex was visualized using stimulation by pulsed sine tones of 500 Hz and 4000 Hz. RESULTS: Following monaural acoustic stimulation, increased activity of the contralateral auditory cortex could be demonstrated in 9 subjects. In one subject, bilateral activity was noted. Concerning the tonotopic organization of the auditory cortex, we could show that the higher frequencies were localized more medially and anteriorly; the lower frequencies were localized more laterally and posteriorly in the superior temporal gyrus. However, considerable overlap was noted. CONCLUSIONS: The overlap of the different frequencies could explain the controversial discussion of the tonotopic organization of the auditory cortex. The results of the monaural acoustic stimulation show clearly the predominant signal increase of contralateral areas in the primary auditory cortex. These results confirm the opinion of the current textbooks that the fiber of the auditory pathways mostly cross. Further investigations using functional MRI are necessary for better understanding of physiological and pathophysiological central-auditory processes.

Acoustic Stimulation↗

PubMed1998

Auditory cortical responses in hearing subjects and unilateral deaf patients as detected by functional magnetic resonance imaging.

Functional magnetic resonance imaging is a non-invasive method for the detection of focal brain activity at high spatial resolution. Acoustic stimulation leads to a blood oxygenation level dependent signal change in the plane of the superior temporal gyrus. The dependence of this response in the auditory cortex on binaural, monaural left and monaural right acoustic stimulation for 10 healthy subjects and five monaural deaf patients is described. Acoustic stimulation consists of 1000 Hz pulsed sine tones at a pulse rate of 6 Hz and a sound pressure level of 95 dB. For monaural stimulation, normal-hearing subjects revealed a strong lateralization of cortical response towards the contralateral hemisphere. The lateralization ratios between left and right hemispheric response areas were 3.4-5.2 for monaural stimulation and nearly balanced for binaural stimulation. Additionally, the sum of cortical activation volumes induced by monaural left and right stimulation was approximately 30% smaller than for binaural stimulation, indicating either inhibitory mechanisms or neuronal facilitation within the auditory pathways. For monaural deaf subjects the lateralization ratio between left to right response was just 1.3 towards the contralateral hemisphere of the healthy ear, which is comparable to binaural responses of normal-hearing subjects. This observation seems to indicate a plasticity or a reorganization of auditory pathways of monaural deaf patients.

Adult↗

PubMed1996

[Local infiltration of epinephrine and bupivacaine before tonsillectomy].

The effects of peritonsillar injections of epinephrine and local anesthetics before tonsillectomy on blood loss and postoperative pain were evaluated in a prospective, randomized double-blind trial on 103 children. Patients were randomly assigned into one of three groups: controls given injections of 0.9% NaCl (n = 34), patients injected with 0.4 ml/kg (1:200,000) epinephrine combined with 0.25% bupivacaine (n = 33) and patients given only 1:200,000 epinephrine (n = 36). All injections and operations were performed by the same surgeon (KS). Blood loss was calculated by weighing all blood aspirated perioperatively and swabs used during surgery. Postoperative pain was assessed at regular intervals by using three methods: (1) use of a visual analogue scale by parents and nurses to estimate pain; (2) postoperative need for nalbuphine as analgesic; (3) the Hannallah-Broadman semi-objective pain score (including crying, anxiety, restlessness, and changes in blood pressure). The mean blood loss in the control group (given NaCl) was 132 g, which was significantly increased when compared with the epinephrine/bupivacaine group (85 g) and the group treated with only epinephrine (90 g). However, analysis of the postoperative pain scores did not reveal any significant differences among groups. These findings indicate that the peritonsillar injection of bupivacaine does not decrease postoperative pain, but peritonsillar injections of epinephrine will significantly reduce blood loss during tonsillectomy.

Adenoidectomy↗

PubMed1995

[Context effects in speech recognition of sentences].

Context plays an important role in speech recognition. The goal of the present study was to quantify context effects in speech recognition using the Basle Sentence Understanding Test. This test consists of two types of sentences according to the amount of contextual information: they contain sentences with highly predictable (HP) final words and sentences with low predictable (LP) final words. The effect of different contextual situations on speech recognition was investigated in this study using the Basle Sentence Understanding Test. The speech recognition threshold of HP sentences was found to be 6 dB lower than that of LP sentences. However, contextual effects can only be demonstrated if the context is clearly understandable. In the Basle Sentence Understanding Test, this is achieved by special masking techniques. The significance of the recognition of the contextual part of the sentence with respect to the recognition of the whole sentence is different in HP and LP sentences.

Adolescent↗

PubMed1995

[The context effect in speech recognition of sentences].

Context plays an important role in speech recognition. The goal of the present study was to quantify context effects in speech recognition using the Basel Sentence Understanding Test. This test consists of two types of sentences according to the amount of contextual information: sentences with high predictable (HP) final words and sentences with low predictable (LP) final words. The effect of different contextual situations on speech recognition was investigated in this study using the Basel Sentence Understanding Test. The speech recognition threshold of HP sentences was found to be 6 dB lower than that of LP sentences. However, contextual effects can only be demonstrated if the context is clearly understandable. In the Basel Sentence Understanding Test, this is achieved by special masking techniques. The significance of the contextual part of the sentence with respect to the recognition of the whole sentence is different in HP and LP sentences.

Adolescent↗

PubMed1995

[Effect of linguistic competence on speech audiometry results using the Basel Sentence Test].

Linguistic competence, such as a mental lexicon knowledge of syntactic rules of the language and the use of semantic constraints, may impact central speech processing and play an important role in speech recognition. The influence of linguistic ability on speech understanding was investigated using the Basel Sentence Understanding Test. The subject's linguistic ability was determined based upon educational background (elementary school, high school and or university) and intelligence quotients (IQ) based on the reduced version of the Hamburg-Wechsler Intelligence Test. Forty normally-hearing subjects listened to five test forms of the Basel Sentence Understanding Test. Each test form comprised a fraction of 15 low-predictable (LP) test items and 15 high-predictable (HP) test items based on the amount of contextual information in the phrases. No effect of educational background and IQ-value could be demonstrated on the scores of LP sentences. However, there was a small but significant influence of educational background and IQ-value on the scores of HP sentences. The implications of these findings on clinical speech audiometry are discussed.

Adult↗

PubMed1994

[New aspects in surgery of the thyroid gland with intraoperative monitoring of the recurrent laryngeal nerve].

A method for electrophysiological monitoring of the recurrent laryngeal nerve during thyroid surgery is described. An electromyographic record from the muscles of the vocal folds is obtained using two fine needle electrodes. The electrodes are placed endoscopically. The nerve is identified by electrical stimulation, and the electromyographic activity is registered using a Nerve Integrity Monitor NIM-2 (Xomed-Treace). Our experience with this method in 43 patients is described. The safety of the integrity of the recurrent laryngeal nerve is increased using intraoperative monitoring. This has led to a modification of the operative concept in thyroid surgery. Electrophysiological monitoring is mandatory in surgery of large goitres, retrotracheal and substernal extension, for re-operations and malignant diseases of the thyroid gland.

Electric Stimulation↗

PubMed1994

Performance of normally hearing and hearing-impaired listeners using a German version of the SPIN test.

Various stages in the development of a German version of the English SPIN (Speech Performance in Noise) test have been reported previously by the authors (Züst & Tschopp, 1993). The test forms consist of 15 sentences each with a length of five to nine syllables. The forms have been constructed with either low predictable (LP) final words or high predictable (HP) final words, based upon the amount of contextual information available in the sentence. The test is performed with a background noise and uses adaptive testing strategies. The proportion of HP to LP responses is compared. Normally, scores of the HP segment are higher than those of the LP segment of the test, because the increased contextual information contributes to a better understanding of the HP final words. The SPIN test results in young normally hearing listeners (n = 12), elderly normally hearing listeners (n = 13), young hearing-impaired subjects (n = 14) and elderly hearing-impaired subjects (n = 19) are reported. The most important findings were that the LP-HP difference was not dependent on the degree of peripheral hearing loss, and that no age-related effects could be demonstrated. The SPIN test results were compared with conventional speech audiometric parameters, hearing threshold levels for pure tones and self-reported hearing handicap. Low to moderate correlations were present but were not consistent across comparisons.

Adult↗

PubMed1993

[Results of a prospective open study of therapy of sudden deafness with flunarizine].

The treatment effect of the lipophilic calcium antagonist flunarizine on the recovery of sudden hearing loss was evaluated in a prospective phase-II study. Thirty-seven patients presenting with recent and sudden onset of unilateral sensorineural hearing loss were treated with 50 mg flunarizine intravenously for the first two days followed by 10 mg flunarizine orally for four weeks. Pure-tone audiometry was done before the beginning of the treatment and after one and four weeks. The absolute and relative hearing gains after one and four weeks were compared to those of 67 similar patients previously treated with saline infusions and placebo tablets in the same institutions during a double blind study (Probst et al. Acta Otolaryngol. 112 (1992) 435-443). The mean absolute hearing gains of the flunarizine group was 17 dB and 21 dB, after one and four weeks respectively (placebo group: 16 dB and 24 dB). The corresponding relative hearing gains (defined as absolute gain divided by initial hearing loss) were 35% and 43% for the flunarizine group and 33% and 42% for the placebo group. We conclude that flunarizine treatment does not improve the recovery of sudden hearing loss.

Administration, Oral↗

PubMed1993

Silicone stents in the management of inoperable tracheobronchial stenoses. Indications and limitations.

BACKGROUND: Various stent models have been developed for the treatment of inoperable stenoses of the central airways caused by external compression. Increasing use is made of the silicone stents designed by Dumon. We tested their technical feasibility, tolerance, and long-term efficacy in relieving respiratory symptoms in patients referred for endoscopic palliation of malignant disease. METHODS: All procedures were performed under general anesthesia with the use of the rigid bronchoscope. We inserted 38 stents in 31 patients (median age, 67 years; 25 men and 6 women) whose airways showed residual obstruction of > 50 percent of the lumen after laser resection of endobronchial tumor and/or mechanical dilatation of extrinsic compressions. RESULTS: Stent placement and removal--where necessary--were easy in all patients, but five stents inserted in three patients with short (< or = 2.5 cm) and conical stenoses migrated, necessitating emergency removal. In 27 of the remaining 28 patients, stent tolerance was excellent; 1 proximal tracheal stent (< 1 cm below the vocal cords) had to be removed because of otalgia and dysphagia. One lethal hemoptysis occurred within hours after a repeated laser therapy and removal of an indwelling stent. No other serious complications occurred. Immediate and lasting relief of dyspnea and improvement in performance status (Karnofsky scale, activity index) was achieved in 90 percent (28/31) of patients (p < 0.01). The influence of adjuvant radiotherapy on local tumor recurrence and survival was analyzed in a subgroup of ten patients with stage IIIB squamous cell carcinoma with comparable performance status. Five did not undergo adjuvant radiotherapy (group A) and five did (group B). In group A, four of five stents were occluded by tumor recurrence above or below the stent after a median follow-up of 2 months; in group B, zero of five were occluded (p < 0.05) after 4 months. Median survival was 4 months in group A and 6 months in group B; the difference did not reach significance. CONCLUSIONS: The silicone stents designed by Dumon are easily inserted and removed; they are also well tolerated and very efficacious in relieving respiratory symptoms caused by extrinsic airway compression. Short and conical stenoses present limitations for their use due to increased risk of migration. Combined treatment with laser resection, stent insertion, and subsequent radiotherapy is necessary to prevent local tumor recurrence and may improve survival.

Adult↗

PubMed1993

Influence of context on speech understanding ability using German sentence test materials.

The use of contextual information for the recognition of subsequent words may be considered as a central auditory process. In the present study, preliminary test forms of a German version of the American SPIN test were evaluated. The test materials consisted of short sentences with a contextual part and a final word that was always a monosyllabic noun. The contribution of context to the recognition of "high predictable" (HP) and "low predictable" (LP) final words of these sentences was investigated. Testing was performed in noise. However, the masking noise was time-weighted such that the masking level was higher for the final word than for the preceding contextual portion of the sentence. At scores of 29.3%, 50% and 70.7% correct, the mean difference in S/N ratio between HP and LP items was approximately 5, 5 and 2.5 dB, respectively. Equal performance for HP and LP items would indicate central auditory dysfunction. Possible diagnostic applications are discussed.

Acoustic Stimulation↗