Biomedical subjects

S Schmerber

Publications and source records attributed to S Schmerber.

26 records · Page 2Linked to original sources

PubMed2001

Accuracy evaluation of a CAS system: laboratory protocol and results with 6D localizers, and clinical experiences in otorhinolaryngology.

OBJECTIVES: The objective of the study reported in this article was to evaluate (1) localizer inaccuracies, one of the major sources of errors in Computer-Assisted Surgery (CAS) systems, and (2) the final errors obtained using surface-based registration in ear, nose, and throat (ENT) surgery. These objectives were met through (1) a technical evaluation of the accuracy and usability of several optical localizers under laboratory test conditions, and (2) a clinical measure of the global errors obtained when using a CAS system including one of the standard localizer systems (Flashpoint 5000) in Functional Endoscopic Sinus Surgery (FESS). PATIENTS AND METHODS: The technical evaluation of localizers consisted of series of geometric tests on four commercial systems. Clinical evaluation included the development of a laboratory CAS system using a markerless, skin surface registration method. This was based on a standard optical digitizing system (Flashpoint 5000), which eliminates the need for the second CT scan, which is normally performed specifically to process the position of the fiducial markers. Global accuracy was then evaluated on 20 patients by subjective and visual comparison when placing a calibrated pointer on anatomical landmarks. RESULTS: The results of the technical study indicate that the four commercial systems tested have levels of inaccuracy deemed acceptable for most CAS applications, including ENT surgery. The clinical study obtained a registration and calibration accuracy of less than 1.5 mm in 89.2% (SD = 0.20 mm) of the cases studied. Our markerless skin surface points registration method is reliable, and allows patient head movements during the procedure. The accuracy tests performed show that this type of system can be used for ENT surgery with satisfaction. CONCLUSION: CAS systems enable the surgeon to have a more thorough understanding of the complicated anatomy of paranasal sinuses, and may be especially helpful in revision surgery when normal anatomic landmarks are lacking. Further studies are necessary in FESS to improve the CAS systems that are currently available, and to determine whether these systems can minimize the overall risk of complications.

Computer Systems↗

PubMed2001

Endonasal endoscopic closure of cerebrospinal fluid rhinorrhea.

The authors review their experience with endoscopic repair of skull base defects associated with cerebrospinal fluid (CSF) rhinorrhea involving the paranasal sinuses. A total of 22 patients was treated endoscopically between 1992 and 1998. The repair method consisted of closure of the CSF fistula with a free autologous abdominal fat graft and fibrin glue, supported with a sheet of silastic. The primary closure rate was 82% (18/22), and the overall closure rate was 95.5% (21/22) without recurrence or complications within an average follow-up of 5 years (14-83 months). A single patient still complains of cerebrospinal rhinorrhea, although this was never proved by any clinical, endoscopic, or biological (beta(2)-transferrin) examination. The repair of ethmoidal-sphenoidal cerebrospinal fluid fistulae by endonasal endoscopic surgery is an excellent technique, both safe and effective. Fat is a material of choice, as it is tight and resists infection well. The technique and indications for endoscopic management of cerebrospinal fluid leaks are discussed.

Journal Article↗

PubMed2001

A multicenter study of the Vibrant Soundbridge middle ear implant: early clinical results and experience.

OBJECTIVE: The Vibrant Soundbridge (VBS; Symphonix Devices, Inc., San Jose, CA, U.S.A.) is an active, semi-implantable, middle ear hearing device that directly drives the ossicular chain and is used in the treatment of patients with mild to severe sensorineural hearing loss. The benefits of the VBS and the effects of surgery were examined and compared with the preoperative aided condition in 25 patients with implants. STUDY DESIGN: Single-subject repeated-measures evaluations were performed with each patient acting as his or her own control. Objective audiologic measures and subjective questionnaires also were used. SETTING: Five tertiary referral and teaching hospitals. SUBJECTS: Adult patients had bilateral sensorineural hearing loss (average hearing loss, 56 dB; range, 33-80 dB). Twenty-one patients had worn a conventional hearing aid before surgery (11 binaurally, 10 monaurally). Four patients had not used a conventional hearing aid before surgery. INTERVENTION: Rehabilitative. RESULTS: No significant change in residual hearing after surgery was observed. Functional gain was significantly superior with the VBS. No significant differences were observed for aided speech recognition in quiet. A significant improvement in communication in various listening conditions was reported with the VBS as compared with conventional hearing aids. CONCLUSION: The VBS surgical implantation procedure does not affect the residual hearing level in the implanted ear, nor does it present any unacceptable risk. Measurable benefit from the VBS in comparison with conventional amplification was demonstrated with regard to the provision of superior usable amplification and greater ease in communication in daily listening environments for the majority of patients.

Acoustic Stimulation↗

PubMed2001

[Computer-assisted video-endoscopic endonasal surgery].

UNLABELLED: To make the surgical procedure safer and more precise in FESS, a non-invasive markerless computer-assisted system (CAS) is described for intra-operative navigation whenever the critical regions may be affected by surgical manipulation. PATIENTS AND METHODS: Twenty patients with benign diseases of the paranasal sinuses were treated by Computer Assisted Video-endoscopic surgery, between December 1997 and March 1998. For the determination of accuracy and reproducibility of the system, ten anatomical landmarks on each side of the paranasal sinuses were chosen and measured. All of these points were identified on the direct live video-endoscopy image and compared to those obtained with the Optical Digitizing System (Flashpoint 5000(R)), on axial, coronal and sagittal view. The Optical Localizer we used detects the position of the relative coordinates of two rigid bodies made of IR-LED's each, one rigid body is secured to the head' of the patient with a headset, so that patient motion can be tracked, and the second rigid body attached to the operating instrument, leading to direct localization of the tip of the instrument. We use a markerless, skin surface-based registration method, which has the advantage to avoid doing a second CT scan examination usually performed to process the position of the fiducial markers. We register the data from the patient's usual paranasal CT scan. RESULTS: Computer-assisted surgery does not increase significantly the duration of the operation. Our markerless skin surface points registration method is reliable enabling of the movements patient's head during the procedure. Computer assistance can be used in almost any type of endoscopic sinonasal procedure. We obtained a registration and calibration accuracy of less than 1.5 mm in 89.2% of cases. CONCLUSION: CAS enables the surgeon to have a more thorough understanding of the complicated anatomy of paranasal sinuses, and may be especially helpful in revision surgery when normal anatomic landmarks are lacking. Due to the passive optical technology (Passive Polaris(R)), we are continuing clinical studies in ENT surgery in order do improve the system and to simplify its current management.

Adult↗

PubMed2001

[Methods of identification and localization of ethmoid and sphenoid osteomeningeal breaches].

The accurate localization of cerebrospinal fluid (CSF) fistula presenting as rhinorrhea is an essential requirement for successful dural repair, in order to eliminate unsuccessful surgical exploration, and to achieve a definitive closure of the osteo-dural defect. The authors report their experience in 22 patients, and propose a simplified attitude: realization of high resolution CT scan in all cases, in first choice, and a MRI with MR cysternography sequences, in second choice, in case of negative CT scan.

Adult↗

PubMed2001

[Cavernous angiomas of the brain stem: auditory and vestibular manifestations].

AIMS: To establish the correlation between the clinical manifestations of hearing and balance disturbance and the anatomical site within the pons of cavernous angiomas, and to describe their clinical features, and the findings on ABR and MRI. MATERIALS AND METHODS: Two clinical cases of cavernous angioma with cochlear and vestibular manifestations underwent audiometric evaluation, with VNG and ABR as well as CT and MRI scans. CONCLUSION: Cavernous angiomas are rare (less than 2% of intra-cranial space-occupying lesions). Their most common topographical site is midline in the pons, and may give rise to symptoms in attacks (due to episodes of bleeding within the tumour) which may mimic symptoms of peripheral origin (sudden deafness, fluctuating hearing loss, Menière-like vertigo). There may be ectopic remnants of the embryonic blood vascular system. They may be associated with other malformations (intra-cerebral venous angiomas, cavernous angiomas at other sites). Their development is often by sudden progression which may be dramatic, and have accompanying neurological features. For investigating the hearing and balance, ABR is an excellent test, giving a typical picture of a retro-cochlear lesion that necessitates progression to MRI, the investigation of choice. This will demonstrate the typical rosette-like appearance with a heterogeneous T2 image (a less dense peripheral ring, with a denser central signal). There is no specific medical treatment for this condition, and surgery is indicated only exceptionally. There is a contraindication to anticoagulant therapy, to platelet-dispersing medication and to violent sports activities. Two cases of cavernous angioma are reported; one was more anteriorly situated, and had mainly vestibular features, and the other was more posterior near the floor of the IVth ventricule, with mainly auditory features. The correlation of the anatomical and clinical findings with those of the MRI are discussed, especially in relation to our understanding of the auditory and vestibular pathways within the brainstem (the auditory striae, the crossed auditory pathways and the nuclei of the corpus trapezoideum for the auditory effects, and the paramedian reticular nucleus and crossed inter-commissure pathways to the cerebellum and vestibular nuclei, together with the proximity of the direct midline vestibulo-spinal tract, for the vestibular effects).

Adult↗

PubMed2000

Phase II trial of cisplatin, 5-fluorouracil and folinic acid using a weekly 24-h infusion schedule for locally advanced head and neck cancer: a pharmacokinetic and clinical survey.

The objective of this phase II prospective study was to determine the efficacy and the toxicity of a new schedule of neoadjuvant chemotherapy in locally advanced squamous cell carcinomas of the head and neck (SCCHN). Thirty-three patients were included in this study (13 stage III and 20 stage IV). Cisplatin (CDDP: 35 mg/m2), 5-fluorouracil (FU: 2 g/m2) and folinic acid (FA: 500 mg/m2) were administered by continuous i.v. infusion for 24 h, once every 7 days. Six cycles of neoadjuvant chemotherapy were planned before definitive locoregional treatment. A total of 195 cycles were analysed for toxicity: mucositis was observed in 11/195 cycles; 12/195 showed diarrhea and vomiting occurred in 10/195. The myelosuppression was low (neutropenia: 4/195, thrombopenia: 3/195). One treatment-related death was observed after grade IV neutropenia at the fourth cycle. Thirty-two patients were evaluated for response. The objective response rate was 87%, with 50% complete response (CR) and 37% partial response. Failure rate was 13% (stable disease). There was no progressive disease. Survival and DFS duration were significantly higher in cases of CR or in laryngeal localization. The average peak plasma levels for the 6 courses of CDDP, 5-FU, dl-FA and mTHF were 4.9+/-0.76 microM, 4.1+/-0.54 microM, 29.1+/-2.4 microM and 4.8+/-0.31 microM respectively. Therefore, the administration of the 3 drugs by a 24 h continuous i.v. infusion reached an efficient level for drug modulation. This new weekly schedule is as active as other standard therapy in the disease but significantly less toxic as neoadjuvant chemotherapy in advanced untreated SCCHN. With the low toxicities observed with this schedule, additional treatment (surgery and/or radiotherapy) is warranted to evaluate the impact on overall survival of SCCHN.

Adult↗

PubMed1999

[Middle ear cholesteatoma surgery].

UNLABELLED: To verify the efficiency of surgical techniques used by the senior author in cholesteatoma surgery, 1,048 cases operated on between 1966 and 1997 are reviewed: 739 in adults and 309 in children. In adults, the majority of cases were between 16 and 40 (64.5%) without difference between both sexes. On the contrary in children, boys were 200 and girls 109; 30 cases were less than 4. In adults only 312 cases were operated on first hand, instead in children almost all cases were operated on first hand (273 cases). The beginning of the cholesteatoma was usually the Shrapnell membrane in adults (58%) while in children the postero-superior region was as common as the Shrapnell membrane (34% 35%); the cholesteatoma was congenital in 13% of cases. Surgical techniques: Mostly two techniques were used: closed technique in two stages and obliteration technique in one or two stages. The closed technique requires remodeling of the postero-superior region of the bony canal, performing a correct posterior tympanotomy, placing a silastic sheeting in all the middle ear to prevent fibrosis and finally rebuilding all the bony defects and a large part of the tympanic membrane with thin cartilage with its perichondrium. The second stage is performed 18 months later in children, 24 months in adults. The ossiculoplasty is often performed at the first stage if the stapes arch is intact and safe. The obliteration technique requires also a precise removal of the lesions, a lowering of the facial ridge, the rebuilding of the tympanic membrane with fascia and the posterior cavities obliteration with Palva flap and free connective grafts. If the tympanic and posterior cavities are reasonably safe, and if the stapes arch is intact, one stage is performed. Otherwise a second stage is performed usually 18 months later, ossiculoplasty only or combined with a second look of posterior cavities under the flap. RESULTS: Residual cholesteatoma was noticed in adults in 16% of first hand closed technique and 19% of second hand closed technique. It is only of 7% in first hand obliteration technique and 13% in second hand obliteration technique. It was 16% in radical cavity reconstruction. Retraction pocket was almost only observed in closed technique. In adults, an early retraction pocket was observed in 3.5% of cases and in children 12.5% of cases at the moment of the second stage. A larger cartilage more precisely fixed with fibrin glue seems to have almost suppressed the early retraction pocket. Some late retraction pockets nevertheless appeared: 6 cases in adults over 394 and 5 cases in children over 236. Hearing results in adult were the best with first hand closed technique 84% of good results if the stapes was intact and 51% if the crura were missing. If the closed technique was performed second hand, these results were only 57% if the stapes was intact and 29% if the crura were missing. For the obliteration technique these results are for the first hand 70% of good result if the stapes was intact and 60% if the crura were missing, for the second hand, only 36% if the stapes was intact and 39% if the crura were missing. In radical cavity reconstruction 63% of good results were achieved when the stapes was intact and 48% if the crura were missing. The good result is an air-bone gap between 0 and 20 dB for the three frequencies 0.5, 1 and 2 kHz.

Adolescent↗