PubMed Health⌕ Search

Biomedical subjects

W Lamadé

Publications and source records attributed to W Lamadé.

At least 19 recordsLinked to original sources
PubMed2002

The effect of virtual reality and training on liver operation planning.

OBJECTIVE: The three-dimensional relation of a liver tumour to the intrahepatic vascular trees is basis of operation planning in liver surgery. Yet it has not been proven whether 3D reconstruction and further computerised processing will enhance precision of operation planning in liver surgery which has been based on the liver segment classification of Couinaud up to now. DESIGN: Our interdisciplinary group (department of Surgery, German Cancer Research Center and Department of Radiology) has developed a new interactive computer-based quantitative 3D operation planning system for liver surgery which is being introduced into the clinical routine. The system quantifies the organ structures semiautomatically, defines resection planes depending on safety margins and the vascular trees, and presents the data in digital movies as well as in quantitative reports. We conducted a clinical trial to evaluate whether 3D reconstruction will lead to an improved operation planning. Data of 7 virtual patients were presented to a total of 81 surgeons in different levels of training. The tumours had to be assigned to a liver segment and subsequently drawn together with the operation proposals into a liver model. The precision of both was measured quantitatively for each surgeon and stratified concerning 2D and different types of 3D presentations. RESULTS: The 3D anatomy can be visualised in high quality which results in good perception of the third dimension (depth). Tumour assignment to liver segments was significantly correlated to the level of training (p < 0.05). There was a significant increase (p < 0.001) in the precision of tumour localisation by 51% and resection proposal from 2D through 3D reconstructions by 13%-21%. Quantitative differences of the simplified Couinaud's classification of the liver segments compared to the true vascular anatomy of up to 40% were found. CONCLUSION: The impact of individual 3D-reconstruction on surgical planning has been proven to be significant and increases precision quantitatively. The merit of Couinaud's classification may be enhanced by individualisation of the segment borders in future.

Hepatectomy↗
PubMed2000

The impact of 3-dimensional reconstructions on operation planning in liver surgery.

BACKGROUND: Operation planning in liver surgery depends on the precise understanding of the 3-dimensional (D) relation of the tumor to the intrahepatic vascular trees. To our knowledge, the impact of anatomical 3-D reconstructions on precision in operation planning has not yet been studied. HYPOTHESIS: Three-dimensional reconstruction leads to an improvement of the ability to localize the tumor and an increased precision in operation planning in liver surgery. DESIGN: We developed a new interactive computer-based quantitative 3-D operation planning system for liver surgery, which is being introduced to the clinical routine. To evaluate whether 3-D reconstruction leads to improved operation planning, we conducted a clinical trial. The data sets of 7 virtual patients were presented to a total of 81 surgeons in different levels of training. The tumors had to be assigned to a liver segment and subsequently drawn together with the operation proposal into a given liver model. The precision of the assignment to a liver segment according to Couinaud classification and the operation proposal were measured quantitatively for each surgeon and stratified concerning 2-D and different types of 3-D presentations. RESULTS: The ability of correct tumor assignment to a liver segment was significantly correlated to the level of training (P<.05). Compared with 2-D computed tomography scans, 3-D reconstruction leads to a significant increase of precision in tumor localization by 37%. The target area of the resection proposal was improved by up to 31%. CONCLUSION: Three-dimensional reconstruction leads to a significant improvement of tumor localization ability and to an increased precision of operation planning in liver surgery.

Computer Simulation↗
PubMed2000

[First continuous nerve monitoring in thyroid gland surgery].

UNLABELLED: A new "all in one" sensing device was developed for continuous transtracheal intraoperative monitoring and in situ detection of the recurrent laryngeal nerve (RLN) during thyroid surgery. PATIENTS AND METHODS: The new system is based on a double-balloon endotracheal tube with integrated atraumatic stimulating and tracing electrodes. The recurrent laryngeal nerve is stimulated transtracheally and compound action potentials are recorded from the laryngeal muscles. Fifty-five patients were introduced into a phase-one clinical trial. Thirty-five patients with primary thyroid operations, 20 patients with reoperations, 10 of whom had neck dissections. All patients were evaluated laryngoscopically and phoniatrically by an ENT specialist before and after surgery. RESULTS: Compound muscle action potentials were recorded continuously during the whole operation and responded sensitively to tension and pressure to the nerve. There were no accidental permanent RLN palsies. CONCLUSION: The new system offers five advantages: (1) it is atraumatic; (2) it is easy to use; (3) it can monitor continuously with an audio feedback to the surgeon; (4) it works outside the operation field; and (5) it is highly sensitive, even indicating reversible irritation to the nerve.

Adult↗
PubMed2000

[The long gamma nail--indications, technique and results].

The introduction of the Gamma nail (GN) as an intramedullar implant for pertrochanteric femoral fractures that allowed full weight bearing decreased the death rate from 17% (methods without full weight bearing) to 6%. The long Gamma nail (LGN) is a logical supplement of the standard version, designed to treat unstable per-, subtrochanteric and segmental fractures. This study evaluated 44 consecutive operations. Seventy percent of the patients had to be classified ASA III and IV, due to their high morbidity. The median age was 73.5 years. Multiple injuries occurred in 30.2%. All fractures were considered unstable. Surgery was usually performed within 24 h. The median duration of the surgical treatment was 120 min. In five cases technical problems were observed. Radiological controls showed a good positioning of the head screw. Early complications consisted of four local wound infections, three of them deep infections with a osteomyelitis. Deep venous thrombosis was observed in four cases, two of which included a pulmonary embolism (conservative treatment). The 30-day death toll was 2.3% (one patient). The median survival time (using Kaplan-Meier) in the study was 46 months, compared to 80 months in a matched population. This difference has to be linked to high premorbidity. The median duration of admission was 15 days. Mobilisation with full weight bearing was theoretically possible in all cases, but additional injuries or preoperatively impaired walking ability prevented full mobilisation in 15 cases. Functional assessment uncovered a decrease in Merle d,Aubigne score of 26.7% due to an impaired walking ability. Seventy-three percent of the patients regained their preoperative social status. In conclusion the long Gamma nail is a universal, less invasive implant with high early weight bearing. It thus allows early remobilization and reduces lethality in the treatment of complex, unstable coxal fractures.

Adult↗
PubMed1999

[Virtual surgical planning in liver surgery].

UNLABELLED: The operability of a liver tumour depends on its three-dimensional relation to the intrahepatic vascular trees which define autonomously functioning liver (sub-)segments. The aim of our study was to establish a computer-based three-dimensional volumetric operation planning system for the liver. METHODS: Using data from routine helical CT scans the three tissue subclasses of liver parenchyma, liver vessels and liver tumour were segmented semiautomatically. A dedicated segmenting tool was established using region growing algorithms in combination with an "intelligent" border finder. Visualisation is performed by the "Heidelberg Raytracer". The vascular trees are visualised as 3D graphs. Pseudoconnections between portal and hepatic venous trees are separated automatically. Security margins are calculated and the system presents a virtual resection proposal. RESULTS: The 3D anatomy of the liver can be visualised in high quality resulting in good depth perception. Security margins are demonstrated. Dependent liver parenchyma can be recognized automatically on the basis of the vascular trees. The system offers a individualised resection proposal including the tumour, security margin and dependent liver parenchyma. CONCLUSION: Three-dimensional presentation of the individual liver anatomy of a given patient facilitates the perception of the pathology. Virtual reality combined with artificial intelligence allows calculation of complete resection protocols, which can be quantified and modified interactively. This will make operation planning more objective; patient selection may be improved, and in cases of difficult tumour localisation different resection strategies may be tested. Thus virtual reality in liver surgery will improve teaching, surgical training and planning. It may lead to improved surgical care.

Algorithms↗
PubMed1999

Effect of training on the incidence of nerve damage in thyroid surgery.

BACKGROUND: In thyroid surgery early postoperative recurrent laryngeal nerve (RLN) dysfunction offers a sensitive measure of the quality of the operation. The aim of this study was to analyse the effect of training in thyroid surgery on the rate of early functional disturbances of the RLN after thyroid resection. METHODS: In 617 patients (median age 48 years, female to male ratio 2.8:1) who underwent unilateral or bilateral thyroid resection, 1059 RLNs were subjected to operative risk. Laryngoscopy was performed before and after operation. The 45 surgeons were divided into three groups: group 1, specialist thyroid surgeons; group 2, experienced surgeons; and group 3, residents. Personal gain of experience was defined by the preceding number of thyroid operations. Within each group the complication profile was determined by adding the personal complication profiles of each surgeon. RESULTS: The complication rates were low during surgical residency (group 3). In group 2 complication rates increased up to the 50th operation. Group 1 showed the expected exponential decrease to under per cent after another 130 operations. CONCLUSION: Complication rates are affected considerably by the extent of surgical experience in a non-linear and complex logarithmic manner, starting with low rates in the beginner group, peaking after further experience and then decreasing exponentially.

Adolescent↗
PubMed1999

Herpes simplex virus encephalitis: chronic progressive cerebral MRI changes despite good clinical recovery and low viral load - an experimental mouse study.

Cranial magnetic resonance imaging (MRI) is a sensitive diagnostic tool for the in vivo detection of morphological abnormalities in herpes simplex virus encephalitis (HSVE). We performed a long-term MRI study in a mouse model of HSVE. Cranial MRI findings were compared with the viral load within brain tissue, the presence of HSV DNA in the cerebrospinal fluid (CSF), a daily clinical assessment and post-mortem neurohistopathological studies. A 1.5 T cranial MRI scanner with standard spin-echo sequences was used. Viral load within the brain and the presence of HSV DNA in cerebrospinal fluid were determined by a polymerase chain reaction assay. Clinically, animals were severely affected within the first 2 weeks and recovered thereafter. Focal histopathological and MRI abnormalities involved predominantly limbic structures, a pattern that mimics human disease. Severity and extent of abnormalities had increased at 6 months despite clinical improvement. HSV DNA was present in CSF during the acute disease only. Brain viral load peaked at day 10 and declined thereafter. MRI as an in vivo monitoring approach may reveal chronic progressive changes in HSVE, despite clinical recovery and low viral load in the brain. Secondary, not directly virus-mediated, mechanisms of tissue damage may contribute to tissue damage of HSVE.

Animals↗
PubMed1998

Herpes simplex virus encephalitis: cranial magnetic resonance imaging and neuropathology in a mouse model.

We performed a long-term magnetic resonance imaging (MRI) study in a mouse model of herpes simplex virus encephalitis. Mice were infected with herpes simplex virus type 1 (HSV-1) strain F. A 1.5-T cranial MRI scanner with standard spin-echo sequences was used. Neuropathological studies included immunohistochemistry. The presence of HSV DNA in brain tissue was determined with a polymerase chain reaction assay. Clinical assessment was performed daily: within the first 2 weeks the animals were severely affected and recovered thereafter. MRI and histopathological abnormalities corresponded well. HSV DNA was detectable initially and at 6 months. Extent and severity of structural abnormalities increased at 6 months. MRI offers a new in vivo approach for the detection of structural changes in the disease course of experimental herpes simplex virus encephalitis.

Animals↗
PubMed1998

Herpes simplex virus encephalitis: long-term comparative study of viral load and the expression of immunologic nitric oxide synthase in mouse brain tissue.

In the brain tissue of 21 mice infected with herpes simplex virus type 1 (HSV-1) strain F we determined the expression of immunologic nitric oxide synthase (iNOS) as a potential mediator of neuronal injury with a semiquantitative reverse transcription polymerase chain reaction. Viral burden in brain tissue was quantitated with a dilutional polymerase chain reaction assay. Viral burden and iNOS-expression peaked at day 7 following infection. Thereafter viral burden declined to a low baseline value at 6 months following infection, whereas iNOS-expression was still 4-fold increased compared to baseline levels. In experimental herpes simplex virus encephalitis iNOS, as one potent mediator of neuronal injury, is upregulated in the acute and chronic disease. In future, in addition to antiviral treatment, inhibitors of iNOS might offer new therapeutic strategies in herpes simplex virus encephalitis.

Animals↗
PubMed1998

Technical aspects of virtual liver resection planning.

Operability of a liver tumor is depending on its three dimensional relation to the intrahepatic vascular trees which define autonomously functioning liver (sub-)segments. Precise operation planning is complicated by anatomic variability, distortion of the vascular trees by the tumor or preceding liver resections. Because of the missing possibility to track the deformation of the liver during the operation an integration of the resection planning system into an intra-operative navigation system is not feasible. So the main task of an operation planning system in this domain is a quantifiable patient selection by exact prediction of post-operative liver function and a quantifiable resection proposal. The system quantifies the organ structures and resection volumes by means of absolute and relative values. It defines resection planes depending on security margins and the vascular trees and presents the data in visualized form as a 3D movie. The new 3D operation planning system offers quantifiable liver resection proposals based on individualized liver anatomy. The results are visualized in digital movies as well as in quantitative reports.

Humans↗
PubMed1998

[Continuous monitoring of the recurrent laryngeal nerve].

A new "all in one" sensing device for tracing and continuous intraoperative monitoring of the recurrent laryngeal nerve during thyroid surgery is described. The system, based on a double ballooned endotracheal tube, is atraumatic, easy to use and sensitive even to imminent trauma to the nerves. The most striking feature of this instrument is that it operates outside the sterile operating field and truly monitors continuously throughout the operation.

Adult↗
PubMed1997

[Outcome of surgical therapy in asymptomatic primary hyperparathyroidism].

Surgery for symptomatic hyperparathyroidism remains the standard therapy. Asymptomatic primary hyperparathyroidism (pHPT) is being diagnosed with increasing frequency owing to broad serum testing. Indications for surgery in this setting are controversial. For evaluation of surgical safety we performed a retrospective analysis of our patients who were being operated on for asymptomatic pHPT. From January 1988 until August 1995, 243 patients were treated for pHPT and registered prospectively at our unit. Seventy-six patients were classified as asymptomatic. In all, 75% of the patients were female; the mean age was 62 years. In this group, 87% of the patients had cervical sonography in order to localize the adenoma. Highly selective venous catheterization was required in cervical reexplorations. Statistical analysis for potential prognostic factors for the clinical outcome was performed. Successful cervical exploration was possible in 71 patients (94.7%). With 4 patients remaining hypercalcemic, the rate of persistency was 5.2%. Localization procedures were correct in 58% for cervical ultrasound and 77% for selective venous catheterization. Postoperative morbidity included one permanent recurrent laryngeal nerve palsy and 2 patients with hemorrhage who were treated by reoperation. While one case of permanent hypoparathyroidism was well controlled by oral supplementation, 18 patients recovered from temporary hypoparathyroidism. No postoperative mortality occurred. Risk factor analysis revealed only cervical reexplorations for HPT to be associated with a higher morbidity (P = 0.02). Surgery for asymptomatic pHPT can be performed with reasonable safety. Cervical reexplorations in asymptomatic patients should be reserved for special indications. Apart from this small group, all patients should be evaluated for surgery.

Adult↗
PubMed1997

[Transtracheal monitoring of the recurrent laryngeal nerve. Prototype of a new tube].

A new sensing device for the continuous intraoperative monitoring of the recurrent laryngeal nerve is presented. It is based on a double ballooned endotracheal tube including stimulating and tracing electrodes. The system is characterised by three advantages: 1) it is atraumatic, 2) it is operating completely outside the operating field (extraterritorially), 3) nerve function is being monitored continuously from the time of intubation to the time of extubation. The presented system has been evaluated in piglets. First results in humans will be available shortly.

Animals↗
PubMed1995

[Dystopic goiter--aspects of definition and surgical therapy].

The incidence in the literature of dystopic goiter depends on classification of the false endothoracic goiter ("substernal goiter") as dystopic and varies from 2 to 20%. From November 1989 through April 1993 we operated on 530 patients with benign nodular goiters. In 84 patients (15.8%) the operation proved a dystopic goiter. We showed that difficulties in comparing our data with published series were due to misnomers of the dystopic goiter. The dystopic goiter comprises the true endothoracic goiters (alliata vera and isolata vera) as well as the false endothoracic goiters (substernal goiter). The precise classification of the dystopic goiter is crucial to an optimal operative strategy reducing postoperative morbidity.

Adolescent↗
PubMed1991

Elimination of UL56 gene by insertion of LacZ cassette between nucleotide position 116030 to 121753 of the herpes simplex virus type 1 genome abrogates intraperitoneal pathogenicity in tree shrews and mice.

In order to investigate whether or not the UL56 gene is involved in those processes determining the viral pathogenicity and latency, a recombinant virus HSV-1-M-LacZ was constructed in which the DNA sequences between nucleotide position (np) 116030 and 121753 were replaced by the E. coli beta-galactosidase (LacZ) gene. This deletion spans from the carboxyterminus of UL55 (np 116030) to the second exon of IE110 (np 121753) eliminating UL56 and the variable region of the BamHI DNA fragment B which were implicated in intraperitoneal pathogenicity and latency. The host range and growth kinetics of the recombinant virus HSV-1 M-LacZ were comparable to the parental strain HSV-1 F. As expected it was found that HSV-1-M-LacZ lost its virulent phenotype and was not able to develop acute infection in animals. The state of the UL56 gene was investigated by determining the cDNA sequence of the UL56 gene transcript of HSV-1 F using PCR products obtained after amplification of the cDNA with oligonucleotide primers corresponding to the translational start and stop codons of this gene. This analysis revealed that the DNA sequence of the UL56 gene of HSV-1 F differed from those DNA sequences determined for the genomic DNA of HSV-1 strain 17. Between nucleotide position 116343 and 116344 two nucleotides -AG- are inserted which prolong the ORF of the UL56 gene to 233 amino acids with a predicted molecular weight of 30 kDa.

Adrenal Glands↗
PubMedDate not supplied

Virtual planning of liver resections: image processing, visualization and volumetric evaluation.

Operability of a liver tumor depends on its three dimensional relation to the intrahepatic vascular trees as well as the volume ratio of healthy to tumorous tissue. Precise operation planning is complicated by anatomic variability and distortion of the vascular trees by the tumor or preceding liver resections. We have developed a computer based 3D virtual operation planning system which is ready to go in routine use. The main task of a system in this domain is a quantifiable patient selection by exact prediction of post-operative liver function. It provides the means to measure absolute and relative volumes of the organ structures and resected parenchyma. Another important step in the pre-operative phase is to visualize the relation between the tumor, the liver and the vessel trees for each patient. The new 3D operation planning system offers quantifiable liver resection proposals based on individualized liver anatomy. The results are presented as 3D movies or as interactive visualizations as well as in quantitative reports.

Algorithms↗
PubMedDate not supplied

A mouse model of herpes simplex virus encephalitis: diagnostic brain imaging by magnetic resonance imaging.

Herpes simplex virus encephalitis is a severe sporadic encephalitis in man with high mortality and morbidity. A critical step in the establishment of therapy is early diagnosis. Magnetic resonance imaging is a noninvasive, accurate diagnostic test for the detection of central nervous system disease. In an effort to monitor morphological changes in vivo we present a new diagnostic neuroimaging model of experimental herpes simplex virus encephalitis. A mouse model of herpes simplex virus encephalitis was used. 40 SJL mice were intranasally inoculated with an infectious dose of wild-type strain HSV-I F. Morphological abnormalities were studied by cranial magnetic resonance imaging (MRI). These findings were correlated with sequential neuropathological studies. 95% of animals developed cerebral abnormalities on MRI. resembling human HSVE. Areas of increased signal intensity on T2-weighted sequences and focal pathological contrast enhancement were mostly found in the frontal and temporal lobes and thalamic and cerebellar regions. All animals with MRI abnormalities had neuropathological signs of neuronal degeneration and reactive astrocytosis in corresponding regions. The described monitoring system offers a new approach for studies on neurovirulence and therapeutic strategies.

Animals↗