Requirement specification for surgical simulation systems with surgical workflows.

Surgical simulations are normally developed in a cycle of continuous refinement. This leads to high costs in simulator design and as a result to a very limited number of simulators which are used in clinical training scenarios. We propose using Surgical Workflow Analysis for a goal-oriented specification of surgical simulators.

The navigation-controlled drill in temporal bone surgery: a feasibility study.

Background: This study examines the feasibility of a navigation-controlled (NC) drill for surgery on the petrosal bone in an experimental environment. According to the principle of NC, the drill is to be switched off automatically once the borders of the workspace are exceeded during a mastoidectomy.

Materials And Methods: The registration is based on an optical navigation system with navigation software (MiMed).

The value of intraoperative smear examination of stereotaxic brain specimens.

This study was conducted to evaluate the importance of intraoperative smear examinations for the final diagnosis of intracerebral stereotaxic procedures. 125 consecutive patients with suspect intracerebral lesions underwent stereotaxic frame-based biopsies after acquisition of computer tomographic and magnetic resonance images. After secondary image processing, including multiplanar visualization of the target region and target definition, a serial biopsy was realized using an aspiration Sedan needle.

Comprehensive cytogenetic characterization of an esthesioneuroblastoma.

Esthesioneuroblastoma is a malignant neuroectodermal tumor originating from olfactory epithelial cells in the nasal vault. Due to the rarity of this tumor entity, cytogenetic data are very limited. Therefore, we performed comprehensive cytogenetic analyses of an esthesioneuroblastoma, Hyam's grade III-IV, using trypsin-Giemsa staining (GTG banding), multicolor fluorescence in situ hybridization (M-FISH), and locus-specific FISH complemented by molecular karyotyping using high-density single nucleotide polymorphism arrays.

Continuous monitoring of cerebrovascular autoregulation after subarachnoid hemorrhage by brain tissue oxygen pressure reactivity and its relation to delayed cerebral infarction.

Background And Purpose: Disturbances of cerebrovascular autoregulation are thought to be involved in delayed cerebral ischemia and infarction after aneurysmal subarachnoid hemorrhage (SAH). We hypothesized that the continuous monitoring of brain tissue oxygen (PtiO(2)) pressure reactivity enables the detection of impaired autoregulation after SAH and that impaired autoregulation is associated with delayed infarction.

Methods: In 67 patients after severe SAH, continuous monitoring of cerebral perfusion pressure (CPP) and PtiO(2) was performed for an average of 7.

Application of intraoperative 3D ultrasound during navigated tumor resection.

Intraoperative 3D ultrasound (3D-iUS) may enhance the quality of neuronavigation by adding information about brain shift and tumor remnants. The aim of our study was to prove the concept of 3D ultrasound on the basis of technical and human effects. A 3D-ultrasound navigation system consisting of a standard personal computer containing a video grabber card in combination with an optical tracking system (NDI Polaris) and a standard ultrasound device (Siemens Omnia) with a 7.

[Manipulator assisted endoscope guidance in functional endoscopic sinus surgery: proof of concept].

Background: Functional endoscopic sinus surgery (FESS) is characterized by single-handed preparation and guidance of the endoscope by the nondominant hand. This results in an additional extension of operation time by up to 15% and ergonomic deficits. The aim of this study is the conception of an automated assistance system for FESS in view of the following questions: (1) Which degree of surgical automation is suitable for FESS? (2) Which design is suitable? (3) What are the properties of the technical system (planning, time, accuracy, precision) of the selected system? (4) Does the system offer potential for a clinical application?

Methods: In all 49 FESS were analyzed for surgical workflows.

Intracranial dural arteriovenous fistula associated with progressive cervical myelopathy and normal venous drainage of the thoracolumbar cord: case report and review of the literature.

Background: Intracranial dural arteriovenous malformations draining into the perimedullary venous system are rare lesions. In these cases, the selective spinal catheterization of all vessels with potential of causing that malformation was negative, and additional cerebral angiography usually reveals the fistula. Because of venous congestion of the cord caused by the DAVF, a delayed drainage or stagnation of contrast material in the artery of Adamkiewicz was considered as a compelling angiographic disorder so far.

[Clinical efficiency and the influence of human factors on ear, nose, and throat navigation systems].

Background: The aim of this study was to evaluate the Navibase navigation system for ear, nose, and throat (ENT) surgery. A new methodology for evaluating surgical and human factors is developed.

Patients And Methods: The evaluation is based on 102 ENT surgical applications, including 89 cases of functional endoscopic sinus surgery (FESS).

Continuous assessment of cerebrovascular autoregulation after traumatic brain injury using brain tissue oxygen pressure reactivity.

Objective: To evaluate whether two newly developed indexes of brain tissue oxygen pressure reactivity (ORx and bPtio2) provide information on the status of cerebrovascular autoregulation after traumatic brain injury. This was accomplished by analyzing the relationship between these indexes and an index of cerebrovascular pressure reactivity (PRx). PRx is an established parameter for estimation of cerebrovascular autoregulation.

[Improved accuracy and precision of the automated shaver (navigated control) in functional endoscopic sinus surgery].

Background: The feasibility of a navigate-controlled Shaver for the paranasal sinus surgery was proven in an initial study. Deficits showed up in the conversion of the planed cavity. Goal of this study is (1) the development and evaluation of a FESS demonstrator for the investigations to the surgical accuracy and (2) the evaluation of the resulting surgical accuracy for registration and conversion of the work space with an improved rigidity of the Shaver and a completely revised study design.

[Three-dimensional visualization of CT of the neck for surgical planning].

Background: Surgical planning in ENT profits from computer assisted preoperative visualization and planning. The informative capability is to be improved by three-dimensional illustrating of the preoperative available data. The possibility of a 3-D-visualization of lymph nodes stands in the center of the interest.

Evaluation of a navigation system for ENT with surgical efficiency criteria.

The aim of this study is the evaluation of a navigation system (NaviBase) for ENT surgery. For this purpose, a new methodology for the evaluation of surgical and ergonomic system properties has been developed. The practicability of the evaluation instruments will be examined using the example of the overall assessment of the system in comparison with the current surgical standard and with other systems using clinical efficiency criteria.

Surgery of cavernous malformations with and without navigational support--a comparative study.

Background: The aim of this descriptive study was the comparison of the clinical and surgical data of patients who suffered from cavernoma and were treated surgically with and without intraoperative navigation (ultrasound, neuronavigation).

Method: Between 1995 and 2002, 40 patients were treated for cavernous malformations microsurgically: 24 patients (group I) using a neuronavigation system (STP 4.0, SNN, Germany), 7 patients (group II) using ultrasound (Siemens Omnia with 5.

Improvement of brain tissue oxygen and intracranial pressure during and after surgical decompression for diffuse brain oedema and space occupying infarction.

Background: We evaluated the perioperative and intraoperative changes of intracranial pressure (ICP) and partial pressure of brain tissue oxygen (PtiO2) after decompressive craniectomy in patients with diffuse brain oedema and space occupying infarction.

Methods: Ten patients suffering from medically intractable raised intracranial pressure (ICP) were included. The underlying diseases and causes for elevated ICP were diffuse brain oedema after subarachnoid haemorrhage (n = 3) and head injury (n = 3), or space occupying infarction of the middle cerebral artery territory due to vasospasm after SAH (n = 4).

Brain tissue oxygen (PtiO2): a clinical comparison of two monitoring devices.

Background: We investigated the difference between two commercially available sensors for continuous monitoring of brain tissue oxygen (PtiO2). One is a single parameter probe for PtiO2 monitoring (Licox), the other is a multiparamter sensor (Neurotrend) further including measurement of brain temperature, pH, and partial pressure of tissue carbon dioxide.

Methods: In seven patients after subarachnoid hemorrhage or traumatic brain injury continuous monitoring of PtiO2 was performed simultaneously using Licox and Neurotrend.

Surgical PACS for the digital operating room. Systems engineering and specification of user requirements.

For better integration of surgical assist systems into the operating room, a common communication and processing plattform that is based on the users needs is needed. The development of such a system, a Surgical Picture Aquisition and Communication System (S-PACS), according the systems engineering cycle is oulined in this paper. The first two steps (concept and specification) for the engineering of the S-PACS are discussed.

Establishing navigated control in head surgery.

Navigated Control (NC) describes an additional control for a tracked power driven instrument within a preoperatively segmented work space. In head surgery the authors first implemented NC in functional endoscopic sinus surgery (FESS). Recently the feasibility of NC for surgery on the petrosal bone is evaluated.

[Workflow analysis to assess the efficiency of intraoperative technology using the example of functional endoscopic sinus surgery].

Evaluation of the efficiency of surgical technology systems has to date been largely subjective. The aim of this study was to develop an ontology for surgical procedures usable workflow structures, and the evaluation of surgical workflow analysis using the example of functional endoscopic sinus surgery (FESS). A total of 38 procedures (20 patients) were included.

Effect of 3T MRI on the function of shunt valves--evaluation of Paedi GAV, Dual Switch and proGAV.

The MR-compatibility of medical implants and devices becomes more and more important with the increasing number of high-field MR-scanners employed. Until the end of 2004, about twenty 3T MR in Germany will be in clinical practice. Patients with hydrocephalus need frequent follow-up MR-examinations to assure correct functioning of a shunt.

[The reliability of stereotaxy in diagnosis of intracranial space occupying lesions].

A total of 79 patients with a suspect space occupying intracranial lesion was operated stereotactically. After CT and MR image acquisition, entry and target coordinates were defined and biopsy trajectories were simulated preoperatively using a special planning software. Biopsy specimens allowed a satisfactory neuropathological examination and diagnostic result in 74 of 79 (93.

[Accuracy and precision in the evaluation of computer assisted surgical systems. A definition].

Accuracy represents the outstanding criterion for navigation systems. Surgeons have noticed a great discrepancy between the values from the literature and system specifications on one hand, and intraoperative accuracy on the other. A unitary understanding for the term accuracy does not exist in clinical practice.

[Navigated control: a new concept in computer assisted ENT-surgery].

This work conceived and evaluates a mechatronical system for ORL-surgery by example of a Shaver for Functional Endoscopic Sinus Surgery controlled by navigation. The Shaver is automatically on/off-regulated depending on the current position in relation to the planned working space. This working space is defined on the basis of the individual CT data.