Microsurgical Field Research Articles

In Vivo Fluorescence Imaging of Large-Vessel Thrombosis in Mice

Experimental studies of large-vessel thrombosis have been adapted for applications in mice, but they proffer limited quantifiable information in outcome measures. This study presents a novel approach for evaluating large-vessel thrombogenesis with temporally/spatially quantifiable measures and normalization methods for interanimal comparisons. Shuttered, beam-expanded lasers provided uniform narrow-wavelength illumination of a ×100 microsurgical field with a large depth of focus. Thrombosis was generated in murine carotid arteries and femoral veins by brief vascular surface electrolytic injury. Thrombus-targeting fluorophores were injected systemically and subsequently localized at the site of thrombus induction. A low-light digital video camera with filter wheel provided target-specific image acquisition over a 60-minute interval. Platelets accumulated with a subsequent fibrin border emerging to stabilize the clot in both arteries and veins. Coagulation enzyme complexes colocalized with fibrin deposition. Large arteries underwent cyclic massive thromboembolization, whereas veins showed gradual shedding of microemboli and clot contraction. Systemic administration of fibrin- and platelet-inhibiting compounds reduced their respective targets but also often inhibited their clotting counterparts (platelets and fibrin, respectively) in both arteries and veins. Intermediate-level magnified image capture represents a novel approach for analysis of fluorescence-based in vivo imaging, with quantitative application to the study of large-vessel thrombosis.

Use of sodium fluorescein in skull base tumors

Objective:The authors present this study using sodium fluorescein (SF) to enhance skull base tumors by performing a quantitative digital analysis of tumor enhancement. The purpose of this study is to observe the grade of SF enhancement by the tumors.Methods:A prospective experiment within-subjects study design was performed which included six patients with skull base lesions. Digital pictures were taken before and after the SF systemic injection, using the same light source of the microsurgical field. The pictures were analyzed by computer software which calculated the wavelength (WL) of the SF pre- and post-injection.Results:The group of tumors was as follows: one vestibular schwannoma, three meningiomas, one craniopharyngioma and one pituitary adenoma. The SF enhancement in all tumors was strongly positive. The digital analysis of the pictures, considering the SF WL pre- and post-injection, presented P = 0.028 (Wilcoxon T test).Conclusions:The enhancement of the tumors by SF was consistent and evident. The introductory results suggest the possibility of using SF as an adjuvant tool for the skull base surgery. Further studies should test the clinical application of the SF in skull base tumors.

Magnetic Resonance Cisternographic Evaluation of Glossopharyngeal, Vagus, and Accessory Nerves

Purpose The individual visualization of the glossopharyngeal, vagus, and accessory nerves has been a troublesome issue. After the recent developments in the microsurgical field, the detailed knowledge of the relationship of these nerves and the tumour has gained importance. The purpose of this study is to compare the visibility of each of these nerves. Methods Thirty patients (M/F: 14/16; mean age 52.46 years) with complaints of vertigo, tinnitus, and hearing loss were examined with routine temporal magnetic resonance imaging (MRI) study. The imaging protocol consisted of 3-dimensional fast imaging with steady state acquisition in axial and sagittal oblique planes in addition to routine sequences. These images were transferred to a workstation and reformatted. Visibility of the nerves was evaluated by consensus of 2 radiologists who used an evaluation scale of 2 (excellently visible), 1 (partially visible), to 0 (not visible). Results In 26 patients, both sides were scanned; in 4 patients, only one side was scanned. A total of 168 nerves were investigated. The rates for visualization for each nerve were as follows: glossopharyngeal nerve, 100% and 100%; vagus nerve, 67.9% and 100%; and accessory nerve, 10.8% and 83.85% on axial and sagittal oblique 3-dimensional fast imaging with steady state acquisition, respectively. Conclusions Glossopharyngeal, vagus, and accessory nerve assessment improved when images were obtained in the sagittal oblique plane to the jugular foramen.

ASSESSMENT OF FLOW IN PERFORATING ARTERIES DURING INTRACRANIAL ANEURYSM SURGERY USING INTRAOPERATIVE NEAR-INFRARED INDOCYANINE GREEN VIDEOANGIOGRAPHY

Perforating arteries are commonly involved during the surgical dissection and clipping of intracranial aneurysms. Occlusion of perforating arteries is responsible for ischemic infarction and poor outcome. The goal of this study is to describe the usefulness of near-infrared indocyanine green videoangiography (ICGA) for the intraoperative assessment of blood flow in perforating arteries that are visible in the surgical field during clipping of intracranial aneurysms. In addition, we analyzed the incidence of perforating vessels involved during the aneurysm surgery and the incidence of ischemic infarct caused by compromised small arteries. Sixty patients with 64 aneurysms were surgically treated and prospectively included in this study. Intraoperative ICGA was performed using a surgical microscope (Carl Zeiss Co., Oberkochen, Germany) with integrated ICGA technology. The presence and involvement of perforating arteries were analyzed in the microsurgical field during surgical dissection and clip application. Assessment of vascular patency after clipping was also investigated. Only those small arteries that were not visible on preoperative digital subtraction angiography were considered for analysis. The ICGA was able to visualize flow in all patients in whom perforating vessels were found in the microscope field. Among 36 patients whose perforating vessels were visible on ICGA, 11 (30%) presented a close relation between the aneurysm and perforating arteries. In one (9%) of these 11 patients, ICGA showed occlusion of a P1 perforating artery after clip application, which led to immediate correction of the clip confirmed by immediate reestablishment of flow visible with ICGA without clinical consequences. Four patients (6.7%) presented with postoperative perforating artery infarct, three of whom had perforating arteries that were not visible or distant from the aneurysm. The involvement of perforating arteries during clip application for aneurysm occlusion is a usual finding. Intraoperative ICGA may provide visual information with regard to the patency of these small vessels.

Ｂａｓａｌ ｉｎｔｅｒｈｅｍｉｓｐｈｅｒｉｃ ａｐｐｒｏａｃｈにおける大脳半球間裂剥離のトレーニング―レジデントが陥る軟膜損傷のパターンとその対策―

Dissection of the interhemispheric fissure via a basal interhemispheric approach (BIHA) is one of the most difficult skills for young neurosurgeons to acquire. We reviewed operative videos of 30 BIHAs performed by 4 residents in our institute, and investigated how the pia mater or pial capillary vessels were injured. Furthermore, after comparing these procedures with those of senior neurosurgeons in our institute, we discussed factors causing injury of the pia mater or pial capillary vessels and effective remedies to improve skills. As a result, causes of pial injury were roughly divisible into 3 types: microscissor problems; excessive tension on trabecullae; and inappropriate hemostatic technique. Learning the transformation of the interhemispheric fissure accompanying cerebrospinal fluid decreases and the anatomical characteristics of interhemispheric fissure is important for acquiring appropriate brain retraction. Training to find trabecullae to be cut in the narrow microsurgical field is also an important skill to acquire for BIHA.

ASSESSMENT OF FLOW IN PERFORATING ARTERIES DURING INTRACRANIAL ANEURYSM SURGERY USING INTRAOPERATIVE NEAR-INFRARED INDOCYANINE GREEN VIDEOANGIOGRAPHY

Perforating arteries are commonly involved during the surgical dissection and clipping of intracranial aneurysms. Occlusion of perforating arteries is responsible for ischemic infarction and poor outcome. The goal of this study is to describe the usefulness of near-infrared indocyanine green videoangiography (ICGA) for the intraoperative assessment of blood flow in perforating arteries that are visible in the surgical field during clipping of intracranial aneurysms. In addition, we analyzed the incidence of perforating vessels involved during the aneurysm surgery and the incidence of ischemic infarct caused by compromised small arteries. Sixty patients with 64 aneurysms were surgically treated and prospectively included in this study. Intraoperative ICGA was performed using a surgical microscope (Carl Zeiss Co., Oberkochen, Germany) with integrated ICGA technology. The presence and involvement of perforating arteries were analyzed in the microsurgical field during surgical dissection and clip application. Assessment of vascular patency after clipping was also investigated. Only those small arteries that were not visible on preoperative digital subtraction angiography were considered for analysis. The ICGA was able to visualize flow in all patients in whom perforating vessels were found in the microscope field. Among 36 patients whose perforating vessels were visible on ICGA, 11 (30%) presented a close relation between the aneurysm and perforating arteries. In one (9%) of these 11 patients, ICGA showed occlusion of a P1 perforating artery after clip application, which led to immediate correction of the clip confirmed by immediate reestablishment of flow visible with ICGA without clinical consequences. Four patients (6.7%) presented with postoperative perforating artery infarct, three of whom had perforating arteries that were not visible or distant from the aneurysm. The involvement of perforating arteries during clip application for aneurysm occlusion is a usual finding. Intraoperative ICGA may provide visual information with regard to the patency of these small vessels.

Synchronous endoscopy and microsurgery: a novel strategy to approach complex ventricular lesions

Simultaneous endoscopic and microsurgical (synchronous) approaches represent a new paradigm in the treatment of complex ventricular lesions. This technique is well suited for lesions that involve multiple ventricular or cisternal compartments, have a nonlinear axis, or adhere to critical anatomical or neurovascular structures. Two distinct operative corridors, one endoscopic and the other microsurgical, are used during synchronous approaches to address such lesions, increasing the likelihood of a safe and complete resection. The authors present the cases of two children and an adult treated via synchronous approaches. All patients had multi-compartmental lesions involving the ventricles and/or cisterns. One patient presented with a suprasellar Rathke cyst with a significant third ventricular component, one with a hypothalamic hamartoma having a substantial cisternal component, and the remaining patient with a choroid plexus papilloma in the left lateral ventricle that extended from midbody to the temporal horn. In the cases of the Rathke cyst and the hamartoma, debulking in the third ventricle and controlled detachment of the lesion from the hypothalamus were undertaken using endoscopy, and simultaneous resection of the suprasellar component was performed through a subfrontal craniotomy. In the case of the choroid plexus papilloma, selective cautery of the choroidal feeding vessels and detachment from the temporal tela choroidea were performed using endoscopy, and the tumor from the ventricular body to the atrium was resected via a craniotomy. In each case the resection concluded with the intersection of endoscopic and microsurgical fields. All three patients had good outcomes. Endoscopic and microsurgical approaches can be used concurrently to treat multicompartment ventricular and/or cisternal lesions with good results. The probable advantages of this method are more complete resection and improved safety.

Vascularized Flap Coverage on Necrotic Phalangeal Bone in Failed Thumb Replantation

Failure of replantation is one of the most serious complications in replantation surgery. Management of that unhappy situation is a dilemma in the microsurgical field. These authors performed 9 cases of thumb reconstruction in failed thumb replantations from 1996 to 2002. There was early debridement of soft tissue under necrotic changes, resulting in necrotizing phalangeal bone without any soft tissue. Osteosynthesis of the extracted phalangeal bone was carried out with a living portion of the proximal bone. The exposed bony portion was covered with a vascularized flap such as the reversed radial forearm pedicled flap, free radial forearm flap, and neurovascular island finger flap. This procedure was carried out within a week after vascular insufficiency developed.

Volumetric anatomical and functional identification in neuronavigation

In its third decade of development, neuronavigation has matured from pure trajectory planning to an instrument that can provide instant anatomical orientation on basis of three-dimensional (3D) images that closely match the microsurgical field at hand. Functional tissue properties may be incorporated in these images and volumetric rendering allows for visualization of all significant anatomical landmarks in the surgical path in one single view by modulating the opacity of overlying tissue layers. We have explored the possibilities of image guidance based on multimodal 3D images in more than 200 neurosurgical cases, with pathologies ranging from supratentrial tumors to lesions in the skull base and craniocervical junction. MRI (1.5 and 3 T), fMRI, positron emission tomography (PET), computed tomography (CT), CT angiography, and postmyelographic CT have been employed. Target registration error (TRE) and intraoperative shift have been calculated, and time and cost efficiency were estimated. 3D imaging was advantageous for fast orientation in complex morphology (gyri, sulci, dural sinuses, Circle of Willis, nasal cavity and paranasal sinuses), especially in cases where rotation of the operative field of view was necessary during the approach. Depiction of anatomical detail was limited by image resolution and tissue contrast. Virtual and real microscopic individual anatomy could permanently be correlated during surgery. Profound anatomical knowledge as well as repeated assessment of navigation errors was indispensable to detect accuracy changes during surgery. While guidance based on three-dimensional images cannot replace anatomical knowledge and surgical experience it offers a déjà vu experience for the neurosurgeon when the 3D model truly matches the surgical path and field. It relieves surgeons of the task of having to mentally reconstruct and rotate triaxial 2D images, extends their field of view beyond tissue barriers and provides functional information on the operative field that is otherwise invisible and inaccessible. Volumetric anatomical and functional identification based on image-guidance in the operating suite may expand surgical vision and improve patient safety—a major factor in cost-efficiency calculations.

Practical use of digital cameras for microphotography through the operating microscope.

A practical use of personal digital cameras for taking digital photographs in the microsurgical field through an operating microscope is described. This inexpensive and practical method for acquiring microscopic images at the desired magnification combines the advantages of the digital camera and the operating microscope.

Development of micro-active forceps for future microsurgery

A new eye microsurgical system is proposed. The final goal of our research project has been not only to improve surgical instruments, but also to establish a total surgical system applicable to today's most difficult microsurgery, within the eye. The new prototype micro-forceps, which have a joint that enlarges the surgical area and a built-in thin optical fibrescope to increase the dexterity of retinal microsurgery, was designed as the first step in a long-term research plan. The micro-active forceps is equipped with a thin optical fibre inside the stem, giving a lateral view of the retina and a drastic improvement in fine operations. Moreover, this new tool, with an active joint and an end-effector, could find application in other microsurgical fields, such as in the brain, ear, nose and throat.

A practical method of macrophotography in microsurgery.

A simple method to take macrophotographs that show details even in the microsurgical field was discussed. The method uses any single lens up to 80 mm or any zoom lens in the reverse position with a single-lens reflex camera. In this manner, high reproduction ratios larger than the actual size of the object can be achieved.

The trans-supraorbital approach.

The trans-supraorbital approach represents the advantage of combining the keyhole principle and skull base surgery. In cadaveric work the author shows the anatomic fields visualized with this procedure, advantages and potential surgical applications. The experimental surgical procedure was performed on 8 adult skulls and on 3 cadavers with intact cerebral structures. First, a 2 cm supraorbital approach for endoscopic exploration was used. The basic anatomic landmarks and corresponding dimensions of the microsurgical field were recorded and then compared with those from the trans-supraorbital approach, after removing the orbital arch and other parts of the orbital ceiling. This technique offers a 0.5 cm average increase in surgical field from the craniotomy. The surgical distance that results is shorter (about 2 cm), as well as the length of the surgical instruments required. A better microscope illumination in the deep fields, and the possibility of access to the intraorbital region, the superior orbital fissure, the optic foramen, and the cavernous sinus through the clinoid space are also obtained, with minimal cerebral retraction and similar advantages as through the pterional trans-sylvian approach. The author concludes that by extending the craniotomy and decreasing the surgical distance, the microsurgical field is more convenient for microscope-assisted surgery without totally relying on the endoscope, and with minimal brain retraction. It also provides multiple options to approach vascular and tumor lesions found in these microsurgical corridors, combining principles of minimal invasion and skull-base surgery.

A micromanipulator for precise control of a brain retractor

A new microsurgical device for delicate brain retraction is described. The device, a micromanipulator with a holder for a brain spatula fixed at the end of a self-retaining retractor arm, allows smooth, steady, fine displacement of the retractor tip ("minimal sliding retraction"), operated by the surgeon's two fingers. This has proved to be a useful and safe method of retraction for critical brain structures such as blood vessels, cranial nerves and aneurysm domes in deep microsurgical fields.

Automated Photography in Microsurgery

An automated method is proposed for photographing a microsurgical field that avoids missed photographs and time-consuming manipulations. The basic principles applied to microscopic photography are briefly reviewed and instructions are provided for standardized, reproducible, high quality photographs. A limitation at present is that auto-focusing cameras have not yet been adapted for use with surgical microscopes. One type of microscope is discussed and details about the only camera system currently suitable for such a microscope are described.

Rotation of scissors while fixed in the microsurgical field: A technique for increasing the surgeon's efficiency

The use of mechanical support for scissors during microsurgery reduces tremor and improves the surgeon's efficiency. Rotation of such a pair of mechanically supported scissors presents further improvements as it permits the surgeon to cut in all directions while reducing the need for time-consuming instrument transfers. Thus, one pair of scissors can be kept within the field and rotated to the required orientation for cutting.

New options for the microsurgeon: multiple instrumentation in a single microsurgical field.

Abstract Using the Greenberg universal retraction system, a single surgeon can control four or more microinstruments simultaneously in a single microsurgical field. By decreasing the number of hand movements heretofore required and by increasing the surgeon' biotechnological options, the entire microsurgical procedure becomes more efficient and more economical, maximizing the surgeon' capabilities and performance.

A continuous suction device for maintaining a dry microsurgical field.

A device that permits low-pressure, continuous suction in a microsurgical wound in described. The suction apparatus is easily constructed from supplies readily available in most operating rooms.