Masanori Yoshino

Improved preservation of function during acoustic neuroma surgery

OBJECT Restoration of cranial nerve functions during acoustic neuroma (AN) surgery is crucial for good outcome. The effects of minimizing the injury period and maximizing the recuperation period were investigated in 89 patients who consecutively underwent retrosigmoid unilateral AN surgery. METHODS Cochlear nerve and facial nerve functions were evaluated during AN surgery by use of continuous auditory evoked dorsal cochlear nucleus action potential monitoring and facial nerve root exit zone-elicited compound muscle action potential monitoring, respectively. Factors affecting preservation of function at the same (preoperative) grade were analyzed. RESULTS A total of 23 patients underwent standard treatment and investigation of the monitoring threshold for preservation of function; another 66 patients underwent extended recuperation treatment and assessment of its effect on recovery of nerve function. Both types of final action potential monitoring response and extended recuperation treatment were associated with preservation of function at the same grade. CONCLUSIONS Preservation of function was significantly better for patients who received extended recuperation treatment.

Combined use of diffusion tensor tractography and multifused contrast-enhanced FIESTA for predicting facial and cochlear nerve positions in relation to vestibular schwannoma

OBJECT The authors assessed whether the combined use of diffusion tensor tractography (DTT) and contrast-enhanced (CE) fast imaging employing steady-state acquisition (FIESTA) could improve the accuracy of predicting the courses of the facial and cochlear nerves before surgery. METHODS The population was composed of 22 patients with vestibular schwannoma in whom both the facial and cochlear nerves could be identified during surgery. According to DTT, depicted fibers running from the internal auditory canal to the brainstem were judged to represent the facial or vestibulocochlear nerve. With regard to imaging, the authors investigated multifused CE-FIESTA scans, in which all 3D vessel models were shown simultaneously, from various angles. The low-intensity areas running along the tumor from brainstem to the internal auditory canal were judged to represent the facial or vestibulocochlear nerve. RESULTS For all 22 patients, the rate of fibers depicted by DTT coinciding with the facial nerve was 13.6% (3/22), and that of fibers depicted by DTT coinciding with the cochlear nerve was 63.6% (14/22). The rate of candidates for nerves predicted by multifused CE-FIESTA coinciding with the facial nerve was 59.1% (13/22), and that of candidates for nerves predicted by multifused CE-FIESTA coinciding with the cochlear nerve was 4.5% (1/22). The rate of candidates for nerves predicted by combined DTT and multifused CE-FIESTA coinciding with the facial nerve was 63.6% (14/22), and that of candidates for nerves predicted by combined DTT and multifused CE-FIESTA coinciding with the cochlear nerve was 63.6% (14/22). The rate of candidates predicted by DTT coinciding with both facial and cochlear nerves was 0.0% (0/22), that of candidates predicted by multifused CE-FIESTA coinciding with both facial and cochlear nerves was 4.5% (1/22), and that of candidates predicted by combined DTT and multifused CE-FIESTA coinciding with both the facial and cochlear nerves was 45.5% (10/22). CONCLUSIONS By using a combination of DTT and multifused CE-FIESTA, the authors were able to increase the number of vestibular schwannoma patients for whom predicted results corresponded with the courses of both the facial and cochlear nerves, a result that has been considered difficult to achieve by use of a single modality only. Although the 3D image including these prediction results helped with comprehension of the 3D operative anatomy, the reliability of prediction remains to be established.

A high-resolution method with increased matrix size can characterize small arteries around a giant aneurysm in three dimensions.

Visualization of the small arteries around a giant intracranial aneurysm remains challenging, even with three-dimensional (3D) rotational angiography. Here we present a new method with the increased matrix size to visualize three-dimensional course of the anterior choroidal artery around a giant aneurysm to help estimate the risk of intraoperative complications.

Ptosis as Partial Oculomotor Nerve Palsy Due to Compression by Infundibular Dilatation of Posterior Communicating Artery, Visualized with Three-Dimensional Computer Graphics: Case Report

Oculomotor nerve palsy (ONP) due to internal carotid-posterior communicating artery (PcomA) aneurysm generally manifests as partial nerve palsy including pupillary dysfunction. In contrast, infundibular dilatation (ID) of the PcomA has no pathogenic significance, and mechanical compression of the cranial nerve is extremely rare. We describe a 60-year-old woman who presented with progressive ptosis due to mechanical compression of the oculomotor nerve by an ID of the PcomA. Three-dimensional computer graphics (3DCG) accurately visualized the mechanical compression by the ID, and her ptosis was improved after clipping of the ID. ID of the PcomA may cause ONP by mechanical compression and is treatable surgically. 3DCG are effective for the diagnosis and preoperative simulation.

Surgical Simulation of Cerebrovascular Disease With Multimodal Fusion 3-Dimensional Computer Graphics

Although recent advancements in medical imaging technology have allowed detailed preoperative examinations, neurosurgeons still have to interpret large amounts of medical imaging data. In various modalities such as computed tomography (CT), magnetic resonance imaging (MRI), and angiography, there are multiple sequences and 3-dimensional (3-D) images, and it is not uncommon for there to be several hundred to several thousand section images per case. Clinicians have to interpret each of these multimodalities/sequences individually and consolidate this information in their heads to form a 3-D image that can be used in preoperative planning. From the perspectives of accuracy, reproducibility, and sharing information with other people, it is hard to ensure sufficient precision. Furthermore, the spatial resolution of the 3-D images used in today’s clinical settings is inferior to that in 2-dimensional (2-D) imaging because the processing methods are limited. Consequently, ascertaining detailed findings from 3-D images alone is unsatisfactory; clinicians must additionally interpret 2-D section images of the same site. In this report, we describe the fusion of all image data required for preoperative examination and the construction of 3-D computer graphics (3-DCG) with a high spatial resolution using our own image processing technique. We then apply this to surgical strategies in cerebral vascular disease and report our experience and the usefulness of the technique.

Ruptured infectious aneurysms of the distal MCA treated with trapping and STA – MCA bypass surgery

Abstract We describe two patients with ruptured infectious aneurysms of the distal MCA, which were successfully treated by trapping and superficial temporal artery (STA)-middle cerebral artery (MCA) bypass surgery. Our patients had not experienced any ischemic attack postoperatively. Trapping and STA-MCA bypass surgery can be a useful option.

Usefulness of high-resolution 3D multifusion medical imaging for preoperative planning in patients with posterior fossa hemangioblastoma: technical note

Successful resection of hemangioblastoma depends on preoperative assessment of the precise locations of feeding arteries and draining veins. Simultaneous 3D visualization of feeding arteries, draining veins, and surrounding structures is needed. The present study evaluated the usefulness of high-resolution 3D multifusion medical imaging (hr-3DMMI) for preoperative planning of hemangioblastoma. The hr-3DMMI combined MRI, MR angiography, thin-slice CT, and 3D rotated angiography. Surface rendering was mainly used for the creation of hr-3DMMI using multiple thresholds to create 3D models, and processing took approximately 3-5 hours. This hr-3DMMI technique was used in 5 patients for preoperative planning and the imaging findings were compared with the operative findings. Hr-3DMMI could simulate the whole 3D tumor as a unique sphere and show the precise penetration points of both feeding arteries and draining veins with the same spatial relationships as the original tumor. All feeding arteries and draining veins were found intraoperatively at the same position as estimated preoperatively, and were occluded as planned preoperatively. This hr-3DMMI technique could demonstrate the precise locations of feeding arteries and draining veins preoperatively and estimate the appropriate route for resection of the tumor. Hr-3DMMI is expected to be a very useful support tool for surgery of hemangioblastoma.

A Microscopic Optically Tracking Navigation System That Uses High-resolution 3D Computer Graphics

Three-dimensional (3D) computer graphics (CG) are useful for preoperative planning of neurosurgical operations. However, application of 3D CG to intraoperative navigation is not widespread because existing commercial operative navigation systems do not show 3D CG in sufficient detail. We have developed a microscopic optically tracking navigation system that uses high-resolution 3D CG. This article presents the technical details of our microscopic optically tracking navigation system. Our navigation system consists of three components: the operative microscope, registration, and the image display system. An optical tracker was attached to the microscope to monitor the position and attitude of the microscope in real time; point-pair registration was used to register the operation room coordinate system, and the image coordinate system; and the image display system showed the 3D CG image in the field-of-view of the microscope. Ten neurosurgeons (seven males, two females; mean age 32.9 years) participated in an experiment to assess the accuracy of this system using a phantom model. Accuracy of our system was compared with the commercial system. The 3D CG provided by the navigation system coincided well with the operative scene under the microscope. Target registration error for our system was 2.9 ± 1.9 mm. Our navigation system provides a clear image of the operation position and the surrounding structures. Systems like this may reduce intraoperative complications.

Light axis adjustment with a sterilised photostimulation device for visually evoked potential monitoring

Abstract Intraoperative monitoring of visually evoked potentials (VEPs) is sometimes unachievable because of light axis misalignments caused by frontal scalp-flap reflection and intraoperative manipulation. Here, we present a new method of intraoperative VEP monitoring that involves a sterilised photostimulation device that can be adjusted in position following disturbances from frontal scalp-flap reflection or intraoperative manipulation.

Successful surgical strategy for a cervical hemangioblastoma: Case report

Background: Hemangioblastomas are hypervascular lesions and hence their surgical management is challenging. In particular, if complete resection is to be attained, all feeding and draining vessels must be occluded. Although most intramedullary spinal cord tumors are treated utilizing a posterior approach, we describe an anterior surgical strategy for resection of an intramedullary cervical hemangioblastoma. Case Description: A 36-year-old female with a spinal hemangioblastoma located in the anterior cervical spinal cord presented with a long-standing history of motor weakness of the right upper extremity. Magnetic resonance imaging revealed a large multilevel extensive syrinx and a focal intramedullary enhanced tumor at the C6 level. Angiography showed that the main feeder to the tumor was the left radicular artery (C8), which originated from the thyrocervical trunk, penetrated the dura mater, and branched both rostrally and caudally into the anterior spinal artery (ASA). Three-dimensional computer graphic images showed the tumor was located in the anterior part of the spinal cord, adjacent to and supplied by the ASA. The planned anterior surgical approach involved a total corpectomy of C6 and partial corpectomies of C5 and C7. The tumor was entirely removed despite multiple adhesions, and was successfully freed from the ASA. Patency of the ASA was confirmed utilizing intraoperative indocyanine green videoangiography. Intraoperatively, no monitoring changes were encountered. The pathological diagnosis was of a hemangioblastoma. No postoperative deficit occurred. Conclusions: An anterior approach for the resection of an anteriorly located intramedullary spinal hemangioblastomas was successfully accomplished in this case.