Peter Hwang

A collaborative virtual reality environment for neurosurgical planning and training.

OBJECTIVE We have developed a highly interactive virtual environment that enables collaborative examination of stereoscopic three-dimensional (3-D) medical imaging data for planning, discussing, or teaching neurosurgical approaches and strategies. MATERIALS AND METHODS The system consists of an interactive console with which the user manipulates 3-D data using hand-held and tracked devices within a 3-D virtual workspace and a stereoscopic projection system. The projection system displays the 3-D data on a large screen while the user is working with it. This setup allows users to interact intuitively with complex 3-D data while sharing this information with a larger audience. RESULTS We have been using this system on a routine clinical basis and during neurosurgical training courses to collaboratively plan and discuss neurosurgical procedures with 3-D reconstructions of patient-specific magnetic resonance and computed tomographic imaging data or with a virtual model of the temporal bone. Working collaboratively with the 3-D information of a large, interactive, stereoscopic projection provides an unambiguous way to analyze and understand the anatomic spatial relationships of different surgical corridors. In our experience, the system creates a unique forum for open and precise discussion of neurosurgical approaches. CONCLUSION We believe the system provides a highly effective way to work with 3-D data in a group, and it significantly enhances teaching of neurosurgical anatomy and operative strategies.

Neurosurgical management of intracranial aneurysms following unsuccessful or incomplete endovascular therapy

The publication of the ISAT trial in 2002 has resulted in increasing numbers of patients with aneurysmal subarachnoid haemorrhage undergoing endovascular coiling, as first line treatment for aneurysm occlusion. During the first 2-year period post-ISAT, in which all suitable intracranial aneurysms were coiled first, we had to perform surgery in seven patients out of 54 who underwent initial coiling. The reasons for subsequent surgery were failed coiling, residual or recurrent aneurysm necks and delayed aneurysmal rebleeding despite coiling. We reviewed our surgical experience with the repair of these previously coiled aneurysms to identify unique technical difficulties. In particular, we found that an aneurysm height to neck ratio of less than 2:1 after coiling, and the use of stent-assisted coiling presented formidable challenges to direct clipping.

The epidemiology of BCVI at a single state trauma centre

BACKGROUND Blunt carotid and vertebral artery injury (BCVI) is a relatively uncommon but potentially devastating injury. The aim of our study was to highlight the incidence, patterns, presentation and associations of BCVI at our institution. METHODS Retrospective data between 1st January 2003 and 31st December 2006 was obtained from The Alfred Hospitals health information system, patient medical records and the Department of Neurosurgerys database. Injuries were graded using the Denver grading scale. RESULTS 67 patients (0.64%) out of 10,417 minor and major trauma admissions, were diagnosed with BCVI. 33 (49%) sustained blunt carotid and 34 (51%) sustained blunt vertebral injuries. Motor vehicle accident (MVA) was the cause in 43 out of 67. 35% had associated head injury whilst 57% had concurrent cervical spine fractures. Odds ratio analysis showed that MVA victims with concomitant upper cervical spine injury were 22.9 times more likely to suffer BCVI than those without such risk factors. Approximately 50% of patients had a Glasgow coma score of 14 or less (GCS < or = 14). Grade 4 BCVI was most common. Stroke occurred in 22 (32%) and mortality in 14 (20%). CONCLUSION BCVI although infrequent, is a serious injury. Our study suggests that MVA patients with cervical spine fractures especially of the upper C-spine are at much higher risk of BCVI than those without such injuries.

Idiopathic Spinal Subarachnoid Hemorrhage: A Case Report and Review of the Literature.

Study Design Case report. Objective Spinal subarachnoid hemorrhage (SSAH) makes up less than 1.5% of all the cases of subarachnoid hemorrhage. Most cases of spontaneous SSAH occur in association with coagulopathy, lumbar punctures, or minor trauma. Idiopathic SSAH is extremely rare with only 17 cases published. Idiopathic SSAH presents a diagnostic dilemma, and the appropriate investigations and treatment remain a matter of controversy. We report a case of idiopathic SSAH and a review of the literature regarding its clinical presentation, diagnosis, and treatment. Methods A 73-year-old woman presented to the emergency department after spontaneously developing severe right leg and lower back pain while bending over to vomit. After a review of the patients history and examination, the magnetic resonance imaging (MRI) of the thoracolumbar spine revealed T1 hyperintensity and T2 hypointensity, a diffusion-restricted collection at the T11–T12 level, and a posterior collection from L3 to S1 producing a mild displacement of the thecal sac. Results The patient was taken for an L5 laminectomy. Intraoperatively, rust-colored, xanthochromic fluid was drained from the subarachnoid space, confirming SSAH. The thecal sac was decompressed. The cultures and Gram stains were negative. Computer tomography (CT) and CT angiography of the brain were normal. She recovered postoperatively with resolution of the pain and no further episodes of hemorrhage after 2 years of follow-up. Repeat thoracolumbar MRI, selective spinal angiogram, and six-vessel cerebral angiogram did not reveal pathology. Conclusion We suggest a clinical algorithm to aid in the diagnosis and management of such patients.

Dementia resulting from expansion of basilar artery aneurysm: two case reports and a review of the literature

BackgroundDementia places a large burden on the economy, with financial and emotional costs incurred by patients, caregivers and the health sector.Methods and ResultsWe report the first published case series of giant basilar aneurysm leading to progressive cognitive and functional decline. We review the literature regarding giant aneurysms and their association with dementia and the possible underlying pathophysiological mechanism.ConclusionsThis report highlights a number of therapeutic considerations when determining the best management strategy for these difficult lesions.