Biomedical subjects

G Michael Lemole

Publications and source records attributed to G Michael Lemole.

7 recordsLinked to original sources

PubMed2006

Second generation haptic ventriculostomy simulator using the ImmersiveTouch system.

Ventriculostomy is a neurosurgical procedure that consists of the insertion of a catheter into the ventricles of the brain for relieving the intracranial pressure. A distinct "popping" sensation is felt as the catheter enters the ventricles. Early ventriculostomy simulators provided some basic audio/visual feedback to simulate the procedure, displaying a 3D virtual model of a human head. Without any tactile feedback, the usefulness of such simulators was very limited. The first generation haptic ventriculostomy simulators incorporated a haptic device to generate a virtual resistance and "give" upon ventricular entry. While this created considerable excitement as a novelty device for cannulating ventricles, its usefulness for teaching and measuring neurosurgical expertise was still very limited. Poor collocation between the haptic device stylus held by the surgeon and the visual representation of the virtual catheter, as well as the lack of a correct viewer-centered perspective, created enormous confusion for the neurosurgeons who diverted their attention from the actual ventriculostomy procedure to overcoming the limitations of the simulator. We present a second generation haptic ventriculostomy simulator succeeding over the major first generation limitations by introducing a head and hand tracking system as well as a high-resolution high-visual-acuity stereoscopic display to enhance the perception and realism of the virtual ventriculostomy.

Computer Simulation↗

PubMed2004

Thoracoscopic placement of dual-rod instrumentation in thoracic spinal trauma.

OBJECTIVE AND IMPORTANCE: Traditionally, thoracic fractures that require anterior stabilization are treated through an open thoracotomy approach. Thoracoscopic instrumentation avoids many of the complications associated with an open thoracotomy but is technically challenging. We report the first cases of dual-rod internal fixation systems placed thoracoscopically for thoracic spinal trauma. CLINICAL PRESENTATION: Two male patients sustained midthoracic spinal trauma falling from motorcycles in separate incidents. Both injuries led to unstable spinal columns, but the patients had no neurological deficits and had minimal spinal cord compression. One patient had a complex spiral fracture from T6 to T8; the other had T7 burst and T8 compression fractures. Based on the complex morphological features of the patients' fractures, anterior internal fixation was the treatment of choice for both. The two available options for an anterior stabilization were open thoracotomy and thoracoscopic instrumentation. Because extensive decompression was unnecessary, a thoracoscopic approach was used. INTERVENTION: A dual-rod internal fixation system (Medtronic Sofamor Danek, Inc., Memphis, TN) was placed with two screws each in the T6 and T9 vertebral bodies of each patient. Thoracoscopy was used for direct visualization of the operative site with fluoroscopic guidance for screw placement. Surgery was completed without complications, and both patients did well afterward. Upright and supine x-rays demonstrated that the constructs were stable at 10 weeks and 6 months, respectively. CONCLUSION: Thoracoscopic instrumentation offers the advantages of a minimally invasive approach but is technically challenging. The characteristics of dual-rod fixation systems (small-profile components and step-wise insertion) provide the best biomechanical profile and facilitate thoracoscopic instrumentation.

Adult↗

PubMed2003

Scalp arteriovenous malformation draining into the superior sagittal sinus associated with an intracranial arteriovenous malformation: just a coincidence? Case report.

OBJECTIVE AND IMPORTANCE: Recent experimental and clinical evidence suggests that hemodynamic changes in the venous system can induce the formation of new arteriovenous malformations (AVMs). In a rat model, increased venous pressure induces the formation of soft tissue and dural AVMs. We report a clinical observation that may support these data. CLINICAL PRESENTATION: A 4-year-old boy with a midline scalp AVM draining into the superior sagittal sinus had an associated intracranial/parenchymal AVM. The cerebral AVM increased venous pressure in the superior sagittal sinus as revealed by angiography. INTERVENTION: The scalp AVM was resected, and the intracranial AVM was treated by use of the gamma knife. CONCLUSION: On the basis of reported experimental data and the morphological and hemodynamic characteristics in this patient's two lesions, we suggest that the scalp AVM might have been induced by hypertension in the superior sagittal sinus. This clinical observation supports the notion suggested by experimental studies that hemodynamic changes can induce the formation of associated AVMs.

Angiography, Digital Subtraction↗

PubMed2003

Modifications to the orbitozygomatic approach. Technical note.

The orbitozygomatic craniotomy is one of the workhorse approaches of skull base surgery, providing wide, multidirectional access to the anterior and middle cranial fossae as well as the basilar apex. Complete removal of the orbitozygomatic bar increases the angles of exposure, decreases the working depth of the surgical field, and minimizes brain retraction. In many cases, however, only a portion of the exposure provided by the full orbitozygomatic approach is needed. Tailoring the extent of the bone resection to the specific lesion being treated can help lower approach-related morbidity while maintaining its advantages. The authors describe the technical details of the supraorbital and subtemporal modified orbitozygomatic approaches and discuss the surgical indications for their use. Modifications to the orbitozygomatic approach are an example of the ongoing adaptation of skull base procedures to general neurosurgical practice.

Brain Diseases↗

PubMed2002

Anterior communicating artery aneurysms.

ANTERIOR COMMUNICATING ARTERY aneurysms are complex lesions for which surgical success requires extensive preoperative and intraoperative planning. Adherence to the tenets of aneurysm surgery, including vascular control and preservation of perforating arteries, is essential for their exclusion from the circulation.

Brain↗

PubMed2002

Interactive stereoscopic virtual reality: a new tool for neurosurgical education. Technical note.

The goal of this study was to develop a new method for neurosurgical education based on interactive stereoscopic virtual reality (ISVR). Interactive stereoscopic virtual reality can be used to recreate the three-dimensional (3D) experience of neurosurgical approaches much more realistically than standard educational methods. The demonstration of complex 3D relationships is unrivaled and easily combined with interactive learning and multimedia capabilities. Interactive stereoscopic virtual reality permits the accurate recreation of neurosurgical approaches through integration of several forms of stereoscopic multimedia (video, interactive anatomy, and computer-rendered animations). The content explored using ISVR is obtained through a combination of approach-based cadaver dissections, live surgical images and videos, and computer-rendered animations. These media are combined through an interactive software interface to demonstrate key aspects of a neurosurgical approach (for example, patient positioning, draping, incision, individual surgical steps, alternative steps, relevant anatomy). The ISVR platform is designed for use on a desktop personal computer with newly developed, inexpensive, platform-independent shutter glasses. Interactive stereoscopic virtual reality has been used to capture the anatomy and methods of several neurosurgical approaches. In this paper the authors report their experience with ISVR and describe its potential advantages. The success of a neurosurgical approach is contingent on the mastery of complex, 3D anatomy. A new technology for neurosurgical education, ISVR can improve understanding and speed the learning process. It is an effective tool for neurosurgical education, bridging the substantial gap between textbooks and intraoperative training.

Computer-Assisted Instruction↗

PubMed2002

Cerebral revascularization performed using posterior inferior cerebellar artery-posterior inferior cerebellar artery bypass. Report of four cases and literature review.

Cerebral revascularization is often required for the surgical treatment of complex intracranial aneurysms. In certain anatomical locations, vascular anatomy and redundancy make in situ bypass possible. The authors present four patients who underwent revascularization performed using the rarely reported posterior inferior cerebellar artery (PICA)-PICA in situ bypass after their aneurysms had been trapped. At Barrow Neurological Institute, between 1991 and the present, four male patients underwent PICA-PICA by-passes to treat aneurysms involving the vertebral artery, the PICA, or both. The mean age of these patients was 34 years (range 5-49 years). Follow-up studies revealed patent bypasses and no evidence of infarction. Patient outcomes were excellent or good. Multiple surgical techniques have been described for revascularization of at-risk cerebral territories. Often, the blood supply must be derived from extracranial sources through a mobilized pedicle or interposited graft. Certain anatomical locations such as the vertebrobasilar junction, the anterior circle of Willis, and the middle cerebral artery bifurcation are amenable to in situ bypass because there is vessel redundancy or proximity to the contralateral analogous vessel. The advantages of an in situ bypass include one suture line, a short bypass distance, and a close match with the caliber of the recipient graft. Although technically challenging, this technique can be successful and should be considered for appropriate candidates.

Adult↗