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Biomedical subjects

L Fernando Gonzalez

Publications and source records attributed to L Fernando Gonzalez.

23 records · Page 2Linked to original sources
PubMed2003

Craniovertebral junction fixation with transarticular screws: biomechanical analysis of a novel technique.

OBJECT: The authors compared the biomechanical stability resulting from the use of a new technique for occipitoatlantal motion segment fixation with an established method and assessed the additional stability provided by combining the two techniques. METHODS: Specimens were loaded using nonconstraining pure moments while recording the three-dimensional angular movement at occiput (Oc)-C1 and C1-2. Specimens were tested intact and after destabilization and fixation as follows: 1) Oc-C1 transarticular screws plus C1-2 transarticular screws; 2) occipitocervical transarticular (OCTA) plate in which C1-2 transarticular screws attach to a loop from Oc to C-2; and (3) OCTA plate plus Oc-C1 transarticular screws. Occipitoatlantal transarticular screws reduced motion to well within the normal range. The OCTA loop and transarticular screws allowed a very small neutral zone, elastic zone, and range of motion during lateral bending and axial rotation. The transarticular screws, however, were less effective than the OCTA loop in resisting flexion and extension. CONCLUSIONS: Biomechanically, Oc-C1 transarticular screws performed well enough to be considered as an alternative for Oc-C1 fixation, especially when instability at C1-2 is minimal. Techniques for augmenting these screws posteriorly by using a wired bone graft buttress, as is currently undertaken with C1-2 transarticular screws, may be needed for optimal performance.

Adult↗
PubMed2003

Distinction between paraclinoid and cavernous sinus aneurysms with computed tomographic angiography.

OBJECTIVE: To examine the reliability of using the optic strut as a landmark in computed tomographic (CT) angiography, to differentiate between intradural and extradural (cavernous sinus) aneurysms involving the paraclinoid segment of the internal carotid artery (ICA). METHODS: Microanatomic dissections were performed with five cadaveric heads (10 sides), to establish the relationships of the optic strut to the cavernous sinus and the ICA. Results from these anatomic studies were compared with intraoperative and CT angiographic findings for four patients with nine intracranial aneurysms involving the paraclinoid segment of the ICA. RESULTS: The inferior boundary of the optic strut accurately localized the point at which the ICA pierced the oculomotor membrane (proximal dural ring) and exited the cavernous sinus. The optic strut and its relationship to the ICA could be well observed on CT angiograms. During surgery, six of six aneurysms that arose distal to the optic strut were identified intradurally and were successfully clipped. Conversely, all aneurysms that arose proximal to the optic strut were observed to lie within the cavernous sinus. An aneurysm at the optic strut was within the clinoid segment or interdural, between the proximal and distal rings. CONCLUSION: The optic strut, as identified with CT angiography, provided a reliable anatomic landmark for accurate discrimination between intradural and extradural (cavernous sinus) aneurysms.

Adult↗
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

Working area and angle of attack in three cranial base approaches: pterional, orbitozygomatic, and maxillary extension of the orbitozygomatic approach.

OBJECTIVE: This study was designed to quantify the operative exposure obtained in the pterional, orbitozygomatic, and modified orbitozygomatic with maxillary extension surgical approaches. METHODS: The pterional and orbitozygomatic approaches and a variation of the orbitozygomatic osteotomy that included an extra centimeter of bone resection in the inferior direction ("maxillary extension") were performed on cadaveric heads. For each surgical exposure, the working area was determined by using triangles defined with anatomic points. The "angle of attack" of the approaches for the same target point was determined with the use of a robotic microscope. RESULTS: The maximum allowable angle of attack was significantly greater with the orbitozygomatic approach (37.2 +/- 4.7 degrees) than that with the pterional approach (27.1 +/- 4.3 degrees) (P < 0.001). The angle of attack with the maxillary extension (42.0 +/- 4.9 degrees) was significantly greater than that with the orbitozygomatic approach (P < 0.001). The working areas were 281, 343, and 371 mm(2) for the pterional, orbitozygomatic, and maxillary extension approaches, respectively. The orbitozygomatic approach with maxillary extension had a significantly larger working area than the pterional approach (P = 0.011). CONCLUSION: Increments in bony removal open a wider angle in which to work more than they increase the actual amount of working area. Increasing the amount of bone removed by using an orbitozygomatic approach instead of a pterional approach converts a narrow space into a wide portal, allowing surgeons to work closer to the surgical target while decreasing the need for brain retraction. Extending the orbitozygomatic approach into the maxillary region also improves the exposure area and angle, but less significantly.

Cadaver↗