Biomedical subjects

M E Leventon

Publications and source records attributed to M E Leventon.

5 recordsLinked to original sources

PubMed1998

Three-dimensional image reconstruction for low-grade glioma surgery.

Three-dimensional image reconstruction for preoperative surgical planning and intraoperative navigation for the resection of low-grade gliomas was performed in 20 patients. Thirteen of these surgeries were performed while the patient received a local anesthetic to allow for cortical mapping. Ninety percent of the patients were functionally intact postoperatively. The authors propose that the combination of the three-dimensional image reconstruction and surgical navigation, in conjunction with intraoperative cortical mapping, provides an additional means for surgeons to improve the safety and precision of the procedures.

Journal Article↗

PubMed1998

Experimentation with a transcranial magnetic stimulation system for functional brain mapping.

We describe functional brain mapping experiments using a transcranial magnetic stimulation (TMS) device. This device, when placed on a subject's scalp, stimulates the underlying neurons by generating focused magnetic field pulses. A brain mapping is then generated by measuring responses of different motor and sensory functions to this stimulation. The key process in generating this mapping is the association of the 3-D positions and orientations of the TMS probe on the scalp to a 3-D brain reconstruction such as is feasible with a magnetic resonance image (MRI). We have developed a registration system which not only generates functional brain maps using such a device, but also provides real-time feedback to guide the technician in placing the probe at appropriate points on the head to achieve the desired map resolution. Functional areas we have mapped are the motor and visual cortex. Validation experiments focus on repeatability tests for mapping the same subjects several times. Applications of the technique include neuroanatomy research, surgical planning and guidance, treatment and disease monitoring, and therapeutic procedures.

Brain Mapping↗

PubMed1998

Visual hemifield mapping using transcranial magnetic stimulation coregistered with cortical surfaces derived from magnetic resonance images.

The perception of a visual stimulus can be inhibited by occipital transcranial magnetic stimulation. This visual suppression effect has been attributed to disruption in the cortical gray matter of primary visual cortex or in the fiber tracts leading to V1 from the thalamus. However, others have suggested that the visual suppression effect is caused by disruption in secondary visual cortex. Here the authors used a figure-eight coil, which produces a focal magnetic field, and a Quadropulse stimulator to produce visual suppression contralateral to the stimulated hemisphere in five normal volunteer subjects. The authors coregistered the stimulation sites with magnetic resonance images in these same subjects using optical digitization. The stimulation sites were mapped onto the surface of the occipital lobes in three-dimensional reconstructions of the cortical surface to show the distribution of the visual suppression effect. The results were consistent with disruption of secondary visual cortical areas.

Adult↗

PubMed1998

Excision of cortical dysplasia in the language area with use of a surgical navigator: a case report.

PURPOSE: We have developed an intraoperative optical tracking-based navigational system that allows localization in the operative space. Using three-dimensional reconstruction, this system has provided precise spatial information for intraoperative cortical mapping in patients with intractable epilepsy in whom the lesion lies close to eloquent cortex. METHODS: A 23-year-old man with intractable complex partial seizures (CPS) presented to our institution. Proton-density magnetic resonance imaging (MRI) showed a 3-cm lesion which lay 2 cm beneath the left frontal operculum. A three-dimensional model of the patient was reconstructed using MR modalities. Intraoperatively, subdural grid and strips were placed over the lesion and their electrodes were registered to the three-dimensional model, which was displayed on a monitor. The navigational system was used to localize each electrode on the three-dimensional model. By the second operation, the sites of seizure activity were established and recorded on the three-dimensional model. A bipolar stimulator was also used to determine the speech area. RESULTS: The lesion, which proved to be cortical dysplasia, was removed completely and the cortical speech area was avoided. During the postoperative period, the patient had no neurological symptoms and no seizure activity. CONCLUSIONS: The localization of a lesion and its correlation with epileptogenic foci is important in optimizing treatment in patients with cortical dysplasia. Our navigational system provided accurate localization of the lesion and correlation with the epileptogenic focus and related eloquent cortex. We believe that the safe removal of the lesion was facilitated by this system.

Adult↗

PubMed1997

Three-dimensional reconstruction and surgical navigation in pediatric epilepsy surgery.

We have used MRI-based three-dimensional (3D) reconstruction and a real-time, frameless, stereotactic navigation device to facilitate the removal of seizure foci in children suffering from intractable epilepsy. Using this system, the location of subdural grid and strip electrodes is recorded on the 3D model to facilitate focus localization and resection. Ten operations were performed, including 2 girls and 8 boys ranging in age from 3 to 17, during which 3D reconstruction and surgical instrument tracking navigation was used. In all the cases, the patients tolerated the procedure well and showed no postoperative neurological deficits. We believe this to be a valuable tool for a complete and safe resection of seizure foci, thereby reducing the incidence of postoperative neurological deficits and significantly improving the overall quality of life of the patients.

Adolescent↗