Tag: Pyramidal tract

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Surgical strategy to avoid ischemic complications of the pyramidal tract in resective epilepsy surgery of the insula

J Neurosurg 128:1173–1177, 2018

Surgical treatment of the insula is notorious for its high probability of motor complications, particularly when resecting the superoposterior part. Ischemic damage to the pyramidal tract in the corona radiata has been regarded as the cause of these complications, resulting from occlusion of the perforating arteries to the pyramidal tract through the insular cortex. The authors describe a strategy in which a small piece of gray matter is spared at the bottom of the periinsular sulcus, where the perforating arteries pass en route to the pyramidal tract, in order to avoid these complications.

This method was successfully applied in 3 patients harboring focal cortical dysplasia in the posterior insula and frontoparietal operculum surrounding the periinsular sulcus. None of the patients developed permanent postoperative motor deficits, and seizure control was achieved in all 3 cases.

The method described in this paper can be adopted for functional preservation of the pyramidal tract in the corona radiata when resecting epileptogenic pathologies involving insular and opercular regions.

 

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Surgical results of tumor resection using tractography-integrated navigation-guided fence-post catheter techniques and motor-evoked potentials for preservation of motor function in patients with glioblastomas near the pyramidal tracts

Surgical results of tumor resection using tractography-integrated

Neurosurg Rev (2015) 38:293–307

The current optimal surgery for glioblastomas (GBMs) near the pyramidal tract (PT) is to remove as much tumor as possible and to preserve motor function. The purpose of this study is to investigate the usefulness of tractography integrated navigation-guided fence-post catheter techniques and motor-evoked potentials (MEPs) for preserving postoperative motor function after GBM surgery.

We retrospectively examined 49 patients who underwent resection for GBM near the PT. Diffusion tensor (DT) imaging-based tractography of the PT was performed preoperatively and integrated into the navigation system. When possible, silicon catheters were used as “fence-posts” and were inserted along the tumor boundaries, avoiding the PT, before tumor removal using the navigation system (fence-post catheter techniques). Cortical and subcortical MEPs were also monitored during resection of the tumor. Fence-post catheter techniques using a tractography integrated navigation system were used in 45 of 49 patients.

This technique enabled placement of the catheters, avoided the motor pathways, and allowed easier resection of the tumors. Tumors near the PT were resected using subcortical and cortical MEPs. The amplitudes of cortical MEPs after tumor removal were maintained at over 33 % of those obtained before resection.

Thirty-six patients showed obvious responses of subcortical MEPs at ≤20 mA. The degree of resection was gross total in 21 patients, subtotal in 21, and partial in seven. One month after surgery, only one patient showed worsened motor function.

Therefore, fence-post catheter techniques using a tractography-integrated navigation system and MEPs may contribute to preserving motor function after surgery for GBMs that are near the PT.

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Clinical Application of Motor Pathway Mapping Using Diffusion Tensor Imaging Tractography and Intraoperative Direct Subcortical Stimulation in Cerebral Glioma Surgery

Neurosurgery 71:1170–1184, 2012

Glioma surgery in eloquent areas remains a challenge because of the risk of postoperative motor deficits.

OBJECTIVE: To prospectively evaluate the efficiency of using a combination of diffusion tensor imaging (DTI) tractography functional neuronavigation and direct subcortical stimulation (DsCS) to yield a maximally safe resection of cerebral glioma in eloquent areas.

METHODS: A prospective cohort study was conducted in 58 subjects with an initial diagnosis of primary cerebral glioma within or adjacent to the pyramidal tract (PT). The white matter beneath the resection cavity was stimulated along the PT, which was visualized with DTI tractography. The intercept between the PT border and DsCS site was measured. The sensitivity and specificity of DTI tractography for PT mapping were evaluated. The efficiency of the combined use of both techniques on motor function preservation was assessed.

RESULTS: Postoperative analysis showed gross total resection in 40 patients (69.0%). Seventeen patients (29.3%) experienced postoperative worsening; 1-month motor deficit was observed in 6 subjects (10.3%). DsCS verified a high concordance rate with DTI tractography for PT mapping. The sensitivity and specificity of DTI were 92.6% and 93.2%, respectively. The intercepts between positive DsCS sites and imaged PTs were 2.0 to 14.7 mm (5.262.2 mm). The 6-month Karnofsky Performance Scale scores in 50 postoperative subjects were significantly increased compared with their preoperative scores.

CONCLUSION: DTI tractography is effective but not completely reliable in delineating the descending motor pathways. Integration of DTI and DsCS favors patient-specific surgery for cerebral glioma in eloquent areas.

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Accuracy of Diffusion Tensor Magnetic Resonance Imaging-Based Tractography for Surgery of Gliomas Near the Pyramidal Tract

Neurosurgery 70:283–294, 2012 DOI: 10.1227/NEU.0b013e31823020e6

Diffusion tensor (DT) imaging-based fiber tracking is a noninvasive magnetic resonance technique that can delineate the course of white matter fibers.

OBJECTIVE: To evaluate the accuracy and usefulness of this DT imaging-based fiber tracking for surgery in patients with gliomas near the pyramidal tract (PT).

METHODS: Subjects comprised 32 patients with gliomas near the PT. DT imagingbased fiber tracks of the PT were generated before and within 3 days after surgery in all patients. A tractography-integrated navigation system was used during the operation. Cortical and subcortical motor-evoked potentials (MEPs) were also monitored during resection to maximize the preservation of motor function. The threshold intensity for subcortical MEPs was examined by searching the stimulus points and changing the stimulus intensity. Minimum distance between the resection border and the illustrated PT was measured on postoperative tractography.

RESULTS: In all subjects, DT imaging-based tractography of the PT was successfully performed, preoperatively demonstrating the relationship between tumors and the PT. With the use of the tractography-integrated navigation system and intraoperative MEPs, motor function was preserved postoperatively in all patients. A significant correlation was seen between threshold intensity for subcortical MEPs and the distance between the resection border and PT on postoperative DT imaging.

CONCLUSION: DT imaging-based fiber tracking is a reliable and accurate method for mapping the course of subcortical PTs. Fiber tracking and intraoperative MEPs were useful for preserving motor function in patients with gliomas near the PT.

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