An alternative path to atrial lesions through a contralateral interhemispheric transfalcine transcingular infra-precuneus approach: A case report

Background: The surgical management of lesions located in the trigone of the lateral ventricle remains a neurosurgical challenge. Previously described approaches to the atrium include the transtemporal, parietal transcortical, parietal trans intraparietal sulcus, occipital transcingulate, posterior transcallosal, and transfalcine transprecuneus. However, reaching this area specifically through the cingulate cortex below the subparietal sulcus has not been described thus far. Case Description: We present here the removal of a left atrial meningioma through a right parietal “contralateral interhemispheric transfalcine transcingular infra-precuneus” approach and compare it with previously described midline approaches to the atrium. To accomplish this, a right parietal craniotomy was performed. After the left subprecuneus cingulate cortex was exposed through a window in the falx, a limited corticotomy was performed, which allowed the tumor to be reached after deepening the bipolar dissection by 8 mm. Postoperative magnetic resonance imaging showed complete resection of the lesion sparing the corpus callosum, forceps major, and sagittal stratum. Although this approach disrupts the posterior cingulate fasciculus, no deficits have been described so far after unilaterally disrupting the posterior cingulate cortex or the posterior part of the cingulate fasciculus. In fact, a thorough postoperative cognitive examination did not show any deficits. Conclusion: The “contralateral interhemispheric transfalcine transcingular infra-precuneus” approach combines the advantages of several previously described approaches. Since it conserves the major white matter tracts that surround the atrium and has a shorter attack angle than the contralateral transfalcine transprecuneus approach, we believe that it could be a potentially new alternative path to reach atrial lesions.

Effects of Intraoperative Magnetic Resonance Thermal Imaging Signal Artifact During Laser Interstitial Thermal Therapy on Thermal Damage Estimate and Postoperative Magnetic Resonance Imaging Ablative Area Concordance

BACKGROUND Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive procedure that utilizes intraoperative magnetic resonance thermal imaging (MRTI) to generate a thermal damage estimate (TDE) of the ablative area. In select cases, the MRTI contains a signal artifact or defect that distorts the ablative region. No study has considered the impact of this artifact on TDE accuracy. OBJECTIVE To determine the effect of intraoperative MRTI signal artifact on postoperative magnetic resonance imaging (MRI)-predicted ablative area. METHODS All ablations were performed using the Visualase MRI-Guided Laser Ablation System (Medtronic). Patients were grouped based on whether the intraoperative MRTI contained signal artifact that distorted the ablative region. Cross-sectional area of the ablative lesion from the MRI image was measured, and the difference between intraoperative TDE and postoperative MRI cross-sectional area was calculated and compared between groups with and without intraoperative MRTI artifact. RESULTS A total of 91 patients undergoing MRgLITT for various surgical indications were examined. MRTI artifact was observed in 43.9% of cases overall. The mean absolute difference between TDE and the postoperative MRI cross-sectional area was 94.8 mm2 (SEM = 11.6) in the group with intraoperative MRTI artifact and 54.4 mm2 (SEM = 5.5) in the nonartifact group. CONCLUSION MRTI signal artifact is common during LITT. The presence of signal artifact during intraoperative MRTI results in higher variation between intraoperative TDE and postoperative MRI cross-sectional ablative area. In cases in which intraoperative MRTI artifact is observed, there may be a larger degree of variation between observed intraoperative TDE and measured postoperative MRTI ablative area.

Hamstring Anterior Cruciate Ligament Reconstruction Using an Adjustable-Loop Cortical Suspension Device: Immediate Postoperative Magnetic Resonance Imaging

The purpose of this study is to determine whether the hamstring grafts are fully inserted into the femoral tunnel with the adjustable loop using immediate postoperative magnetic resonance imaging (MRI) after anterior cruciate ligament (ACL) reconstructions. A total of 62 consecutive patients underwent hamstring ACL reconstruction using an adjustable-loop cortical suspension device for the femoral fixation and the Intrafix sheath and screw for the tibial fixation. Multiplanar reformatted images of 3-T MRI scans were obtained at the 1st postoperative day before weight bearing is initiated in all patients to evaluate the gap (the tunnel–graft gap) between the top of the hamstring graft and top of the femoral tunnel. Postoperative MRI scans showed that the tunnel–graft gap was 1.5 ± 2.7 mm (range, 0–12 mm). In 43 (69.4%) patients, there was no gap between the top of the femoral tunnel and hamstring graft. In 19 (30.6%) patients, there was a gap between the tunnel and graft, and nine patients demonstrated a tunnel–graft gap greater than 5 mm. Immediate postoperative MRI scans demonstrated that an adjustable-loop cortical suspension device may not pull the hamstring graft completely into the femoral tunnel.