Intracranial Pressure Evaluation in Swine During Full-Endoscopic Lumbar Spine Surgery.

BACKGROUND: Neurological complications during full-endoscopic spine surgery (FESS) might be attributed to intracranial pressure (ICP) increase due to continuous saline infusion (CSI). Understanding CSI and ICP correlation might modify irrigation pump usage. This study aimed to evaluate invasive ICP during interlaminar FESS; correlate ICP with irrigation pump parameters (IPPs); evaluate ICP during saline outflow occlusion, commonly used to control bleeding and improve the surgeon's view; and, after durotomy, simulate accidental dural tear. METHODS: Five swine were monitored, submitted to total intravenous anesthesia, and positioned ventrally. A parenchymal catheter was installed through a skull burr for ICP monitoring. Lumbar interlaminar FESS was performed until exposure of neural structures. CSI was used within progressively higher IPPs (A [60 mm Hg, 350 mL/minute] to D [150 mm Hg, 700 mL/minute]), and ICP was documented. During each IPP, different situations were grouped: intact dura with open channels (A1-D1) or occlusion test (A2-D2); dural tear with open channels (Ax1-Dx1) or occlusion test (Ax2-Dx2). ICP <20 mm Hg was defined as safe. RESULTS: Basal average ICP was 8.1 mm Hg. Adjustment in total intravenous anesthesia or suspension of tests was necessary due to critical ICP or animal discomfort. It was safe to operate with all IPPs with opened drainage channels (A1-D1) even with dural tear (Ax1-Dx1). Several occlusion tests (A2-D2, Ax2-Dx2) caused ICP increase (e.g., 86.1 mm Hg) influenced by anesthetic state and hemodynamics. CONCLUSIONS: During FESS, CSI might critically raise ICP. Keeping drainage channels open, with ideal anesthetic state, ICP remains safe even with high IPPs, despite dural tear. Drainage occlusions can quickly raise ICP, being even more severe with higher IPPs. Total intravenous anesthesia may protect from ICP increase and may allow longer drainage occlusion or higher IPPs.

Expression of microRNAs miR-21 and miR-326 associated with HIF-1α regulation in neurospheres of glioblastoma submitted to ionizing radiation treatment.

Background: Glioblastoma is an incurable neoplasm. Its hypoxia mechanism associated with cancer stem cells (CSCs) demonstrates hypoxia-inducible factor 1α (HIF-1α) expression regulation, which is directly related to tumor malignancy. The aim of this study was to identify a possible tumor malignancy signature associated with regulation of HIF-1α by microRNAs miR-21 and miR-326 in the subpopulation of tumor stem cells which were irradiated by ion in primary culture of patients diagnosed with glioblastoma. Materials and methods: We used cellular cultures from surgery biopsies of ten patients with glioblastoma. MicroRNA expressions were analyzed through real-time polymerase chain reaction (PCR ) and correlated with mortality and recurrence. The ROC curve displayed the cutoff point of the respective microRNAs in relation to the clinical prognosis, separating them by group. Results: The miR-21 addressed high level of expression in the irradiated neurosphere group (p = 0.0028). However, miR-21 was not associated with recurrence and mortality. miR-326 can be associated with tumoral recurrence (p = 0.032) in both groups; every 0.5 units of miR-326 increased the chances of recurrence by 1,024 (2.4%). Conclusion: The high expression of miR-21 in the irradiated group suggests its role in the regulation of HIF-1α and in the radioresistant neurospheres. miR-326 increased the chances of recurrence in both groups, also demonstrating that positive regulation from miR-326 does not depend on ionizing radiation treatment.

Full Endoscopic Thoracic Discectomy: Is the Interlaminar Approach an Alternative to the Transforaminal Approach? A Technical Note.

BACKGROUND: Various approaches are used for decompressive surgeries in the thoracic spine depending on the location and consistency of the pathology, always avoiding manipulation of the thoracic spinal cord. Recently, there has been an effort to achieve adequate results and reduce morbidity with minimally invasive surgeries. Good outcomes and the advantages of full endoscopic spine surgery (FESS) have been proven for surgerical correction of herniated discs and stenoses in the lumbar and cervical spine. Similar evidence has recently been described for the thoracic spine, but it has not previously been reported in Brazil. Although the transforaminal approach is already established for the thoracic spine, the newly described interlaminar approach is equally efficient, and both techniques must be considered when treating thoracic spine diseases. The objective of the present article was to present the full endoscopic interlaminar and transforaminal techniques in patients with symptomatic disc herniation of the thoracic spine, discuss the rationality for implementing FESS in thoracic spine, and discuss the rationality in choosing between both approaches. METHODS: Two patients were submitted to thoracic FESS. A transforaminal approach was chosen for a T10-T11 foraminal disc herniation; an interlaminar approach was selected for a paramedian T7-T8 disc extrusion. Data regarding operating time, intraoperative images, hospital stay, visual analog scales before and after FESS, course of recovery, and surgery satisfaction were evaluated. RESULTS: The patients had eventless surgeries, improved from preoperative pain without morbidity. Both were satisfied and recovered well. Hospital stay was less than 6 hours after surgery. CONCLUSIONS: Transforaminal and interlaminar FESS for thoracic disc herniation are safe, efficient, and minimally invasive alternatives. CLINICAL RELEVANCE: Despite being an innovative technique with evident advantages, it should be carefully considered along with conventional technique for the treatment of thoracic spine diseases, since its clinical relevance is yet to be determined.

Experimental Model for Interlaminar Endoscopic Spine Procedures.

BACKGROUND: Endoscopic spinal surgery is becoming quite popular, and the pursuit of a training model to improve surgeons' skills is imperative to overcome the limited availability of human cadavers. Our goal was to determine whether the porcine spine could be a representative model for learning and practicing interlaminar percutaneous endoscopic lumbar procedures (IL-PELPs). METHODS: Lumbar and cervical segments of the porcine cadaver spine were used for the IL-PELP. We have described the technical notes on the difficulties of the procedure and the relevant anatomical features. To endorse the porcine cadaver for this procedure, 5 neurosurgeons underwent 1 day of training and completed a survey. RESULTS: The porcine lumbar spine has small interlaminar windows, and laminectomy is necessary, mimicking the translaminar approaches for higher human lumbar spine levels. The porcine cervical spine has wide and high interlaminar windows and mimics the human L5-S1 interlaminar approach. Entering the spinal canal with the working sheath and endoscope and training the rotation maneuver to access the disc space is only possible in the lumbar segment. It was possible to perform flavectomy and to identify and dissect the dural sac and nerve root in both the lumbar and cervical spine. The neurosurgeons considered the porcine model of good operability and, although different, possible to apply in humans. CONCLUSIONS: The porcine spine is an effective and representative model for learning and practicing IL-PELPs. Although the described anatomical differences should be known, they did not interfere in performing the main surgical steps and maneuvers for IL-PELPs in the porcine model.

Experimental model for transforaminal endoscopic spine

Abstract Purpose: To validate the porcine spine as a model for learning and practicing transforaminal percutaneous endoscopic lumbar procedures (TF-PELP). Methods: TF-PELP was performed in three porcine cadaver lumbar spine levels. Anatomical features of the current cadaver were compared to human and porcine spines. Performance and documentation of endoscopic procedures were described. Results: This study shows that this representative animal model reflects anatomical characteristics of the human spine. Transforaminal approaches were successfully completed. Although lower disc heights make disc puncture more difficult, the outside-in technique is feasible and more useful to identify anatomical parameters and to practice different surgical steps and maneuvers. Conclusion: This is an effective and representative model for learning and practicing this procedure. Difficulties of the procedure, as well as the differences compared to the human spine, were described.

Experimental model for transforaminal endoscopic spine.

PURPOSE: To validate the porcine spine as a model for learning and practicing transforaminal percutaneous endoscopic lumbar procedures (TF-PELP). METHODS: TF-PELP was performed in three porcine cadaver lumbar spine levels. Anatomical features of the current cadaver were compared to human and porcine spines. Performance and documentation of endoscopic procedures were described. RESULTS: This study shows that this representative animal model reflects anatomical characteristics of the human spine. Transforaminal approaches were successfully completed. Although lower disc heights make disc puncture more difficult, the outside-in technique is feasible and more useful to identify anatomical parameters and to practice different surgical steps and maneuvers. CONCLUSION: This is an effective and representative model for learning and practicing this procedure. Difficulties of the procedure, as well as the differences compared to the human spine, were described.