Balloon-Assisted Corpus Callosotomy. Reducing the Impact of Transcallosal Approaches.

BACKGROUND: The interhemispheric transcallosal approach is widely used to remove intraventricular lesions. Corpus callosotomy gives immediate access to the ventricular chambers but is invasive in nature. Loss of callosal fibers, although normally tolerate, may cause disturbances ranging from a classical disconnection syndrome up to minor neuropsychological changes. OBJECTIVE: To open an operative window in the corpus callosum through separation rather than disconnection of the white matter fibers. METHODS: In 7 patients undergoing the interhemispheric transcallosal approach for intraventricular lesions, lying around or below the foramen of Monro, a stoma was created within the corpus callosum by using a 4F Fogarty catheter. The series included 3 colloid of the third ventricle, 2 thalamic cavernomas, 1 subependymoma, and 1 ependymoma of the foramen of Monro. We illustrate the technique and the clinico-radiological outcome, focusing on the size of callosotomy as seen on postoperative MRI. RESULTS: The balloon-assisted corpus callosotomy provided a circular, smooth-walled access to the ventricular chambers, which allowed uncomplicated removal of the lesions. On postoperative MRI, the size of the callosotomy shrinked compared with surgery (2.8-6.4 mm at follow-up vs 6-9 mm as measured intraoperatively). No signs of disconnection syndrome or new permanent deficits were observed in this series. CONCLUSION: The balloon-assisted technique produces a small callosotomy, without clinical consequences, showing a self-closing trend on postoperative MRI. This technique is a rewarding tool to reduce the impact of callosotomy while keeping the advantages of microsurgical interhemispheric approaches.

Interhemispheric contralateral approach: the falx as a retractor.

The contralateral transfalcine approach is a valuable option to access lesions around the mesial surface of the brain hemispheres. Despite a favourable perspective, surgical manoeuvres within the interhemispheric fissure carry a risk of inadvertent injury to the healthy cortex on the craniotomy side. To overcome this drawback, a new method of brain retraction was developed. After dissecting the interhemispheric fissure, the falx was incised in an upside-down U-shaped manner and hinged inferiorly, taking care not to violate the inferior sagittal sinus. The falcine flap was reflected laterally and fixed to the lateral edge of the craniotomy, providing homogeneous retraction of the ipsilateral mesial cortex. Surgery proceeded with the brain surface hidden from the surgeon's view and protected by the flap. The absence of retractor devices hindering the surgeon's movements further simplified the procedure.

Mini-craniotomy for intra-axial brain tumors: a comparison with conventional craniotomy in 306 patients harboring non-dural based lesions.

The use of a mini-craniotomy approach involving linear skin incision and a bone flap of about 3 cm has been reported for several neurosurgical diseases, such as aneurysms or cranial base tumors. More superficial lesions, including intra-axial tumors, may occasionally raise concerns due to insufficient control of the tumor boundaries. The convenience of a minimally invasive approach to intrinsic brain tumors was evaluated by comparing 161 patients who underwent mini-craniotomy (MC) for intra-axial brain tumors with a group of 145 patients operated on by the same surgical team through a conventional craniotomy (CC). Groups were propensity-matched for age, preoperative condition, size and location of the tumor, and pathological diagnosis. Results were analyzed focusing on operative time, the extent of resection, clinical outcome, hospitalization time, and time to start adjuvant therapy. Mini-craniotomy was equally effective in terms of extent of resection (GTR: 70.9% in the MC group vs 70.5% in the CC group) but had shorter operative time (average: 165 min in the MC group vs 205 min in the CC group p < 0.001) and lower rate of postoperative complications both superficial (1.03% vs 6.5% in the CC group p = 0.009) and deep (4% in the MC group vs 5.5% in the CC group p = 0,47). No relationship was found between the size or location of the tumor and resection rate. The MC group had reduced hospitalization time (average: 5.8 days vs 7.6 in CC group p < 0.001) and faster access to adjuvant therapies. 92.5% of the MC patients, which were scheduled for treatment, started radiotherapy within 8 weeks after surgery as opposed to 84.1% in the CC group (p = 0.04). These findings support the increasing use of mini-craniotomy for intra-axial brain tumors.

Indocyanine Green Videoangiography in the Surgical Treatment of Spinal Dural Arterovenous Fistula: A Useful Application.

BACKGROUND: Indocyanine green videoangiography (ICG-V) is used with increasing frequency in neurovascular surgery. ICG-V use in spinal dural arteriovenous fistulas (DAVFs) allows visualization of the hemodynamics of the fistula and to confirm its exclusion after ligation of the feeder. Here, we illustrate how ICG-V is useful for centering the surgical exposure during mini-invasive approaches to spinal DAVFs. METHODS: An overweight 66-year-old woman with progressive paraparesis and sphincter disturbances underwent treatment for a spinal DAVF fed by the left T6 radicular artery. After intraoperative fluoroscopy, T6 hemilaminectomy was performed. Because of slight misplacement of the bone opening, the feeder was not visible at the dural opening. We placed a temporary clip on a perimedullary arterialized vein and performed ICG-V while removing the clip. RESULTS: Reviewing the video clip and analyzing the direction of ICG flow inside the perimedullary venous plexus allowed us to locate the fistula with respect to the bone window and to extend the laminectomy in the correct direction. CONCLUSIONS: IGC-V can be helpful in mini-invasive approaches to spinal DAVFs to recalibrate the bone opening after misplacement of the initial hemilaminectomy.

Does Navigation Improve Pedicle Screw Placement Accuracy? Comparison Between Navigated and Non-navigated Percutaneous and Open Fixations.

BACKGROUND: The aim of our study was to assess how a preoperative computed tomography (CT)-based navigation system affected the correctness and safety of transpedicular screw insertion, compared with standard techniques. METHOD: Between January 2012 and February 2014, 203 patients underwent thoracic and lumbar fixation, with open and percutaneous techniques; 218 screws were implanted through an open navigated technique (1.0 Spine & Trauma 3d ver. 2.0 BrainLab, Feldkirchen Germany) in 43 patients; 220 screws were inserted with an open free-hand technique in 45 patients; 230 screws were implanted in 56 patients using percutaneous CT-based navigation; and 236 screws were inserted in 59 patients using a percutaneous fluoroscopy-guided technique. To our knowledge, this is the first work comparing these four different techniques. The position of each screw was evaluated on CT scan reconstruction and classified according to a four-point grading scale (grade 0: no breach, grade 1: breach < 2 mm, grade 2: breach between 2 and 4 mm; grade 3: breach >4 mm). Statistical analysis was assessed by two-way analysis of variance (ANOVA) t test, while the Fisher least significant difference (LSD) method was employed to determine statistical significance. RESULTS: Statistical analysis showed a significant difference in accuracy between the open CT-based navigation and the percutaneous CT-based navigation techniques (P= 0.0263) and between the open CT-based navigation and the percutaneous fluoroscopy-guided techniques (P=0.0258): a particular difference was observed in anterior misplacement between open CT-based navigation and the percutaneous fluoroscopy-guided technique (P= 0.0153). CONCLUSIONS: Our results confirm the advantages of the navigation technique, which ensures greater accuracy, in open as well as percutaneous procedures.

Transpedicular Approach to Thoracic Disc Herniaton Guided by 3D Navigation System.

BACKGROUND: The choice of surgical approach for thoracic disc herniation should consider the location on the axial plane and the consistency of the herniated disc. Calcified midline disc herniations are difficult to remove with a transpedicular approach because of limitations due to blind spots; so they are usually treated via a transthoracic approach, although this entails a high risk of thoracopulmonary injuries. METHODS: In this work we present two cases of calcified midline thoracic disc herniations treated with a transpedicular approach, improved by using a three-dimensional (3D) neuronavigation system to verify the extent of removal on the blind side. RESULTS: Postoperative computed tomography (CT) scans demonstrated that this original technical innovation, in the two present cases, allowed us to reach the side opposite the disc herniation and to assess the extent of resection at the end of the procedure. CONCLUSIONS: The employment of a neuronavigation system in the transpedicular approach allowed safe and effective removal of calcified midline thoracic disc herniations. We did not observe any postoperative neurological worsening, onset of spinal instability, or other adverse events.