Self-closing Nitinol U-Clips for intracranial arterial microanastomosis: a preliminary experience on seven cases

A new design of a Nitinol ring-like wire for suturing in deep surgical field

The present work proposes a new suturing procedure based on self-accommodating suture points. Each suture point is made of a commercial NiTi wire hot-shaped in a single loop ring; a standard suture needle is then fixed at one end of the NiTi suture. According to this simple geometry, several NiTi suture stitches have been prepared and tested by tensile test to verify the closing force in comparison to that of commercial sutures. Further experimental tests have also been performed on anatomic samples from animals to verify the handiness of the NiTi suture. Moreover, surface quality of sutures has been carefully investigated via microscopy. Results show that the NiTi suture expresses high stiffness and a good surface quality. In addition, the absence of manual knotting allows for a simple, fast and safe procedure.

A neuronavigation-based method for locating the superficial temporal artery during extra-intracranial bypass surgery

The superficial temporal artery (STA) is frequently used as donor vessel in extracranial to intracranial bypass surgery. Current techniques typically rely on a Doppler vascular probe to identify the STA trajectory prior to the skin incision; however, this step can be time consuming and difficult when the arterial course is tortuous. We tested an alternative neuronavigation-based technique for locating the STA. In this method, preoperative magnetic resonance angiography (MRA) or computed tomography angiography (CTA) was used to determine STA outlines that were then projected and traced onto the skin. The neuronavigation-based technique was applied to eight STA dissections. The accuracy of this method was evaluated by comparing the navigation-based STA course with the doppler-based one and the actual STA course intraoperatively. STA trajectory was determined before surgery by using three imaging techniques: CTA (3 cases), three-dimensional (3D) contrast-enhanced T1-weighted MRA (4 cases), and/or 3D time-of-flight MRA (5 cases). In all cases, the neuronavigation-based STA position was confirmed with the Doppler vascular probe before skin incision and corresponded to the actual vessel position intraoperatively. As long as the skin is not mobilized during preoperative image acquisition and surgery, this neuronavigation-based approach is a valid method to identify STA course. During the preoperative planning process, the STA trajectory should be analyzed from its origin at the level of the foramen spinosum to avoid mistaking nearby venous structures as the STA.

Circumferential watertight dural repair using nitinol U-clips in expanded endonasal and sublabial approaches to the cranial base

BACKGROUND

In recent years, significant advances have been made in the field of expanded endonasal approaches that permit treatment of different cranial base intradural lesions.

OBJECTIVE

To report our technique of cranial base dural repair by the application of nitinol U-Clips in endoscope-assisted extended endonasal or sublabial approaches. Closure techniques and postoperative cerebrospinal (CSF) leaks are reported.

METHODS

We reviewed 11 patients with different kinds of cranial base tumors or vascular diseases (2 tuberculum sellae meningiomas, 1 planum sphenoidale meningioma, 4 craniopharyngiomas, 1 recurrent clival chordoma, 1 esthesioneuroblastoma, 1 ethmoidal melanoma metastasis, 1 basilar trunk aneurysm) who underwent an endoscope-assisted extended endonasal or sublabial approach. Dural repair was performed using nitinol U-Clips to circumferentially suture AlloDerm or fascia lata directly to the existing dural borders. Lumbar drainage was not used in 9 patients and was used in 2 patients for 5 days. Patients were evaluated for the appearance of CSF leaks.

RESULTS

Postoperative CSF leak was observed in 1 patient (9%). This required a second transnasal repair.

CONCLUSION

Circumferential dural closure with U-Clips is a useful adjunct to prevent CSF leaks after expanded endonasal or sublabial approaches to the cranial base for treatment of intracranial pathology.

Indocyanine green (ICG) temporary clipping test to assess collateral circulation before venous sacrifice

BACKGROUND

As a general principle, sacrifice of cerebral veins at surgery is avoided. However, at times sacrifice of a vein may be desirable to increase surgical exposure. At present, no method exists to predict whether such sacrifice will be accommodated by the presence of collateral venous drainage. We show a simple technique to examine cerebral venous blood flow using indocyanine green videoangiography.

METHODS

In two patients, parasagittal meningiomas were found to be associated with paramedian veins that impeded complete removal of the tumors. The suitability of veins removal was assessed by applying a temporary aneurysm clip and performing an indocyanine green videoangiogram.

RESULTS

In one patient, stasis was observed in the vein. In the second patient, a collateral flow allowed the venous blood to drain. The former test was considered a counterindication for venous sacrifice, whereas the latter supported its feasibility. The vein was preserved in the former case and coagulated in the latter. In both cases, the patients did well.

CONCLUSIONS

Although our limited study cannot prove that venous congestion or infarction can be avoided with this technique, it does provide direct evidence of the presence or absence of collaterals that can help guide intraoperative surgical decision-making.

Venous sacrifice in neurosurgery: new insights from venous indocyanine green videoangiography

OBJECT

The purpose of this paper is to evaluate whether venous indocyanine green (ICG) videoangiography has any potential for predicting the presence of a safe collateral circulation for veins that are at risk for intentional or unintentional damage during surgery.

METHODS

The authors performed venous ICG videoangiography during 153 consecutive neurosurgical procedures. On those occasions in which a venous sacrifice occurred during surgery, whether that sacrifice was preplanned (intended) or unintended, venous ICG videoangiography was repeated so as to allow us to study the effect of venous sacrifice. A specific test to predict the presence of venous collateral circulation was also applied in 8 of these cases.

RESULTS

Venous ICG videoangiography allowed for an intraoperative real-time flow assessment of the exposed veins with excellent image quality and resolution in all cases. The veins observed in this study were found to be extremely different with respect to flow dynamics and could be divided in 3 groups: 1) arterialized veins; 2) fast-draining veins with uniform filling and clear flow direction; and 3) slow-draining veins with nonuniform filling. Temporary clipping was found to be a simple and reversible way to test for the presence of potential anastomotic circulation.

CONCLUSIONS

Venous ICG videoangiography is able to reveal substantial variability in the venous flow dynamics. "Slow veins," when they are tributaries of bridging veins, might hide a potential for anastomotic circulation that deserve further investigation.