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Johannes Goldberg, Peter Vajkoczy and Nils Hecht

OBJECTIVE

In superficial temporal artery–middle cerebral artery (STA-MCA) bypass surgery, recipient vessel properties are likely one of the main reasons for bypass failure. In daily practice, most surgeons select the recipient with the largest diameter. However, selection of the ideal recipient remains debatable because there are no objective selection criteria if multiple potential recipients exist. Here, the authors assessed the benefit of using indocyanine green videoangiography (ICG-VA) to optimize recipient vessel selection in patients undergoing STA-MCA bypass surgery for hemodynamic compromise.

METHODS

All patients who had undergone STA-MCA bypass procedures with pre- and postanastomosis ICG-VA between 2010 and 2019 were eligible for inclusion in this study. The primary bypass surgeon was blinded to the preanastomosis ICG-VA. Preanastomosis white-light and ICG-VA images were compared to determine the identifiability of potential recipient vessels and pathological flow patterns. After completion of the anastomosis, a second (postanastomosis) ICG-VA image was used to analyze the flow increase within the chosen recipient based on the vessel diameter, initial recipient blood flow, initial sequence of appearance on ICG-VA, initial blood flow direction within the recipient, and orientation of the bypass graft. ICG-VA, FLOW 800, and intraoperative white-light images, as well as demographic, clinical, and radiographic patient data, were retrospectively analyzed by a clinician who was not directly involved in the patients’ care.

RESULTS

Sixty patients underwent 65 STA-MCA bypass procedures with pre- and postanastomosis ICG-VA. The ICG-VA permitted identification of a significantly higher number of potential recipient vessels (median 4, range 1–9) than the white-light images (median 2, range 1–5; p < 0.001), with detection of pathological flow patterns in 20% of all procedures. No association was found between the diameter and blood flow within potential recipients (Spearman r = 0.07, p = 0.69). After bypass grafting, the highest flow increase was noted in recipients with an initially low flow (p < 0.01), a late appearance (p < 0.01), and an initially retrograde flow direction (p = 0.02). Interestingly, flow increase was not significantly influenced by the recipient diameter (p = 0.09) or graft orientation (p = 0.44).

CONCLUSIONS

ICG-VA facilitates identification of potential recipient vessels and detection of pathological flow patterns. Recipients with an initially low flow, a late appearance, and a retrograde flow seem to bear the highest potential for flow increase, possibly due to a higher hemodynamic need for revascularization.

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Nils Hecht, Johannes Woitzik, Jens P. Dreier and Peter Vajkoczy

Object

Currently, reliable low-cost and noninvasive techniques to assess cerebral perfusion in the operating room are not available. The authors report on their first clinical experience with laser speckle contrast analysis (LASCA) as a complementary imaging tool for the noninvasive and dynamic assessment of cerebral blood flow (CBF) during neurovascular surgery. The purpose of this preliminary study was to address the general feasibility of LASCA in terms of handling and image quality and to provide an example of its clinical implications.

Methods

Laser speckle contrast analysis was performed in patients undergoing cerebral revascularization procedures for the treatment of hemodynamic compromise and complex aneurysms. The portable LASCA device was centered over the surgical field, and continuous 5-minute recordings of relative CBF were obtained. In the case of flow augmentation for hemodynamic compromise, CBF monitoring was performed before and after completion of the anastomosis. In the case of flow replacement for parent artery sacrifice, CBF monitoring was performed during consecutive 30-second test occlusions of the radial artery graft after proximal internal carotid artery sacrifice and the subsequent initiation of blood flow through the bypass.

Results

In all cases, the authors achieved good visualization of relative CBF in addition to flow imaging in both the bypass graft and the cortical vasculature. During a sudden CBF decrease after test occlusion of the radial artery graft and subsequent flow initiation through the bypass, LASCA allowed immediate visualization and measurement of relative CBF in excellent spatiotemporal resolution.

Conclusions

In this study LASCA offered noninvasive and rapid intraoperative assessment of relative CBF, which can be used for optimizing neurovascular procedures.

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Marcus Czabanka, Julien Haemmerli, Nils Hecht, Bettina Foehre, Klaus Arden, Thomas Liebig, Johannes Woitzik and Peter Vajkoczy

OBJECTIVE

Spinal navigation techniques for surgical fixation of unstable C1–2 pathologies are challenged by complex osseous and neurovascular anatomy, instability of the pathology, and unreliable preoperative registration techniques. An intraoperative CT scanner with autoregistration of C-1 and C-2 promises sufficient accuracy of spinal navigation without the need for further registration procedures. The aim of this study was to analyze the accuracy and reliability of posterior C1–2 fixation using intraoperative mobile CT scanner–guided navigation.

METHODS

In the period from July 2014 to February 2016, 10 consecutive patients with instability of C1–2 underwent posterior fixation using C-2 pedicle screws and C-1 lateral mass screws, and 2 patients underwent posterior fixation from C-1 to C-3. Spinal navigation was performed using intraoperative mobile CT. Following navigated screw insertion in C-1 and C-2, intraoperative CT was repeated to check for the accuracy of screw placement. In this study, the accuracy of screw positioning was retrospectively analyzed and graded by an independent observer.

RESULTS

The authors retrospectively analyzed the records of 10 females and 2 males, with a mean age of 80.7 ± 4.95 years (range 42–90 years). Unstable pathologies, which were verified by fracture dislocation or by flexion/extension radiographs, included 8 Anderson Type II fractures, 1 unstable Anderson Type III fracture, 1 hangman fracture Levine Effendi Ia, 1 complex hangman-Anderson Type III fracture, and 1 destructive rheumatoid arthritis of C1–2. In 4 patients, critical anatomy was observed: high-riding vertebral artery (3 patients) and arthritis-induced partial osseous destruction of the C-1 lateral mass (1 patient). A total of 48 navigated screws were placed. Correct screw positioning was observed in 47 screws (97.9%). Minor pedicle breach was observed in 1 screw (2.1%). No screw displacement occurred (accuracy rate 97.9%).

CONCLUSION

Spinal navigation using intraoperative mobile CT scanning was reliable and safe for posterior fixation in unstable C1–2 pathologies with high accuracy in this patient series.