Clinical Neurology and Neurosurgery 137 (2015) 79–82
Contents lists available at ScienceDirect
Clinical Neurology and Neurosurgery journal homepage: www.elsevier.com/locate/clineuro
Neuronavigated microvascular Doppler sonography for intraoperative monitoring of blood flow velocity changes during aneurysm surgery – A feasible monitoring technique Vesna Malinova ∗ , Kajetan von Eckardstein, Veit Rohde, Dorothee Mielke Department of Neurosurgery, Georg August University Göttingen, Germany
a r t i c l e
i n f o
Article history: Received 1 May 2015 Received in revised form 26 June 2015 Accepted 28 June 2015 Available online 2 July 2015 Keywords: Microvascular Doppler Neuronavigation Aneurysm surgery
a b s t r a c t Introduction and aim of the study: The intraoperative microvascular Doppler sonography (iMDS) is a wellestablished tool in vascular surgery for blood flow velocity (BFV) monitoring, capable of detecting vessel occlusion. However, identification of subtotal vessel compromise is more difficult, since the measured BFV may substantially vary with changing insonation angles and insonated vessel segments. To keep these parameters constant we combined neuronavigation with iMDS (niMDS). The question was if niMDS allows the detection of subtotal vessel compromise in aneurysm surgery. Methods: During surgery, the 3-dimensional reconstruction of the CT-angiography, which was obtained routinely prior to surgery, was displayed by the neuronavigational system. Prior to clipping, neuronavigation was used to define target point and trajectory, which, by coupling the neuronavigational pointer with the Doppler probe, correspond to the insonated vessel segment and the insonation angle. After clipping, for each vessel segment, the same trajectory was used for all consecutive measurements. The mean BFVs pre- and post-clipping were documented. Results: We performed 82 BFV-measurements in 39 aneurysm surgeries. Mean deviation between preand post-clipping BFV values was 2.12 cm/s. There was a significant correlation between the mean BFV values before and after clipping (r = 0.45 [95% CI 17–66%]; p = 0.002). One patient experienced new neurological deficits due to occlusion of a perforating vessel that was not insonated. Conclusion: The study could not answer the question if niMDS can detect BFV changes after clipping indicating vessel compromise, as no subtotal vessel occlusion occurred in the 39 operations. However, we proofed that niMDS-measured BFVs only varied minimally in uncompromised vessels pre- and postclipping, suggesting that vessel compromises might be easily detected during aneurysm surgery. © 2015 Elsevier B.V. All rights reserved.
1. Introduction Cerebral ischemia due to unintended occlusion of adjacent or parent arteries by an incorrectly placed clip might result in poor outcome in aneurysm surgery. Therefore, it is essential to identify an occlusion of adjacent vessels as a sequel of inaccurate clip position shortly after clip placement [1,2]. In previous angiographic studies, the rate of adjacent vessel occlusion was as high as 25–35% [3]. Intraoperative angiography and endoscopic/microscopic ICG angiography as imaging techniques visualizing blood flow have
∗ Corresponding author at: Department of Neurosurgery, Georg-AugustUniversity, Robert-Koch-Straße 40, 37075 Göttingen, Germany. E-mail address: [email protected] (V. Malinova). http://dx.doi.org/10.1016/j.clineuro.2015.06.021 0303-8467/© 2015 Elsevier B.V. All rights reserved.
been used for detection of vessel occlusion by inaccurate clip placement [4]. Another frequently used and well-established technique is intraoperative microvascular Doppler sonography (iMDS), which measures blood flow velocities (BFVs) and allows identifying vessel occlusion by a loss of the blood flow related Doppler signal [5,6]. Arterial stenosis instead of occlusion likewise can result in cerebral ischemia but is more difficult to be identified by digital subtraction angiography (DSA) and indocyanine-green (ICG) angiography. Theoretically, iMDS should be capable detecting arterial stenosis by displaying a BFV drop. However, the measured BFV depends both on the insonated vessel segment as well as on the insonation angle, which are difficult to keep identical before and after clip placement. Changing the insonated vessel segment and/or the insonation angle might lead to intraoperative BFV changes that are not related to vessel occlusion, but might result in false interpretation by the surgeon. Today, neuronavigation is routinely used
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V. Malinova et al. / Clinical Neurology and Neurosurgery 137 (2015) 79–82
during neurosurgical procedures and allows defining targets and trajectories in order to optimize operative results. Aim of this study was to evaluate the technical feasibility and usefulness of neuronavigated iMDS (niMDS) during aneurysm surgery for keeping the initially chosen insonation angle as well as the vessel segment constant, possibly allowing identification of minor BFV changes. 2. Materials and methods 2.1. Compliance with ethics requirements All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008 [7]. 2.2. Patients NiMDS was performed in 39 patients (11 male, 28 female patients, mean age 49.6 years [range 30–78 years]) who underwent aneurysm clipping. Twenty-nine patients had unruptured and 10 patients ruptured aneurysms. Of the 39 patients, 23 had an aneurysm of the middle cerebral artery (MCA), 7 of the anterior communicating artery (AComA), 6 of the internal carotid artery (ICA), 2 of the posterior communicating artery (PComA) and one of the anterior cerebral artery (ACA). In all 39 patients the pterional approach was used. All patients had a preoperative CT-angiography (CTA) as part of the routine preoperative diagnostic work-up. Autosegmentation of the CTA data was applied to create a 3dimensional reconstruction of the basal arteries and the aneurysm using the BrainLab software iPlan 3.0 (Fa. BrainLab® Feldkirchen, Germany). The 3-dimensional reconstruction of the aneurysm and the arteries was displayed on the screen of the navigational system. ICG-angiography was performed routinely after clipping to exclude adjacent vessel occlusion and/or residual aneurysm perfusion.
Fig. 1. Microprobe connected with the navigation pointer.
2.4. Statistical analysis Statistical analysis was performed by means of the GraphPad Prism (GraphPad Sorfware, La Jolla, CA 92037 USA) statistical program. Two-tailed p-value of
Contents lists available at ScienceDirect
Clinical Neurology and Neurosurgery journal homepage: www.elsevier.com/locate/clineuro
Neuronavigated microvascular Doppler sonography for intraoperative monitoring of blood flow velocity changes during aneurysm surgery – A feasible monitoring technique Vesna Malinova ∗ , Kajetan von Eckardstein, Veit Rohde, Dorothee Mielke Department of Neurosurgery, Georg August University Göttingen, Germany
a r t i c l e
i n f o
Article history: Received 1 May 2015 Received in revised form 26 June 2015 Accepted 28 June 2015 Available online 2 July 2015 Keywords: Microvascular Doppler Neuronavigation Aneurysm surgery
a b s t r a c t Introduction and aim of the study: The intraoperative microvascular Doppler sonography (iMDS) is a wellestablished tool in vascular surgery for blood flow velocity (BFV) monitoring, capable of detecting vessel occlusion. However, identification of subtotal vessel compromise is more difficult, since the measured BFV may substantially vary with changing insonation angles and insonated vessel segments. To keep these parameters constant we combined neuronavigation with iMDS (niMDS). The question was if niMDS allows the detection of subtotal vessel compromise in aneurysm surgery. Methods: During surgery, the 3-dimensional reconstruction of the CT-angiography, which was obtained routinely prior to surgery, was displayed by the neuronavigational system. Prior to clipping, neuronavigation was used to define target point and trajectory, which, by coupling the neuronavigational pointer with the Doppler probe, correspond to the insonated vessel segment and the insonation angle. After clipping, for each vessel segment, the same trajectory was used for all consecutive measurements. The mean BFVs pre- and post-clipping were documented. Results: We performed 82 BFV-measurements in 39 aneurysm surgeries. Mean deviation between preand post-clipping BFV values was 2.12 cm/s. There was a significant correlation between the mean BFV values before and after clipping (r = 0.45 [95% CI 17–66%]; p = 0.002). One patient experienced new neurological deficits due to occlusion of a perforating vessel that was not insonated. Conclusion: The study could not answer the question if niMDS can detect BFV changes after clipping indicating vessel compromise, as no subtotal vessel occlusion occurred in the 39 operations. However, we proofed that niMDS-measured BFVs only varied minimally in uncompromised vessels pre- and postclipping, suggesting that vessel compromises might be easily detected during aneurysm surgery. © 2015 Elsevier B.V. All rights reserved.
1. Introduction Cerebral ischemia due to unintended occlusion of adjacent or parent arteries by an incorrectly placed clip might result in poor outcome in aneurysm surgery. Therefore, it is essential to identify an occlusion of adjacent vessels as a sequel of inaccurate clip position shortly after clip placement [1,2]. In previous angiographic studies, the rate of adjacent vessel occlusion was as high as 25–35% [3]. Intraoperative angiography and endoscopic/microscopic ICG angiography as imaging techniques visualizing blood flow have
∗ Corresponding author at: Department of Neurosurgery, Georg-AugustUniversity, Robert-Koch-Straße 40, 37075 Göttingen, Germany. E-mail address: [email protected] (V. Malinova). http://dx.doi.org/10.1016/j.clineuro.2015.06.021 0303-8467/© 2015 Elsevier B.V. All rights reserved.
been used for detection of vessel occlusion by inaccurate clip placement [4]. Another frequently used and well-established technique is intraoperative microvascular Doppler sonography (iMDS), which measures blood flow velocities (BFVs) and allows identifying vessel occlusion by a loss of the blood flow related Doppler signal [5,6]. Arterial stenosis instead of occlusion likewise can result in cerebral ischemia but is more difficult to be identified by digital subtraction angiography (DSA) and indocyanine-green (ICG) angiography. Theoretically, iMDS should be capable detecting arterial stenosis by displaying a BFV drop. However, the measured BFV depends both on the insonated vessel segment as well as on the insonation angle, which are difficult to keep identical before and after clip placement. Changing the insonated vessel segment and/or the insonation angle might lead to intraoperative BFV changes that are not related to vessel occlusion, but might result in false interpretation by the surgeon. Today, neuronavigation is routinely used
80
V. Malinova et al. / Clinical Neurology and Neurosurgery 137 (2015) 79–82
during neurosurgical procedures and allows defining targets and trajectories in order to optimize operative results. Aim of this study was to evaluate the technical feasibility and usefulness of neuronavigated iMDS (niMDS) during aneurysm surgery for keeping the initially chosen insonation angle as well as the vessel segment constant, possibly allowing identification of minor BFV changes. 2. Materials and methods 2.1. Compliance with ethics requirements All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008 [7]. 2.2. Patients NiMDS was performed in 39 patients (11 male, 28 female patients, mean age 49.6 years [range 30–78 years]) who underwent aneurysm clipping. Twenty-nine patients had unruptured and 10 patients ruptured aneurysms. Of the 39 patients, 23 had an aneurysm of the middle cerebral artery (MCA), 7 of the anterior communicating artery (AComA), 6 of the internal carotid artery (ICA), 2 of the posterior communicating artery (PComA) and one of the anterior cerebral artery (ACA). In all 39 patients the pterional approach was used. All patients had a preoperative CT-angiography (CTA) as part of the routine preoperative diagnostic work-up. Autosegmentation of the CTA data was applied to create a 3dimensional reconstruction of the basal arteries and the aneurysm using the BrainLab software iPlan 3.0 (Fa. BrainLab® Feldkirchen, Germany). The 3-dimensional reconstruction of the aneurysm and the arteries was displayed on the screen of the navigational system. ICG-angiography was performed routinely after clipping to exclude adjacent vessel occlusion and/or residual aneurysm perfusion.
Fig. 1. Microprobe connected with the navigation pointer.
2.4. Statistical analysis Statistical analysis was performed by means of the GraphPad Prism (GraphPad Sorfware, La Jolla, CA 92037 USA) statistical program. Two-tailed p-value of
