Objective To describe our experience with very distal placement of the Neuron 6 F 0.053 inch inner luminal diameter guide catheter (Penumbra Inc, San Leandro, California, USA) within the intracranial and extracranial vasculature to allow treatment of various neurovascular pathologies. Previously, this was thought to be only possible with a microcatheter.
Methods 12 cases are presented in which traditional guide catheters were unable to successfully navigate tortuous anatomy or provide stable support for intervention.
Results The Neuron 6 F 0.053 inch inner luminal diameter delivery catheter (Penumbra) was placed in a very distal location within the internal carotid artery, external carotid artery and venous system enabling successful endovascular treatment of the intracranial pathology with no related neurological complications.
Conclusion All lesions were successfully treated through a microcatheter advanced in a coaxial fashion through the distally placed guide catheter. There were no complications related to the distal position of the guide catheter.
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Neuroendovascular technology has advanced tremendously since its inception in the early 1990s. Despite these advancements, tortuous cerebral vasculature often proves to be a limiting factor in the endovascular treatment of certain intracranial lesions.1–5 Indeed, there are two key considerations in the successful endovascular treatment of distal intracranial pathology. The first is a stable, safe and feasible guide catheter position. The second is the support this provides to the microcatheter to gain intralesional access. To address these key issues, the Neuron 6 French (F) 0.053 inch inner luminal diameter guide catheters (Penumbra Inc, San Leandro, California, USA) were developed. The flexibility in the distal end of this guide catheter allows it to negotiate very tortuous vascular anatomy. Additionally, its rigidity is enough to provide added support and stability for the microcatheter. The initial experience in seven cases where this catheter was applied to good effect was recently documented in the literature.6 Subsequently, there have been two further small case series studies reporting the utility of the Neuron 6 F 0.053 inch inner luminal diameter guide catheter.7 8 These three series involved cases in which the Neuron guide catheter was placed at the level of the skull base. The routine placement of a guide catheter above the level of the skull base was previously thought to be not possible without causing significant complications. The purpose of this article is to describe our experience with very distal placement of the Neuron 6 F 0.053 inch inner luminal diameter guide catheter within the intracranial and extracranial vasculature to allow for treatment of various neurovascular pathologies. Previously, this was thought to be only possible with a microcatheter.
Materials and methods
Institutional Review Board approval was obtained from the University of Michigan. From May to July 2010, 12 consecutive patients underwent neurointerventions utilizing the Neuron 6 F 0.053 inch inner luminal diameter guide catheter. The patients' charts and angiograms were reviewed in a retrospective manner. The type of intervention, attempt at using a conventional guide catheter, sex, age, position of the guide catheter placement, complications and type of procedure were recorded.
In the 12 patients, an attempt was made to treat the neurovascular pathology with a 6 F 0.070 inch inner luminal diameter guide catheter (Cordis, Miami Lakes, Florida, USA) but due to either tortuous supra-aortic, intracranial or extracranial vasculature, a stable position could not be obtained for advancement of the microcatheter. Two patients presented for the treatment of a carotid cavernous fistula, two patients presented for embolization of an intracranial arteriovenous malformation, two patients presented with left M1 segment stenosis, one patient presented for embolization of a dural arteriovenous fistula, four patients presented for treatment of an intracranial aneurysm and one patient for balloon angioplasty following vasospasm after subarachnoid hemorrhage (table 1). The average age of the patients was 49 years (range 17–67). There were nine women and three men in the series. The Neuron 6 F 0.053 inch inner luminal diameter guide catheter was used in each of the 12 cases and was placed within the distal intracranial or extracranial circulation. In the 12 cases the Neuron guide catheter was exchanged after routine diagnostic angiography and positioned with the intended vessel, after placement of a 6 F sheath (Cook, Bloomington, Indiana, USA) in the femoral artery. In two of the cases, a tri-axial technique was utilized with placement of the Neuron guide catheter through a 6 F shuttle sheath (Cook). The guide catheter was positioned in the following locations for treatment: origin of the ophthalmic artery, M1 segment, A1 segment, P1 segment, basilar artery, origin of the anterior inferior cerebellar artery, distal cavernous segment of internal carotid artery (ICA), supraclinoid segment of the ICA and distal superficial temporal vein. Various microcatheters and wires were then advanced coaxially through the guide catheter and positioned distally with the intracranial or extracranial arterial or venous systems for treatment. There were no complications related to placement of the Neuron guide catheter in these distal locations.
Case No 1
A 53-year-old woman presented with pulsatile tinnitus for 1 year. On physical examination the patient had left conjunctival injection and proptosis. Subsequent workup revealed a type D carotid cavernous fistula with supply from multiple arterial feeders off both internal and external carotid arteries (figure 1A).9 10 The superficial temporal and angular veins were hypertrophied. There was also evidence of cortical venous reflux through the sphenoparietal sinus thus increasing the risk of intracranial hemorrhage.11 12
Given the patient's symptoms and risk of intracranial hemorrhage, a decision was made to treat the fistula. The patient was placed under general anesthesia. The right common femoral vein was punctured under ultrasound guidance and a 6 F sheath was placed (Cook). A 6 F MPC Cordis guide catheter (Cordis) was placed within the left internal jugular vein. We then tried to advance a microcatheter into the cavernous sinus through the inferior petrosal sinus and pterygoid venous plexus but we were unsuccessful. We also tried to place the guide catheter into the left superficial temporal and angular vein to provide stability in the hope of trying to advance a microcatheter through these veins into the cavernous sinus. However, due to the stiffness of the guide catheter, this could not be accomplished. The procedure was halted due to radiation exposure and volume of contrast the patient received.
Two weeks later, access was gained in the right common femoral vein and a 6 F (80 cm) Pinnacle Destination Sheath (Terumo Medical Corporation, Somerset, New Jersey, USA) placed into the superior vena cava. This time the Neuron guide catheter was chosen as it harbors a softer and flexible tip. A 6 F 115 cm length, 12 cm distal floppy 0.053 inch inner lumen diameter Neuron guide catheter (Penumbra) was advanced over a 0.035 glide wire (Terumo Medical Corporation) through the brachiocephalic vein, left external jugular vein and left superficial temporal vein into the superior ophthalmic vein (figure 1B). This distal access was only feasible due to the soft and flexible tip of the Neuron guide catheter. The catheter was able to make a complete 360° turn to gain such a distal position. Next, a SL-10 microcatheter (Boston Scientific, Natick, Massachusetts, USA) and a Mirage 0.008 inch microwire (ev3, Plymouth, Minnesota, USA) were advanced through the guide catheter through the superior ophthalmic vein into the cavernous sinus (figure 1C). The patient then underwent coil embolization of the left cavernous sinus with occlusion of the carotid cavernous fistula without any complications (figure 1D).
Case No 2
A 67-year-old woman with a history of a grade IV subarachnoid hemorrhage from a ruptured fusiform basilar artery aneurysm previously coiled on five prior occasions presented with new severe recurrent headaches. An attempt at placement of a stent within the parent vessel utilizing a conventional guide catheter was previously aborted due to the guide catheter causing severe spasm and migrating proximally. The right common femoral vein was punctured under ultrasound guidance and a 25 cm 6 F sheath placed. A 5 F vertebral catheter was then advanced into the left subclavian vein. Utilizing roadmap, the proximal left vertebral artery was catheterized. A left vertebral arteriogram was obtained showing a fusiform aneurysm involving the distal basilar artery incorporating both superior cerebellar arteries and the left P1 segment (figure 2A). There was a fetal origin of the right posterior cerebral artery. Next, utilizing roadmap, a 6 F 115 cm length, 12 cm distal floppy, 0.053 inch inner luminal diameter Neuron guide catheter was advanced over a 0.035 glide wire into the mid-basilar artery. Next, a high flow renegade microcatheter (Boston Scientific) was advanced over a synchro 14 wire (Boston Scientific) into the left P3 segment (figure 2B). The guide catheter during this maneuver was advanced slightly more distal to the origin of the left P1 segment. A 2.5 mm×2 cm Neuroform-3 stent (Boston Scientific Neurovascular, Fremont, California, USA) was then deployed from the left P1 segment into the distal basilar artery. Nine coils were then placed within the aneurysm, being careful not to occlude the origin of both superior cerebellar arteries. A final left vertebral arteriogram was obtained, demonstrating near complete occlusion of the aneurysm (figure 2C). The patient awoke neurologically intact and was discharged home the following morning. At 6 months the patient is alive and well.
Case No 3
A 44-year-old-man with a history of PTEN hamartoma syndrome, also known as Bannayan–Riley–Ruvalcaba, presented with recurrent severe headaches and bilateral tinnitus. On physical examination both eyes were proptotic with dilated superficial veins over the left and right forehead. A bruit could be heard over both occipital regions. In addition, ophthalmology examination revealed optic disc edema with elevated CSF pressure by lumbar puncture, most likely from pseudotumor cerebri from the patient's multiple arteriovenous shunts. Initial angiogram demonstrated a complex dural/pial arteriovenous malformation with supply from the external and internal carotid artery branches along with multiple intracranial arteriovenous malformations. Significant cortical reflux was also noted. MRI showed a remote area of hemorrhage within his right parietal region. A decision was made to try and concentrate treatment in the region of the prior hemorrhage. The right external carotid artery branches supplying the fistula were occluded in three sessions within the injection of ethylene vinyl alcohol (Onyx; ev3) into multiple right external carotid artery branches. During the fourth session, there was de novo development of a high flow dural arterial venous fistula on the left side with supply off the recurrent meningeal artery, which arose off the ophthalmic artery.
The right common femoral artery was punctured under ultrasound and a 6 F sheath (Cook) placed. A 5 F vertebral catheter (Cook) was then advanced into the left internal and external carotid artery and an angiogram obtained. This demonstrated a high flow dural fistula with supply off the left recurrent meningeal artery (figure 3A). The 5 F vertebral catheter was then exchanged for a Neuron 6 F 115 cm length, 12 cm distal floppy, 0.053 inch inner luminal diameter guide catheter, which was advanced into the cavernous segment of the left internal carotid artery. We then tried to advance a 0.024 inch inner luminal diameter Progreat microcatheter (Terumo Medical Corporation) into the left ophthalmic artery over a synchro 14 wire (Boston Scientific); however, it kept herniating into the internal carotid artery. We were finally able to advance the microcatheter into the proximal ophthalmic artery with the synchro 14 wire (Boston Scientific) in a distal location within the venous outflow vein; however, the microcatheter would not make the acute bend backward into the recurrent meningeal artery. The guide catheter was then gently advanced over the microcatheter and wire into the origin of the ophthalmic artery. With the guide catheter in this position, we were then able to make the acute bend and advance the catheter into the venous outflow vessel (figure 3B). The main draining vein to the arteriovenous junction was then embolized with 5 Azur 18 coils (Terumo Medical Corporation) followed by 0.7 ml of n-butyl cyanoacrylate (Cordis) (figure 3C). Repeat left internal carotid angiogram demonstrated occlusion of this portion of the dural arteriovenous fistula (figure 3D). The patient awoke at his neurological baseline, and was discharge home the following day. At the 3 week follow-up, he was alive and well with significant improvement in his tinnitus and headaches.
Prior to the inception of the Neuron 6 F 0.053 inch inner luminal diameter guide catheter, distal access into the intracranial circulation was limited by the poor flexibility and stiffness of the tip of a conventional guide catheter.13 This prevented distal access to provide stable and robust support for placement of a microcatheter into the intracranial circulation. An unstable microcatheter, where redundancy develops rapidly within tortuous cerebral vasculature, can lead to the microcatheter being ticked out from its target location or an unforeseen ‘jump forward’ with potentially catastrophic consequences. Additionally, it can cause proximal migration of the rigid conventional guide catheter resulting in loss of position or control of the tip of the microcatheter. The rigid tip and inherent shape retention of a conventional guide catheter causes abrupt distortion and straightening of cerebral vessels that can cause local spasm and/or potential vessel dissection. Placement of these conventional guide catheters is avoided at or distal to the skull base due to the lack of an external elastic lamina in these vessels, making them less resilient to standard endovascular manipulation.
Various strategies have been applied over the years to increase proximal guide stability. These include the ‘buddy wire’14 15 and the coaxial double guiding–catheter technique.8 Other strategies include access from the upper limb (brachial or radial artery) or a direct carotid puncture. Cai et al treated 63 patients older than 70 years of age with ruptured and unruptured aneurysms.16 Ten of them needed a direct carotid artery puncture, one needed a brachial approach for treatment and in another three cases selective catheterization of the aneurysm was unsuccessful. In another study by Lylyk et al, two of 36 cases selected for angioplasty of a stenotic intracranial atherosclerotic segment or dissection in the supraclinoid ICA were unable to be accessed due to the tortuous anatomy of the cervical ICA and the anterior bend of the cavernous segment of the ICA.17 Another technique described by Eckard et al is called the ‘stiff guide’ technique.3 They encountered difficulty with stability of the guide catheter in the treatment of a 60-year-old patient with a distal left ICA stenosis. Initially, they tried to place a 4 mm×18 mm coronary balloon mounted stent (Velocity; Cordis) across a distal left ICA stenosis through a 6 F, 90 cm Arrow sheath (Arrow International, Reading, Pennsylvania, USA) positioned in the proximal left ICA. However, the guide sheath kept backing out into the aortic arch due to tortuosity within the proximal common carotid artery. Eventually they were able to cross and treat the stenosis by placing a 0.038 inch stiff shaft glidewire (Terumo Medical Corporation) alongside the stent catheter in the sheath.
There are several advantages of a distal location of the guide catheter in close proximity to the target lesion. A distal guide placement not only avoids chances of significant proximal migration but also enables an early detection of guide catheter movement even in a magnified working projection. Furthermore, with distal cervical vascular tortuosity, there is increased friction between the microcatheter and the arterial wall, thus possibly limiting placement of the microcatheter into the target lesion. Placement of a major portion of the microcatheter within the guide catheter after distal placement allows for reduced friction during manipulation of the microcatheter. In addition, a reduced guide catheter tip to target lesion distance enables more one to one movements of the microcatheter by eliminating unfavorable tangential force vectors on the microcatheter due to vessel tortuosity. This reduces the risk of vessel dissection and other complications of inadvertent and uncontrolled movement of the microcatheter.
The Neuron delivery catheter was specifically designed to negotiate very tortuous vascular anatomy and be rigid enough to provide added support and stability for safe distal microcatheter manipulation. It is essentially a guide catheter with microcatheter technology. The 0.053 inch inner luminal diameter catheter with hydrophilic coating consists of a 6 F coil reinforced shaft that tapers to 5 F with a flexible 6 cm or 12 cm distal zone. The 0.070 inch inner luminal diameter catheter is a 6 F coil reinforced shaft that remains 6 F at the distal end with a flexible 6 cm or 8 cm distal zone. The 0.053 inch catheter is available in 105 cm and 115 cm lengths whereas the 0.070 inch catheter is available in 95 cm and 105 cm lengths.
There are limitations with the 6 F 0.053 inch guide catheter. To allow distal placement of the guide catheter into the intracranial circulation, the distal tip is a smaller diameter than a conventional guide catheter. The 0.053 guide catheter cannot accommodate a balloon and microcatheter simultaneously, therefore aneurysm embolization with balloon and stent assisted coiling or HD 500 (ev3) must be performed with two separate catheters. In addition, the current 0.053 guide catheter cannot accommodate the MERCI (Concentric Medical, Mountain View, California, USA) or the Penumbra System (Penumbra) acute stroke mechanical thrombectomy devices. The advantage of the 0.070 inch inner luminal diameter catheter is the ability to place a microcatheter and balloon or stent within it and still be able to perform an intraprocedural roadmap and angiographic run. The manufacturer suggests the best stability of the 0.053 inch guide catheter is offered by placement of the guide catheter tip at the distal end of two tandem curves within the target vessel. The 0.070 inch guide catheter needs to be only placed past one curve in the target vessel to provide stability. The soft straight tip makes direct catheterization of the supra-aortic vessels very challenging. Hence the authors like other users recommend an exchange technique to introduce the neuron guide catheter into the vertebral or the common carotid artery. In cases of extreme tortuosity where proximal support is needed at the aortic arch, a 6 F Shuttle sheath (Cook) is utilized. The Neuron guide catheter is then inserted through the shuttle sheath and further distal access into the internal carotid artery is usually possible with a standard length 0.035 inch glide wire (Terumo Medical Corporation). Ultra-distal access is often desirable in the treatment of complex anterior communicating artery or middle cerebral artery bifurcation aneurysms. In these situations, the smaller inner luminal diameter 0.053 inch catheter negotiates vascular tortuosity better than the 0.070 inner luminal diameter catheters. Ultra-distal access into the A1, M1 and P1 segments can be readily achieved with the Neuron guide catheter utilizing the tri-axial technique. Previously, this was thought to be only possible with a microcatheter. With the tri-axial technique, there is less friction between the Neuron guide catheter and arterial wall proximally due to the guide catheter being positioned within the shuttle sheath. This allows more proximal support and a decrease in the amount of friction proximally on the guide catheter with the vessel wall, so that the neuron guide catheter can be advanced into a more distal location.
Treatment of an arteriovenous malformation and dural arteriovenous fistula are possibly made simpler and more feasible by the utilization of this guide catheter. To treat these lesions, typically a very distal location of the microcatheter within the arterial feeder is desirable to prevent non-target embolization. The microcatheter has to negotiate extreme, smaller branch vessel tortuosity to wedge in an intra-nidal safe location for liquid embolic agents to be used. The Neuron guide catheter with it being placed in a more distal location than a conventional guide catheter allows for more proximal support so a microcatheter can be advanced in a very distal peri-nidal location. In some of these situations, endovascular treatment would have been impossible without the added advantage of the Neuron guide catheter.
Tortuous vascular anatomy is a significant limitation in the endovascular treatment of cerebral vascular pathology. Introduction of the Neuron 6 F 0.053 inch inner luminal diameter guide catheter represents a definite advance in overcoming this hurdle. This has enabled the endovascular neurosurgeon to treat even more complex intracranial vascular pathology, as demonstrated in our series.
Competing interests None.
Patient Consent Obtained.
Ethics approval Institutional Review Board approval was obtained from the University of Michigan.
Provenance and peer review Not commissioned; externally peer reviewed.
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