the field of neurointerventional radiology is constantly advancing , especially over the past two decades . new technology deriving from advances in material sciences is constantly being developed , and tried and tested in this field to improve patient care and safety in the delivery of minimally invasive treatments for cerebrovascular pathologies.1 
 2 the fundamental of a successful endovascular intervention is a safe guide catheter position placed as close to the target of treatment as possible in a safe and efficient manner . the devices  coils , stents , balloons , and so forth  can then be used to treat the pathology . the ability to treat increasing spectrum pathologies is partly dependent on the successful positioning of such a device . despite improvement of the materials and catheters used , the extra- and intracranial tortuous vasculature poses challenges in the treatment of cerebrovascular pathologies . various alternative methods have been used to overcome this problem by direct carotid and vertebral artery puncture , radial / brachial access , and adaptation of catheter techniques such as buddy wire , coaxial delivery of guide catheters.39 in a recent review by turk et al,10 the safety and efficacy of the newer generation 0.070 guide catheter was demonstrated with high success and a low complication rate while obtaining intracranial access . in the above - mentioned review , neuron ( penumbra inc , oakland , california , usa ) 0.070 with further recent advancement , especially in aneurysm embolization using flow diversion and flow disruption , there is a need for a stable construct to deliver these devices owing to their material stiffness . at the same time , adequate angiographic visualization of the target lesion is also necessary to plan and perform safe treatment . this warrants a 6f guide catheter that can provide stable , safe , and consistent distal intracranial access . in our study , we aim to assess the safety and efficacy of a newer generation benchmark ( penumbra inc ) 0.071  inch inner diameter guide catheter used in the treatment of intracranial cerebrovascular pathologies . this catheter is an improved version of neuron 0.070 , with an ideal combination of both hyperflexible and atraumatic distal tip yet ultrasupportive proximal shaft that provides enhanced trackability and stability . a retrospective review was carried out of sequential consecutive use of the benchmark guide catheter in the 4-month period of september 2014 through december 2014 , in the therapeutic management of various neuroendovascular intracranial pathologies . we excluded those cases where guide catheter stability was not needed , such as extracranial interventions including external carotid access , and cervical carotid and vertebral artery interventions . clinical performance or success of guide catheter placement was measured by the number of acute right angle ( 90 ) turns the catheter could achieve safely , especially in the anterior and posterior circulation ( figure 1 ) . a score of 1 is given for each curve negotiated ; an acute 90 curve in the cervical carotid is given a score of 1 ( figure 2a , b ) . a score of 0 is given if the guide catheter is placed in a straight cervical carotid or v2 segment of the vertebral artery . lateral view of ( a ) internal carotid artery and ( b ) anteroposterior view of vertebral artery demonstrating the scoring system used for assigning the clinical performance of the benchmark catheter over 90 turns . ( a and b ) anteroposterior and lateral view of the internal carotid artery ( ica ) illustrating cervical 90 turns and how the scoring system is adapted to assess clinical performance of the benchmark catheter . if the guide catheter lands in the cervical ica , a score of 2 is given for crossing two acute 90 curves in the cervical carotid . ( c and d ) the reversal of access was judged on the back out of the benchmark catheter at the end of the procedure . in this example the initial score was 2 with the access landing zone ( white thin arrow ) in the vertical petrous ica . the final position of the guide catheter position ( white thick arrow ) was in the cervical ica . . the reversal score would be 2 owing to back out by two 90 curves . a failure in clinical performance of the guide catheter was measured by the reversal ( back out by one 90 turn ) of access during the procedure by recording the final guide catheter position ( figure 2c , d ) . the guide catheter  related complications were only considered if they were directly related to placement and delivery of the catheter during access . sixty - two benchmark guide catheters were used during the study : 47 in the anterior circulation , 10 in the posterior circulation , 4 in the external carotid , and 1 in the venous sinus . five cases with access to the external carotid artery and venous sinus were excluded as it was deemed that guide catheter stability would not affect the success of the procedure . the procedures included treatments of 54 aneurysms , of which 45 were primary bare coil embolizations , 3 stent - assisted coiling , 2 web embolizations , 2 primary intracranial stenting , 1 pulse rider  assisted coiling , and 1 flow diverter treatment . the remaining three were arteriovenous malformation embolisations : two involved anterior and one involved posterior circulation . when the target pathology was in the anterior circulation , the benchmark was able to cross at least one 90 turn in 87% of cases , and an intracranial access ( horizontal petrous internal carotid artery ( ica ) and above ) was obtained in 85% of the cases ( tables 1 and 2 ) . in total of 47 cases of anterior circulation access , successful intracranial guide catheter placements were included in 9 cases in the horizontal petrous segment , 23 cases in the vertical petrous segment , and 8 cases in the cavernous petrous segment . reversal of access of 15% ( four cases by one 90 turn and three cases by two 90 turns ) was seen in the anterior circulation . the vertical petrous and cavernous segment placement accounted for 86% and 14% chances of guide catheter kickback during the procedure . number of 90 turns negotiated by benchmark results are shown as number ( % ) . landing and final position to illustrate success and failure in clinical performance results are shown as number ( % ) . ica , internal carotid artery . when the target pathology was in the posterior circulation in a total of 10 cases , the benchmark was able to cross at least one 90 turn in 80% of cases ( table 2 ) . the levels of access were as follows : v2 segment ( 20% ) , proximal ( 20% ) , mid ( 30% ) , and distal ( 30% ) access in the vertebral v3 segment . the benchmark provided support to complete the intervention in 100% of cases , regardless of the final location of the catheter tip . overall , even after reversal of access during a procedure , the benchmark was able to provide intracranial access in 85% of cases , especially in the anterior circulation . we report no complications of dissection or thromboembolic events related to the benchmark catheter in our current series . all our guide catheter positions were safely achieved over a 0.035 terumo glidewire without the need for an inner small guide catheter for negotiation . the positioning of the benchmark guide catheter in its target location is achieved by an exchange maneuver over a long stiff 0.035 terumo glide wire across the aortic arch . there were two cases of cervical ica acute 90 loops in our series ; a representative example is shown in figure 2 . in our report we describe our experience with the newer generation 6f or 0.071 inner diameter benchmark guide catheter for distal intracranial access in therapeutic neuroendovascular treatments . a successful and safe neuroendovascular treatment is based on the fundamentals of a stable and distal ( close to target ) position of the guide catheter . traditional or conventional guide catheters relied on catheter stiffness to provide stability , thus inherently jeopardizing the navigability.1 the current generation guide catheter technology is based on varying lengths of material and stiffness in the construct to provide optimal stability with a suitable navigability for safety in the intracranial circulation . these recent technological advances have overcome the alternative methods of catheter stability and access using direct cervical carotid puncture , radial artery access , and other catheter - related techniques such as buddy wire.39 the traditional aim of guide catheter positioning in the intracranial vasculature is twofold . first , is to gain access close to the target pathology for safe one - to - one manipulation of microwire and catheters . second , is to prevent proximal migration of the guide catheter due to tension and redundancy created within the tortuous cranial vasculature with resultant loss of microcatheter position . the benchmark guide catheter deals with both these concerns , delivering next - generation guide catheter performance through optimized support and stability . the atraumatic hyperflexible distal tip of the benchmark allows access as close to the target as needed . the optimized proximal shaft stiffness provides two features : first , it provides enhanced support at the aortic arch , even in cases with difficult anatomy ; second , the translation of the movement to the distal tip while gaining access is smooth and close to a 1:1 ratio , leading to optimized smooth navigability . the lack of the latter feature is mostly the cause of dissection while gaining access in previous generation guide catheters . the most recent and largest review on current generation guide catheter safety and efficacy was published by turk et al,10 where the performance of the neuron 0.070 catheters was illustrated . the benchmark 0.071 inner diameter distal guide catheter for intracranial access is an improvement in technology over the 0.070 neuron . the benchmark catheter provides a hyperflexible distal tip and improved proximal support for stable , safe , and consistent intracranial access . in our series we were able to show that the tracking and arch support features of the benchmark enabled successful completion of all interventions , regardless of final guide catheter position . these results may even underestimate the performance owing to factors such as variance of the threshold of catheter tip landing zone among operators . in our experience , an understanding of the material and technique plays an important role in establishing stable and safe guide catheter tip position . the practice in our center is to guide the benchmark over a stiff terumo 0.035 glidewire , which in our hands has provided safe delivery of the catheter to its landing . the previous generation 0.070 neuron in our experience requires catheter hub manipulation to navigate around the sharp carotid siphons . the new benchmark catheter tracks and navigates with ease over a 0.035 terumo glidewire at the sharp angles owing to its hyperflexible and atraumatic distal tip . to an extent , benchmark even bypasses the learning curve among practitioners in transition between use of older and newer generation guide catheters . however , careful and safe cautious delivery of the catheter is always recommended . in our series there was an increased chance of reversal if the landing zone was within the vertical petrous ica . this might be explained by the fact that the most common landing zone was the vertical petrous in our series , at close to 50% of cases . however , we would still recommend the vertical petrous ica as the most desirable position for guide catheter landing in our practice . this landing zone position will allow stable access even after reversal into the horizontal petrous ica . also , the guide catheter can be negotiated over the microcatheter , if necessary , to reclaim the landing zone for stability if safe to do so . the limitations of the study for comparisons with other devices are its retrospective design and its modest sample size . however , such a retrospective study can provide useful information about safety of the device as previous case series and comparative studies1012 have used conventional rigid catheters and newer generation guide catheters , the authors felt there was only a need to establish the safety and efficacy of this newer device . this benchmark device is an improved version of the previous generation 6f neuron , which has an established safety and efficacy record among practitioners in our study . our study represents clinical experience in a tertiary neurosciences center with a high volume neuroendovascular practice , where benchmark is the newest guide catheter to be adopted as a primary access device . in our experience benchmark can be easily , safely , and consistently positioned in a desired location within the intracranial arteries over a 0.035 terumo glidewire that provides a stable position for intervention and adequate angiography .
backgrounda stable guide catheter position within the intracranial vasculature is critical for safe , successful endovascular treatment.objectiveto present ourinitial experience with the 0.071  inch inner diameter benchmark guide catheter used in the treatment of intracranial cerebrovascular pathologies , demonstrating its safety and efficacy.methodswe retrospectively reviewed use of the benchmark guide catheter from september through december 2014 in the management of various neuroendovascular intracranial pathologies . 
 clinical performance and complication rates were evaluated , with particular consideration of vessel tortuosity . 
 a total of 62 benchmarks were used , 47 in the anterior circulation , 10 in the posterior circulation , 4 in the external carotid , and 1 in the venous sinus . 
 the five cases with access to the external carotid and venous sinus were excluded.resultsthe benchmark was able to cross at least one 90 turn in 49 ( 86% ) of the 57 patients . 
 reversal of the catheter was seen in 15% of 47 anterior circulation cases ( 4 at one 90 turn ; 3 at two 90 turns ) . 
 we report no complications of dissection or thromboembolic events . 
 all guide catheter positions were safely achieved over a 0.035 terumo stiff glidewire without need for an inner smaller lumen guide catheter for navigation.conclusionsbenchmark is a new guide catheter , with an ideal combination of both hyperflexible , atraumatic distal tip and optimized proximal shaft support to provide stable 6f primary access for a successful neurointerventional procedure . 
 benchmark can be easily , safely , and consistently positioned in a desired location within intracranial arteries providing a stable position for intervention and adequate angiography .