For the purpose of this report we will define endoneuro-surgery as intradural surgery performed using parallel rod-lens endoscopy as the sole visualization tool, in contradis-tinction to through-channel endoscopy (ventriculoscopy)or microsurgery. Endoneurosurgery can be classified intoexpanded endonasal approaches or endoport surgery de-pending on the corridor used; that is, paranasal sinus ortranscortical approaches, respectively.1,2 We will discussthe techniques used to achieve hemostasis in each of theseendoneurosurgical approaches together because they areidentical, relying on the concept of corridor surgery. Withthe increasing popularity of expanded endonasal approach-es over the past decade, the ability to achieve intraoperativehemostasis is one of the greatest concerns for surgeonscontemplating endoneurosurgical procedures. It is essentialthat surgeons specializing in endoscopy become comfort-able with a variety of hemostatic techniques before per-forming intradural procedures.

Prevention of bleeding is obviously the best solution.Dissection techniques that minimize the risk of vessel injuryduring tumor removal should be adopted. The principles ofendoneurosurgical dissection are identical to those ofmicrosurgical dissection; specifically, tumor debulking, ex-tracapsular sharp dissection, and countertraction using gen-tle suction. The absolute avoidance of pulling takes prec-edence over all other considerations, including the extent oftumor removal. Nevertheless, vascular injuries may occur

not only because of excessive pulling on tumor tissues butalso from inadequate visualization of dissection planes,blind instrumentation, direct or indirect injury (thermal in-jury) from powered instruments (drills, microdebriders, ul-trasonic aspirators), and tumor vascularity. Despite applica-tion of an ideal technique, bleeding is often unavoidable andhemostasis is required to deal with both planned and un-planned events.

We have found it useful to categorize bleeding based ontwo factors; the source (venous or arterial) and the rate(high-flow or low-flow bleeding). Venous bleeding can in-volve low flow, as is the case of diffuse generalized oozingfrom the mucosa, or it can be high-flow focal bleedingfrom the cavernous sinus. Similarly, arterial bleeding canbe low flow, as occurs from small perforating vessels, orhigh flow, as is the case with carotid artery injuries.

The choice of hemostatic techniques not only dependson the source and rate of the hemorrhage but is also influ-enced by factors such as the type of tissue (mucosa, bone,and tumor); the proximity of neurovascular structures; andthe area (extradural or intradural) of dissection. At the out-set it is important to mention that the principles of endoneu-rosurgical hemostasis are identical to those of microsurgi-cal hemostasis, and the reader may find these to be obviousand repetitive. We do not wish to redevelop these time-test-ed principles, however, but to rather to demonstrate thatthey are completely applicable and, with some modifica-

Neurosurg Focus 19 (1):E7, 2005

Endoneurosurgical hemostasis techniques: lessons learnedfrom 400 cases

AMIN KASSAM, M.D., CARL H. SNYDERMAN, M.D., RICARDO L. CARRAU, M.D.,PAUL GARDNER, M.D., AND ARLAN MINTZ, M.SC., M.D.

Minimally Invasive Endoneurosurgical Center, University of Pittsburgh Medical Center, Pittsburgh,Pennsylvania

The increasing popularity of minimally invasive neurosurgery has led to the development of transnasal expandedapproaches for the treatment of skull base lesions. One of the greatest challenges in safely accomplishing resection oftumors, particularly intradural lesions, is effective hemostasis. Over the past 7 years the authors have progressivelydeveloped an organized approach to address this challenge. This has required the development of new instrumentationas well as variations on standard techniques. In this report they present the technique that has evolved at their institu-tion for endoneurosurgical hemostasis.

KEY WORDS • hemostasis • hemorrhage • arterial bleeding • venous bleeding •endoscopy • transsphenoidal approach

Neurosurg. Focus / Volume 19 / July, 2005 1

Unauthenticated | Downloaded 05/24/21 09:26 AM UTC

tions, are effective in establishing endoneurosurgical hemo-stasis. In this paper we will present an algorithm for endo-neurosurgical hemostasis based on the factors discussedearlier and our learning curve over the past 7 years.

ENDONEUROSURGICAL HEMOSTASIS

Equipment and Hemostatic Materials

Before discussing hemostatic techniques it is importantto be aware of the equipment and materials available. Themost important equipment for the endoneurosurgeon is thebipolar electrocautery. Standard bayonet designs are toolarge for a transnasal route, especially for expanded endo-nasal approaches; instead, a pistol-grip design should beused. There are five endobipolar cautery devices available,which vary based on the fineness and configuration of thedistal tip (Fig. 1). Therefore, the appropriate bipolar devicecan be selected based on the geometry of the vessel, its site,caliber, and proximity to critical neurovascular structures.This allows selective cauterization of tissues with minimalthermal spread to surrounding areas. Monopolar cauterycan be used only on intranasal tissues and should not be us-ed within the sphenoidal sinus, on the skull base, or intra-cranially. The risk of thermal dispersion in these confinedareas, and of creating neurovascular injuries, is significant.Special hemoclip appliers are available that are designedfor endoscopic use.

A variety of hemostatic materials are available. All ofthese products require direct contact with the bleeding tis-sues and work by promoting platelet aggregation andformation of a stable clot. Examples of such hemostaticmaterials include Avitene (Ethicon [Johnson and John-son], Somerville, NJ), Floseal (Baxter International, Inc.,Deerfield, IL), and Syvek (Marine Polymer, Boston, MA).These materials are most effective for venous hemostasisand low-flow arterial bleeding. An important considerationin selecting and delivering the specific agent is the need tomaintain visualization within these corridors. We havefound that the application of dry Avitene to the bleedingsite with gentle pressure is the most effective means ofachieving hemostasis without interfering with visualizationof the rest of the surgical field.

Special mention should be made of warm water irriga-tion. It is a common misconception that cold water irriga-tion provides the best hemostasis. Nevertheless, the amountof vascular constriction that occurs with cold water is insuf-ficient to provide effective hemostasis. Clinical trials of hotwater irrigation, in contrast, show that it is nearly as effec-tive as surgical techniques for the treatment of epistaxis.3The ideal temperature for coagulation has been determinedto be approximately 40˚C.4 We have found, however, thatirrigation with saline that is just warm to the touch is ade-quate. A number of different mechanisms for this methodof hemostasis have been proposed, including activation ofplatelet aggregation, enhanced coagulation, and interstitialedema. Warm saline irrigation is performed whenever thereis diffuse oozing, either from traumatized nasal mucosa,denuded bone surface, or the dissected surface of the tumoror brain. Gentle irrigation of the brain surface with a softcatheter is effective in clearing the field so that bleedingsites can be visualized and selectively cauterized or com-pressed with a hemostatic material. Care should be taken to

A. Kassam, et al.

2 Neurosurg. Focus / Volume 19 / July, 2005

Fig. 1. Intraoperative views demonstrating the different types ofendonasal bipolar cautery devices. A: Endoscopic view obtainedduring endonasal resection of an olfactory groove meningioma.The bipolar devices used have the two blades placed along a verti-cal plane with insulation close to the distal end. These devices aremost useful for coagulating the tumor capsule (TC) during the dis-section. The suction (S) is brought close to the target to providegood visualization. B: Endonasal view obtained during endo-scopic resection of a clival chordoma, demonstrating a more ag-gressive bipolar cautery with the blades oriented along a horizon-tal plane and bent approximately 30˚ to improve visualization. Thedevices are not fully insulated up to the distal tip, and in sealing thetear (T) in the vessel the tissue between the noninsulated portion ofthe proximal tips is also coagulated. C: Endoscopic view demon-strating the fine endoscopic bipolars. Note the insulation extends toallow for focal exposure of the fine tips preventing heat dispersion.

Unauthenticated | Downloaded 05/24/21 09:26 AM UTC

avoid excessive irrigation pressures because hydrodissec-tion of the tissues could occur.

Specific hemostasis techniques have been developed forboth venous and arterial bleeding that is encountered dur-ing expanded endonasal approaches. These techniques areas follows.

VENOUS HEMOSTASIS

Low-Flow Bleeding

Diffuse venous bleeding from mucosa and bone re-sponds very well to warm saline irrigation, and this is ourpreferred method. For extradural application, this is deliv-ered with a bulb syringe; for intradural application, an ex-ternal ventricular drain catheter or similar soft catheter isused. Focal bleeding from bone may be controlled by drill-ing with a diamond burr or application of bone wax with apledget.

Focal venous bleeding from the cavernous or anothervenous sinus can be quite brisk and the rapidity of bloodloss can be underestimated because of the clearance ofblood with the suction device. Constant communicationwith the anesthesiologist is essential so that volume loss canbe anticipated and blood replacement can be instituted. It issometimes necessary to work through the blood loss untiltumor dissection in the cavernous sinus is completed. Webelieve that focal bleeding from the cavernous sinus is bestcontrolled with precision application of Avitene on a pled-get. The pledget must be dry, with the Avitene placed on theinside, creating a “sandwich” of the substance (Fig. 2). Thisis applied directly to the bleeding point and may need to bereplaced with exchanges multiple times until bleeding iscontrolled.

The technique for the exchange requires two surgeons,because Avitene can only be effective if it is directly andprecisely applied over the focal site of the bleeding. Thesurgeon performing the dissection brings the “sandwich”into the field and prepares it for positioning. Once it is closeto the target, the surgeon handling the endoscope then re-moves the previous “sandwich,” allowing the surgeon per-forming the dissection to use a suction device with onehand while laying the replacement “sandwich” on the tar-get (Fig. 2, Video 1). It is best to treat each bleeding sourceas it arises rather than trying to deal with multiple bleeding

sites at the same time. Venous bleeding from large veins ishalted using the technique for low-flow arterial bleedingdescribed later.

Video 1. Technique for Avitene “sandwich” exchange.(Click here to view with Windows Media Player and a broad-band connection, here to view with a dial-up connection, orhere to view with RealPlayer.)

ARTERIAL HEMOSTASIS

High-Flow Arterial Bleeding

In the case of high-flow bleeding it is critical to confinethe flow to a specific portion of the artery to allow for thedirect application of bipolar coagulation. Blood has a tre-mendous capacity for heat dispersion; therefore, diffusecauterization without identifying the small segment of thevessel with the laceration will not be effective. The suctiondevice is used to isolate the bleeding site by maintaining adry field and directing the stream of blood away from the tipof the endoscope. Once the hole in the artery can be seenclearly, the bipolar electrocautery is applied along the side-wall of the vessel (Fig. 3). The specific type of endoneuro-surgical bipolar device chosen will vary depending on thefactors previously discussed. Gentle irrigation with salinehelps prevent sticking of the bipolar electrocautery blades tothe vessel.

A critical difference in comparison with microsurgery isthe ability to maintain visualization by using the endoscopeduring the course of this type of bleeding. This requires asignificant amount of collective experience among the teammembers to be able to navigate through the bleeding andmaintain vision. Although the principles are the same, withthe surgeon who is performing the dissection managing thetwo primary suction devices while the endoscopist uses athird one to follow the flow of blood to the focal site, a keydifference is the need for two surgeons to maintain visual-ization (Video 2).

Video 2. Technique for bipolar cautery in high-flow arterialbleeding. (Click here to view with Windows Media Player anda broadband connection, here to view with a dial-up connec-tion, or here to view with RealPlayer.)

In cases involving these larger vessels with high-flowhemorrhage, the immediate and delayed consequences of

Neurosurg. Focus / Volume 19 / July, 2005

Endoneurosurgical hemostasis techniques: lessons from 400 cases

3

Fig. 2. Photographs showing preparation of the Avitene “sandwich.”

Unauthenticated | Downloaded 05/24/21 09:26 AM UTC

the thermal injury to the vessel wall that occurs during thecoagulation needs to be borne in mind. The probability ofimmediate occlusion of the vessel is extremely high and thetolerance of the distal circulation will be contingent on thecollateral supply. Therefore, an assessment of this eventual-ity must be considered during perioperative and intraopera-tive planning. The surgeon must be very vigilant for thedelayed sequelae of thermal injury and the development ofa pseudoaneurysm. Therefore, early and delayed postoper-ative arteriograms are important.

Low-Flow Arterial Bleeding

For low-flow bleeding from small arterioles, the techni-que is similar, with selective use of bipolar electrocautery.One should bear in mind, however, that small vessels suchas perforating arteries from which this type of bleeding isoften sustained are in critical locations, and so heat disper-sion to adjacent structures becomes a paramount issue.Continued irrigation with saline during cauterization helpsdisperse the heat. In these low-flow hemorrhages, isolatedsegmental packing can be judiciously used. There are avariety of hemostatic materials such as Avitene and Syvek(off-label indication) that we have found useful. Neverthe-less, extreme caution must be exercised here. We do notfavor this approach unless the packing can be applied focal-ly with no possibility that the vessel will retract or allowbleeding to continue in a retrograde fashion into the adja-cent brain. This will inevitably lead to parenchymal hemor-rhage, with devastating consequences. Therefore, we rarelyuse this technique and do so only when these contraindica-tions are not present. Furthermore, if packing is required itis positioned just on the affected vessel to allow visualiza-tion of all of the surrounding neural tissue. Only enoughpressure is maintained to tamponade the bleeding while stillbeing able to see the normal physiological pulsations in thesurrounding brain (Video 3).

Video 3. Technique for halting low-flow bleeding from arte-rioles (P1 perforating artery). (Click here to view with WindowsMedia Player and a broadband connection, here to view with adial-up connection, or here to view with RealPlayer.)

ADDITIONAL SPECIAL CONSIDERATIONS

Carotid Artery Injury

When a major carotid artery injury occurs, the immediateconcern is maintaining visualization so that the actual de-fect can be seen. This requires the active participation ofboth surgeons with the use of two suction devices in addi-tion to the endoscope and dissection instrument. Pressure isapplied with a pledget to achieve immediate control. Theanesthesiologist takes appropriate measures to maintainblood pressure and restore intravascular volume. A hypo-tensive state should be avoided; the blood pressure shouldbe high enough to maintain collateral cerebral perfusion.Neurophysiological monitoring may provide early evidenceof inadequate perfusion.

In our opinion, every effort should be made to control thebleeding intraoperatively. Indiscriminate packing should beavoided because this will not prevent bleeding intracranial-ly. The edge of the bleeding site is then cauterized with bi-polar electrocautery as the pledget is moved aside. Only ifthe bleeding cannot be stopped with these measures is thesite packed focally and the patient transported to the angi-ography suite for placement of a stent if possible or perma-nent occlusion of the vessel if not. If adequate collateral cir-culation is not present, a vascular bypass procedure isperformed in the same session.

Devascularization of Tumor Tissues

Preoperative strategies include devascularization of the

A. Kassam, et al.

4 Neurosurg. Focus / Volume 19 / July, 2005

Fig. 3. Schematic views illustrating the endoneurosurgical he-mostasis technique. A: Drawing showing a longitudinal tear (T)in the side wall of the vessel along the long axis of the lumen (L).B: Drawing showing the technique used to isolate the large tear byplacing the suction (Sx) into a segment of the artery to allow for thebipolar (BP) cautery device to create a seal (S). Most of the bloodat this point is being suctioned away, allowing the bipolar device toseal the vessel wall. C and D: Once the vessel wall is partiallysealed the suction is moved along the long axis of the tear to fur-ther segregate the bleeding and seal the tear.

Unauthenticated | Downloaded 05/24/21 09:26 AM UTC

tumor by angiographically guided embolization of the vas-cular bed when possible. The majority of tumors in this lo-cation receive their blood supply from small feeding vesselsthat can be difficult to cannulate for direct embolizationwith particulate matter. In the absence of direct cannulation,the use of alcohol embolization has been suggested. Basedon our experience, we have abandoned the use of intraarte-rial infiltration of the tumor bed with alcohol. Although it iseffective, we have observed a number of complicationsrelated to diffusion of the alcohol to critical vascular terri-tories; these include secondary strokes of the cortex and is-chemic injury to the contents of the cavernous sinus.

With the use of the expanded endonasal approach, wehave been able to gain circumferential access to these le-sions, obviating the need for this type of embolization in themajority of cases, even in tumors that are known for beinghypervascular (angiofibromas, meningiomas, paraganglio-mas). With large intranasal lesions, debulking of the tumorto the level of the skull base may be necessary to obtain ac-cess to the remaining blood supply. Devascularization oftumors can be achieved by ligation of feeding arteries. Fortumors in the sinonasal space, the key arterial supply isfrom the internal maxillary artery and its branches. The crit-ical branches are the sphenopalatine and posterior nasalarteries, which can be accessed early. These vessels exit thesphenopalatine foramen at the posterior–superior corner ofthe maxillary sinus, deep to the attachment of the middleturbinate. A maxillary antrostomy is made and a subperio-steal dissection is performed to identify the foramen. Ov-erlying bone is removed with a 1-mm angled Kerrison ron-geur to expose the main trunk of the vessel before thebranching point, and a hemoclip is placed.

Tumors that involve the anterior cranial base often re-ceive the majority of their blood supply from the anteriorand posterior ethmoid arteries. A complete ethmoidectomyis first necessary to expose the roof of the ethmoid sinus.The anterior ethmoid artery crosses the skull base just pos-terior to the nasofrontal recess. The thin lamina papyraceaof the medial orbital wall is fractured and removed up to theplane of the cranial base. Further elevation of the perios-teum on the orbital side exposes the vessel where it leavesthe orbit, and a hemoclip can be placed (Fig. 4). The poste-rior ethmoid artery is similarly ligated in the roof of theposterior ethmoid air cells.

The expanded endonasal approach provides early expo-sure of the dural base, facilitating further devascularizationin the case of anterior base lesions. The best example of thisis anterior base meningiomas, which receive a blood sup-ply from the dural base in addition to the ethmoid arteries.It is not uncommon in anterior skull base meningiomas tofind an additional feeding artery arising from the distal por-tion of this paraclinoid carotid at the level of the optico-carotid recess. This vessel should be specifically identifiedand coagulated. Care should be taken to prevent the proxi-mal stump from bleeding and retracting into the orbit,resulting in a retrobulbar hematoma.

DISCUSSION

The principles discussed earlier are identical to those ap-plied in achieving hemostasis when using an operating mi-croscope. In this paper we have provided some important

considerations that are important in executing these princi-ples when using an endoscope to achieve hemostasis. Themost common concerns raised when discussing the abilityto effect endoneurosurgical hemostasis have centered onthe lack of true three-dimensional visualization and the ne-cessity of working in a relatively narrow corridor at a dis-tance. Together these concerns have raised questions aboutthe ability to maintain visualization, particularly duringhigh-flow arterial bleeding.

To address these questions, several key endoneurosurgi-cal principles and critical equipment used in the procedurehave been emphasized throughout this paper. The most im-portant of these is the concept of team surgery, which rep-resents perhaps the most fundamental difference frommicrosurgery. It is our opinion that in situations in whichbleeding is likely to be encountered, team surgery is man-datory. The value of having a team of surgeons workingsimultaneously is most evident when a vascular crisis oc-curs. A single surgeon cannot hold an endoscope, suctionblood, and achieve hemostasis without help. A stationary

Neurosurg. Focus / Volume 19 / July, 2005

Endoneurosurgical hemostasis techniques: lessons from 400 cases

5

Fig. 4. A: Endoscopic endonasal view demonstrating the iso-lation of the left anterior ethmoidal artery (AE). The vessel can beseen exiting the periorbita (PO) laterally and running into the crib-riform plate (CP) medially. The lamina papyracea has beenremoved, exposing the periorbita, and wide bilateral ethmoidec-tomies have been undertaken. B: Endoscopic view demonstrat-ing the position of the hemoclip (HC) directly at the point of exitof the anterior ethmoidal artery from the periorbita.

Unauthenticated | Downloaded 05/24/21 09:26 AM UTC

endoscope holder may suffice during uncomplicated dis-section but is woefully inadequate if an artery is squirtingtoward the end of the endoscope. With profuse hemor-rhage, it may even be necessary to use two suction devicessimultaneously to maintain visualization. An inexperiencedassistant is unlikely to be helpful in such a situation.

Currently the most significant limitation of endoneuro-surgical hemostasis is the inability to repair large arteriesprimarily. Endoscopic suturing techniques are not yet avail-able to reconstruct tears in large vessels primarily. This rep-resents a major difference when compared with micro-surgery. Endoneurosurgical techniques for application ofvascular clips, including encircling clips, are currentlyavailable. Nevertheless, we will need to develop techniquesand instruments to reconstruct large vessels in those rare sit-uations in which this is warranted.

CONCLUSIONS

Endoscopic hemostatic techniques must be mastered toperform effective and safe endoneurosurgery. The risk ofvascular complications is minimized with adequate preop-erative preparation, sound anatomical knowledge, properdissection techniques, familiarity with hemostatic materi-als, and treatment algorithms for emergency situations.

Based on our experience with 400 cases between 1998 and2005, we have found the algorithm described to be aneffective means of securing hemostasis during endoscopicendonasal surgery for both intra- and extradural lesions.

References

1. Harris AE, Hadjipanayis CG, et al: Microsurgical removal ofintraventricular lesions using endoscopic visualization and ster-eotactic guidance. Neurosurgery 56 (Suppl 1):S-125–S-132,2005

2. Kassam AB, Snyderman C, Gardner P, et al: The expanded en-donasal approach: a fully endoscopic transnasal approach andresection of the odontoid process: technical case report. Neuro-surgery 57 (Suppl 1):E213–E214, 2005

3. Stangerup SE, Dommerby H, Lau T: Hot-water irrigation as atreatment of posterior epistaxis. Rhinology 34:18–20, 1996

4. Stangerup SE, Thomsen HK: Histological changes in the nasalmucosa after hot-water irrigation. An animal experimental study.Rhinology 34:14–17, 1996

Manuscript received June 8, 2005.Accepted in final form June 28, 2005.Address reprint requests to: Amin B. Kassam, M.D., University

of Pittsburgh School of Medicine, 203 Lothrop Street, Suite 500,Pittsburgh, Pennsylvania 15213. email: kassamab@upmc.edu.

A. Kassam, et al.

6 Neurosurg. Focus / Volume 19 / July, 2005

Unauthenticated | Downloaded 05/24/21 09:26 AM UTC