Having absolute hemostasis is crucial in skull base surgery, because bleeding decreases visualization and increases the risk of postoperative complications. Achieving hemostasis starts from the preoperative evaluation. A thorough clinical history and routine tests guide the surgeon to minimize bleeding risk preoperatively, and comprehensive study of preoperative images helps the surgeon to predict bleeding risk and to consider preoperative embolization in suitable cases. Many hemostatic agents are available to control intraoperative bleeding; understanding of their indications and properties is crucial to achieve hemostasis. Whether endoscopic or transcranial approach, microsurgical techniques to avoid and control bleeding are the same.
Key learning points
At the end of this article, the reader will:
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Understand the importance of hemostasis during endoscopic endonasal approach to skull base and intradural surgery.
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Be able to better understand the techniques for hemostasis in endoscopic endonasal surgery, including pituitary surgery.
Introduction
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Bleeding makes visualization difficult, which makes the surgical approach unsafe.
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Increased risk of intraoperative complications and inadvertent neurovascular injury.
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Poor hemostasis is the major leading cause of postoperative hematoma, which is the most common cause for reoperation, and surgical morbidity and mortality.
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The widespread use of antiplatelets and anticoagulation for cardiovascular diseases adds greater challenges for surgeons.
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Increased risk of blood transfusion, which had its own risks:
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Infection
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Coagulopathy
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Fluid overload
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Skull base surgery, whether transcranial or endoscopic, is based on good exposure and visualization. Surgeons achieve that by better anatomic understanding, appropriate access, generous bone removal, and the adjunct use of neuronavigation. However, visualization can be jeopardized by uncontrolled bleeding. If hemostasis is not achieved, this delays the procedure and puts the patient at risk for intraoperative complications, including inadvertent vascular injury and postoperative hemorrhage. The cause of difficult intraoperative hemostasis in neurosurgical patients is multifactorial. Degree of vascularity of the tumor, thromboplastin released from neural tissues, presence of vascular malformation, intrinsic hemostatic abnormality, or antiplatelet and anticoagulation therapy are all possible causes of difficult hemostasis, in addition to inadequate surgical technique.
Introduction
- •
Bleeding makes visualization difficult, which makes the surgical approach unsafe.
- •
Increased risk of intraoperative complications and inadvertent neurovascular injury.
- •
Poor hemostasis is the major leading cause of postoperative hematoma, which is the most common cause for reoperation, and surgical morbidity and mortality.
- •
The widespread use of antiplatelets and anticoagulation for cardiovascular diseases adds greater challenges for surgeons.
- •
Increased risk of blood transfusion, which had its own risks:
- ○
Infection
- ○
Coagulopathy
- ○
Fluid overload
- ○
Skull base surgery, whether transcranial or endoscopic, is based on good exposure and visualization. Surgeons achieve that by better anatomic understanding, appropriate access, generous bone removal, and the adjunct use of neuronavigation. However, visualization can be jeopardized by uncontrolled bleeding. If hemostasis is not achieved, this delays the procedure and puts the patient at risk for intraoperative complications, including inadvertent vascular injury and postoperative hemorrhage. The cause of difficult intraoperative hemostasis in neurosurgical patients is multifactorial. Degree of vascularity of the tumor, thromboplastin released from neural tissues, presence of vascular malformation, intrinsic hemostatic abnormality, or antiplatelet and anticoagulation therapy are all possible causes of difficult hemostasis, in addition to inadequate surgical technique.
Preoperative work-up and interventions
Patient history is an important element to detect patients at risk for difficult hemostasis despite normal routine coagulation profile. A suggested list of questions that can be asked in preadmission evaluation can detect those patients at risk ( Box 1 ).
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Have you noticed any nose bleeding without obvious trauma?
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Do you often develop bruises even without bumping into anything?
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Have you noticed that your gums are bleeding without any obvious cause?
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Do you develop bleeds or hematomas more than once a week?
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Do you think that after cuts or abrasion you bleed for longer than usual?
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Have you ever had prolonged or sever bleeding after an operation?
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Have you ever had prolonged bleeding after tooth extraction?
- 8.
Have you ever received blood or blood products during an operation?
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Do you have a family member who had a bleeding problem?
- 10.
Are you taking any pain killer, in particularly antiinflammatory medications?
- 11.
Are you taking any medications, in particularly aspirin or blood thinners?
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Do you think that you have prolonged menstruation (>7 days) and/or a high frequency of tampon change?
Any affirmative answers require further history, investigation, hematology consult, or postponement of the surgery.
In addition to preoperative patient assessment and laboratory tests, review of medical imaging for features of hypervascularity, such as flow void in MRI, and risk for potential vascular injury, such as close proximity to internal carotid artery (ICA) or any of its branches, is essential. Preoperative embolization is an important adjunct that should be considered in some cases. Embolization should be performed 24 to 72 hours before surgery to allow adequate thrombosis and avoid recanalization. The external carotid artery branches can be accessed for embolization, if there is no contraindication, such as direct anastomosis between ophthalmic and middle meningeal arteries. Access through the ICA or vertebral artery is not feasible most of the time and it is limited to balloon test occlusion or complete occlusion if radical resection with high-flow bypass is planned. In a study involving 15 patients, the external carotid branches were successfully occluded in most patients, with no adverse effects. A suggested algorithm is presented in ( Fig. 1 ).
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Mechanical compression: patties, bipolar or monopolar cautery, clips, bone wax, Gelfoam
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Enhance coagulation or platelet aggregation: Surgicel, Avitene
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Introduce coagulation factors topically: fibrin sealants (eg, Tisseel), gelatin-thrombin matrix sealant (eg, Floseal, Surgiflo)
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Multiple mechanisms: warm irrigation
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Systemic agents: tranexamic acid, recombinant factor VII (rFVIIa), prothrombin complex concentrate (PCC), platelets transfusion
Mechanical compression
Compression with a cottonoid patty over the area of bleeding allows clot formation and enhances vasoconstriction. It works most effectively with capillary and venous bleeding. This technique is not advisable in deep and narrow spaces and over delicate neural structures, such as the optic nerve.
Bipolar cautery
Bipolar cautery is effective in controlling bleeding, especially from an arterial source. It is the mainstay method to control hemostasis during surgery. However, this method can place adjacent healthy cranial nerves at risk of thermal injury. Furthermore, it can cause complete vessel lumen occlusion with subsequent compromise of the perfused territory of neural tissue. When controlling bleeding form venous sinuses, the bipolar blades have to approximate the leaflets of the opening before applying the current in order to seal the opening. If not applied correctly, this method can enlarge an opening in venous sinus bleeding. If bipolar cautery does not achieve hemostasis, applying pressure and using other products might be more effective.
Standard bayonet designs are used for transcranial procedures, and there are different types on the market. However, the best types are capable of coagulation and dissect the sylvian fissure or around the tumor using an irrigating tip to decrease eschar adhesion, and can also hold cottonoid patties. However, bayonet bipolars are too large for the endonasal route, especially for expanded endonasal approaches. Instead, a pistol-grip design can be used.
Monopolar Cautery
Monopolar cautery is a powerful coagulating and cutting technique. It uses an electric current conducted between its tip and the tissue. It is used for temporalis muscle dissection, suboccipital muscle dissection, and for the nasal stage of endoscopic skull base surgery. In endoscopic skull base surgery, suction monopolar cautery is a useful tool, particularly to control arterial mucosal bleeding, such as from the septal branch of the sphenopalatine artery. Monopolar cautery should not be used within the sphenoid sinus, on the skull base, near major vessels or nerves.
Warm Saline Irrigation
Warm saline irrigation is used whenever there is diffuse oozing, either from traumatized nasal mucosa, denuded bone surface, or the dissected surface of the tumor or brain. Gentle irrigation of the brain surface with a soft catheter is effective in clearing the field so that bleeding sites can be visualized and selectively cauterized or compressed with a hemostatic material. Care should be taken to avoid excessive irrigation pressure because hydrodissection of the tissues could occur.
Bone Wax
Bone wax consists of beeswax and a softening agent such as paraffin or Vaseline, and is commonly used to stop bleeding resulting from cut bone by physically stopping blood flow from the damaged vessels in the bone. Examples of bone wax applications in the skull base include during sphenoid wing drilling in pterional craniotomy, and during drilling the clivus in the endoscopic approach to the posterior fossa. Some adverse reactions have been reported, including impeded bone healing, allergic reactions, and granuloma formation.
Conventional Local Hemostatic Adjuncts
Conventional local hemostatic adjuncts tend to work by forming a mesh that encourages clot formation. These agents include various absorbable gelatin sponges (eg, Gelfoam; Baxter, CA), which has the capability to absorb blood up to 10 times its own weight, and which then creates a tamponade over the bleeding site. Microfibrillar collagen (eg, Avitene; Davol, RI) promotes platelet aggregation and adhesion without directly affecting the coagulation cascade. Oxidized regenerated cellulose (eg, Surgicel; Ethicon, NJ) creates an acidic milieu that promotes reaction with blood to precipitate an artificial coagulum that provides a substrate for further clot formation.
An intact patient coagulation cascade with the full spectrum of available clotting factors is required for these products to work effectively, thus they do not work well in the setting of thrombocytopenia.
Fibrin Sealants
The most common example of those is Tisseel (Baxter, IL). It acts by introducing a boost of fibrin locally, so it bypasses the coagulation cascade and induces clot formation. In skull base surgery, open or endoscopic, it has been used mainly for prevention and treatment of cerebrospinal fluid leak.
Gelatin-Thrombin Matrix Sealant
The most common 2 examples are Floseal (Baxter, IL) and Surgiflo (Ethicon, NJ). It had 2 components: bovine gelatin, which works by mechanical tamponade, and thrombin, which converts fibrinogen to fibrin and forms a stable clot in the presence of factor XIII. It does not work in cases of fibrinogen deficiency, which occurs in 1 in 1000,000 individuals. Because of the cost, it is largely limited to persistent and excessive bleeding that is not amenable to standard techniques of hemostasis. It has major value in the endoscopic approach because of limited space and the ease of applying it over the area of bleeding ( Fig. 2 ).
