Highlights
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The overall incidence of complications associated with primary brain tumor resection worldwide ranges from 20% to 35%.
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These complications can be broadly divided into neurologic, regional, and systemic complications.
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The surgery of superior sagittal sinus meningioma carries high risk of complications.
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Due to the advancements in neuroimaging, neuroanesthesia, and surgical adjunct precision in modern times, gross total resection of a primary brain tumor can be performed without significant complications.
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The careful selection of patients, a proper surgical plan, meticulous operative technique, anticipation of a complication, and the precautions to avoid the same are the main keys to a good surgical outcome.
Introduction
The surgical management of brain tumors has taken a paradigm shift over the last century from the Cushing era of cytoreduction surgery to the present golden period of advanced tumor surgery. Neurosurgical adjuncts such as cortical mapping, frameless stereotaxy, and intraoperative magnetic resonance imaging (MRI) play a huge role in the safe resection of primary brain tumors with absent or minimal complications. The objectives of brain tumor resection are the establishment of exact histopathologic diagnosis, neurologic recovery, and prolongation of patient survival. The overall incidence of complications associated with primary brain tumor resection worldwide ranges from 20% to 35%. This chapter throws light on a variety of complications associated with resection of primary brain lesions, its classification, diagnostic methods, and management strategies.
The definition of complication in primary brain tumor surgery is mostly subjective. Most surgical series define the adverse events as complications without giving due regard to whether they are expected. Apart from the surgeon’s knowledge and skill, there are various factors directly or indirectly involved in the incidence of a complication. The patient’s age, physical/neurologic status, previous treatment, tumor size and location, extent of resection, availability of monitoring/operative navigational devices, and histopathologic characteristics are a few of them. The neurosurgeon should have good acumen on all tumor-related complications because it helps in better counseling of the patient and family, both before and after surgery.
Classification of Neurosurgical Complications
A neurosurgical complication is not a single entity. It encompasses a spectrum of surgical complications as well as medical complications that may happen in the perioperative period ( Table 20.1 ). Sawaya et al. provide a rational framework for categorizing complications associated with brain tumor surgery. In this classification pattern, the neurosurgery-related complications are broadly organized into neurologic, regional, and systemic complications. Neurologic complications are adverse events that directly impair motor, sensory, language, or visual functions (e.g., hematoma, vascular injury, edema), whereas regional complications are related either to the wound (e.g., infection, pseudomeningocele) or to the brain (e.g., seizures, hydrocephalus), but they are not associated with any neurologic deficits. Systemic complications include more generalized medical conditions (e.g., thromboembolism, pneumonia). Neurologic complications are the most common cause of postoperative mortality. These three complications can be further subclassified into major and minor complications based on the severity, duration of deficit, and need of reexploration surgery.
| Neurologic | Regional | Systemic |
|---|---|---|
| Motor deficit Sensory deficit Aphasia/dysphasia Visual field deficit | Hydrocephalus Seizure Pneumocephalus Wound infection Meningitis Brain abscess | Pulmonary embolism Deep vein thrombosis Pneumonia Urinary infection Sepsis Myocardial infarction Gastrointestinal bleed Electrolyte disturbances |
Complications and Strategy for Their Avoidance
Neurologic Complications
The incidence of a new neurologic deficit (minor or major) after craniotomy for intrinsic tumor ranges from 10% to 25% in many surgical series. Several predictors of adverse neurologic outcome have been described in previous surgical series: age older than 60 years, Karnofsky Performance Scale (KPS) score less than 60, deep tumor location, and tumor in proximity to eloquent brain areas. The surgical strategy must be ideally planned based on these factors.
The main causes for neurologic complications are direct brain parenchymal injury, brain edema, vascular injury, and hematoma. The wrong localization of the tumor in relation to the adjacent eloquent brain areas is the main reason for inadvertent brain injury. Brain edema is also a notorious cause of neurosurgical morbidity. The predisposing factors for postoperative brain edema include excessive brain retraction and subtotal resection of the tumors, commonly high-grade gliomas. The incidence rate of vascular injury associated with primary brain tumor surgery is around 1% to 2%. A major venous occlusion can result in a hemorrhagic stroke where the neurologic manifestations may be delayed, whereas an arterial occlusion or injury can have an immediate catastrophic effect. The probable difference between these two problems is that in the former case, there can be a gradual recovery over a period of time, whereas in the latter it may permanently affect the patient’s quality of life. Postoperative hematomas, including subdural and extradural hematomas, cause neurologic deficits in 1% to 5% of patients; they are usually detected in the early postoperative period when the patient develops altered sensorium, seizures, or focal neurologic deficit.
The conventional knowledge of the tumor in relation to the normal brain and precise eloquent areas as well as the tumor’s identification/confirmation using various adjuncts such as cortical mapping, frameless stereotactic navigation, intraoperative MRI, or awake stimulation helps to a great extent in avoiding direct brain injury. Similarly, excessive brain retraction can be minimized by proper positioning of the patient, hyperventilation, high-dose corticosteroids, diuretics, and intermittent retractor placement. Frameless stereotaxy also helps in determining the optimal surgical trajectory and reduces the need for prolonged retraction and consequent cerebral edema. The gross total resection of a malignant glioma is associated with reduced postoperative edema/hematoma (wounded glioma syndrome) and the resulting morbidity compared with its partial-resection counterparts. The risk of vascular injury while performing surgery can be reduced by the strong anatomic suspicion of the location of vascular structures, early identification of arteries and veins, judicious sacrifice of draining veins, careful and intermittent retraction, surgery along the subpial plane, and careful use of an ultrasonic aspirator. Most of the operative site hematomas can be avoided by careful preoperative preparation, meticulous operative technique, and vigilant postoperative care.
Regional Complications
Regional complications are events associated with the surgical site (e.g., infection, pseudomeningocele) or the brain (e.g., seizures, hydrocephalus, pneumocephalus) without any neurologic deficits. A complication occurs in 1% to 5% of patients undergoing craniotomy for removal of intrinsic brain tumors. Redo surgery and radiotherapy are two plausible factors that can lead to wound infection. The tumor proximity to the motor cortex and a history of preoperative epilepsy are the strongest predictors for seizures. Local factors such as degree of cortical injury, prolonged retraction while performing the operation, and postoperative edema/hematoma as well as systemic factors such as hyponatremia and acidosis influence the incidence of postoperative seizures. Even though there is a controversy regarding the administration of prophylactic antiepileptics, most surgical series demonstrated a lower frequency of seizures in patients who received phenytoin either before or during surgery. Postoperative seizures must be managed aggressively with intravenous (IV) lorazepam, phenytoin, and IV fluids, and computed tomography (CT) imaging must be done to rule out a structural cause.
The risk of postoperative infections ranges from 1% to 2%, and it can extend from superficial to deep, involving bone, meninges, and brain parenchyma. The most common microbes involved are Staphylococcus aureus and S. epidermidis, although nosocomial infections can happen also with Gram-negative organisms. The predisposing factors for wound infection are proximity to paranasal sinus, presence of foreign body, prolonged surgery, corticosteroid administration, cerebrospinal fluid fistula, previous surgery, and cytotoxic therapy. The administration of prophylactic antibiotics and meticulous wound closure help in reducing the incidence of postoperative wound infection.
Systemic Complications
The incidence of medical complications ranges from 5% to 10% of patients undergoing craniotomy and removal of primary brain tumor. The spectrum of medical complications includes deep venous thrombosis, pulmonary embolism, myocardial infarction, infection, gastrointestinal hemorrhage, and electrolyte disturbances, of which the most frequent is deep venous thrombosis. The predisposing factors are elderly population, poor KPS score, preexisting medical conditions, prolonged surgery, and bed rest.
Several perioperative mechanical and pharmacologic prophylactic measures can reduce the risk of thromboembolic events. The use of elastic stockings and compression boots and the administration of minidose heparin (5000 units subcutaneously twice a day) or low-molecular-weight heparin after craniotomies are some of them. The neurosurgeon should keep a vigilant eye in the postoperative period to avoid or minimize the aforementioned complications to a great extent.
Next is an example of primary brain tumor; superior sagittal sinus (SSS) meningioma and the complications associated with its resection are discussed.
Neurosurgical Complications After Resection of Superior Sagittal Sinus Meningioma
The treatment of meningiomas that invade the intracranial venous system remains a significant and controversial challenge for neurosurgeons. Specifically, damage to the major dural venous sinuses, the deep cerebral veins, and the vein of Labbé, among others, can lead to major complications such as seizures, hemorrhage, sinus occlusion, corticovenous thrombosis, and regional or diffuse brain swelling. These complications can lead to significant morbidity and mortality. Meningiomas in the parasagittal region comprise 21% to 31% of all intracranial meningiomas. Invasion of the SSS is common with these lesions and increases the risk of subtotal resection and thus recurrence. Meningiomas along the SSS range from 14.8% to 33.9% in the anterior third, from 44.8% to 70.4% in the middle third, and from 9.2% to 29.6% in the posterior third of the sinus. Those lesions involving the posterior two-thirds of the SSS pose a substantially increased risk, whereas the previous literature has supported the sacrifice of the anterior one-third, with minimal consequence.
There is a current lack of large published series of parasagittal meningiomas that invade the SSS. Due to this, there are no accepted guidelines for the management of these lesions or their complications, and treatment paradigms vary significantly between institutions.
Anatomic Insights
Venous Anatomy
The intracranial venous system can be divided into a superficial and a deep system ( Fig. 20.1 ). The superficial system is comprised of the sagittal sinuses and cortical veins. The deep system drains the deep gray structures via the internal cerebral veins, basal veins of Rosenthal, vein of Galen, and the straight sinus. The SSS, the lateral sinuses (including the transverse and sigmoid sinus), and the cavernous sinus are the most frequently thrombosed dural sinuses, followed by the straight sinus and vein of Galen. Studies have shown a permanent morbidity range of 6% to 20% from cerebral venous thrombosis, although prognosis is thought to be better than for arterial stroke. Detailed evaluation of the venous sinuses and information on patency are best obtained via a venous MR angiogram, CT venography, or a digital subtraction angiography with late venous phases.
Dural Sinuses
Superficial veins of both hemispheres drain via the SSS, which starts at the foramen cecum and runs posteriorly toward the internal occipital protuberance, at which point it joins the straight and lateral sinuses to form the torcular Herophili. The SSS increases in size from anterior to posterior and ranges in width from 4.3 to 9.9 mm. As mentioned, the sacrifice of the anterior one-third of the SSS is usually well tolerated, but complications can include akinetic mutism, short-term memory deficits, or personality changes from compromise of prefrontal afferent drainage. At times, this anterior portion is narrow or absent, replaced by two superior cerebral veins. The middle one-third of the SSS drains the central group of cortical veins, and, as such, its sacrifice has the potential to cause bilateral hemiplegia or akinesia. A good landmark for division of the anterior and middle one-third of the SSS is the coronal suture. Occlusion of the posterior one-third of the SSS, or the torcular Herophili, carries a significant risk of potentially fatal diffuse brain edema. Fibrous septa at the inferior angle of the sinus, in addition to turbulent flow from draining superficial cortical veins, are felt to account for a greater risk of SSS thrombosis. The SSS, along with the other dural venous sinuses, receives blood from diploic, meningeal, and emissary veins. This accounts for the frequent occurrence of cerebral venous thrombosis as a complication of infectious pathologies, such as in cavernous sinus thrombosis in facial infections, lateral sinus thrombosis in chronic otitis media, and sagittal sinus infection in scalp infections. Because the dural sinuses contain the pacchionian or arachnoid granulations, thrombosis can lead to intracranial hypertension and papilledema.
The Superficial Veins of the Brain
The superficial veins can be classified into three categories: (1) midline afferents to the SSS, (2) inferior cerebral afferents to the transverse sinus, or (3) superficial sylvian afferents to the cavernous sinus. Midline afferents are primarily encountered when using interhemispheric approaches. Sacrifice of the midline central group of veins within 2 cm posterior to the coronal suture carries a significant risk. Other small-caliber midline veins can be taken with minimal risk. The vein of Trolard, or the superior anastomotic vein, is the primary connecting midline afferent and usually enters into the SSS in the postcentral region. Inferior cerebral veins are cortical bridging veins that primarily channel into the basal sinuses or the deep venous system. Small-caliber veins in this system can usually be sacrificed with minimal consequence if they do not contribute significantly to the Labbé system. The vein of Labbé, or inferior anastomotic vein, connects the superficial sylvian vein and the transverse sinus. Injury to the vein of Labbé, particularly in the dominant hemisphere, can cause an infarct in the posterior hemisphere with severe, permanent neurologic deficit. The superficial sylvian vein is formed from the connection of the temporosylvian veins and enters into the cavernous sinus.
Important superficial veins include:
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Superior cerebral veins: drain the superior surface; empty into the SSS
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Superficial middle cerebral vein: drains the lateral surface of each hemisphere; empties into the cavernous or sphenopalatine sinuses
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Inferior cerebral veins: drain the inferior aspect of each cerebral hemisphere; empty into the cavernous and transverse sinuses.
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Superior anastomotic vein (vein of Trolard): connects the superficial middle cerebral vein and the SSS
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Inferior anastomotic vein (vein of Labbé): connects the superficial middle cerebral vein and the transverse sinus
The Deep Veins of the Brain
The deep veins of the brain drain into the confluence of the Galen complex, which, in turn, drains into the straight sinus. In addition to the paired internal cerebral veins, the Galen system also receives the paired basilar veins of Rosenthal (which begins at the anterior perforated substance by the union of the anterior cerebral vein, the middle cerebral vein, and the striate vein); the veins from the corpus callosum, the cerebellum, and the occipital cortex; and the vermian precentral vein. The deep veins are often encountered when operating in the lateral ventricle, third ventricle, and pineal region. The great cerebral vein of Galen is approximately 1 to 2 cm long and passes posterosuperiorly behind the splenium of the corpus callosum in the quadrigeminal cistern. Injury or occlusion of the vein of Galen can have catastrophic consequences. There have been case reports of ligation of the vein of Galen without significant clinical sequelae, but this is likely due to the development of collateral circulation and to the significant anatomic variation of the vein of Galen and its tributaries.
Surgical Resection of SSS Meningiomas
Meningiomas invading the SSS remain a challenging lesion for neurosurgeons. They can be difficult to resect completely and carry significant risk of morbidity, including intraoperative and postoperative hemorrhage, sinus occlusion, and corticovenous thrombosis. Although subtotal resection is associated with a high rate of recurrence, absolute care must be taken to preserve the collateral channels at all steps of the surgery.
Venous invasion by the meningioma can range from invasion of the outer surface of the venous wall to complete invasion and occlusion of the sinus. The first detailed classification scheme was proposed by Merrem and Krause et al. and then later modified by Bonnal and Brotchi et al. A simplified version was proposed by Sindou and Hallacq in 1998. This classification included the categorization described later.
With the advent of microsurgical techniques, intracranial dural venous sinus reconstruction became possible. In 1971, Kapp et al. used an autogenous great saphenous vein and shunt device to reconstruct the SSS. This was followed by Marks et al. in 1986 and Sakaki et al. in 1987. Reconstructive materials have included autologous great saphenous vein, neck superficial veins, Dacron, and silicone tubing. Sindou and Hallacq reported a series of 47 meningiomas: 41 of the sagittal sinus, 4 of the transverse sinus, and 2 torcular. A gross total resection was achieved in all cases. Thirty-nine patients were reported as having good outcomes and resumed their previous activities, whereas five patients had permanent neurologic deficit due to central venous infarction (all in the middle one-third of the sagittal sinus). Three patients died from brain swelling; all three involved meningiomas totally occluding the sinus, and in all three patients resection was achieved without sinus reconstruction. Nine patches, six Gore-Tex bypasses, and nine autologous vein bypasses were employed. The authors recommended the following: excision of the outer layer of sinus wall and coagulation of dural attachment in Type 1, removal of intraluminal fragment and repair of dural defect with a patch in Type 2, resection of sinus wall and repair by patch graft in Type 3, repair by patch or bypass with saphenous or external jugular vein graft in Type 4, and removal of involved portion of sinus and restoration by venous bypass in Types 5 and 6.
Mathiesen et al. supported the practice of sagittal sinus repair or reconstruction after resection by invasive meningiomas when attempting a macroscopic radical removal. They proposed a direct primary repair when resecting just an invaded edge; closure with a patch graft of dural, falcine, or pericranial tissue when resecting one to two invaded walls; and using an interposition venous graft when resecting three sinus walls. In this prospective study of 100 patients, the authors had good to excellent outcomes in 94 patients but found that microscopic radical resection was difficult to achieve. Gamma Knife radiosurgery was used as an adjunct in patients with tumors of low proliferative index, and the authors felt that tumor control was better when Gamma Knife radiosurgery was used as a primary treatment strategy than when it was employed only after tumor progression.
Over time, however, extensive reconstruction of the SSS after meningioma resection has played a diminishing role. In 2014, Mantovani et al. reported on the management of meningiomas invading the major dural venous sinuses. The authors reported on 38 patients who underwent operations for meningioma resection: 26 patients with lesions in the SSS, 5 with lesions in the torcular Herophili, 5 with lesions in the transverse sinus, and 2 with lesions in the sigmoid sinus. Twenty-seven patients had World Health Organization (WHO) Grade I meningiomas, and 11 had WHO Grade II meningiomas. In 50% of cases (13 patients), the sinus was completely occluded. A gross total resection was achieved in 86.9% of patients. Sinus reconstruction was performed in 21 cases: 13 by direct suture and 8 using a patch. Postoperatively, the sinus was found to be patent in 52.4% of patients and narrowed in 33.3% of patients. Correspondingly, an occlusion rate of 14.3% was found. No deaths were reported, and one major postoperative complication occurred. Further diminishing the role of sinus reconstruction, DiMeco et al. reported on their surgical experience in 108 cases of meningiomas invading the SSS. Thirty patients with meningiomas completely occluding the SSS had complete resection of the involved portion of sinus, and Simpson Grade I or II resection was achieved in 100 patients. Two perioperative deaths were noted. Serious complications included brain swelling in 9 patients (8.3%) and postoperative hematoma in 2 patients (1.85%). At a mean follow-up of 79.5 months, tumor recurrence was noted in 15 patients (13.9%). The authors concluded that if extreme care is taken to preserve cortical veins, good results are achieved without reconstruction of the sinus.
Surgical management of meningiomas of the SSS remains controversial. Resection should be offered to those with symptoms or with lesions that exhibit growth. Close examination of preoperative imaging for extent of SSS invasion is essential to guide the surgeon’s goals of care. After exposure or injury of the sagittal sinus during meningioma surgery, the patient is at risk for intraoperative excessive blood loss or air embolism. In most cases, injury is controllable with packing by Surgicel, Gelfoam, and microsurgical patties. Care should be taken with injectable thrombotic agents to avoid inadvertent occlusion. If there is planned resection of a portion of the SSS during surgery, a preoperative formal angiogram may be very helpful in evaluating the collateral venous anatomy to avoid inadvertently interrupting critical pathways.
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