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Posterior Cerebral Artery Pseudoaneurysm, a Rare Complication of Pituitary Tumor Transsphenoidal Surgery: Case Report and Literature Review
Case Report
Posterior Cerebral Artery Pseudoaneurysm, a Rare Complication of Pituitary Tumor Transsphenoidal Surgery: Case Report and Literature Review Chih-Hsun Lee, Shu-Mei Chen, Tai-Ngar Lui
Key words Iatrogenic - Pituitary adenoma - Posterior cerebral artery aneurysm - Pseudoaneurysm - Transsphenoidal surgery - Vascular injury -
Abbreviations and Acronyms CT: Computed tomography PCA: Posterior cerebral artery Department of Neurosurgery, Taipei Medical University e Wan-Fang Hospital, Taipei, Taiwan To whom correspondence should be addressed: Tai-Ngar Lui, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2015). http://dx.doi.org/10.1016/j.wneu.2015.04.043
Endoscopic endonasal transsphenoidal surgery for pituitary tumors has been the standard therapy for decades. This approach offers surgeons an effective, safe, and wide exposure to the pituitary gland, with a relatively low mortality rate and acceptable complication rates. However, severe complications, including cerebrospinal fistula, meningitis, neural component injury, and vascular injury, may occur. One of the most common and severe complications is carotid artery injury; however, only 2 posterior cerebral artery injuries with pseudoaneurysm formation have been reported previously. One of them received bypass surgery and recovered well, but the other received endovascular treatment and died of intracranial hypertension. Herein, we report a rare case of iatrogenic pseudoaneurysm formation with hemorrhage after transsphenoidal surgery, in which tumor traction-related adjacent vessel injury was most likely. Aneurysm clipping, vascular bypass, and embolization are considered reasonable choices depending on the patient’s condition for iatrogenic aneurysm formation. In our case, no surgical or endovascular intervention was performed, and the aneurysm healed spontaneously 3 weeks later.
Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2015 Elsevier Inc. All rights reserved.
INTRODUCTION Pituitary tumors are not rare and can be detected early by the use of advanced neuroimaging technology. Several different approaches to the pituitary gland are used, including the endoscopic endonasal transsphenoidal approach, which has gained in popularity since its introduction in the 1980s. It provides neurosurgeons with a rapid, safe, and wide exposure, as well as a relatively low mortality rate (3, 7). Most pituitary tumors can be managed safely with this procedure. According to the literature, the mean operative mortality rate is approximately 0.9% with the endoscopic endonasal transsphenoidal approach; however, several operative complications, including cerebrospinal fluid fistulas (1%e3.9%), related vessel injury, optic nerve injury, and meningitis have been reported with incidence rates ranging from 1% to 2% (5). Injuries of the carotid artery are the most common vessel injury during the endoscopic endonasal transsphenoidal approach for pituitary tumors. Many cases of posterior cerebral artery (PCA) pseudoaneurysm
formation have been reported after blunt or penetrating trauma history; however, only 3 cases of iatrogenic PCA pseudoaneurysm formation have been reported, 2 of which occurred after the endoscopic endonasal transsphenoidal approach (4, 8). CASE REPORT A 32-year-old woman presented with bitemporal hemianopsia and progressive deterioration of visual acuity for 2 months. Her medical history was otherwise unremarkable, and the result of a laboratory study showed hypogonadism. Computed tomography (CT) scan and magnetic resonance angiography of the brain disclosed a huge sellar tumor with upward extension and invasion of the left parasellar region. No significant abnormal vascular lesions were noted (Figure 1AeD). The endoscopic endonasal transsphenoidal approach was used to remove the pituitary tumor after a lumbar drain was inserted. No significant bleeding or vascular injuries were noted during the operation; however, persistent unconsciousness with dilated pupils were noted after surgery. An emergency CT scan of the brain revealed diffuse intraventricular, subarachnoid hemorrhages and acute ventricle dilation
WORLD NEUROSURGERY - [-]: ---, MONTH 2015
(Figure 2A). Bilateral external ventricular drainage was performed immediately to control her increased intracranial pressure. Cerebral angiography and CT angiography revealed one out-pouching aneurysm of approximately 2.1 2.9 mm in size at the left P1 segment of the PCA with a superior direction (Figure 2B). We controlled the blood pressure and intracranial pressure carefully by ventriculostomy drainage. We also used nimodipine to prevent vasospasm. Intracranial pressure remained stable, and no new associated hemorrhage occurred in the following weeks. Her neurologic condition improved gradually, and repeat angiography about 3 weeks after the operation showed no visible aneurysm (Figure 3A). After cerebrospinal fluid shunting and rehabilitation, her neurologic condition recovered so that she could obey simple orders with mild right hemiparesis. We repeated magnetic resonance angiography every year and found no vascular lesion for 3 years (Figure 3B). DISCUSSION Vascular complications of transsphenoidal surgery can lead to mortality and serious neurologic morbidity. Perforation or
www.WORLDNEUROSURGERY.org
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CASE REPORT CHIH-HSUN LEE ET AL.
POSTERIOR CEREBRAL ARTERY PSEUDOANEURYSM
Figure 1. (A) Sagittal view, (B) coronary view, and (C) axial view of a large sellar tumor with upward extension and left parasellar region invasion, 34.1 36.9 28.2 mm in size. (D) Magnetic resonance angiography showed no obvious vascular lesions before surgery.
laceration of the carotid arteries is a very serious complication and unfortunately is a relatively common type of injury in the transsphenoidal approach (7). Other vascular injuries include sphenopalatine arteries, branches of the internal maxillary
artery, and the meningohypophyseal trunk. Injury to the PCA, however, rarely has been reported. In our case, a newly formed PCA pseudoaneurysm was found after transsphenoidal surgery. There were 2 probable
Figure 2. (A) Postoperative computed tomography scan showed diffuse intraventricular, subarachnoid hemorrhages and hydrocephalus. One posterior cerebral artery aneurysm was also seen on computed tomography angiography (arrow). (B) Cerebral angiography revealed one saccular out-pouching aneurysm approaching 2.1 2.9 mm in size at the left P1 segment of the posterior cerebral artery in a superior direction (arrow).
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mechanisms including direct instrumental injury or secondary injury by tumor capsule traction or irritation during the operation. Because no direct exposure of the PCA or acute bleeding were seen during surgery, secondary vascular injury was more likely. Because no direct opening of the posterior wall of tumor capsule was performed, no obvious intraoperative hemorrhage was found. We assume that the P1 segment of the PCA and its perforators were injured during the resection and tumor traction, thereby weakening the artery wall. Pseudoaneurysm formation and intraventricular and subarachnoid hemorrhage then led to a coma and other neurologic deficits in the patient. Traumatic or iatrogenic vascular injuries and pseudoaneurysm formation have been reported previously; however, the nature history of iatrogenic pseudoaneurysm is still unknown, especially posterior circulation aneurysms (1). Intracranial pseudoaneurysms are thought to be prone to rupture, but data are still lacking (9). Traditional treatment strategies for the management of pseudoaneurysms include surgical or endovascular treatment. Surgical treatment for pseudoaneurysm involves direct clipping, wrapping, trapping, artery ligation, and bypass for revascularization. Direct surgical repair of such lesions may be difficult to manipulate, and definite treatment may require parent vessel sacrifice or artery reconstruction with bypass grafting (6). Alternatively, endovascular therapy such as coil embolization with or without stents may also achieve aneurysm obliteration effectively. Conservative treatment of iatrogenic pseudoaneurysms also has been reported in some situations, especially when no mass effect is seen or the patient’s neurologic condition is stable (1, 2, 4, 6, 8, 9). In addition, perforator arteries from posterior circulation have a low flow and favor spontaneous partial or complete thrombosis of an aneurysmal sac. In some studies, posterior circulation perforator aneurysms with similar characteristics to our case such as very small size and the proximal part of the perforator arteries were observed to spontaneously heal (1, 2, 4, 6). There were 2 reported cases of inatrogenic aneurysm of the PCA after transsphenoidaal surgery (4, 8). One of them
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2015.04.043
CASE REPORT CHIH-HSUN LEE ET AL.
POSTERIOR CEREBRAL ARTERY PSEUDOANEURYSM
resolution of perforator aneurysms of the posterior circulation. J Neurosurgery 121:1107-1111, 2014. 2. Chang SW, Abla AA, Kakarla UK, Sauvageau E, Dashti SR, Nakaji P, Zabramski JM, Albuquerque FC, McDougall CG, Spetzler RF: Treatment of distal posterior cerebral artery aneurysms: a critical appraisal of the occipital artery-to posterior cerebral artery bypass. Neurosurgery 67:16-26, 2010. 3. Charalampaki P, Ayyad A, Alfons Kockro R, Perneczky A: Surgical complications after endoscopic transsphenoidal pituitary surgery. J Clin Neurosci 16:786-789, 2009. 4. Ciceri EF, Regna-Gladin C, Erbetta A, Chiapparini L, Nappini S, Savoriardo M, Di Meco F: Iatrogenic intracranial pseudoaneurysms: neuroradiological and therapeutical considerations, including endovascular options. Neurol Sci 27:317-322, 2006. Figure 3. (A) Magnetic resonance angiography (MRA) performed 3 weeks later showed no visible aneurysm. (B) MRA was performed each year for 3 years after the operation and no aneurysm were found.
received external ventricular drain placement but the patient’s condition worsened, with declining mental status. Superior cerebellar artery-posterior cerebral bypass and aneurysm trapped were performed later. The patient recovered steadily with mild left hemiparesis. Another patient was treated with parent artery occlusion, but the patient died of intracranial hypertension. In our experience, we controlled the patient’s blood pressure and prevented the catastrophic hemorrhage. We also treated the hemorrhage-associated intracranial hypertension after aneurysm bleeding. Fortunately, the patient stabilized and the PCA aneurysm resolved spontaneously without surgical or endovascular treatment. Iatrogenic injury, including vascular and nerve injuries, usually occur during aggressive dissection of pituitary tumors, especially when the tumor extends to the surrounding space. As in our case, a large pituitary tumor extending upward or backward may result in adhesion or encasement of surrounding blood vessels. In these situations, gentle and careful curettage and
dissection should be considered to prevent related vascular or nerve injuries. In conclusion, iatrogenic vascular injury with pseudoaneurysm formation is a rare but serious event they may result in mortality or severe neurologic morbidity. According to the current case, dissection should be performed carefully and gently in pituitary tumors that are out-pouching or involve upward or backward extension. Aggressive dissection should be preformed carefully because of the high risk of vascular injury with intracranial hemorrhage. Direct surgical treatment for posterior circulation pseudoaneurysm is challenging, and endovascular therapy can be an effective alternative for iatrogenic vascular injuries. In some situations, especially without intracranial hypertension or progressive hemorrhage, conservative treatment with regular image follow-up could be an effective treatment.
5. Ciric I, Ragin A, Baumgartner C, Pierce D: Complications of transsphenoidal surgery: results of a national survey review of the literature and personal experience. Neurosurg 40:225-237, 1997. 6. Kadyrov KA, Friedman JA, Nichols DA, CohenGadol AA, Link MJ, Piepgras DG: Endovascular treatment of an internal carotid artery pseudoaneurysm following transsphenoidal surgery. J Neurosurgery 96:624-627, 2002. 7. Laws ER Jr: Vascular complications of transsphenoidal surgery. Pituitary 2:163-170, 1999. 8. Rodríguez-Hernández A, Huang C, Lawton MT: Superior cerebellar artery-posterior cerebellar artery bypass: in situ bypass for posterior cerebral artery revascularization. J Neurosurg 118:1053-1057, 2013. 9. Taqi MA, Lazzaro MA, Pandya DJ, Badruddin A, Zaidat OO: Dissecting aneurysms of posterior cerebral artery: clinical presentation, angiographic findings, treatment, and outcome. Front Neurol 2: 38, 2011.
Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Received 21 January 2015; accepted 16 April 2015 Citation: World Neurosurg. (2015). http://dx.doi.org/10.1016/j.wneu.2015.04.043 Journal homepage: www.WORLDNEUROSURGERY.org
REFERENCES
Available online: www.sciencedirect.com
1. Adrien C, Pierre-Henri L, Pieere T, Catherine C, Aapolline K, Klaus M, Frederic R: Spontaneous
1878-8750/$ - see front matter ª 2015 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY - [-]: ---, MONTH 2015
www.WORLDNEUROSURGERY.org
1.E3
Posterior Cerebral Artery Pseudoaneurysm, a Rare Complication of Pituitary Tumor Transsphenoidal Surgery: Case Report and Literature Review Chih-Hsun Lee, Shu-Mei Chen, Tai-Ngar Lui
Key words Iatrogenic - Pituitary adenoma - Posterior cerebral artery aneurysm - Pseudoaneurysm - Transsphenoidal surgery - Vascular injury -
Abbreviations and Acronyms CT: Computed tomography PCA: Posterior cerebral artery Department of Neurosurgery, Taipei Medical University e Wan-Fang Hospital, Taipei, Taiwan To whom correspondence should be addressed: Tai-Ngar Lui, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2015). http://dx.doi.org/10.1016/j.wneu.2015.04.043
Endoscopic endonasal transsphenoidal surgery for pituitary tumors has been the standard therapy for decades. This approach offers surgeons an effective, safe, and wide exposure to the pituitary gland, with a relatively low mortality rate and acceptable complication rates. However, severe complications, including cerebrospinal fistula, meningitis, neural component injury, and vascular injury, may occur. One of the most common and severe complications is carotid artery injury; however, only 2 posterior cerebral artery injuries with pseudoaneurysm formation have been reported previously. One of them received bypass surgery and recovered well, but the other received endovascular treatment and died of intracranial hypertension. Herein, we report a rare case of iatrogenic pseudoaneurysm formation with hemorrhage after transsphenoidal surgery, in which tumor traction-related adjacent vessel injury was most likely. Aneurysm clipping, vascular bypass, and embolization are considered reasonable choices depending on the patient’s condition for iatrogenic aneurysm formation. In our case, no surgical or endovascular intervention was performed, and the aneurysm healed spontaneously 3 weeks later.
Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2015 Elsevier Inc. All rights reserved.
INTRODUCTION Pituitary tumors are not rare and can be detected early by the use of advanced neuroimaging technology. Several different approaches to the pituitary gland are used, including the endoscopic endonasal transsphenoidal approach, which has gained in popularity since its introduction in the 1980s. It provides neurosurgeons with a rapid, safe, and wide exposure, as well as a relatively low mortality rate (3, 7). Most pituitary tumors can be managed safely with this procedure. According to the literature, the mean operative mortality rate is approximately 0.9% with the endoscopic endonasal transsphenoidal approach; however, several operative complications, including cerebrospinal fluid fistulas (1%e3.9%), related vessel injury, optic nerve injury, and meningitis have been reported with incidence rates ranging from 1% to 2% (5). Injuries of the carotid artery are the most common vessel injury during the endoscopic endonasal transsphenoidal approach for pituitary tumors. Many cases of posterior cerebral artery (PCA) pseudoaneurysm
formation have been reported after blunt or penetrating trauma history; however, only 3 cases of iatrogenic PCA pseudoaneurysm formation have been reported, 2 of which occurred after the endoscopic endonasal transsphenoidal approach (4, 8). CASE REPORT A 32-year-old woman presented with bitemporal hemianopsia and progressive deterioration of visual acuity for 2 months. Her medical history was otherwise unremarkable, and the result of a laboratory study showed hypogonadism. Computed tomography (CT) scan and magnetic resonance angiography of the brain disclosed a huge sellar tumor with upward extension and invasion of the left parasellar region. No significant abnormal vascular lesions were noted (Figure 1AeD). The endoscopic endonasal transsphenoidal approach was used to remove the pituitary tumor after a lumbar drain was inserted. No significant bleeding or vascular injuries were noted during the operation; however, persistent unconsciousness with dilated pupils were noted after surgery. An emergency CT scan of the brain revealed diffuse intraventricular, subarachnoid hemorrhages and acute ventricle dilation
WORLD NEUROSURGERY - [-]: ---, MONTH 2015
(Figure 2A). Bilateral external ventricular drainage was performed immediately to control her increased intracranial pressure. Cerebral angiography and CT angiography revealed one out-pouching aneurysm of approximately 2.1 2.9 mm in size at the left P1 segment of the PCA with a superior direction (Figure 2B). We controlled the blood pressure and intracranial pressure carefully by ventriculostomy drainage. We also used nimodipine to prevent vasospasm. Intracranial pressure remained stable, and no new associated hemorrhage occurred in the following weeks. Her neurologic condition improved gradually, and repeat angiography about 3 weeks after the operation showed no visible aneurysm (Figure 3A). After cerebrospinal fluid shunting and rehabilitation, her neurologic condition recovered so that she could obey simple orders with mild right hemiparesis. We repeated magnetic resonance angiography every year and found no vascular lesion for 3 years (Figure 3B). DISCUSSION Vascular complications of transsphenoidal surgery can lead to mortality and serious neurologic morbidity. Perforation or
www.WORLDNEUROSURGERY.org
1.E1
CASE REPORT CHIH-HSUN LEE ET AL.
POSTERIOR CEREBRAL ARTERY PSEUDOANEURYSM
Figure 1. (A) Sagittal view, (B) coronary view, and (C) axial view of a large sellar tumor with upward extension and left parasellar region invasion, 34.1 36.9 28.2 mm in size. (D) Magnetic resonance angiography showed no obvious vascular lesions before surgery.
laceration of the carotid arteries is a very serious complication and unfortunately is a relatively common type of injury in the transsphenoidal approach (7). Other vascular injuries include sphenopalatine arteries, branches of the internal maxillary
artery, and the meningohypophyseal trunk. Injury to the PCA, however, rarely has been reported. In our case, a newly formed PCA pseudoaneurysm was found after transsphenoidal surgery. There were 2 probable
Figure 2. (A) Postoperative computed tomography scan showed diffuse intraventricular, subarachnoid hemorrhages and hydrocephalus. One posterior cerebral artery aneurysm was also seen on computed tomography angiography (arrow). (B) Cerebral angiography revealed one saccular out-pouching aneurysm approaching 2.1 2.9 mm in size at the left P1 segment of the posterior cerebral artery in a superior direction (arrow).
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www.SCIENCEDIRECT.com
mechanisms including direct instrumental injury or secondary injury by tumor capsule traction or irritation during the operation. Because no direct exposure of the PCA or acute bleeding were seen during surgery, secondary vascular injury was more likely. Because no direct opening of the posterior wall of tumor capsule was performed, no obvious intraoperative hemorrhage was found. We assume that the P1 segment of the PCA and its perforators were injured during the resection and tumor traction, thereby weakening the artery wall. Pseudoaneurysm formation and intraventricular and subarachnoid hemorrhage then led to a coma and other neurologic deficits in the patient. Traumatic or iatrogenic vascular injuries and pseudoaneurysm formation have been reported previously; however, the nature history of iatrogenic pseudoaneurysm is still unknown, especially posterior circulation aneurysms (1). Intracranial pseudoaneurysms are thought to be prone to rupture, but data are still lacking (9). Traditional treatment strategies for the management of pseudoaneurysms include surgical or endovascular treatment. Surgical treatment for pseudoaneurysm involves direct clipping, wrapping, trapping, artery ligation, and bypass for revascularization. Direct surgical repair of such lesions may be difficult to manipulate, and definite treatment may require parent vessel sacrifice or artery reconstruction with bypass grafting (6). Alternatively, endovascular therapy such as coil embolization with or without stents may also achieve aneurysm obliteration effectively. Conservative treatment of iatrogenic pseudoaneurysms also has been reported in some situations, especially when no mass effect is seen or the patient’s neurologic condition is stable (1, 2, 4, 6, 8, 9). In addition, perforator arteries from posterior circulation have a low flow and favor spontaneous partial or complete thrombosis of an aneurysmal sac. In some studies, posterior circulation perforator aneurysms with similar characteristics to our case such as very small size and the proximal part of the perforator arteries were observed to spontaneously heal (1, 2, 4, 6). There were 2 reported cases of inatrogenic aneurysm of the PCA after transsphenoidaal surgery (4, 8). One of them
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2015.04.043
CASE REPORT CHIH-HSUN LEE ET AL.
POSTERIOR CEREBRAL ARTERY PSEUDOANEURYSM
resolution of perforator aneurysms of the posterior circulation. J Neurosurgery 121:1107-1111, 2014. 2. Chang SW, Abla AA, Kakarla UK, Sauvageau E, Dashti SR, Nakaji P, Zabramski JM, Albuquerque FC, McDougall CG, Spetzler RF: Treatment of distal posterior cerebral artery aneurysms: a critical appraisal of the occipital artery-to posterior cerebral artery bypass. Neurosurgery 67:16-26, 2010. 3. Charalampaki P, Ayyad A, Alfons Kockro R, Perneczky A: Surgical complications after endoscopic transsphenoidal pituitary surgery. J Clin Neurosci 16:786-789, 2009. 4. Ciceri EF, Regna-Gladin C, Erbetta A, Chiapparini L, Nappini S, Savoriardo M, Di Meco F: Iatrogenic intracranial pseudoaneurysms: neuroradiological and therapeutical considerations, including endovascular options. Neurol Sci 27:317-322, 2006. Figure 3. (A) Magnetic resonance angiography (MRA) performed 3 weeks later showed no visible aneurysm. (B) MRA was performed each year for 3 years after the operation and no aneurysm were found.
received external ventricular drain placement but the patient’s condition worsened, with declining mental status. Superior cerebellar artery-posterior cerebral bypass and aneurysm trapped were performed later. The patient recovered steadily with mild left hemiparesis. Another patient was treated with parent artery occlusion, but the patient died of intracranial hypertension. In our experience, we controlled the patient’s blood pressure and prevented the catastrophic hemorrhage. We also treated the hemorrhage-associated intracranial hypertension after aneurysm bleeding. Fortunately, the patient stabilized and the PCA aneurysm resolved spontaneously without surgical or endovascular treatment. Iatrogenic injury, including vascular and nerve injuries, usually occur during aggressive dissection of pituitary tumors, especially when the tumor extends to the surrounding space. As in our case, a large pituitary tumor extending upward or backward may result in adhesion or encasement of surrounding blood vessels. In these situations, gentle and careful curettage and
dissection should be considered to prevent related vascular or nerve injuries. In conclusion, iatrogenic vascular injury with pseudoaneurysm formation is a rare but serious event they may result in mortality or severe neurologic morbidity. According to the current case, dissection should be performed carefully and gently in pituitary tumors that are out-pouching or involve upward or backward extension. Aggressive dissection should be preformed carefully because of the high risk of vascular injury with intracranial hemorrhage. Direct surgical treatment for posterior circulation pseudoaneurysm is challenging, and endovascular therapy can be an effective alternative for iatrogenic vascular injuries. In some situations, especially without intracranial hypertension or progressive hemorrhage, conservative treatment with regular image follow-up could be an effective treatment.
5. Ciric I, Ragin A, Baumgartner C, Pierce D: Complications of transsphenoidal surgery: results of a national survey review of the literature and personal experience. Neurosurg 40:225-237, 1997. 6. Kadyrov KA, Friedman JA, Nichols DA, CohenGadol AA, Link MJ, Piepgras DG: Endovascular treatment of an internal carotid artery pseudoaneurysm following transsphenoidal surgery. J Neurosurgery 96:624-627, 2002. 7. Laws ER Jr: Vascular complications of transsphenoidal surgery. Pituitary 2:163-170, 1999. 8. Rodríguez-Hernández A, Huang C, Lawton MT: Superior cerebellar artery-posterior cerebellar artery bypass: in situ bypass for posterior cerebral artery revascularization. J Neurosurg 118:1053-1057, 2013. 9. Taqi MA, Lazzaro MA, Pandya DJ, Badruddin A, Zaidat OO: Dissecting aneurysms of posterior cerebral artery: clinical presentation, angiographic findings, treatment, and outcome. Front Neurol 2: 38, 2011.
Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Received 21 January 2015; accepted 16 April 2015 Citation: World Neurosurg. (2015). http://dx.doi.org/10.1016/j.wneu.2015.04.043 Journal homepage: www.WORLDNEUROSURGERY.org
REFERENCES
Available online: www.sciencedirect.com
1. Adrien C, Pierre-Henri L, Pieere T, Catherine C, Aapolline K, Klaus M, Frederic R: Spontaneous
1878-8750/$ - see front matter ª 2015 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY - [-]: ---, MONTH 2015
www.WORLDNEUROSURGERY.org
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