Case Report
e271
Endonasal Endoscopic Release of a Delayed Tension Pneumocephalus After Craniofacial Resection of a Tumor of the Anterior Skull Base Allan Vescan3
Christian Zweifel1
1 Division of Neurosurgery, Toronto Western Hospital, University of
Toronto, Toronto, Ontario, Canada 2 Department of Neurosurgery, University of Tübingen, Tübingen, Germany 3 Department of Otolaryngology–Head and Neck Surgery, University of Toronto, Toronto, Ontario, Canada
Gelareh Zadeh1
Fred Gentili1
Address for correspondence Boris Krischek, MD, PhD, Department of Neurosurgery, University of Cologne, Kerpener Strasse 62, Cologne, 50937, Germany (e-mail: [email protected]).
J Neurol Surg A 2013;74(Suppl 1):e271–e274.
Abstract
Keywords
► tension pneumocephalus ► endonasal endoscopic approach ► craniofacial resection ► pericranial flap
Tension pneumocephalus is a rare complication that can occur after craniofacial resection of lesions of the anterior skull base. Early diagnosis is important to avoid potential serious neurologic deficits, including death. It has been associated with the perioperative placement of a lumbar drainage and with esthesioneuroblastoma. Therapy consists of evacuation of the intracranial air as well as conservative measures. Here we report a case of a patient with an ethmoidal esthesioneuroblastoma who underwent a traditional microsurgical craniofacial resection and developed a delayed epidural tension pneumocephalus. This was treated by performing an incision in the pericranial flap covering the anterior cranial base defect using an endonasal endoscopic approach. To our knowledge, this particular treatment technique has not been reported before in this context.
Introduction Craniofacial resections of lesions of the anterior skull base may give rise to complications such as tension pneumocephalus that result in significant morbidity and mortality. Tension pneumocephalus represents a rare but potentially fatal sequela of a direct communication between the paranasal sinuses and the intracranial vault.1,2 A certain degree of intracranial air is normal after craniotomy; however, persistent, expanding, or spontaneously developing pneumocephalus represents a pathophysiological mechanism with the potential for significant consequences for the patient.1 Previous reports of tension pneumocephalus as a consequence of craniofacial resection of lesions of the anterior skull base described treatment consisting of needle aspiration in combination with conservative measures such as placing the patient in the supine or head-down position and inhalation of highly concentrated oxygen.2
received September 18, 2012 accepted after revision April 2, 2013 published online October 24, 2013
We present a case of a delayed symptomatic epidural tension pneumocephalus after craniofacial resection of a tumor of the anterior skull base. The treatment consisted of endonasal endoscopic incision of the pericranial flap that was covering the anterior cranial base defect after the initial surgery. To our knowledge, this has not been described previously.
Case Report A 74-year-old woman had presented with nasal obstruction. Investigation revealed the presence of a paranasal sinus lesion (►Fig. 1). An initial biopsy led to the preliminary diagnosis of esthesioneuroblastoma. Three-dimensional imaging confirmed that the lesion had transgressed the skull base with an intracranial component. The patient underwent preoperative radiation therapy. At the end of her therapy, surgical resection was planned. Because of the involvement of the intracranial compartment and extension over and
© 2013 Georg Thieme Verlag KG Stuttgart · New York
DOI http://dx.doi.org/ 10.1055/s-0033-1349337. ISSN 2193-6315.
This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.
Boris Krischek1,2
Endonasal Endoscopic Release of a Delayed Tension Pneumocephalus
Krischek et al.
Fig. 1 T1-weighted magnetic resonance images with gadolinium on coronal (A) and sagittal (B) views showing the transbasal and transdural breakthrough of the esthesioneuroblastoma and involvement of the lamina papyracea of the left side.
involvement of the orbit, it was thought that this would not be a case feasible for endoscopic resection. The patient underwent a bicoronal transbasal craniotomy and total removal of the skull-based olfactory neuroblastoma and an en bloc tumor removal in the paranasal sinuses with ethmoidectomies and sphenoidotomies. Subsequently, the dural defect was covered with fascia lata and the skull base defect was covered with a pericranial flap. There were no immediate postoperative complications. The postoperative computed tomography (CT) showed intracranial air in the anterior fossa. Neurologically, the patient recovered well. There were no signs of obtundation during the further course of her hospital stay. The final histopathologic diagnosis was olfactory neuroblastoma, with remaining positive margins in the right ethmoid area as well as periorbitally on the left side. Intraoperatively, the margins had been reported as negative. A routine magnetic resonance
imaging (MRI) was performed 2 weeks after surgical resection showing residual intracranial air divided into two compartments, possibly by the dura (►Fig. 2). At the time, the patient had no new neurologic deficits. Eight weeks after the initial surgery, the patient presented to the emergency department with a decreased level of consciousness (Glasgow Coma Scale score 13). According to her husband, the patient had a cold a few days earlier and had experienced several sneezing spells. CT and MRI showed a significant increase of the intracranial air compared with the previous imaging, without any signs for an intracranial abscess (►Figs. 3 and 4). There was no history of cerebrospinal fluid (CSF) leak. The patient underwent endonasal endoscopic exploration of the postoperative skull base defect. The pericranial flap that was used to cover the anterior skull base defect was bulging inferiorly under tension. The flap was incised, which led to an instant
Fig. 2 Radiologic follow-up 2 weeks after surgery. Axial (A), sagittal (B), and coronal (C) T1-weighted magnetic resonance images with gadolinium showing intracranial air in two compartments that were possibly separated by the dura (arrows). Journal of Neurological Surgery—Part A
Vol. 74
Suppl. 1/2013
This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.
e272
Krischek et al.
Fig. 3 Eight weeks after surgery, axial (A) and sagittal (B) computed tomography images showing compression of the frontal lobes by the epidural air entrapment and the large bony defect after resection of the anterior skull base.
deflation while making a hissing sound, and thereby the tension was released. Further intracranial endoscopic inspection beyond the pericranial flap allowed visualization of the previous watertight closure of the dural defect. Further skull base or dural reconstruction was not necessary. Bilateral nasal trumpets were sewn into the anterior nasal septum to avoid further increased intracranial pressure (ICP). A postoperative CT scan (►Fig. 5) showed a marked decrease of the previously noted intracranial air. During follow-up in the clinic 4 weeks later, the patient was doing well.
Discussion In general, there are two accepted theories for the development of tension pneumocephalus. The first is the “inverted
bottle mechanism” in which there is a pressure gradient between the intracranial compartment and the extracranial compartment, leading to a volume replacement by air (e.g., CSF leak).3 The air in these cases is mostly intracerebrally. In our case, the air was purely epidural, and there was no clinical sign of a CSF leak. The second mechanism is the “ball valve mechanism” in which the pressure in the extracranial compartment is temporarily increased (e.g., by sneezing, coughing, blowing the nose) and thereby forces air through a defect (path of least resistance) that is then entrapped. In this case, the dural defect after tumor resection was patched with fascia lata, leading to a water-tight closure, and the extensive skull base defect along the anterior fossa was covered with pericranium. The air was entrapped between the pericranium and the dura (►Figs. 3 and 4). Most probably there
Fig. 4 Postoperative T1-weighted axial (A) and sagittal (B) magnetic resonance images with gadolinium showing the epidural tension pneumocephalus. Journal of Neurological Surgery—Part A
Vol. 74
Suppl. 1/2013
e273
This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.
Endonasal Endoscopic Release of a Delayed Tension Pneumocephalus
Endonasal Endoscopic Release of a Delayed Tension Pneumocephalus
Krischek et al.
and the administration of oxygen at a high concentration (nitrogen washout).2 A further step that was described was then to drain the air via a preexisting burr hole (in the case of previous craniofacial resection) by fine-needle aspiration or catheter drainage via a close water-seal drainage system.6 Because of the accessibility, in our case, the endoscopic incision of the “air-entrapping“ pericranial flap was sufficient to relieve the patient of the space-occupying lesion. The overall use of lumbar drains during conventional craniofacial resection seems to have decreased, which could lead to an overall reduction of the advent of tension pneumocephalus.7 Furthermore, it is possible that the occurrence of the craniofacial resection–associated tension pneumocephalus has been further decreased because more recently the progress of endoscopic skull base surgery allows an endonasal resection of malignancies of the sinonasal tract and anterior skull base lesions, which until a few years ago were only amenable to microscopic craniofacial surgery.8,9 Fig. 5 Sagittal computed tomography images 8 weeks after endonasal endoscopic release of the tension pneumocephalus.
was an entry site (ball valve) that allowed air to get into this space during bursts of increased pressure in the sinonasal tract (e.g., sneezing).The entrapped air was then unable to escape; it accumulated under pressure and behaved as a space-occupying lesion displacing and compressing the adjacent brain. This led to displacement of the frontal lobes and compression and effacement of the ventricular system. The actual defect was not identifiable on imaging, nor was it visualized later during the endoscopic inspection. The incision into the pericranial flap was sufficient to decompress the entrapped air. Tension pneumocephalus has been described to be associated with craniofacial resection with a frequency of up to 10%.2 Wanamaker et al describe their experience in 2 cases out of a series of 45 craniofacial resections that they treated with needle aspiration through an existing burr hole. They had proposed routine perioperative airway diversion (tracheostomy) because of the difficulty of obtaining an airtight closure after skull base reconstruction. The procedure diverts the airstream and prevents the development of tension pneumocephalus.2 However, cases of tension pneumocephalus have occurred despite airway diversion.4 In 1994, Yates et al described a case series of 22 craniofacial operations, of which 7 developed pneumocephalus, and out of those, 2 developed a tension pneumocephalus. In these cases, the use of lumbar drainage correlated strongly with tension pneumocephalus as well as the diagnosis of esthesioneuroblastoma.5 Depending on the severity of the increased ICP, typical management includes airway control, hyperventilation, fluid restriction, and osmotic diuresis. Also, if there is a lumbar drain in place, it is clamped because as CSF drains, air can enter the cranial cavity via potential cranial–dural defects, thus potentiating the tension pneumocephalus. In the presence of increased ICP, continued spinal fluid drainage can increase the risk of brain herniation.5 In less acute situations, the treatment of tension pneumocephalus can be begun with placing the patient placed in supine or head-down position Journal of Neurological Surgery—Part A
Vol. 74
Suppl. 1/2013
Conclusion Tension pneumocephalus can be a life-threatening complication that may occur in association with craniofacial resection of anterior skull base lesions or other anterior skull base surgeries. It should be treated promptly upon diagnosis. It requires decompression. In case of anterior epidural air entrapment this could be easily achieved through endonasal endoscopic release. Conflict of Interest None
References 1 Clark DW, Citardi MJ, Fakhri S. Endoscopic management of skull
2
3
4
5
6
7
8
9
base defects associated with persistent pneumocephalus following previous open repair: a preliminary report. Otolaryngol Head Neck Surg 2010;142(6):820–826 Wanamaker JR, Mehle ME, Wood BG, Lavertu P. Tension pneumocephalus following craniofacial resection. Head Neck 1995;17 (2):152–156 Campanelli J, Odland R. Management of tension pneumocephalus caused by endoscopic sinus surgery. Otolaryngol Head Neck Surg 1997;116(2):247–250 Price JC, Loury M, Carson B, Johns ME. The pericranial flap for reconstruction of anterior skull base defects. Laryngoscope 1988;98(11):1159–1164 Yates H, Hamill M, Borel CO, Toung TJ. Incidence and perioperative management of tension pneumocephalus following craniofacial resection. J Neurosurg Anesthesiol 1994;6(1):15–20 Arbit E, Shah J, Bedford R, Carlon G. Tension pneumocephalus: treatment with controlled decompression via a closed water-seal drainage system. Case report. J Neurosurg 1991;74(1):139–142 Cantu G, Solero CL, Miceli R, et al. Anterior craniofacial resection for malignant paranasal tumors: a monoinstitutional experience of 366 cases. Head Neck 2012;34(1):78–87 Nicolai P, Battaglia P, Bignami M, et al. Endoscopic surgery for malignant tumors of the sinonasal tract and adjacent skull base: a 10-year experience. Am J Rhinol 2008;22(3):308–316 Nicolai P, Castelnuovo P, Bolzoni Villaret A. Endoscopic resection of sinonasal malignancies. Curr Oncol Rep 2011;13(2):138–144
This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.
e274
Copyright of Journal of Neurological Surgery. Part A. Central European Neurosurgery is the property of Georg Thieme Verlag Stuttgart and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
Copyright of Journal of Neurological Surgery. Part A. Central European Neurosurgery is the property of Georg Thieme Verlag Stuttgart and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
e271
Endonasal Endoscopic Release of a Delayed Tension Pneumocephalus After Craniofacial Resection of a Tumor of the Anterior Skull Base Allan Vescan3
Christian Zweifel1
1 Division of Neurosurgery, Toronto Western Hospital, University of
Toronto, Toronto, Ontario, Canada 2 Department of Neurosurgery, University of Tübingen, Tübingen, Germany 3 Department of Otolaryngology–Head and Neck Surgery, University of Toronto, Toronto, Ontario, Canada
Gelareh Zadeh1
Fred Gentili1
Address for correspondence Boris Krischek, MD, PhD, Department of Neurosurgery, University of Cologne, Kerpener Strasse 62, Cologne, 50937, Germany (e-mail: [email protected]).
J Neurol Surg A 2013;74(Suppl 1):e271–e274.
Abstract
Keywords
► tension pneumocephalus ► endonasal endoscopic approach ► craniofacial resection ► pericranial flap
Tension pneumocephalus is a rare complication that can occur after craniofacial resection of lesions of the anterior skull base. Early diagnosis is important to avoid potential serious neurologic deficits, including death. It has been associated with the perioperative placement of a lumbar drainage and with esthesioneuroblastoma. Therapy consists of evacuation of the intracranial air as well as conservative measures. Here we report a case of a patient with an ethmoidal esthesioneuroblastoma who underwent a traditional microsurgical craniofacial resection and developed a delayed epidural tension pneumocephalus. This was treated by performing an incision in the pericranial flap covering the anterior cranial base defect using an endonasal endoscopic approach. To our knowledge, this particular treatment technique has not been reported before in this context.
Introduction Craniofacial resections of lesions of the anterior skull base may give rise to complications such as tension pneumocephalus that result in significant morbidity and mortality. Tension pneumocephalus represents a rare but potentially fatal sequela of a direct communication between the paranasal sinuses and the intracranial vault.1,2 A certain degree of intracranial air is normal after craniotomy; however, persistent, expanding, or spontaneously developing pneumocephalus represents a pathophysiological mechanism with the potential for significant consequences for the patient.1 Previous reports of tension pneumocephalus as a consequence of craniofacial resection of lesions of the anterior skull base described treatment consisting of needle aspiration in combination with conservative measures such as placing the patient in the supine or head-down position and inhalation of highly concentrated oxygen.2
received September 18, 2012 accepted after revision April 2, 2013 published online October 24, 2013
We present a case of a delayed symptomatic epidural tension pneumocephalus after craniofacial resection of a tumor of the anterior skull base. The treatment consisted of endonasal endoscopic incision of the pericranial flap that was covering the anterior cranial base defect after the initial surgery. To our knowledge, this has not been described previously.
Case Report A 74-year-old woman had presented with nasal obstruction. Investigation revealed the presence of a paranasal sinus lesion (►Fig. 1). An initial biopsy led to the preliminary diagnosis of esthesioneuroblastoma. Three-dimensional imaging confirmed that the lesion had transgressed the skull base with an intracranial component. The patient underwent preoperative radiation therapy. At the end of her therapy, surgical resection was planned. Because of the involvement of the intracranial compartment and extension over and
© 2013 Georg Thieme Verlag KG Stuttgart · New York
DOI http://dx.doi.org/ 10.1055/s-0033-1349337. ISSN 2193-6315.
This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.
Boris Krischek1,2
Endonasal Endoscopic Release of a Delayed Tension Pneumocephalus
Krischek et al.
Fig. 1 T1-weighted magnetic resonance images with gadolinium on coronal (A) and sagittal (B) views showing the transbasal and transdural breakthrough of the esthesioneuroblastoma and involvement of the lamina papyracea of the left side.
involvement of the orbit, it was thought that this would not be a case feasible for endoscopic resection. The patient underwent a bicoronal transbasal craniotomy and total removal of the skull-based olfactory neuroblastoma and an en bloc tumor removal in the paranasal sinuses with ethmoidectomies and sphenoidotomies. Subsequently, the dural defect was covered with fascia lata and the skull base defect was covered with a pericranial flap. There were no immediate postoperative complications. The postoperative computed tomography (CT) showed intracranial air in the anterior fossa. Neurologically, the patient recovered well. There were no signs of obtundation during the further course of her hospital stay. The final histopathologic diagnosis was olfactory neuroblastoma, with remaining positive margins in the right ethmoid area as well as periorbitally on the left side. Intraoperatively, the margins had been reported as negative. A routine magnetic resonance
imaging (MRI) was performed 2 weeks after surgical resection showing residual intracranial air divided into two compartments, possibly by the dura (►Fig. 2). At the time, the patient had no new neurologic deficits. Eight weeks after the initial surgery, the patient presented to the emergency department with a decreased level of consciousness (Glasgow Coma Scale score 13). According to her husband, the patient had a cold a few days earlier and had experienced several sneezing spells. CT and MRI showed a significant increase of the intracranial air compared with the previous imaging, without any signs for an intracranial abscess (►Figs. 3 and 4). There was no history of cerebrospinal fluid (CSF) leak. The patient underwent endonasal endoscopic exploration of the postoperative skull base defect. The pericranial flap that was used to cover the anterior skull base defect was bulging inferiorly under tension. The flap was incised, which led to an instant
Fig. 2 Radiologic follow-up 2 weeks after surgery. Axial (A), sagittal (B), and coronal (C) T1-weighted magnetic resonance images with gadolinium showing intracranial air in two compartments that were possibly separated by the dura (arrows). Journal of Neurological Surgery—Part A
Vol. 74
Suppl. 1/2013
This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.
e272
Krischek et al.
Fig. 3 Eight weeks after surgery, axial (A) and sagittal (B) computed tomography images showing compression of the frontal lobes by the epidural air entrapment and the large bony defect after resection of the anterior skull base.
deflation while making a hissing sound, and thereby the tension was released. Further intracranial endoscopic inspection beyond the pericranial flap allowed visualization of the previous watertight closure of the dural defect. Further skull base or dural reconstruction was not necessary. Bilateral nasal trumpets were sewn into the anterior nasal septum to avoid further increased intracranial pressure (ICP). A postoperative CT scan (►Fig. 5) showed a marked decrease of the previously noted intracranial air. During follow-up in the clinic 4 weeks later, the patient was doing well.
Discussion In general, there are two accepted theories for the development of tension pneumocephalus. The first is the “inverted
bottle mechanism” in which there is a pressure gradient between the intracranial compartment and the extracranial compartment, leading to a volume replacement by air (e.g., CSF leak).3 The air in these cases is mostly intracerebrally. In our case, the air was purely epidural, and there was no clinical sign of a CSF leak. The second mechanism is the “ball valve mechanism” in which the pressure in the extracranial compartment is temporarily increased (e.g., by sneezing, coughing, blowing the nose) and thereby forces air through a defect (path of least resistance) that is then entrapped. In this case, the dural defect after tumor resection was patched with fascia lata, leading to a water-tight closure, and the extensive skull base defect along the anterior fossa was covered with pericranium. The air was entrapped between the pericranium and the dura (►Figs. 3 and 4). Most probably there
Fig. 4 Postoperative T1-weighted axial (A) and sagittal (B) magnetic resonance images with gadolinium showing the epidural tension pneumocephalus. Journal of Neurological Surgery—Part A
Vol. 74
Suppl. 1/2013
e273
This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.
Endonasal Endoscopic Release of a Delayed Tension Pneumocephalus
Endonasal Endoscopic Release of a Delayed Tension Pneumocephalus
Krischek et al.
and the administration of oxygen at a high concentration (nitrogen washout).2 A further step that was described was then to drain the air via a preexisting burr hole (in the case of previous craniofacial resection) by fine-needle aspiration or catheter drainage via a close water-seal drainage system.6 Because of the accessibility, in our case, the endoscopic incision of the “air-entrapping“ pericranial flap was sufficient to relieve the patient of the space-occupying lesion. The overall use of lumbar drains during conventional craniofacial resection seems to have decreased, which could lead to an overall reduction of the advent of tension pneumocephalus.7 Furthermore, it is possible that the occurrence of the craniofacial resection–associated tension pneumocephalus has been further decreased because more recently the progress of endoscopic skull base surgery allows an endonasal resection of malignancies of the sinonasal tract and anterior skull base lesions, which until a few years ago were only amenable to microscopic craniofacial surgery.8,9 Fig. 5 Sagittal computed tomography images 8 weeks after endonasal endoscopic release of the tension pneumocephalus.
was an entry site (ball valve) that allowed air to get into this space during bursts of increased pressure in the sinonasal tract (e.g., sneezing).The entrapped air was then unable to escape; it accumulated under pressure and behaved as a space-occupying lesion displacing and compressing the adjacent brain. This led to displacement of the frontal lobes and compression and effacement of the ventricular system. The actual defect was not identifiable on imaging, nor was it visualized later during the endoscopic inspection. The incision into the pericranial flap was sufficient to decompress the entrapped air. Tension pneumocephalus has been described to be associated with craniofacial resection with a frequency of up to 10%.2 Wanamaker et al describe their experience in 2 cases out of a series of 45 craniofacial resections that they treated with needle aspiration through an existing burr hole. They had proposed routine perioperative airway diversion (tracheostomy) because of the difficulty of obtaining an airtight closure after skull base reconstruction. The procedure diverts the airstream and prevents the development of tension pneumocephalus.2 However, cases of tension pneumocephalus have occurred despite airway diversion.4 In 1994, Yates et al described a case series of 22 craniofacial operations, of which 7 developed pneumocephalus, and out of those, 2 developed a tension pneumocephalus. In these cases, the use of lumbar drainage correlated strongly with tension pneumocephalus as well as the diagnosis of esthesioneuroblastoma.5 Depending on the severity of the increased ICP, typical management includes airway control, hyperventilation, fluid restriction, and osmotic diuresis. Also, if there is a lumbar drain in place, it is clamped because as CSF drains, air can enter the cranial cavity via potential cranial–dural defects, thus potentiating the tension pneumocephalus. In the presence of increased ICP, continued spinal fluid drainage can increase the risk of brain herniation.5 In less acute situations, the treatment of tension pneumocephalus can be begun with placing the patient placed in supine or head-down position Journal of Neurological Surgery—Part A
Vol. 74
Suppl. 1/2013
Conclusion Tension pneumocephalus can be a life-threatening complication that may occur in association with craniofacial resection of anterior skull base lesions or other anterior skull base surgeries. It should be treated promptly upon diagnosis. It requires decompression. In case of anterior epidural air entrapment this could be easily achieved through endonasal endoscopic release. Conflict of Interest None
References 1 Clark DW, Citardi MJ, Fakhri S. Endoscopic management of skull
2
3
4
5
6
7
8
9
base defects associated with persistent pneumocephalus following previous open repair: a preliminary report. Otolaryngol Head Neck Surg 2010;142(6):820–826 Wanamaker JR, Mehle ME, Wood BG, Lavertu P. Tension pneumocephalus following craniofacial resection. Head Neck 1995;17 (2):152–156 Campanelli J, Odland R. Management of tension pneumocephalus caused by endoscopic sinus surgery. Otolaryngol Head Neck Surg 1997;116(2):247–250 Price JC, Loury M, Carson B, Johns ME. The pericranial flap for reconstruction of anterior skull base defects. Laryngoscope 1988;98(11):1159–1164 Yates H, Hamill M, Borel CO, Toung TJ. Incidence and perioperative management of tension pneumocephalus following craniofacial resection. J Neurosurg Anesthesiol 1994;6(1):15–20 Arbit E, Shah J, Bedford R, Carlon G. Tension pneumocephalus: treatment with controlled decompression via a closed water-seal drainage system. Case report. J Neurosurg 1991;74(1):139–142 Cantu G, Solero CL, Miceli R, et al. Anterior craniofacial resection for malignant paranasal tumors: a monoinstitutional experience of 366 cases. Head Neck 2012;34(1):78–87 Nicolai P, Battaglia P, Bignami M, et al. Endoscopic surgery for malignant tumors of the sinonasal tract and adjacent skull base: a 10-year experience. Am J Rhinol 2008;22(3):308–316 Nicolai P, Castelnuovo P, Bolzoni Villaret A. Endoscopic resection of sinonasal malignancies. Curr Oncol Rep 2011;13(2):138–144
This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.
e274
Copyright of Journal of Neurological Surgery. Part A. Central European Neurosurgery is the property of Georg Thieme Verlag Stuttgart and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
Copyright of Journal of Neurological Surgery. Part A. Central European Neurosurgery is the property of Georg Thieme Verlag Stuttgart and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
