British Journal of Neurosurgery, December 2014; 28(6): 802–804 © 2014 The Neurosurgical Foundation ISSN: 0268-8697 print / ISSN 1360-046X online DOI: 10.3109/02688697.2014.918581
SHORT REPORT
Endoscopic endonasal resection of large skull base schwannoma Salima Sofia Wahab1, Ashok Rokade2, Salil Nair2 & Nijaguna V. Mathad1 1Department of Neurosurgery, Wessex Neurological Centre, Southampton University Hospital, Southampton, UK,
and 2Department of Ear Nose and Throat Surgery, Royal Hampshire County Hospital, Winchester, UK
both sphenopalatine arteries (SPA) were injected with 2% Xylocaine with adrenaline (1 in 80,000). Image guidance was employed. Both middle turbinates were amputated. A left nasospetal flap (NSF) was elevated based on the posterior septal vessels. This was tucked into the left maxillary sinus. A large posterior septectomy was created, by removing the omer and perpendicular plate of the ethmoid. The right septal mucosa was trimmed posteriorly and swung across the midline and sutured anteriorly to the left septal incision and thus covering the exposed septal cartilage. This manoeuvre significantly reduces postoperative crusting that can occur following the harvesting of a NSF. Bilateral frontoethmoidectomies were performed. On the right side a medial maxillectomy was performed. The right SPA was identified, cauterised and divided. The posterior wall of the maxillary sinus was gently removed to expose the tumour within the pterygopalatine fossa (PPF) and extending laterally into the infratemporal fossa. The tumour had expanded to obliterate the fat of the retromaxillary space. The sphenoid ostium was identified. The anterior face, rostrum and floor were removed with a combination of Kerrison punches and a diamond burr. The sphenoid was opened widely from the planum sphenoidale superiorly to the orbital apex laterally on the left side. Once the bony exposure was complete, the tumour was incised and an intra-tumoural debulking undertaken (Fig. 2). The tumour capsule was carefully dissected from the left internal carotid artery, followed by the right cavernous sinus and finally from the medial temporal dura. There was no evidence of a CSF leak. The right lateral tumour extension was delivered by gentle medial traction and capsular dissection. The only persistent attachment to the tumour was by a thin nerve at the junction of the horizontal and vertical portion of the internal carotid artery. This nerve was divided to achieve total excision of the tumour. The exposed medial temporal dura, PPF and adjacent sphenoid were covered with the nasoseptal flap, Surgicell® (Ethicon) squares and Tisseal. A dissolvable nasal dressing was used to provide some internal support.
Abstract Schwannomas of the skull base can pose a surgical challenge due to their anatomical location. To date extensive craniofacial approaches have had to be used to access these lesions. We present a patient where an expanded endoscopic endonasal approach was used to address a large skull base schwannoma with good results. The approach confers significantly less morbidity and a substantially shorter hospital stay. Keywords: endoscopy; endonasal; schwannoma; skull base
Introduction Schwannomas of the skull base can pose a significant management dilemma when planning a surgical approach for resection. We present a case where an expanded endoscopic endonasal approach was used to resect such a large skull base lesion. Improved instrumentation, and collaborative working between neurosurgical and otolaryngology colleagues, has fostered greater understanding of the relevant anatomy and facilitated techniques in the endoscopic endonasal approach.
Case presentation A previously fit and well 36-year-old man presented with transient diplopia. Clinical examination did not reveal any neurological deficits. An MRI scan (Fig. 1) revealed a large central skull base tumour occupying the sphenoid sinus and right pterygopalatine fossa, with displacement of the cavernous sinus and extension into the right middle cranial fossa. An endoscopic biopsy confirmed schwannoma. Following discussion at the regional Skull Base Multidisciplinary Meeting, the patient was offered the option of an endoscopic endonasal or transfacial approach. He opted for endonasal surgery. The nasal cavity was prepared with a mixture of topical adrenaline (1 in 10,000), 4% cocaine hydrochloride and saline on neuropatties. The axilla of the both middle turbinates, the anterior nasal septum and the region of the
Correspondence: Salima Sofia Wahab, Department of Neurosurgery, Wessex Neurological Centre, Southampton University Hospital, Tremona Road, Southampton SO16 6YD, UK. E-mail: [email protected] Received for publication 12 December 2013; accepted 21 April 2014
802
Endoscopic endonasal resection of large skull base schwannoma
803
Fig. 3. Post-operative magnetic resonance imaging demonstrating gross total resection of tumour.
Fig. 1. Pre-operative magnetic resonance imaging of large central skull base tumour.
Following surgery, the patient was encouraged to use Sinus Rinse (Neilmed Pharmaceuticals) four times daily for six weeks. Postoperative MRI scanning confirmed complete excision of the tumour (Fig. 3). Forty-eight hours following surgery the patient was discharged home. At follow-up there was some nasal debris and crusting, as one would expect following a routine sinus surgical procedure. This was cleared with endonasal suction. Currently, three years from his operation, he has minimal nasal symptoms such as dryness and crusting. Careful examination of his cranial nerves did not reveal any deficits.
Discussion The most common schwannomas of the skull base are vestibular schwannomas,1 followed by trigeminal schwannoma, which accounts for about 8% of intracranial schwannomas. Other schwannomas of the skull base and head and neck region are rarer, arising in the orbit, jugular foramen, nasal cavity, and olfactory nerve sheath. Depending on the location, size, and nerve of origin, they can manifest in a variety of motor and sensory symptoms, including muscle weakness, pain, numbness, parasthesia, and sensory deficit.
We believe that this schwannoma originated from the right vidian nerve. This is supported by a number of points, including, centring of the tumour on the pterygoid crest, attached nerve fibres at the genu of internal carotid artery, postoperative dryness of the nasal cavity and absence of sensory deficits in right V2 distribution. However, this patient does not have postoperative dryness of the eye as seen after vidian neurectomies. Schwannomas of the skull base provide a surgical challenge due to their anatomical location. Patients are usually offered a craniofacial approach for resection of tumours in this location. Depending on their location and extension different surgical approaches are employed for removal. These procedures include transfacial, transmaxillary, presigmoid, retrosigmoid, frontotemporal, trans-sylvian transtentorial, and subfrontal approaches. As nonvestibular schwannomas are less common, their resection strategies are not as thoroughly investigated. Previous studies on surgical treatments of nonvestibular schwannoma looked at microsurgical approaches or a combination of radiosurgery and microsurgery. In the Sarma et al.2 report of microsurgical resection of nonvestibular schwannomas, new cranial nerve deficits were observed in 24% of the patients, and the cerebrospinal fluid (CSF) leak occurred in 10.9% of patients. Neither of these two complications occurred in our patient. Improved four-handed surgical techniques in endoscopic endonasal skull base surgery have meant that this approach is increasingly being considered as a viable option to manage these lesions. Given the anatomical constraints, it is important to remember that this approach requires an experienced endoscopic skull base team. There is a technical learning curve. The endoscopic endonasal approach can provide direct access for tumours of the skull base. Resection through the endonasal corridor does not require brain retraction. There is reduced morbidity and shorter
Fig. 2. Intra-operative imaging demonstrating resection of tumour.
804 S. S. Wahab et al. hospital stays associated with this approach. Careful case selection of lesions in favourable anatomical sites is essential. There are only a few case reports where this approach has been used for these lesions. The largest series was reported by the Pittsburgh group.3 11 of the 17 patients reviewed in this study had a one-stage procedure using the endoscopic endonasal approach only. 80% of patients had gross total or near total (⬎ 90%) resection of tumours. Whether an extended endoscopic approach to the skull base is more effective than other conventional approaches requires a larger comparative case series, with longer follow-up and evaluation of patients over several years.
Declaration of interest: The authors report no declaration of interest. The authors alone are responsible for the content and writing of the paper.
References 1. Prabhu SS, Demonte F. Treatment of skull base tumors. Curr Opin Oncol 2003;15:209–12. 2. Sarma S, Sekhar LN, Schessel DA . Nonvestibular schwannomas of the brain: a 7-year experience. Neurosurgery 2002;50:437–48. 3. Shin SS, Gardner PA , Stefko ST, et al. Endoscopic endonasal approach for non-vestibular schwannomas. Neurosurgery 2011; 69:1046–57.
Copyright of British Journal of Neurosurgery is the property of Taylor & Francis Ltd 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.
SHORT REPORT
Endoscopic endonasal resection of large skull base schwannoma Salima Sofia Wahab1, Ashok Rokade2, Salil Nair2 & Nijaguna V. Mathad1 1Department of Neurosurgery, Wessex Neurological Centre, Southampton University Hospital, Southampton, UK,
and 2Department of Ear Nose and Throat Surgery, Royal Hampshire County Hospital, Winchester, UK
both sphenopalatine arteries (SPA) were injected with 2% Xylocaine with adrenaline (1 in 80,000). Image guidance was employed. Both middle turbinates were amputated. A left nasospetal flap (NSF) was elevated based on the posterior septal vessels. This was tucked into the left maxillary sinus. A large posterior septectomy was created, by removing the omer and perpendicular plate of the ethmoid. The right septal mucosa was trimmed posteriorly and swung across the midline and sutured anteriorly to the left septal incision and thus covering the exposed septal cartilage. This manoeuvre significantly reduces postoperative crusting that can occur following the harvesting of a NSF. Bilateral frontoethmoidectomies were performed. On the right side a medial maxillectomy was performed. The right SPA was identified, cauterised and divided. The posterior wall of the maxillary sinus was gently removed to expose the tumour within the pterygopalatine fossa (PPF) and extending laterally into the infratemporal fossa. The tumour had expanded to obliterate the fat of the retromaxillary space. The sphenoid ostium was identified. The anterior face, rostrum and floor were removed with a combination of Kerrison punches and a diamond burr. The sphenoid was opened widely from the planum sphenoidale superiorly to the orbital apex laterally on the left side. Once the bony exposure was complete, the tumour was incised and an intra-tumoural debulking undertaken (Fig. 2). The tumour capsule was carefully dissected from the left internal carotid artery, followed by the right cavernous sinus and finally from the medial temporal dura. There was no evidence of a CSF leak. The right lateral tumour extension was delivered by gentle medial traction and capsular dissection. The only persistent attachment to the tumour was by a thin nerve at the junction of the horizontal and vertical portion of the internal carotid artery. This nerve was divided to achieve total excision of the tumour. The exposed medial temporal dura, PPF and adjacent sphenoid were covered with the nasoseptal flap, Surgicell® (Ethicon) squares and Tisseal. A dissolvable nasal dressing was used to provide some internal support.
Abstract Schwannomas of the skull base can pose a surgical challenge due to their anatomical location. To date extensive craniofacial approaches have had to be used to access these lesions. We present a patient where an expanded endoscopic endonasal approach was used to address a large skull base schwannoma with good results. The approach confers significantly less morbidity and a substantially shorter hospital stay. Keywords: endoscopy; endonasal; schwannoma; skull base
Introduction Schwannomas of the skull base can pose a significant management dilemma when planning a surgical approach for resection. We present a case where an expanded endoscopic endonasal approach was used to resect such a large skull base lesion. Improved instrumentation, and collaborative working between neurosurgical and otolaryngology colleagues, has fostered greater understanding of the relevant anatomy and facilitated techniques in the endoscopic endonasal approach.
Case presentation A previously fit and well 36-year-old man presented with transient diplopia. Clinical examination did not reveal any neurological deficits. An MRI scan (Fig. 1) revealed a large central skull base tumour occupying the sphenoid sinus and right pterygopalatine fossa, with displacement of the cavernous sinus and extension into the right middle cranial fossa. An endoscopic biopsy confirmed schwannoma. Following discussion at the regional Skull Base Multidisciplinary Meeting, the patient was offered the option of an endoscopic endonasal or transfacial approach. He opted for endonasal surgery. The nasal cavity was prepared with a mixture of topical adrenaline (1 in 10,000), 4% cocaine hydrochloride and saline on neuropatties. The axilla of the both middle turbinates, the anterior nasal septum and the region of the
Correspondence: Salima Sofia Wahab, Department of Neurosurgery, Wessex Neurological Centre, Southampton University Hospital, Tremona Road, Southampton SO16 6YD, UK. E-mail: [email protected] Received for publication 12 December 2013; accepted 21 April 2014
802
Endoscopic endonasal resection of large skull base schwannoma
803
Fig. 3. Post-operative magnetic resonance imaging demonstrating gross total resection of tumour.
Fig. 1. Pre-operative magnetic resonance imaging of large central skull base tumour.
Following surgery, the patient was encouraged to use Sinus Rinse (Neilmed Pharmaceuticals) four times daily for six weeks. Postoperative MRI scanning confirmed complete excision of the tumour (Fig. 3). Forty-eight hours following surgery the patient was discharged home. At follow-up there was some nasal debris and crusting, as one would expect following a routine sinus surgical procedure. This was cleared with endonasal suction. Currently, three years from his operation, he has minimal nasal symptoms such as dryness and crusting. Careful examination of his cranial nerves did not reveal any deficits.
Discussion The most common schwannomas of the skull base are vestibular schwannomas,1 followed by trigeminal schwannoma, which accounts for about 8% of intracranial schwannomas. Other schwannomas of the skull base and head and neck region are rarer, arising in the orbit, jugular foramen, nasal cavity, and olfactory nerve sheath. Depending on the location, size, and nerve of origin, they can manifest in a variety of motor and sensory symptoms, including muscle weakness, pain, numbness, parasthesia, and sensory deficit.
We believe that this schwannoma originated from the right vidian nerve. This is supported by a number of points, including, centring of the tumour on the pterygoid crest, attached nerve fibres at the genu of internal carotid artery, postoperative dryness of the nasal cavity and absence of sensory deficits in right V2 distribution. However, this patient does not have postoperative dryness of the eye as seen after vidian neurectomies. Schwannomas of the skull base provide a surgical challenge due to their anatomical location. Patients are usually offered a craniofacial approach for resection of tumours in this location. Depending on their location and extension different surgical approaches are employed for removal. These procedures include transfacial, transmaxillary, presigmoid, retrosigmoid, frontotemporal, trans-sylvian transtentorial, and subfrontal approaches. As nonvestibular schwannomas are less common, their resection strategies are not as thoroughly investigated. Previous studies on surgical treatments of nonvestibular schwannoma looked at microsurgical approaches or a combination of radiosurgery and microsurgery. In the Sarma et al.2 report of microsurgical resection of nonvestibular schwannomas, new cranial nerve deficits were observed in 24% of the patients, and the cerebrospinal fluid (CSF) leak occurred in 10.9% of patients. Neither of these two complications occurred in our patient. Improved four-handed surgical techniques in endoscopic endonasal skull base surgery have meant that this approach is increasingly being considered as a viable option to manage these lesions. Given the anatomical constraints, it is important to remember that this approach requires an experienced endoscopic skull base team. There is a technical learning curve. The endoscopic endonasal approach can provide direct access for tumours of the skull base. Resection through the endonasal corridor does not require brain retraction. There is reduced morbidity and shorter
Fig. 2. Intra-operative imaging demonstrating resection of tumour.
804 S. S. Wahab et al. hospital stays associated with this approach. Careful case selection of lesions in favourable anatomical sites is essential. There are only a few case reports where this approach has been used for these lesions. The largest series was reported by the Pittsburgh group.3 11 of the 17 patients reviewed in this study had a one-stage procedure using the endoscopic endonasal approach only. 80% of patients had gross total or near total (⬎ 90%) resection of tumours. Whether an extended endoscopic approach to the skull base is more effective than other conventional approaches requires a larger comparative case series, with longer follow-up and evaluation of patients over several years.
Declaration of interest: The authors report no declaration of interest. The authors alone are responsible for the content and writing of the paper.
References 1. Prabhu SS, Demonte F. Treatment of skull base tumors. Curr Opin Oncol 2003;15:209–12. 2. Sarma S, Sekhar LN, Schessel DA . Nonvestibular schwannomas of the brain: a 7-year experience. Neurosurgery 2002;50:437–48. 3. Shin SS, Gardner PA , Stefko ST, et al. Endoscopic endonasal approach for non-vestibular schwannomas. Neurosurgery 2011; 69:1046–57.
Copyright of British Journal of Neurosurgery is the property of Taylor & Francis Ltd 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.
