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Endoscopic endonasal transclival approach to a pontine cavernous malformation: Case report
International Journal of Pediatric Otorhinolaryngology 79 (2015) 1584–1588
Contents lists available at ScienceDirect
International Journal of Pediatric Otorhinolaryngology journal homepage: www.elsevier.com/locate/ijporl
Case report
Endoscopic endonasal transclival approach to a pontine cavernous malformation: Case report Iacopo Dallan a,b, Paolo Battaglia b,c, Matteo de Notaris d, Michele Caniglia e, Mario Turri-Zanoni b,c,* a
Otorhinolaryngology 1st Unit, Azienda Ospedaliero—Universitaria Pisana, Pisa, Italy Head and Neck Surgery & Forensic Dissection Research Center (HNS&FDRc), University of Insubria, Varese, Italy Unit of Otorhinolaryngology, Department of Biotechnology and Life Sciences (DBSV), University of Insubria, Varese, Italy d Department of Neurosurgery, Azienda Ospedaliera G. Rummo, Benevento, Italy e Department of Neurosurgery, Azienda Ospedaliero—Universitaria Pisana, Pisa, Italy b c
A R T I C L E I N F O
A B S T R A C T
Article history: Received 15 April 2015 Received in revised form 16 June 2015 Accepted 18 June 2015 Available online 27 June 2015
Cavernous malformations of the brainstem are difficult to manage because of their location in eloquent tissue and their high propensity for symptomatic bleeding. Traditional neurosurgical approaches are often associated with significant morbidities. Here we present the case of a 15 year-old male patient with an acute onset of severe cephalalgia associated with neurological signs (right cranial nerve VI, VII and VIII palsies). MRI revealed a ventral pontine cavernous malformation with signs of recent bleeding. The lesion was removed by way of an endoscopic endonasal transclival approach. Post-operative neurological examination showed a dramatic improvement in cranial nerves function. The patient remains stable two years after surgery. ß 2015 Elsevier Ireland Ltd. All rights reserved.
Keywords: Brainstem hemorrhage Cavernoma Endonasal Endoscopic Skull Base Transclival
1. Introduction Brainstem cavernous malformations (BCM) are rare, benign, vascular lesions which have a great propensity for symptomatic bleeding, estimated at around 6% per year [1]. This high bleeding rate associated as it is with the compact eloquent brainstem structure makes BCM worthy of significant attention. Despite being histologically benign, BCM should be considered risky lesions which not infrequently demonstrate clinically malignant behavior. Historically, BCM have been resected through traditional neurosurgical approaches such as orbito-zygomatic-pterional, suboccipital, retrosigmoid, lateral supracerebellar infratentorial and far-lateral craniotomy [2,3]. Morbidity associated with these approaches has generally been related to the damage inflicted while entering the dorsal brainstem to remove intra-axial or ventrally placed lesions. As a result, the management of BCM is
* Corresponding author at: Unit of Otorhinolaryngology, Department of Biotechnology and Life Sciences (DBSV), University of Insubria, Via Guicciardini 9, Varese, Italy. Tel.: +39 0332 393278; fax: +39 0332 393279. E-mail address: [email protected] (M. Turri-Zanoni). http://dx.doi.org/10.1016/j.ijporl.2015.06.024 0165-5876/ß 2015 Elsevier Ireland Ltd. All rights reserved.
challenging and careful evaluation of the risks of high surgical morbidity as opposed to those of repeated hemorrhages should be undertaken. Recently, transnasal resection of selected BCM has been proposed, reporting encouraging outcomes and reduced morbidity for the patients [4,5]. Herein we present a case of symptomatic ventral pontine cavernous malformation managed through an endoscopic endonasal transclival approach. Surgical tricks and technical nuances are given and a pertinent literature review is presented. Written informed consent was obtained from the patient’s parents for the publication of this report and any accompanying images. 2. Case report 2.1. History A 15 year-old male patient presented in the Emergency Department with acute onset of severe cephalalgia with vomiting and neurological signs including diplopia, sudden hearing loss and facial palsy. Emergent CT scan showed a hemorrhage in the pons and cerebellum. Magnetic resonance imaging (MRI) revealed a one centimetre contrast-enhanced exophytic lesion in the
I. Dallan et al. / International Journal of Pediatric Otorhinolaryngology 79 (2015) 1584–1588
ventromedial pons, eccentric to the right side and consistent with a BCM with a diffuse hematoma involving the pons and middle cerebellar peduncle. The lesion reached the ventral surface of the pons but clear definition of the margins of the lesion was difficult (Fig. 1A–C). Given the very anterior location, a transclival approach was proposed. Preoperative counseling included extensive discussion with the patient and his parents about the risks of surgery as opposed to the possibility of future re-bleeding resulting in further loss of function. 2.2. Operation The patient was placed supine on the operating table with his head in slight extension and rotated 158 toward the surgeon’s side. Close cooperation between otolaryngologists and neurosurgeons using the two nostrils and four hands technique when performing the operation simultaneously was of added advantage in all surgical phases. The surgical procedure started with the bilateral harvesting of the pedicled nasoseptal flaps which were elevated and stored each in the ipsilateral maxillary sinus. Partial middle turbinectomy and removal of the posterior half of the nasal septum were then performed in order to create adequate space for a two-nostrils four hands operation. The anterior wall and the floor of the sphenoid sinus were removed, exposing the clival region. The clivus was then drilled down to the clival periosteum in the midline. The spheno-clival synchondorosis was visualized and removed. A small amount of bone was left on the paraclival carotids as we did not expect to need a larger window. Basilar plexus was adequately coagulated and the dura was cut in a right paramedian position, exposing the pontine region.
1585
An ecchymotic and swollen pons, in very close relationship with clival dura was seen once the dural window was completed. The hematoma pushed the basilar artery toward the left side. A small corticectomy was performed on the right paramedian pons and the intrapontine hematoma was evacuated (Fig. 2A–D). The core of the cavernoma was identified, with difficulty given the recent bleeding inside the pons, and removed as much as possible, stopping once the yellowish color of the healthy parenchyma was seen. Subtotal resection of the cavernoma was finally achieved. Throughout the procedure a magnetic navigation imageguidance system (Medtronic Navigation, Inc, Louisville, Colorado) was used. Skull base reconstruction was performed in a multilayer fashion by inserting fat tissue and autologous ilio-tibial tract intradurally. Another fascial layer was placed extracranially and reinforced with fat. Then the bilateral vascularized pedicled nasoseptal flaps were overlaid to complete the skull base reconstruction (Fig. 2E and F). The flaps were gently pressed to evacuate any air bubbles or vacuum space that may have been interposed in the skull base reconstruction and finally they were fixed with fibrin glue and buttressed with Gelfoam pledgets (Pharmacia, Kalamazoo, MI, USA). Nasal packing was placed bilaterally on the floor of the nasal cavities solely to ensure hemostasis as it was not needed to hold the skull base reconstruction. 2.3. Post-operative course After surgery, the patient was observed in the neurosurgical intensive care unit. An early postoperative CT scan showed the absence of major complications. Nasal packing was removed on the
Fig. 1. Preoperative MR imaging scans in axial (A and B) and sagittal (C) view of the ventral pontine cavernous malformation, in right paramedian position. A hypointense hemosiderin ring (pointed with red arrowheads) surrounding the hyperintense lesion (marked with white asterisk) was seen on T2-weightened sequences due to a diffusion of iron from red cells, confirming the clinical suspicion of a recent hemorrhagic episodes. The postoperative MR imaging scans (D–F) performed 1 year after surgery confirmed the complete removal of the lesion. Legend: BA, basilar artery; ICA, internal carotid artery). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
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Fig. 2. Endoscopic endonasal views of the intraoperative phases (A–E) and of the postoperative control three months after surgery (F). The yellow arrows point at the pontine cavernoma, exposed through a transclival window. Legend: NSF, nasoseptal flap; P pons; PCFd, dura mater of the posterior cranial fossa; SS, sphenoid sinus. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
third postoperative day. The patient was discharged home ten days after surgery. 2.4. Follow-up No post-operative CSF leakage was observed during follow up. Neurological examination two months after surgery revealed a dramatic improvement of the VI, VII and VIII cranial nerves’ palsy/ dysfunction (Figs. 3 and 4). At his two-year follow-up examination, the patient was clinically stable with no neurological deficits. His last MRI study showed a stable minimal residual of cavernous malformation in the deep right paramedian pons (Fig. 1D–F). After careful discussion with the patient’s parents and, given the well known potential complications associated with surgery, it was decided not to proceed to a second surgery and to continue with the clinical and radiological follow up. 3. Discussion Brainstem cavernomas have recently been classified as lowflow and low-pressure venous malformations by the International Society for the Study of Vascular anomalies (ISSVA) [6]. This supports the concept that these are benign vascular lesions which only displace surrounding brain tissue. However they do also
demonstrate a high risk of bleeding and rebleeding with subsequent neurologic sequelae. For this reason the management of BCM is challenging and the balance between the benefits of resection should be weighed against the possible morbidity resulting from surgery. The treatment of intrinsic and ventrally situated brainstem cavernoma is exceptionally complex because surgical removal through traditional approaches can be risky, even in skilled hands, given the need to pass through potential eloquent areas. As a possible alternative, brainstem cavernous malformations which are not suitable for surgery may be managed with stereotactic radiosurgery [7]. Unfortunately the real impact of this treatment in preventing re-bleeding is unproven and the following adverse radiation events are at present uncertain due to the limited experiences available in the literature [2]. Furthermore, for such a very young patient as ours this solution would not seem to be the first option. At present, indications for the surgical removal of brainstem cavernoma include progressive neurological deficits, critical presentation such as coma or cardiopulmonary instability, and overt acute or subacute hemorrhage on MRI [8]. The risks and benefits associated with surgical resection of brainstem cavernous malformations were well highlighted by Gross et al. in a metaanalysis of 1390 surgical cases treated through external approaches and which obtained a 91% rate of complete excision with a mortality rate of 1.5% [9]. With regard to the timing of surgery after a hemorrhage episode, although some authors advocate delaying surgery until the subacute phase when the blood products will undergo liquefaction, waiting much beyond the first several weeks could risk the development of gliosis, which may hinder a complete resection of the cavernoma [1]. It was for this reason that we decided to undertake the surgery some days after acute onset. The choice of surgical approach has to be tailored to each individual patient and based upon the location of the cavernoma within the brainstem, focusing on where the lesion has reached the brainstem surface. External approaches provide access to the antero-lateral brainstem but in cases of ventrally placed cavernoma they carry the risk of non-negligible morbidities. This is because of the necessity of traversing a greater width of normal brainstem tissue to access the cavernoma, whichever side is chosen for approach. In cases of ventral pontine cavernous malformation such as that described here, the shortest distance between the cavernoma and normal brainstem is undoubtedly the direct ventral approach. For this reason the transoral transclival approach was proposed by Reisch et al. in a report on two successfully treated cases, as minimizing the intraoperative trauma to eloquent nervous structures and subsequent morbidity for the patients [10]. Recently, advances in endoscopic techniques and equipment enable surgeons to approach such areas using the transnasal corridor, without the need to pass through normal brainstem tissue and also avoiding brain retraction or cranial nerve manipulation [4,5]. However, the endoscopic endonasal approach to the pontine region presents some technical difficulties and requires considerable skill and expertise. First of all, control of bleeding is usually challenging via the endonasal corridor. In particular, the surgeon has to manage carefully the pronounced vascularity of the basilar plexus between the periosteum and the dura which is generally associated with significant intraoperative bleeding that may be controlled with the aid of bipolar forceps or hemostatic agents. In addition, the endoscopic endonasal resection is associated with considerable risk of CSF leakage that represents the most common complication of this approach as demonstrated by recent case-reports in which this technique was employed to treat
I. Dallan et al. / International Journal of Pediatric Otorhinolaryngology 79 (2015) 1584–1588
1587
Fig. 3. Preoperative (A and B) and postoperative (C and D) neurologic examination, showing the dramatic improvement of the cranial nerve VI function after surgery.
pontine lesions [4,5]. It is worth noting that over the years the rates of CSF-leakage have decreased significantly with the advent of vascularized pedicled flaps, refinements in surgical techniques and specific instrumentation [11]. In this regard, the routine use of lumbar drainage after endoscopic skull base repair is controversial. In our hands the use of lumbar drain is limited to very selected cases (intracranial hypertension or intraoperative third ventricle opening) and in the case here presented it was not necessary. When operating in the brainstem, the avoidance of injury to normal nervous tissue is paramount but the line between
respecting the brainstem parenchyma and achieving the complete removal of the lesion is often very fine. In this case, after the corticectomy the hematoma was partially evacuated and the anterior wall of the cavernoma identified. The lesion was then gently taken out in a piecemeal fashion from the brainstem. Unfortunately the presence of blood in various degree of degeneration associated with a swollen pons made the recognition of the deeper cleavage plane difficult and we stopped the resection once the yellowish color of the healthy brainstem tissue was visualized. As a matter of fact, on the basis of this case, we are not sure that an early surgery could be considered easier and more effective, in terms of radicality, than a delayed surgery. Another key point in such a surgery is to preserve the developmental venous anomalies, which are invariably present all around the cavernous malformation, because, if a large venous plexus is occluded, brainstem venous infarction may produce clinically significant deficits [9]. That was our aim in this case. At our patient’s two-year follow-up, MRI evaluation confirmed the subtotal resection of the cavernoma with a stable residual part in the deep right paramedian pons. Clinically speaking the patient is well and no clinical signs of VI and VII cranial nerve deficit are present. After a careful discussion with the parents of the patient and given the well known possible complications associated with surgery, we have decided not to proceed to a second surgery and to continue with the clinical and radiological follow up. 4. Conclusion
Fig. 4. Preoperative (A and B) and postoperative (C and D) neurologic examination, showing the dramatic improvement of the cranial nerve VII function after surgery.
The aim of surgery in BCM is to create as small and minimallyinvasive corridor as feasible according to a ‘‘minimal access’’ technique. In accordance with this philosophy, in cases of ventrally located cavernomas the endoscopic endonasal transclival corridor should be considered as a possible alternative to traditional neurosurgical approaches as it offers reduced postoperative morbidity with a short hospitalization time. This kind of surgery should only be performed by very skilled surgeons and in carefully selected cases.
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I. Dallan et al. / International Journal of Pediatric Otorhinolaryngology 79 (2015) 1584–1588
Conflict of interest statement All the authors certify that they have no conflict of interest or financial relationship with any entity mentioned in the paper. Acknowledgment No sponsor is involved in the paper. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.ijporl.2015.06.024.
[3] [4]
[5]
[6] [7]
[8] [9]
References [10] [1] J.C. Mai, D. Ramanathan, L.J. Kim, L.N. Sekhar, Surgical resection of cavernous malformations of the brainstem: evolution of a minimally invasive technique, World Neurosurg. 79 (2013) 691–703. [2] A.A. Abla, G.P. Lekovic, J.D. Turner, J.G. de Oliveira, R. Porter, R.F. Spetzler, Advances in the treatment and outcome of brainstem cavernous malformation
[11]
surgery: a single-center case series of 300 surgically treated patients, Neurosurgery 68 (2011) 403–414. A.A. Abla, R.F. Spetzler, Brainstem cavernoma surgery: the state of the art, World Neurosurg. 80 (2013) 44–46. M.R. Sanborn, M.J. Kramarz, P.B. Storm, N.D. Adappa, J.N. Palmer, J.Y. Lee, Endoscopic, endonasal, transclival resection of a pontine cavernoma: case report, Neurosurgery 71 (2012) 198–203. M.M. Kimball, S.B. Lewis, J.W. Werning, J.D. Mocco, Resection of a pontine cavernous malformation via an endoscopic endonasal approach: a case report, Neurosurgery 71 (2012) 186–193. P. Wo´jcicki, K. Wo´jcicka, Epidemiology, diagnostics and treatment of vascular tumours and malformations, Adv. Clin. Exp. Med. 23 (2014) 475–484. L.D. Lunsford, A.A. Khan, A. Niranjan, H. Kano, J.C. Flickinger, D. Kondziolka, Stereotactic radiosurgery for symptomatic solitary cerebral cavernous malformations considered high risk for resection, J. Neurosurg. 113 (2010) 23–29. C.C. Wang, A. Liu, J.T. Zhang, B. Sun, Y.L. Zhao, Surgical management of brain-stem cavernous malformations: report of 137 cases, Surg. Neurol. 59 (2003) 444–454. B.A. Gross, H.H. Batjer, I.A. Awad, B.R. Bendok, R. Du, Brainstem cavernous malformations: 1390 surgical cases from the literature, World Neurosurg. 80 (2013) 89–93. R. Reisch, M. Bettag, A. Perneczky, Transoral transclival removal of anteriorly placed cavernous malformations of the brainstem, Surg. Neurol. 56 (2001) 106–115. C.H. Snyderman, H. Pant, R.L. Carrau, D. Prevedello, P. Gardner, A.B. Kassam, What are the limits of endoscopic sinus surgery? The expanded endonasal approach to the skull base, Keio J. Med. 58 (2009) 152–160.
Contents lists available at ScienceDirect
International Journal of Pediatric Otorhinolaryngology journal homepage: www.elsevier.com/locate/ijporl
Case report
Endoscopic endonasal transclival approach to a pontine cavernous malformation: Case report Iacopo Dallan a,b, Paolo Battaglia b,c, Matteo de Notaris d, Michele Caniglia e, Mario Turri-Zanoni b,c,* a
Otorhinolaryngology 1st Unit, Azienda Ospedaliero—Universitaria Pisana, Pisa, Italy Head and Neck Surgery & Forensic Dissection Research Center (HNS&FDRc), University of Insubria, Varese, Italy Unit of Otorhinolaryngology, Department of Biotechnology and Life Sciences (DBSV), University of Insubria, Varese, Italy d Department of Neurosurgery, Azienda Ospedaliera G. Rummo, Benevento, Italy e Department of Neurosurgery, Azienda Ospedaliero—Universitaria Pisana, Pisa, Italy b c
A R T I C L E I N F O
A B S T R A C T
Article history: Received 15 April 2015 Received in revised form 16 June 2015 Accepted 18 June 2015 Available online 27 June 2015
Cavernous malformations of the brainstem are difficult to manage because of their location in eloquent tissue and their high propensity for symptomatic bleeding. Traditional neurosurgical approaches are often associated with significant morbidities. Here we present the case of a 15 year-old male patient with an acute onset of severe cephalalgia associated with neurological signs (right cranial nerve VI, VII and VIII palsies). MRI revealed a ventral pontine cavernous malformation with signs of recent bleeding. The lesion was removed by way of an endoscopic endonasal transclival approach. Post-operative neurological examination showed a dramatic improvement in cranial nerves function. The patient remains stable two years after surgery. ß 2015 Elsevier Ireland Ltd. All rights reserved.
Keywords: Brainstem hemorrhage Cavernoma Endonasal Endoscopic Skull Base Transclival
1. Introduction Brainstem cavernous malformations (BCM) are rare, benign, vascular lesions which have a great propensity for symptomatic bleeding, estimated at around 6% per year [1]. This high bleeding rate associated as it is with the compact eloquent brainstem structure makes BCM worthy of significant attention. Despite being histologically benign, BCM should be considered risky lesions which not infrequently demonstrate clinically malignant behavior. Historically, BCM have been resected through traditional neurosurgical approaches such as orbito-zygomatic-pterional, suboccipital, retrosigmoid, lateral supracerebellar infratentorial and far-lateral craniotomy [2,3]. Morbidity associated with these approaches has generally been related to the damage inflicted while entering the dorsal brainstem to remove intra-axial or ventrally placed lesions. As a result, the management of BCM is
* Corresponding author at: Unit of Otorhinolaryngology, Department of Biotechnology and Life Sciences (DBSV), University of Insubria, Via Guicciardini 9, Varese, Italy. Tel.: +39 0332 393278; fax: +39 0332 393279. E-mail address: [email protected] (M. Turri-Zanoni). http://dx.doi.org/10.1016/j.ijporl.2015.06.024 0165-5876/ß 2015 Elsevier Ireland Ltd. All rights reserved.
challenging and careful evaluation of the risks of high surgical morbidity as opposed to those of repeated hemorrhages should be undertaken. Recently, transnasal resection of selected BCM has been proposed, reporting encouraging outcomes and reduced morbidity for the patients [4,5]. Herein we present a case of symptomatic ventral pontine cavernous malformation managed through an endoscopic endonasal transclival approach. Surgical tricks and technical nuances are given and a pertinent literature review is presented. Written informed consent was obtained from the patient’s parents for the publication of this report and any accompanying images. 2. Case report 2.1. History A 15 year-old male patient presented in the Emergency Department with acute onset of severe cephalalgia with vomiting and neurological signs including diplopia, sudden hearing loss and facial palsy. Emergent CT scan showed a hemorrhage in the pons and cerebellum. Magnetic resonance imaging (MRI) revealed a one centimetre contrast-enhanced exophytic lesion in the
I. Dallan et al. / International Journal of Pediatric Otorhinolaryngology 79 (2015) 1584–1588
ventromedial pons, eccentric to the right side and consistent with a BCM with a diffuse hematoma involving the pons and middle cerebellar peduncle. The lesion reached the ventral surface of the pons but clear definition of the margins of the lesion was difficult (Fig. 1A–C). Given the very anterior location, a transclival approach was proposed. Preoperative counseling included extensive discussion with the patient and his parents about the risks of surgery as opposed to the possibility of future re-bleeding resulting in further loss of function. 2.2. Operation The patient was placed supine on the operating table with his head in slight extension and rotated 158 toward the surgeon’s side. Close cooperation between otolaryngologists and neurosurgeons using the two nostrils and four hands technique when performing the operation simultaneously was of added advantage in all surgical phases. The surgical procedure started with the bilateral harvesting of the pedicled nasoseptal flaps which were elevated and stored each in the ipsilateral maxillary sinus. Partial middle turbinectomy and removal of the posterior half of the nasal septum were then performed in order to create adequate space for a two-nostrils four hands operation. The anterior wall and the floor of the sphenoid sinus were removed, exposing the clival region. The clivus was then drilled down to the clival periosteum in the midline. The spheno-clival synchondorosis was visualized and removed. A small amount of bone was left on the paraclival carotids as we did not expect to need a larger window. Basilar plexus was adequately coagulated and the dura was cut in a right paramedian position, exposing the pontine region.
1585
An ecchymotic and swollen pons, in very close relationship with clival dura was seen once the dural window was completed. The hematoma pushed the basilar artery toward the left side. A small corticectomy was performed on the right paramedian pons and the intrapontine hematoma was evacuated (Fig. 2A–D). The core of the cavernoma was identified, with difficulty given the recent bleeding inside the pons, and removed as much as possible, stopping once the yellowish color of the healthy parenchyma was seen. Subtotal resection of the cavernoma was finally achieved. Throughout the procedure a magnetic navigation imageguidance system (Medtronic Navigation, Inc, Louisville, Colorado) was used. Skull base reconstruction was performed in a multilayer fashion by inserting fat tissue and autologous ilio-tibial tract intradurally. Another fascial layer was placed extracranially and reinforced with fat. Then the bilateral vascularized pedicled nasoseptal flaps were overlaid to complete the skull base reconstruction (Fig. 2E and F). The flaps were gently pressed to evacuate any air bubbles or vacuum space that may have been interposed in the skull base reconstruction and finally they were fixed with fibrin glue and buttressed with Gelfoam pledgets (Pharmacia, Kalamazoo, MI, USA). Nasal packing was placed bilaterally on the floor of the nasal cavities solely to ensure hemostasis as it was not needed to hold the skull base reconstruction. 2.3. Post-operative course After surgery, the patient was observed in the neurosurgical intensive care unit. An early postoperative CT scan showed the absence of major complications. Nasal packing was removed on the
Fig. 1. Preoperative MR imaging scans in axial (A and B) and sagittal (C) view of the ventral pontine cavernous malformation, in right paramedian position. A hypointense hemosiderin ring (pointed with red arrowheads) surrounding the hyperintense lesion (marked with white asterisk) was seen on T2-weightened sequences due to a diffusion of iron from red cells, confirming the clinical suspicion of a recent hemorrhagic episodes. The postoperative MR imaging scans (D–F) performed 1 year after surgery confirmed the complete removal of the lesion. Legend: BA, basilar artery; ICA, internal carotid artery). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
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Fig. 2. Endoscopic endonasal views of the intraoperative phases (A–E) and of the postoperative control three months after surgery (F). The yellow arrows point at the pontine cavernoma, exposed through a transclival window. Legend: NSF, nasoseptal flap; P pons; PCFd, dura mater of the posterior cranial fossa; SS, sphenoid sinus. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
third postoperative day. The patient was discharged home ten days after surgery. 2.4. Follow-up No post-operative CSF leakage was observed during follow up. Neurological examination two months after surgery revealed a dramatic improvement of the VI, VII and VIII cranial nerves’ palsy/ dysfunction (Figs. 3 and 4). At his two-year follow-up examination, the patient was clinically stable with no neurological deficits. His last MRI study showed a stable minimal residual of cavernous malformation in the deep right paramedian pons (Fig. 1D–F). After careful discussion with the patient’s parents and, given the well known potential complications associated with surgery, it was decided not to proceed to a second surgery and to continue with the clinical and radiological follow up. 3. Discussion Brainstem cavernomas have recently been classified as lowflow and low-pressure venous malformations by the International Society for the Study of Vascular anomalies (ISSVA) [6]. This supports the concept that these are benign vascular lesions which only displace surrounding brain tissue. However they do also
demonstrate a high risk of bleeding and rebleeding with subsequent neurologic sequelae. For this reason the management of BCM is challenging and the balance between the benefits of resection should be weighed against the possible morbidity resulting from surgery. The treatment of intrinsic and ventrally situated brainstem cavernoma is exceptionally complex because surgical removal through traditional approaches can be risky, even in skilled hands, given the need to pass through potential eloquent areas. As a possible alternative, brainstem cavernous malformations which are not suitable for surgery may be managed with stereotactic radiosurgery [7]. Unfortunately the real impact of this treatment in preventing re-bleeding is unproven and the following adverse radiation events are at present uncertain due to the limited experiences available in the literature [2]. Furthermore, for such a very young patient as ours this solution would not seem to be the first option. At present, indications for the surgical removal of brainstem cavernoma include progressive neurological deficits, critical presentation such as coma or cardiopulmonary instability, and overt acute or subacute hemorrhage on MRI [8]. The risks and benefits associated with surgical resection of brainstem cavernous malformations were well highlighted by Gross et al. in a metaanalysis of 1390 surgical cases treated through external approaches and which obtained a 91% rate of complete excision with a mortality rate of 1.5% [9]. With regard to the timing of surgery after a hemorrhage episode, although some authors advocate delaying surgery until the subacute phase when the blood products will undergo liquefaction, waiting much beyond the first several weeks could risk the development of gliosis, which may hinder a complete resection of the cavernoma [1]. It was for this reason that we decided to undertake the surgery some days after acute onset. The choice of surgical approach has to be tailored to each individual patient and based upon the location of the cavernoma within the brainstem, focusing on where the lesion has reached the brainstem surface. External approaches provide access to the antero-lateral brainstem but in cases of ventrally placed cavernoma they carry the risk of non-negligible morbidities. This is because of the necessity of traversing a greater width of normal brainstem tissue to access the cavernoma, whichever side is chosen for approach. In cases of ventral pontine cavernous malformation such as that described here, the shortest distance between the cavernoma and normal brainstem is undoubtedly the direct ventral approach. For this reason the transoral transclival approach was proposed by Reisch et al. in a report on two successfully treated cases, as minimizing the intraoperative trauma to eloquent nervous structures and subsequent morbidity for the patients [10]. Recently, advances in endoscopic techniques and equipment enable surgeons to approach such areas using the transnasal corridor, without the need to pass through normal brainstem tissue and also avoiding brain retraction or cranial nerve manipulation [4,5]. However, the endoscopic endonasal approach to the pontine region presents some technical difficulties and requires considerable skill and expertise. First of all, control of bleeding is usually challenging via the endonasal corridor. In particular, the surgeon has to manage carefully the pronounced vascularity of the basilar plexus between the periosteum and the dura which is generally associated with significant intraoperative bleeding that may be controlled with the aid of bipolar forceps or hemostatic agents. In addition, the endoscopic endonasal resection is associated with considerable risk of CSF leakage that represents the most common complication of this approach as demonstrated by recent case-reports in which this technique was employed to treat
I. Dallan et al. / International Journal of Pediatric Otorhinolaryngology 79 (2015) 1584–1588
1587
Fig. 3. Preoperative (A and B) and postoperative (C and D) neurologic examination, showing the dramatic improvement of the cranial nerve VI function after surgery.
pontine lesions [4,5]. It is worth noting that over the years the rates of CSF-leakage have decreased significantly with the advent of vascularized pedicled flaps, refinements in surgical techniques and specific instrumentation [11]. In this regard, the routine use of lumbar drainage after endoscopic skull base repair is controversial. In our hands the use of lumbar drain is limited to very selected cases (intracranial hypertension or intraoperative third ventricle opening) and in the case here presented it was not necessary. When operating in the brainstem, the avoidance of injury to normal nervous tissue is paramount but the line between
respecting the brainstem parenchyma and achieving the complete removal of the lesion is often very fine. In this case, after the corticectomy the hematoma was partially evacuated and the anterior wall of the cavernoma identified. The lesion was then gently taken out in a piecemeal fashion from the brainstem. Unfortunately the presence of blood in various degree of degeneration associated with a swollen pons made the recognition of the deeper cleavage plane difficult and we stopped the resection once the yellowish color of the healthy brainstem tissue was visualized. As a matter of fact, on the basis of this case, we are not sure that an early surgery could be considered easier and more effective, in terms of radicality, than a delayed surgery. Another key point in such a surgery is to preserve the developmental venous anomalies, which are invariably present all around the cavernous malformation, because, if a large venous plexus is occluded, brainstem venous infarction may produce clinically significant deficits [9]. That was our aim in this case. At our patient’s two-year follow-up, MRI evaluation confirmed the subtotal resection of the cavernoma with a stable residual part in the deep right paramedian pons. Clinically speaking the patient is well and no clinical signs of VI and VII cranial nerve deficit are present. After a careful discussion with the parents of the patient and given the well known possible complications associated with surgery, we have decided not to proceed to a second surgery and to continue with the clinical and radiological follow up. 4. Conclusion
Fig. 4. Preoperative (A and B) and postoperative (C and D) neurologic examination, showing the dramatic improvement of the cranial nerve VII function after surgery.
The aim of surgery in BCM is to create as small and minimallyinvasive corridor as feasible according to a ‘‘minimal access’’ technique. In accordance with this philosophy, in cases of ventrally located cavernomas the endoscopic endonasal transclival corridor should be considered as a possible alternative to traditional neurosurgical approaches as it offers reduced postoperative morbidity with a short hospitalization time. This kind of surgery should only be performed by very skilled surgeons and in carefully selected cases.
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Conflict of interest statement All the authors certify that they have no conflict of interest or financial relationship with any entity mentioned in the paper. Acknowledgment No sponsor is involved in the paper. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.ijporl.2015.06.024.
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