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Meningocele and Meningoencephalocele of the Lateral Wall of Sphenoidal Sinus: The Role of the Endoscopic Endonasal Surgery
Accepted Manuscript Meningocele and meningo-encephalocele of the lateral wall of sphenoidal sinus: the role of the endoscopic endonasal surgery Matteo Zoli, Paolo Farneti, Michael Ghirelli, Marco Giulioni, Giorgio Frank, Diego Mazzatenta, Ernesto Pasquini PII:
S1878-8750(15)01515-6
DOI:
10.1016/j.wneu.2015.11.001
Reference:
WNEU 3392
To appear in:
World Neurosurgery
Received Date: 3 October 2015 Accepted Date: 1 November 2015
Please cite this article as: Zoli M, Farneti P, Ghirelli M, Giulioni M, Frank G, Mazzatenta D, Pasquini E, Meningocele and meningo-encephalocele of the lateral wall of sphenoidal sinus: the role of the endoscopic endonasal surgery, World Neurosurgery (2015), doi: 10.1016/j.wneu.2015.11.001. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Meningocele and meningo-encephalocele of the lateral wall of sphenoidal sinus: the role of the endoscopic endonasal surgery. Zoli Matteo, Farneti Paolo°, Ghirelli Michael*, Giulioni Marco^, Frank Giorgio, Mazzatenta Diego, Pasquini Ernesto*
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Center of surgery for pituitary tumors and endoscopic skull base surgery. Department of Neurosurgery. IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy. ° ENT Department, Sant’Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy * ENT Department, Azienda USL, Bologna, Italy * ^ Department of Neurosurgery. IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy
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The authors state that the content of the submitting manuscript, in part or in full, has not been published previously and has not been submitted elsewhere for review. There is no financial support received in conjunction with the generation of this submission and no conflict of interest. The Authors certify that this manuscript is a unique submission and is not being considered for publication with any other source in any medium. The Authors have nothing to declare and nothing to disclose. Correspondence to:
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Matteo Zoli, M.D., Centre of Pituitary Tumors and Endoscopic Skull Base Surgery, IRCCS Scienze Neurologiche, Bologna, Italy. Tel. +39 051 6225514 Fax + 39 051 6225347 e-mail: [email protected] Figures: Figures 1-3 are black and white.
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Key Words: Meningocele; meningoencephalocele; sphenoidal sinus; endoscopic endonasal approach, epilepsy; CSF leak; epileptic surgery
Abbreviations
EEA: endoscopic endonasal approach CSF: cerebro-spinal fluid LWSS: lateral wall of sphenoidal sinus MRI: magnetic resonance imaging
ACCEPTED MANUSCRIPT Abstract
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Backgrounds. Meningocele and meningo-encephalocele of the lateral wall of the sphenoidal sinus (LWSS) are rare lesions, crossing the borders of multiple disciplines such as Ear-Nose-Throat, maxillofacial and neurological surgery. We reviewed our surgical experience to analyze the role of the endoscopic endonasal approach (EEA) and consider these pathologies from different perspectives. Methods. All consecutive cases of meningocele and meningo-encephalocele of LWSS operated through an EEA since 1998 to 2015 in our Institutions have been collected. Medical history, focusing on previous episodes of CSF leak, meningitis or seizures, was considered. The outcome was assessed considering the medical condition and the post-operative neuroimaging. Results. The series includes 23 patients (7 males, 16 females). Mean age was 52 years (26-73). Eleven cases were meningo-encephaloceles and 12 meningoceles. A frank CSF leak occurred on in 19 patients and was associated to meningitis in 3. Two were presenting a history of epilepsy. No complications were observed but one case presented seizures at the awaking. At follow-up (mean 84 months, 4-167) each patient is in good clinical conditions with no further episodes of leaking or seizures. Conclusions. Endoscopic endonasal surgery is a safe and effective approach for meningocele and meningo-encephalocele of LWSS, allowing to resect the herniated tissue and repair the osteo-dural defect. The favorable clinical outcome and the possible effectiveness on seizures lead us to support this approach as first minimally invasive treatment also in presence of epilepsy, as a first low risk epilepsy surgical procedure.
Introduction Meningocele and meningo-encephalocele of the lateral wall of the sphenoidal sinus (LWSS) are a peculiar pathology which crosses the borders of multiple disciplines such as Ear-Nose-Throat (ENT), maxillofacial and neurological surgery (1,2,3). It is an example of how the same pathology
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considered from the different perspectives of each of these specialities can be differently approached, diagnosed and treated (1,2,3). It consists in the outbreaking into the sphenoidal sinus of fossa media dura layers with or without the involvement of brain parenchyma of the temporal lobe. In the ENT-focused literature, it has been reported in dozens of cases, and thus it can be considered an infrequent pathology (4-8). Conversely, it appears rarely in neurosurgical literature in just few scattered single case reports (9-12). More relevantly, in mainly ENT-focused literature the main reported symptom is represented by the CSF leak with meningitis requiring an urgent surgical procedure, on the other hand in the neurosurgical literature attention is more focused on epileptic seizures, caused by these brain herniations, and on the more effective elective surgical strategy to resolve this symptom (1-12). Therefore, the choice between the possible treatments, consisting in the endoscopic endonasal or in the craniotomic surgery, depends not only on the surgeon expertise with one technique, but also on his/her viewpoint. The first technique allows the resection of the herniated tissue and the repair of the bone and dura defects; the second one, apart from the repair of the cranio-meningeal defect, allows the surgeon to extend the resection not only to the herniated brain but also to the surrounding epileptogenic tissues. We reviewed our endoscopic endonasal surgical experience focusing on this controversial issue. Material and Methods
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All consecutive cases of meningocele or meningo-encephalocele of the LWSS operated on through an endoscopic endonasal approach from 1998 to April 2015 at the Center of pituitary and endoscopic skull base surgery of IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy, and ENT Departments of Bellaria Hospital, Bologna, Italy have been retrospectively collected. The presence of CSF leak at the hospital admission or in the previous times was analyzed. In all cases with frank rhinorrhea, a sample of fluid was collected and the Beta Trace Protein concentration was measured to confirm the suspect of CSF leak. In unclear cases, a pre-operative fluorescein test was performed, to avoid misdiagnosis. The medical history of the patient was also considered to identify previous episodes of meningitis. In case of suspect meningitis at the admission a lumbar puncture was performed to confirm the diagnosis and to orientate the antibiotic therapy on the basis of the cultural examination and of the antiobiogram. Furthermore, the medical history was evaluated for the presence of epileptic seizures. All patients undergone a tiny slices CT scan to delineate the bone defect at the skull base. A brain MRI was performed to assess the obliteration of the sphenoidal sinus by CSF or by herniated meninges and brain tissue and to consider the presence of potentially epileptogenic lesions in temporal lobes. Medical reports were analyzed to describe the post-operative course, the hospital staying time, and complications. All patients underwent a first nasal medical and surgical field toilette 30 days after surgery. Then, a CT scan and and/or MRI were repeated after 3 months to assess the repair of the meningocele or meningo-encephalocele. At this time, the medical conditions of the patient were re-assessed with particular attention to epileptic seizures. Afterward, clinical and neuroradiological follow-up was repeated annually, consisting in a MRI or CT scan, a nasal medication and a clinical examination of the patient. Surgical technique. The patient is placed under general anesthesia after oral intubation, and a topic nasal decongestion is performed with 5 % lidocainenaphazoline. An ethmoidotomy followed by wide middle antrostomy is performed on the side of the herniation. Then, the sphenotomy is carried out in order to visualize the defect present at the level of the lateral wall of the sphenoid sinus. At this time, two situations are needed to be considered differently: on one hand meningocele or meningo-encephalocele occupying the sphenoid sinus and eventually extended to the sphenoethmoidal area through the enlarged sphenoid ostium and, on the other, rare but often huge cerebral tissue herniation occupying beyond the sphenoidal sinus also the pterygopalatine and/or infratemporal fossa. In the first case to
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expose and control the bone defect, it is necessary to drill out the upper portion of pterygoid plate as much as possible to expose and control the lateral wall of the sphenoid sinus. The meningocele or meningo-encephalocele is subsequently isolated at the level of its lateral portion, and is cauterized and can be resected only when the presence of any arterial vessels in the herniated tissue is ruled out. When the latter condition occurs, the resection should be very cautious removing the erniated tissue and preserving the herniated vessel. In cases of wide pneumatization of the lateral recess of sphenoid sinus the drilling of the pterygoid process until the foramen rotundum can be enough to expose the meningocele or meningo-encephalocele, which are usually lateral to V2, and thus to repair the defect with mucoperiostium from the middle turbinate in overlay fashion with (for large bone defect) or without (for little bone defect) a piece of bone or cartilage inserted extradurally to buttress the graft (figure 1 a,b,c). Conversely, for cases with a poor pneumatization of the lateral recess of sphenoid sinus is necessary to drill out completely the upper portion of pterygoid plate with closure of sphenopalatine artery to gain sufficient working room. In these cases we prefer to close the defect with bone or cartilage, abdominal fat and covering mucoperiostium graft, excluding the lateral recess (figure 1 d,e,f). For uncommon cases of meningocele or meningo-encephalocele involving the pterygopalatine or infratemporal fossa, the necessary wider exposure can be performed through a combined transsphenoidal-transmaxillary approach, which requires the removal of the vertical portion of palatine bone, of the posterior wall of maxillary sinus and the harvesting of a posterior mucoperioriostial nasal septal flap connected to the vascular content of infratemporal fossa (Fig. 2 a,b,c). After the usual management of meningocele or meningo-encephalocele and the bone defect closure with bone or cartilage, the infratemporal or pterygopalatine fossae can be packed with abdominal fat, covered with the pterygomaxillary content and the posterior nasal septal flap (Fig. 2 d,e,f). Results
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The series consists of 23 patients, 7 were males and 16 were females. They underwent 24 surgical procedures, because one patient, affected by arrested hydrocephalus, presented a controlateral recurrence of meningocele (Table 1). Mean age was 52 years (median: 53, range: 26-73). In 11 cases (48%) the herniation was constituted by meningeal and brain tissues, while in 12 (52%) only by the meningeal sac with no brain involvement. CSF leak was the most common presenting symptom (Table 1). It occurred on in 19 cases (82%) and it was associated to meningitis in 3 (13%) cases. One patient presented with meningitis and intracranial hypertension without evidence of CSF leak. At pre-operative neuroimaging a pneumoencephalus was revealed, thus we argued a valve mechanism causing the meningitis and the intracranial hypertension. Other two patients arrived to our attention with no leak at moment but with a history of recurrent CSF leaks and meningitis misdiagnosed up to that time. One of these two was admitted in our hospital in a comatose state due to a meningoencephalitis. The other presented a focal epileptic seizures with secondary generalization and status epilepticus 10 days after the resolution of the last meningitic episode (pt. 22 in table 1). In a latter patient of our series, the meningoencephalocele was an incidental finding in a CT scan performed for other purposes. Among these 23 patients, two cases were presenting an history of epileptic seizures (Table 1). The first one (pt. 19 at table 1) presented her first epileptic attack of absence when she was 7 years old. The neurological investigations showed focal anomalies at electroencephalogram located in the left temporal lobe. At neuroimaging, a meningo-encephalocele of the left lateral wall of sphenoidal sinus, involving the left temporal lobe, was observed and she was suggested to start a medical therapy with carbamazepine (Fig. 3 a,b). The control of seizures was achieved and after 12 years of treatment, the medical therapy was discontinued, but she went to our attention few years later because she presented CSF leak and meningitis. The second (pt. 17 at table 1) presented the first absence crisis when she was 15 years old. Electroencephalographic investigations did not show any specific abnormalities, and a medical treatment with phenytoin was started. The medical treatment was discontinued after 17 years. In 2012, a right lateral wall meningoencephalocele was incidentally observed in a CT scan performed for a chronic sinusitis.
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At pre-operative MRI, no associated temporal lobe anomalies have been detected. Interestingly, the silvian fissure was wider than the contralateral in 15 cases (65%) (5 meningocele and 10 meningoencephalocele), and 5 (21%) ( 1 meningocele and 4 meningoencephalocele), were presenting an enlargement of ipsilateral temporal horn of the lateral ventricle. Twelve cases (52%) were on the left side and 11 (48%) on the right. In each case, the resection of the herniated tissue was performed and bone defect was identified and skeletonized. A multilayer closure with fascia lata, mucoperiustium and bone or fat or with the nasoseptal flap was performed in all cases. External lumbar drainage was adopted only in one case, in whom it was placed before the patient was referred to our attention. No complications were observed but one patient presented epileptic seizures at the awaking (pt. 17 at table 1). All patients presenting meningitis underwent antibiotic therapy up to the normalization of the bio-humoral and CSF parameters. No patients developed neurological sequelae, even the case presented with meningoencephalitis. At follow-up (mean 84 months, median: 85, range 4-167) all patients are in good clinical conditions with no further episodes of leaking or seizures. None required a revision surgery. Discussion
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The meningocele and meningoencephalocele of the LWSS consist in the herniation of the meninges alone or with brain tissue respectively, through a defect in the skull base. The location of the defect is specific in the parasellar area, in the lateral recess of the sphenoidal sinus, laterally to V2 course (1-9). From here the herniated tissue protrudes downward into the lateral recess of the sphenoid sinus and can involve also the ethmoidal sinuses or the pterygopalatine or infratemporal fossae (1319). The specificity of the location depends from the peculiar pathogenesis of this meningocele. Indeed, herniation is the consequence of a failure of ossification and fusion of ossifications centers of the sphenoid (18-20). Normally, at birth the embryonic portions of sphenoid bones fuse, leaving some cartilaginous portion corresponding to the future lateral wall of sphenoid sinus. The ossification of this cartilage occurs in the neonatal time. If fusion fails, a bony gap, located in the posterior part of sphenoid sinus and lateral to V2, called Sternberg canal or lateral craniopharyngeal canal, remains (18-20). The cartilage is however reabsorbed and only fibrous connective tissue fills the canal. During childhood, up to pubertal time, the sphenoid sinus enlarges, reaching its final pneumatization. If this bone reabsorption reaches the Sternberg canal, this represents a weak point, where more easily meningocele or meningo-encephalocele can occur (18-20). In uncommon cases the meningocele or meningo-encephalocele of the lateral wall of the sphenoid sinus can be acquired (traumatic or promoted by obesity, hydrocephalus or other causes of intracranial hypertension). Meningocele is rare and meningo-encephalocele is even rarer. In the literature single cases are mainly reported, while series are extremely uncommon and include few cases (1-13, 21-27). A prevalence in female is reported as confirmed in our series (males/females: 7/16) (21-22). It can be an incidental finding and a single similar case is present also in our series. Even in this circumstance the surgical treatment should be suggested to prevent meningitis and its possible serious and also fatal course. In symptomatic cases the most common clinical manifestation is represented by CSF leak, as observed in our series: actual CSF leak was present in 19 cases, while a history of previous CSF leak was referred in other two cases. Furthermore, in an additional patient with no evidence of CSF leak, a pneumocephalus was detectable, suggesting the presence of a communication between subarachnoid space and sphenoid sinus. Meningitis and meningo-encephalitis may be a complicating event. In our series meningitis was present in six cases, associated in all cases to an overt or suspected CSF leak. Epilepsy associated to meningocele or meningo-encephalocele, mainly in the form of temporal lobe seizures, sometimes refractory to the medical treatment, is rarer (312). It may be caused by the traction of the herniated tissue on the temporal lobe, or by associated malformations (heterotopia, diffuse cortical dysplasia and schizencephaly) (3-12, 28-34). In our series only two patients presented with a history of epilepsy. Also in these cases the endoscopic endonasal surgery has been preferred because it provides a direct, extra-cranial access to the lesion and
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does not require brain manipulation. The transpterygoid approach, as firstly suggested by Bolger in 2005, may represent the approach of choice for these lesions, allowing an excellent, direct and frontal exposure of the lateral recess of the sphenoid sinus and adeguate working room, avoiding any morbidity related to brain manipulation (9). Predictable sequelae may be trigeminal paresthesia (due to the manipulation of the maxillary nerve) and rarely tear dryness (due to vidian nerve manipulation). At the beginning of our experience we performed the plastic repair with the multilayer technique. Since a couple of years, we use, in selected case involving the pterygopalatine or infratemporal fossa, as outermost layer a naso-septal pedicled flap. Both techniques in our hands has proved to be effective, allowing to repair the CSF leak. A topic that has been poorly considered in literature is whether the endoscopic endonasal surgery, beyond its effective role in the CSF leak repair, could also represent an alternative to transcranial resective surgery for those patients presenting a temporal epilepsy (3). In a recent series, Saavalainen et al., reporting 23 patients with meningo-encephalocele and epilepsy, demonstrated that in a selected subgroup of this patients a more limited transcranial surgery, sparing the medial structures of temporal lobe, can give good results in terms of seizures control (35). Moreover, Faulkner et al. in 2010 had reported the use of endoscopic endonasal treatment in a meningo-encephalocele causing refractory epilepsy (3). These Authors demonstrated that a limited resection of the herniated brain through a ventral route could be enough to manage the associated epileptic seizure. Thus, they conclude that even in presence of epilepsy the endoscopic endonasal approach can be a valid and minimally invasive alternative to conventional transcranial surgery (3). Beyond its good tolerability, low complications rate and fast recovery time, it avoids the infrequent but serious complications related with the resective surgery on the temporal lobe (3-12, 28-34). In our series, there are only two patients with the association between meningo-encephalocele and seizures, representing the 9% of our patients. In both cases seizures were not refractory to medical treatment and surgery was performed with other aim. However, at follow-up, they did not present any further seizures. We admit that our data are partial and present multiple bias, not allowing us to try any conclusion on the role of endoscopic endonasal surgery in the treatment of epilepsy. However, this experience, which confirms Faulkner report, lead us to consider this type of surgery as a minimally invasive option than the conventional transcranial surgery for selected cases of meningo-encephalocele. In fact, the question on the role of endoscopic endonasal surgery to treat epilepsy is part of the broader, crucial and unresolved controversy on the treatment of epilepsy: should surgery be limited to resect the lesion or should it be extended to the epileptic foci (3,12,28-30,34)? To solve the controversy a wide series of cases treated with both methods, the endoscopic endonasal surgery and the transcranial surgery is necessary. In these cases, a complete epileptologic assessment, to determine the location of the epileptic foci in relationship to the meningo-encephalocele, is needed in order to select which cases can be suitable to the endoscopic endonasal lesion resection (3,35). Waiting a convincing scientific answer, our and Faulkner experience give support to the working hypothesis to adopt the endoscopic endonasal resection of the meningocele or meningo-encephalocele as first low risk epilepsy surgical procedure with the aim of treating the epileptic manifestations of these lesions in patient with no other epileptogenic temporal anomalies associated.
Conclusions
The meningocele and meningo-encephalocele of the lateral wall of sphenoid sinus are uncommon but potentially life-threatening diseases. They can be an incidental finding or may be symptomatic, presenting multiple clinical manifestations: mainly CSF leak and meningitis, more rarely seizures. Endoscopic endonasal surgery is a safe, effective, minimally invasive and well tolerated approach for these lesions, allowing to resect the herniated tissue and repair the dural and bone defect. Studies on the role of endoscopic endonasal technique in the management of patients with temporal lobe seizures are still lacking, but there are preliminary experiences supporting the use of this technique like a first low risk attempt.
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Fig. 1. Intra-operative images. 0° scope. A: Drilling of pterygoid plate to gain a more lateral access to sphenoidal sinus. B: The bone defect on the later wall of sphenoidal sinus is evident and the the herniated tissue is visible (in this case a pre-operative fluorescine test was performed). C: After resection of the meningocele, the bone defect is closed through multilayer technique and a piece of bone is placed. D: For cases with a poor pneumatization of the lateral recess of sphenoid sinus, the defect is closed with bone and covered with fat. E: the fat is then covered with a mucoperiostium graft, excluding the lateral recess. F: Schematic drawing of our closure technique for cases with poor pneumatization (blue line: dura, green line: piece of bone placed as closure, yellow: fat, red line: mucoperiostium).
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Fig. 2. Intra-operative images. 0° scope. A: Harvesting of the naso-septal flap. B: Enlarging the spheno-palatine foramen, to expose the pterygo-palatine artery, before drilling the vertical process of palatine bone. C: Coagulation and cut of the meningo-encephalocele. D: the bone defect on the lateral recess of the sphenoidal sinus is dissected. D: repair of the bone defect through the nasoseptal flap while the infratemporal or pterygopalatine fossae are packed with abdominal fat, covered with the pterygomaxillary content and the posterior nasal septal flap. F: Schematic drawing of our closure technique for cases meningocele or meningo-encephalocele involving the pterygopalatine or infratemporal fossa (red line: nasa-septal flap, green line: piece of bone or cartilage, blue line: middle fossa dura, yellow: pterygopalatine fossa fat).
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Fig. 3. MRI. T2 WI. A: axial view. B: coronal view. The meningoencephalocele of the left temporal lobe in the sphenoidal sinus and invading the pterygoplatine fossa is appreciable.
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Age
CSF Leak
Headache
Meningitis
Seizures
Herniation
Side
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F
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NO
NO
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M
64
YES
NO
NO
NO
MC
LEFT
3
F
68
YES
NO
NO
NO
ME
RIGHT
4*
M
62
YES
YES
NO
NO
MC
LEFT
5
F
52
YES
YES
NO
NO
ME
LEFT
6
F
45
YES
NO
NO
7
F
55
YES
NO
NO
8
F
63
YES
NO
NO
9
F
62
YES
NO
NO
10
F
60
YES
YES
NO
11
M
49
YES
NO
12
F
62
YES
13
F
49
YES
14
M
65
YES
15
F
26
NO
16
M
49
YES
17
F
37
NO
18
F
37
19
F
30
20
M
37
21
F
37
22
M
62
23
F
37
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PT
ME
LEFT
NO
MC
RIGHT
NO
ME
LEFT
NO
MC
RIGHT
NO
MC
LEFT
NO
NO
MC
RIGHT
NO
NO
NO
MC
LEFT
NO
NO
NO
MC
LEFT
NO
NO
NO
ME
LEFT
YES
YES
NO
MC
LEFT
YES
NO
NO
ME
LEFT
NO
NO
YES
ME
RIGHT
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NO
YES
YES
NO
ME
RIGHT
YES
YES
YES
YES
ME
LEFT
NO
YES
YES
NO
ME
RIGHT
YES
YES
YES
NO
MC
RIGHT
NO
YES
YES
YES
ME
RIGHT
YES
YES
NO
NO
MC
RIGHT
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YES
Table 1: The clinical features of the cases of the series are reported. One patient (4*) presented a contralateral recurrence 5 years later (MC: meningocele, ME: meningoencephalocele)
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S1878-8750(15)01515-6
DOI:
10.1016/j.wneu.2015.11.001
Reference:
WNEU 3392
To appear in:
World Neurosurgery
Received Date: 3 October 2015 Accepted Date: 1 November 2015
Please cite this article as: Zoli M, Farneti P, Ghirelli M, Giulioni M, Frank G, Mazzatenta D, Pasquini E, Meningocele and meningo-encephalocele of the lateral wall of sphenoidal sinus: the role of the endoscopic endonasal surgery, World Neurosurgery (2015), doi: 10.1016/j.wneu.2015.11.001. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Meningocele and meningo-encephalocele of the lateral wall of sphenoidal sinus: the role of the endoscopic endonasal surgery. Zoli Matteo, Farneti Paolo°, Ghirelli Michael*, Giulioni Marco^, Frank Giorgio, Mazzatenta Diego, Pasquini Ernesto*
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Center of surgery for pituitary tumors and endoscopic skull base surgery. Department of Neurosurgery. IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy. ° ENT Department, Sant’Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy * ENT Department, Azienda USL, Bologna, Italy * ^ Department of Neurosurgery. IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy
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The authors state that the content of the submitting manuscript, in part or in full, has not been published previously and has not been submitted elsewhere for review. There is no financial support received in conjunction with the generation of this submission and no conflict of interest. The Authors certify that this manuscript is a unique submission and is not being considered for publication with any other source in any medium. The Authors have nothing to declare and nothing to disclose. Correspondence to:
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Matteo Zoli, M.D., Centre of Pituitary Tumors and Endoscopic Skull Base Surgery, IRCCS Scienze Neurologiche, Bologna, Italy. Tel. +39 051 6225514 Fax + 39 051 6225347 e-mail: [email protected] Figures: Figures 1-3 are black and white.
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Key Words: Meningocele; meningoencephalocele; sphenoidal sinus; endoscopic endonasal approach, epilepsy; CSF leak; epileptic surgery
Abbreviations
EEA: endoscopic endonasal approach CSF: cerebro-spinal fluid LWSS: lateral wall of sphenoidal sinus MRI: magnetic resonance imaging
ACCEPTED MANUSCRIPT Abstract
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Backgrounds. Meningocele and meningo-encephalocele of the lateral wall of the sphenoidal sinus (LWSS) are rare lesions, crossing the borders of multiple disciplines such as Ear-Nose-Throat, maxillofacial and neurological surgery. We reviewed our surgical experience to analyze the role of the endoscopic endonasal approach (EEA) and consider these pathologies from different perspectives. Methods. All consecutive cases of meningocele and meningo-encephalocele of LWSS operated through an EEA since 1998 to 2015 in our Institutions have been collected. Medical history, focusing on previous episodes of CSF leak, meningitis or seizures, was considered. The outcome was assessed considering the medical condition and the post-operative neuroimaging. Results. The series includes 23 patients (7 males, 16 females). Mean age was 52 years (26-73). Eleven cases were meningo-encephaloceles and 12 meningoceles. A frank CSF leak occurred on in 19 patients and was associated to meningitis in 3. Two were presenting a history of epilepsy. No complications were observed but one case presented seizures at the awaking. At follow-up (mean 84 months, 4-167) each patient is in good clinical conditions with no further episodes of leaking or seizures. Conclusions. Endoscopic endonasal surgery is a safe and effective approach for meningocele and meningo-encephalocele of LWSS, allowing to resect the herniated tissue and repair the osteo-dural defect. The favorable clinical outcome and the possible effectiveness on seizures lead us to support this approach as first minimally invasive treatment also in presence of epilepsy, as a first low risk epilepsy surgical procedure.
Introduction Meningocele and meningo-encephalocele of the lateral wall of the sphenoidal sinus (LWSS) are a peculiar pathology which crosses the borders of multiple disciplines such as Ear-Nose-Throat (ENT), maxillofacial and neurological surgery (1,2,3). It is an example of how the same pathology
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considered from the different perspectives of each of these specialities can be differently approached, diagnosed and treated (1,2,3). It consists in the outbreaking into the sphenoidal sinus of fossa media dura layers with or without the involvement of brain parenchyma of the temporal lobe. In the ENT-focused literature, it has been reported in dozens of cases, and thus it can be considered an infrequent pathology (4-8). Conversely, it appears rarely in neurosurgical literature in just few scattered single case reports (9-12). More relevantly, in mainly ENT-focused literature the main reported symptom is represented by the CSF leak with meningitis requiring an urgent surgical procedure, on the other hand in the neurosurgical literature attention is more focused on epileptic seizures, caused by these brain herniations, and on the more effective elective surgical strategy to resolve this symptom (1-12). Therefore, the choice between the possible treatments, consisting in the endoscopic endonasal or in the craniotomic surgery, depends not only on the surgeon expertise with one technique, but also on his/her viewpoint. The first technique allows the resection of the herniated tissue and the repair of the bone and dura defects; the second one, apart from the repair of the cranio-meningeal defect, allows the surgeon to extend the resection not only to the herniated brain but also to the surrounding epileptogenic tissues. We reviewed our endoscopic endonasal surgical experience focusing on this controversial issue. Material and Methods
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All consecutive cases of meningocele or meningo-encephalocele of the LWSS operated on through an endoscopic endonasal approach from 1998 to April 2015 at the Center of pituitary and endoscopic skull base surgery of IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy, and ENT Departments of Bellaria Hospital, Bologna, Italy have been retrospectively collected. The presence of CSF leak at the hospital admission or in the previous times was analyzed. In all cases with frank rhinorrhea, a sample of fluid was collected and the Beta Trace Protein concentration was measured to confirm the suspect of CSF leak. In unclear cases, a pre-operative fluorescein test was performed, to avoid misdiagnosis. The medical history of the patient was also considered to identify previous episodes of meningitis. In case of suspect meningitis at the admission a lumbar puncture was performed to confirm the diagnosis and to orientate the antibiotic therapy on the basis of the cultural examination and of the antiobiogram. Furthermore, the medical history was evaluated for the presence of epileptic seizures. All patients undergone a tiny slices CT scan to delineate the bone defect at the skull base. A brain MRI was performed to assess the obliteration of the sphenoidal sinus by CSF or by herniated meninges and brain tissue and to consider the presence of potentially epileptogenic lesions in temporal lobes. Medical reports were analyzed to describe the post-operative course, the hospital staying time, and complications. All patients underwent a first nasal medical and surgical field toilette 30 days after surgery. Then, a CT scan and and/or MRI were repeated after 3 months to assess the repair of the meningocele or meningo-encephalocele. At this time, the medical conditions of the patient were re-assessed with particular attention to epileptic seizures. Afterward, clinical and neuroradiological follow-up was repeated annually, consisting in a MRI or CT scan, a nasal medication and a clinical examination of the patient. Surgical technique. The patient is placed under general anesthesia after oral intubation, and a topic nasal decongestion is performed with 5 % lidocainenaphazoline. An ethmoidotomy followed by wide middle antrostomy is performed on the side of the herniation. Then, the sphenotomy is carried out in order to visualize the defect present at the level of the lateral wall of the sphenoid sinus. At this time, two situations are needed to be considered differently: on one hand meningocele or meningo-encephalocele occupying the sphenoid sinus and eventually extended to the sphenoethmoidal area through the enlarged sphenoid ostium and, on the other, rare but often huge cerebral tissue herniation occupying beyond the sphenoidal sinus also the pterygopalatine and/or infratemporal fossa. In the first case to
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expose and control the bone defect, it is necessary to drill out the upper portion of pterygoid plate as much as possible to expose and control the lateral wall of the sphenoid sinus. The meningocele or meningo-encephalocele is subsequently isolated at the level of its lateral portion, and is cauterized and can be resected only when the presence of any arterial vessels in the herniated tissue is ruled out. When the latter condition occurs, the resection should be very cautious removing the erniated tissue and preserving the herniated vessel. In cases of wide pneumatization of the lateral recess of sphenoid sinus the drilling of the pterygoid process until the foramen rotundum can be enough to expose the meningocele or meningo-encephalocele, which are usually lateral to V2, and thus to repair the defect with mucoperiostium from the middle turbinate in overlay fashion with (for large bone defect) or without (for little bone defect) a piece of bone or cartilage inserted extradurally to buttress the graft (figure 1 a,b,c). Conversely, for cases with a poor pneumatization of the lateral recess of sphenoid sinus is necessary to drill out completely the upper portion of pterygoid plate with closure of sphenopalatine artery to gain sufficient working room. In these cases we prefer to close the defect with bone or cartilage, abdominal fat and covering mucoperiostium graft, excluding the lateral recess (figure 1 d,e,f). For uncommon cases of meningocele or meningo-encephalocele involving the pterygopalatine or infratemporal fossa, the necessary wider exposure can be performed through a combined transsphenoidal-transmaxillary approach, which requires the removal of the vertical portion of palatine bone, of the posterior wall of maxillary sinus and the harvesting of a posterior mucoperioriostial nasal septal flap connected to the vascular content of infratemporal fossa (Fig. 2 a,b,c). After the usual management of meningocele or meningo-encephalocele and the bone defect closure with bone or cartilage, the infratemporal or pterygopalatine fossae can be packed with abdominal fat, covered with the pterygomaxillary content and the posterior nasal septal flap (Fig. 2 d,e,f). Results
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The series consists of 23 patients, 7 were males and 16 were females. They underwent 24 surgical procedures, because one patient, affected by arrested hydrocephalus, presented a controlateral recurrence of meningocele (Table 1). Mean age was 52 years (median: 53, range: 26-73). In 11 cases (48%) the herniation was constituted by meningeal and brain tissues, while in 12 (52%) only by the meningeal sac with no brain involvement. CSF leak was the most common presenting symptom (Table 1). It occurred on in 19 cases (82%) and it was associated to meningitis in 3 (13%) cases. One patient presented with meningitis and intracranial hypertension without evidence of CSF leak. At pre-operative neuroimaging a pneumoencephalus was revealed, thus we argued a valve mechanism causing the meningitis and the intracranial hypertension. Other two patients arrived to our attention with no leak at moment but with a history of recurrent CSF leaks and meningitis misdiagnosed up to that time. One of these two was admitted in our hospital in a comatose state due to a meningoencephalitis. The other presented a focal epileptic seizures with secondary generalization and status epilepticus 10 days after the resolution of the last meningitic episode (pt. 22 in table 1). In a latter patient of our series, the meningoencephalocele was an incidental finding in a CT scan performed for other purposes. Among these 23 patients, two cases were presenting an history of epileptic seizures (Table 1). The first one (pt. 19 at table 1) presented her first epileptic attack of absence when she was 7 years old. The neurological investigations showed focal anomalies at electroencephalogram located in the left temporal lobe. At neuroimaging, a meningo-encephalocele of the left lateral wall of sphenoidal sinus, involving the left temporal lobe, was observed and she was suggested to start a medical therapy with carbamazepine (Fig. 3 a,b). The control of seizures was achieved and after 12 years of treatment, the medical therapy was discontinued, but she went to our attention few years later because she presented CSF leak and meningitis. The second (pt. 17 at table 1) presented the first absence crisis when she was 15 years old. Electroencephalographic investigations did not show any specific abnormalities, and a medical treatment with phenytoin was started. The medical treatment was discontinued after 17 years. In 2012, a right lateral wall meningoencephalocele was incidentally observed in a CT scan performed for a chronic sinusitis.
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At pre-operative MRI, no associated temporal lobe anomalies have been detected. Interestingly, the silvian fissure was wider than the contralateral in 15 cases (65%) (5 meningocele and 10 meningoencephalocele), and 5 (21%) ( 1 meningocele and 4 meningoencephalocele), were presenting an enlargement of ipsilateral temporal horn of the lateral ventricle. Twelve cases (52%) were on the left side and 11 (48%) on the right. In each case, the resection of the herniated tissue was performed and bone defect was identified and skeletonized. A multilayer closure with fascia lata, mucoperiustium and bone or fat or with the nasoseptal flap was performed in all cases. External lumbar drainage was adopted only in one case, in whom it was placed before the patient was referred to our attention. No complications were observed but one patient presented epileptic seizures at the awaking (pt. 17 at table 1). All patients presenting meningitis underwent antibiotic therapy up to the normalization of the bio-humoral and CSF parameters. No patients developed neurological sequelae, even the case presented with meningoencephalitis. At follow-up (mean 84 months, median: 85, range 4-167) all patients are in good clinical conditions with no further episodes of leaking or seizures. None required a revision surgery. Discussion
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The meningocele and meningoencephalocele of the LWSS consist in the herniation of the meninges alone or with brain tissue respectively, through a defect in the skull base. The location of the defect is specific in the parasellar area, in the lateral recess of the sphenoidal sinus, laterally to V2 course (1-9). From here the herniated tissue protrudes downward into the lateral recess of the sphenoid sinus and can involve also the ethmoidal sinuses or the pterygopalatine or infratemporal fossae (1319). The specificity of the location depends from the peculiar pathogenesis of this meningocele. Indeed, herniation is the consequence of a failure of ossification and fusion of ossifications centers of the sphenoid (18-20). Normally, at birth the embryonic portions of sphenoid bones fuse, leaving some cartilaginous portion corresponding to the future lateral wall of sphenoid sinus. The ossification of this cartilage occurs in the neonatal time. If fusion fails, a bony gap, located in the posterior part of sphenoid sinus and lateral to V2, called Sternberg canal or lateral craniopharyngeal canal, remains (18-20). The cartilage is however reabsorbed and only fibrous connective tissue fills the canal. During childhood, up to pubertal time, the sphenoid sinus enlarges, reaching its final pneumatization. If this bone reabsorption reaches the Sternberg canal, this represents a weak point, where more easily meningocele or meningo-encephalocele can occur (18-20). In uncommon cases the meningocele or meningo-encephalocele of the lateral wall of the sphenoid sinus can be acquired (traumatic or promoted by obesity, hydrocephalus or other causes of intracranial hypertension). Meningocele is rare and meningo-encephalocele is even rarer. In the literature single cases are mainly reported, while series are extremely uncommon and include few cases (1-13, 21-27). A prevalence in female is reported as confirmed in our series (males/females: 7/16) (21-22). It can be an incidental finding and a single similar case is present also in our series. Even in this circumstance the surgical treatment should be suggested to prevent meningitis and its possible serious and also fatal course. In symptomatic cases the most common clinical manifestation is represented by CSF leak, as observed in our series: actual CSF leak was present in 19 cases, while a history of previous CSF leak was referred in other two cases. Furthermore, in an additional patient with no evidence of CSF leak, a pneumocephalus was detectable, suggesting the presence of a communication between subarachnoid space and sphenoid sinus. Meningitis and meningo-encephalitis may be a complicating event. In our series meningitis was present in six cases, associated in all cases to an overt or suspected CSF leak. Epilepsy associated to meningocele or meningo-encephalocele, mainly in the form of temporal lobe seizures, sometimes refractory to the medical treatment, is rarer (312). It may be caused by the traction of the herniated tissue on the temporal lobe, or by associated malformations (heterotopia, diffuse cortical dysplasia and schizencephaly) (3-12, 28-34). In our series only two patients presented with a history of epilepsy. Also in these cases the endoscopic endonasal surgery has been preferred because it provides a direct, extra-cranial access to the lesion and
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does not require brain manipulation. The transpterygoid approach, as firstly suggested by Bolger in 2005, may represent the approach of choice for these lesions, allowing an excellent, direct and frontal exposure of the lateral recess of the sphenoid sinus and adeguate working room, avoiding any morbidity related to brain manipulation (9). Predictable sequelae may be trigeminal paresthesia (due to the manipulation of the maxillary nerve) and rarely tear dryness (due to vidian nerve manipulation). At the beginning of our experience we performed the plastic repair with the multilayer technique. Since a couple of years, we use, in selected case involving the pterygopalatine or infratemporal fossa, as outermost layer a naso-septal pedicled flap. Both techniques in our hands has proved to be effective, allowing to repair the CSF leak. A topic that has been poorly considered in literature is whether the endoscopic endonasal surgery, beyond its effective role in the CSF leak repair, could also represent an alternative to transcranial resective surgery for those patients presenting a temporal epilepsy (3). In a recent series, Saavalainen et al., reporting 23 patients with meningo-encephalocele and epilepsy, demonstrated that in a selected subgroup of this patients a more limited transcranial surgery, sparing the medial structures of temporal lobe, can give good results in terms of seizures control (35). Moreover, Faulkner et al. in 2010 had reported the use of endoscopic endonasal treatment in a meningo-encephalocele causing refractory epilepsy (3). These Authors demonstrated that a limited resection of the herniated brain through a ventral route could be enough to manage the associated epileptic seizure. Thus, they conclude that even in presence of epilepsy the endoscopic endonasal approach can be a valid and minimally invasive alternative to conventional transcranial surgery (3). Beyond its good tolerability, low complications rate and fast recovery time, it avoids the infrequent but serious complications related with the resective surgery on the temporal lobe (3-12, 28-34). In our series, there are only two patients with the association between meningo-encephalocele and seizures, representing the 9% of our patients. In both cases seizures were not refractory to medical treatment and surgery was performed with other aim. However, at follow-up, they did not present any further seizures. We admit that our data are partial and present multiple bias, not allowing us to try any conclusion on the role of endoscopic endonasal surgery in the treatment of epilepsy. However, this experience, which confirms Faulkner report, lead us to consider this type of surgery as a minimally invasive option than the conventional transcranial surgery for selected cases of meningo-encephalocele. In fact, the question on the role of endoscopic endonasal surgery to treat epilepsy is part of the broader, crucial and unresolved controversy on the treatment of epilepsy: should surgery be limited to resect the lesion or should it be extended to the epileptic foci (3,12,28-30,34)? To solve the controversy a wide series of cases treated with both methods, the endoscopic endonasal surgery and the transcranial surgery is necessary. In these cases, a complete epileptologic assessment, to determine the location of the epileptic foci in relationship to the meningo-encephalocele, is needed in order to select which cases can be suitable to the endoscopic endonasal lesion resection (3,35). Waiting a convincing scientific answer, our and Faulkner experience give support to the working hypothesis to adopt the endoscopic endonasal resection of the meningocele or meningo-encephalocele as first low risk epilepsy surgical procedure with the aim of treating the epileptic manifestations of these lesions in patient with no other epileptogenic temporal anomalies associated.
Conclusions
The meningocele and meningo-encephalocele of the lateral wall of sphenoid sinus are uncommon but potentially life-threatening diseases. They can be an incidental finding or may be symptomatic, presenting multiple clinical manifestations: mainly CSF leak and meningitis, more rarely seizures. Endoscopic endonasal surgery is a safe, effective, minimally invasive and well tolerated approach for these lesions, allowing to resect the herniated tissue and repair the dural and bone defect. Studies on the role of endoscopic endonasal technique in the management of patients with temporal lobe seizures are still lacking, but there are preliminary experiences supporting the use of this technique like a first low risk attempt.
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Fig. 1. Intra-operative images. 0° scope. A: Drilling of pterygoid plate to gain a more lateral access to sphenoidal sinus. B: The bone defect on the later wall of sphenoidal sinus is evident and the the herniated tissue is visible (in this case a pre-operative fluorescine test was performed). C: After resection of the meningocele, the bone defect is closed through multilayer technique and a piece of bone is placed. D: For cases with a poor pneumatization of the lateral recess of sphenoid sinus, the defect is closed with bone and covered with fat. E: the fat is then covered with a mucoperiostium graft, excluding the lateral recess. F: Schematic drawing of our closure technique for cases with poor pneumatization (blue line: dura, green line: piece of bone placed as closure, yellow: fat, red line: mucoperiostium).
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Fig. 2. Intra-operative images. 0° scope. A: Harvesting of the naso-septal flap. B: Enlarging the spheno-palatine foramen, to expose the pterygo-palatine artery, before drilling the vertical process of palatine bone. C: Coagulation and cut of the meningo-encephalocele. D: the bone defect on the lateral recess of the sphenoidal sinus is dissected. D: repair of the bone defect through the nasoseptal flap while the infratemporal or pterygopalatine fossae are packed with abdominal fat, covered with the pterygomaxillary content and the posterior nasal septal flap. F: Schematic drawing of our closure technique for cases meningocele or meningo-encephalocele involving the pterygopalatine or infratemporal fossa (red line: nasa-septal flap, green line: piece of bone or cartilage, blue line: middle fossa dura, yellow: pterygopalatine fossa fat).
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Fig. 3. MRI. T2 WI. A: axial view. B: coronal view. The meningoencephalocele of the left temporal lobe in the sphenoidal sinus and invading the pterygoplatine fossa is appreciable.
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ACCEPTED MANUSCRIPT Sex
Age
CSF Leak
Headache
Meningitis
Seizures
Herniation
Side
1
F
73
YES
NO
NO
NO
MC
RIGHT
2
M
64
YES
NO
NO
NO
MC
LEFT
3
F
68
YES
NO
NO
NO
ME
RIGHT
4*
M
62
YES
YES
NO
NO
MC
LEFT
5
F
52
YES
YES
NO
NO
ME
LEFT
6
F
45
YES
NO
NO
7
F
55
YES
NO
NO
8
F
63
YES
NO
NO
9
F
62
YES
NO
NO
10
F
60
YES
YES
NO
11
M
49
YES
NO
12
F
62
YES
13
F
49
YES
14
M
65
YES
15
F
26
NO
16
M
49
YES
17
F
37
NO
18
F
37
19
F
30
20
M
37
21
F
37
22
M
62
23
F
37
RI PT
PT
ME
LEFT
NO
MC
RIGHT
NO
ME
LEFT
NO
MC
RIGHT
NO
MC
LEFT
NO
NO
MC
RIGHT
NO
NO
NO
MC
LEFT
NO
NO
NO
MC
LEFT
NO
NO
NO
ME
LEFT
YES
YES
NO
MC
LEFT
YES
NO
NO
ME
LEFT
NO
NO
YES
ME
RIGHT
TE D
M AN U
SC
NO
YES
YES
NO
ME
RIGHT
YES
YES
YES
YES
ME
LEFT
NO
YES
YES
NO
ME
RIGHT
YES
YES
YES
NO
MC
RIGHT
NO
YES
YES
YES
ME
RIGHT
YES
YES
NO
NO
MC
RIGHT
AC C
EP
YES
Table 1: The clinical features of the cases of the series are reported. One patient (4*) presented a contralateral recurrence 5 years later (MC: meningocele, ME: meningoencephalocele)
AC C
EP
TE D
M AN U
SC
RI PT
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TE D
M AN U
SC
RI PT
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EP
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