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Transalar transsphenoidal meningoencephalocele presenting in the form of recurrent meningitis: Report of two cases and discussion of the diagnosis and treatment
G Model
ARTICLE IN PRESS
ANORL-575; No. of Pages 5
European Annals of Otorhinolaryngology, Head and Neck diseases xxx (2016) xxx–xxx
Available online at
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Case report
Transalar transsphenoidal meningoencephalocele presenting in the form of recurrent meningitis: Report of two cases and discussion of the diagnosis and treatment A. Zoghlami a , N. Bon Mardion a , F. Callonnec b , D. Dehesdin a , F. Proust c , J.-P. Marie a,∗ a
Service d’ORL-CCF, CHU de Rouen, 1, rue de Germont, 76000 Rouen, France Service d’imagerie, centre Henri-Becquerel, rue d’Amiens, 76000 Rouen, France c Service de neurochirurgie, CHU de Rouen, 1, rue de Germont, 76000 Rouen, France b
a r t i c l e
i n f o
a b s t r a c t
Keywords: Malformation Skull base Recurrent meningitis Sphenoid Encephalocele
Introduction: Skull base meningoencephaloceles are rare congenital malformations. The two cases of transalar transsphenoidal malformation reported here differ from the classical transsphenoidal meningoencephalocele. Case reports: Case 1 was a three-and-a-half-year-old boy and case 2 was a 36-year-old man. Both cases presented with clinical features of recurrent meningitis. Surgical management of case 1 was performed via an intradural infratemporal fossa craniotomy with reoperation 2 years later. In the second case, surgery was initially performed via an endonasal approach and then via pterional craniotomy. Reoperation via Sekhar’s transpetrosal approach was also a failure. Only closure of the trigeminal-pontine angle via a suboccipital retrosigmoid approach allowed repair of the defect. Discussion: Surgical access to the pterygopalatine fossa is complex due to its anatomical position and its anatomical relations with nerves and vessels. An endoscopic approach appears to be a valuable alternative to classical craniotomy. Conclusion: In the two cases reported here, neurosurgery allowed lasting closure of the defect. © 2016 Published by Elsevier Masson SAS.
1. Introduction
protrudes into the nasal cavities through the cribriform plate. Sphenomaxillary encephalocele protrudes through the sphenomaxillary fissure into the sphenomaxillary fossa. Transalar transsphenoidal encephaloceles are much more exceptional and are not described in the classical classification of transsphenoidal encephaloceles [1]. These malformations are difficult to diagnose due to their variable clinical expressions, requiring various therapeutic approaches. Surgical access to the pterygopalatine fossa is technically difficult for ENT surgeons and neurosurgeons. We report our experience in the management of this disease.
Skull base meningoencephaloceles are rare congenital malformations with an estimated incidence of 1 in 35,000 births and usually remain asymptomatic. However, they can be responsible for complications in the form of meningitis, particularly pneumococcal meningitis. Midline malformations of the skull base can be associated with abnormalities of the corpus callosum or Chiari malformation. Five anatomical types of encephalocele are distinguished: transsphenoidal, spheno-orbital, sphenoethmoidal, transethmoidal and sphenomaxillary [1]. Transsphenoidal encephalocele, the rarest form, protrudes into the sphenoidal sinus or nasopharynx through the body of the sphenoid. Spheno-orbital encephalocele passes through the sphenomaxillary fissure or the roof of the orbit. Sphenoethmoidal encephalocele protrudes through the sphenoid and posterior ethmoid cells into the nasopharynx. Transethmoidal encephalocele
∗ Corresponding author. E-mail address: [email protected] (J.-P. Marie).
2. Case 1 A three-and-a-half-year-old boy, born at term and with no notable history, presented two episodes of purulent pneumococcal meningitis with decreased susceptibility to penicillin at an interval of two months with a favourable course in response to medical treatment. In this context of recurrent meningitis, skull and brain imaging assessment was performed looking for a congenital or
http://dx.doi.org/10.1016/j.anorl.2016.07.001 1879-7296/© 2016 Published by Elsevier Masson SAS.
Please cite this article in press as: Zoghlami A, et al. Transalar transsphenoidal meningoencephalocele presenting in the form of recurrent meningitis: Report of two cases and discussion of the diagnosis and treatment. European Annals of Otorhinolaryngology, Head and Neck diseases (2016), http://dx.doi.org/10.1016/j.anorl.2016.07.001
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Fourteen months after this first operation, the patient was admitted to the paediatric ward with pneumococcal meningitis. Following a multidisciplinary discussion, it was decided to reoperate the patient via the same left infratemporal fossa craniotomy. This reoperation allowed lasting closure of the dural defect with no further recurrence of infection with a follow-up of nine years. However, the follow-up MRI showed persistence of the meningoencephalocele. Prolonged antibiotic prophylaxis with amoxicillin and an unconventional pneumococcal vaccine, Prevenar® also ensured prevention of recurrent meningitis. 3. Case 2
Fig. 1. a: computed tomography, axial section. Bone defect in the left paramedian part of the middle cranial fossa with dehiscence of the temporal fossa, left foramen ovale, pterygomaxillary fissure and cavernous sinus; b: MRI, coronal sections, T1weighted inversion-recovery sequence. Meningoencephalocele through this defect with invagination of the left temporal lobe (→) and presence of CSF clearly visible on the T2-weighted sequence ().
acquired bone and dural defect in the anterior and middle cranial fossae and petrous temporal bones. Contrast-enhanced computed tomography axial slices demonstrated a malformation of the left paramedian skull base with dehiscence of the temporal fossa, left foramen ovale, pterygomaxillary fissure and cavernous sinus (Fig. 1a). Magnetic resonance imaging was also performed and showed a meningoencephalocele protruding through the bone defect, corresponding to partial invagination of the left temporal lobe. This assessment also revealed an incidental type I Chiari malformation (Fig. 1b). Three months after medical treatment of several episodes of meningitis, surgery was performed by a neurosurgical team via a left infratemporal fossa craniotomy with neuronavigation. This approach initially allowed exposure of the left frontal and temporal regions and the meningoencephalocele was then demonstrated. The extradural portion of cerebral parenchyma was resected via an infratemporal approach and the dura was repaired and reinserted intracranially. The bone defect was repaired by muscle and fibrin sealant. The orifice situated below the cavernous sinus was lined by epicranium and maintained by fibrin sealant. At the end of the operation, the brain herniated through the craniotomy. After closure, emergency computed tomography demonstrated right parietal extradural haematoma under one of the pins of the Mayfield frame. The patient was immediately reoperated to evacuate this extradural haematoma and ensure haemostasis of the epidural artery responsible for the bleeding.
A 36-year-old man, with no history of head injury or intracranial surgery, presented three episodes of pneumococcal meningitis between May 2006 to September 2007. Clinical examination did not reveal any malformation or any signs of neurofibromatosis, but simply cerebrospinal fluid rhinorrhoea. An imaging assessment was therefore performed, comprising computed tomography of the middle and anterior cranial fossae and magnetic resonance imaging looking for a skull base malformation. CT imaging was interpreted as normal and was not contributive. CT cisternography was therefore performed with intrathecal injection of iodinated contrast agent in order to precisely localize the cerebrospinal fluid leak. Helical thin-slice CT acquisition centered on the brain was performed with a bone window setting. The CSF leak was situated on the right side in Meckel’s cave, foramen rotundum, pterygoid canal and along the second division of the trigeminal nerve (Fig. 2). MRI T2-weighted sequence revealed cystic images in the right trigeminal cisterna extending into the canal of the right pterygoid nerve as far as the right pterygopalatine fossa. A first attempt of closure of the defect demonstrated by imaging in the right pterygopalatine canal was performed via a computerassisted endoscopy-guided endonasal approach. The defect was filled with fat and fibrin sealant and the procedure was completed by lumbar drainage to ensure closure of the CSF rhinorrhoea. The patient was readmitted to hospital for purulent meningitis 3 months after the first operation. After multidisciplinary consultation, it was decided to perform right pterional craniotomy. The space in contact with the trigeminal nerve and Meckel’s cave was filled with pericranium and fibrin sealant. Postoperative clinical examination demonstrated right trigeminal nerve palsy. One year after this second operation, this patient was hospitalised for management of Streptococcus salivarius meningitis. Following this episode of recurrence, reoperation was proposed via Sekhar’s extradural lateral transpetrosal approach, which ensured closure of the CSF leak for a period of nine months, after which time the CSF rhinorrhoea recurred. A right suboccipital retrosigmoid approach to the trigeminalpontine angle was then performed with filling of the trigeminal nerve canal, allowing prolonged closure of the CSF leak. However, the patient presents permanent right peripheral facial nerve and trigeminal nerve palsy. No recurrence of CSF rhinorrhoea or meningitis has been observed with a follow-up of 18 months. 4. Discussion Transalar transsphenoidal encephalocele differs from classical transsphenoidal encephalocele, as the encephalocele passes through the greater wing of the sphenoid rather than through the body of the sphenoid. It also differs in terms of the clinical presentation. Only 6 cases of transalar transsphenoidal encephalocele, with
Please cite this article in press as: Zoghlami A, et al. Transalar transsphenoidal meningoencephalocele presenting in the form of recurrent meningitis: Report of two cases and discussion of the diagnosis and treatment. European Annals of Otorhinolaryngology, Head and Neck diseases (2016), http://dx.doi.org/10.1016/j.anorl.2016.07.001
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Fig. 2. CT cisternography, axial (a) and coronal (b) sections showing (→) the CSF leak in Meckel’s cave, foramen rotundum, pterygoid canal and along the second division of the right trigeminal nerve.
nonspecific clinical features, have been reported in the literature [2–6]. However, several symptoms are suggestive of this disease: headache, seizures, trigeminal neuralgia, sensory loss in the territory of the trigeminal nerve, neonatal respiratory distress and CSF rhinorrhoea. Both cases reported here presented several episodes of pneumococcal meningitis. In case 1, the child also presented Chiari malformation, an association that has not been previously described. Other associated malformations or concomitant diseases have also been reported in the literature [3–8]: soft palate angiomas and Wegener’s granulomatosis.
Several anatomical factors predispose to the formation of a bone and dural defect: the thin skull bones, lined by adherent dura mater on the upper surface and fragile mucosa on the lower surface and the frequency of congenital malformations related to the later development of the skull base. The sphenoid, a complex bone structure, constitutes most of the middle cranial fossa. The ossification process of this bone during intrauterine life is complex and involves nineteen distinct ossification points. The greater wing of the sphenoid is formed from the alisphenoid involving two ossification mechanisms. An initially membranous part ossifies during the
Please cite this article in press as: Zoghlami A, et al. Transalar transsphenoidal meningoencephalocele presenting in the form of recurrent meningitis: Report of two cases and discussion of the diagnosis and treatment. European Annals of Otorhinolaryngology, Head and Neck diseases (2016), http://dx.doi.org/10.1016/j.anorl.2016.07.001
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eighth week of pregnancy and forms the majority of the greater wing of the sphenoid and pterygoid process. Another originally cartilaginous part subsequently ossifies to form the middle and anterior roots of the greater wing of the sphenoid. In the first case reported here, the meningoencephalocele followed a course through the membranous portion of the greater wing of the sphenoid. In the second case, the CSF leak was located in the pterygoid process, which is also initially membranous. Other hypotheses concerning the pathogenesis of encephaloceles have been proposed. According to McLaurin et al., an encephalocele can be due to a defect of closure of the anterior neuropore at the fourth week of pregnancy [9]. An increase in intraventricular pressure may also occur during development, which would be responsible for passage of cerebral parenchyma through embryonic orifices or bony zones of least resistance. The role of cerebrospinal fluid pressure variations was discussed by Rovit et al. CSF pressure variations linked to heart beat could induce a CSF leak in a zone of least resistance [8]. Small meningoceles or encephaloceles may therefore be formed at the site of a congenital bone defect or a zone of bone weakness in response to pulsatile CSF pressure. Bone foramina gradually erode to induce cerebrospinal fluid rhinorrhoea when associated with a dural defect. Transalar meningoencephalocele is a complex disease that usually remains asymptomatic. The two cases reported here presented a history of recurrent pneumococcal meningitis. Patients with a history of recurrent meningitis should be investigated to detect a malformation or lesion of the skull base responsible for meningeal contamination. This bone and dural defect may occur in the anterior cranial fossa, middle cranial fossa or the petrosal apex. A combination of CT axial and coronal scans to demonstrate complex bone malformations and MRI T2-weighted inversion-recovery and CIS sequences to detect tissue or fluid malformations is usually sufficient to establish the diagnosis. In case 2, only CT cisternography was able to identify the site of CSF leak. CT cisternography may therefore be used as a second-line examination when CT and/or MRI are not contributive. The treatment of this little-known disease has not been clearly defined. Authors who have reported similar cases proposed various forms of treatment. Treatment decisions must be based on multidisciplinary discussion between ENT surgeons, neurosurgeons, and radiologists. The objective of surgical management is to resect the encephalocele when it contains ectopic brain tissue and to reconstruct a long-term watertight anatomical barrier, isolating the cranial fossa from the sinonasal spaces of the face. Two main types of surgical access to the sphenoid have been proposed: anterior, anterolateral or posterior craniotomies, and transfacial, transoral or transsphenoidal skull base surgery. Mixed approaches combining craniotomy and skull base surgery have also been proposed [10]. Anterior craniotomies comprise transbasal, pterional, infratemporal and orbitozygomatic infratemporal approaches. The transbasal approach is an extradural approach involving dissection of all of the anterior skull base as far as the posterior margins of the lesser wings and the tubercle of the stool. Pterional craniotomy is a unilateral anterolateral approach providing access to the roof of the orbit and the wings of the sphenoid. The infratemporal fossa approach is an intradural approach providing access to the infratemporal fossa and retrochiasmatic region. The orbitozygomatic infratemporal fossa approach is a complex approach allowing exposure of the infratemporal fossa. Posterior craniotomies essentially consist of the lateral suboccipital retrosigmoid approach, an intradural approach providing access to the middle and inferior clivus. Skull base access to the sphenoid can be achieved via a transsphenoidal approach, essentially used in pituitary disease, a
transoral approach that provides access to the clivus and craniocervical junction, Lefort I osteotomy or a unilateral or bilateral transfacial approach, possibly combined with craniotomy. Endoscopic endonasal surgery, possibly computer-assisted, has become increasingly popular over recent years. The endoscopic transpterygoid approach is a minimally invasive alternative to conventional open surgery of the pterygopalatine fossa (PPF). Endoscopic approaches have revolutionized the treatment of skull base disease. The indications, technique, type of filling material and the need for concomitant lumbar drainage remain controversial [11]. The surgical strategy depends on the aetiology and the site of the defect. Endoscopic surgery has the advantage of being less invasive than open craniotomy, thereby limiting the surgical morbidity, while providing satisfactory exposure of the skull base. Cadavre studies have allowed the development of endoscopic surgery based on a precise description of the anatomy of the pterygopalatine fossa (PPF) [12–14], as surgical access to the PPF is difficult due to its site and its complex neurovascular anatomy. Neurosurgical management of case 1 was performed via a pterional craniotomy and, after two operations, allowed filling of the bone and dural defect with a follow-up of nine years. In case 2, surgery via an endonasal approach and a transbasal extradural approach was unsuccessful. Only a suboccipital retrosigmoid approach with filling of Meckel’s cave was able to control the CSF leak, but at the price of disabling complications such as ipsilateral facial and trigeminal nerve palsy. In the two previously published cases [5,7], the patients were treated by craniotomy with resection of the encephalocele and repair of the bone defect. These patients were asymptomatic postoperatively, but follow-up was insufficient to draw any clear conclusions. 5. Conclusion Transalar meningoencephalocele is a complex and rare disease. Recurrent bacterial meningitis should raise the suspicion of a skull base malformation, requiring CT assessment, possibly completed by CT cisternography and magnetic resonance imaging. The therapeutic management of these malformations has not been clearly defined. Operative indications and the surgical approach remain controversial. Access to the sphenoid is particularly difficult due to the adjacent arteries and nerves and is associated with a risk of complications. Endoscopic surgery is a good alternative to craniotomy, which can still be used in the case of failure of endoscopic surgery. In our experience, only an intradural approach appears to allow repair of the bone and dural defect and lasting control of the CSF leak. Disclosure of interest The authors declare that they have no competing interest. References [1] Pollock JA, Newton TH, Hoyt WF. Transsphenoidal and transethmoidal encephaloceles. Radiology 1968;90:442–53. [2] Elster AD, Branch Jr CL. Transalar sphenoidal encephaloceles: clinical and radiologic findings. Radiology 1989;170:245–7. [3] Soyer P, Dobbelaere P, Reizine D, et al. Méningo-encéphalocèle transalaire associée à une angiomatose buccale. À propos d’une observation. J Neuroradiol 1990;17:222–6. [4] Soyer P, Dobbelaere P, Benoit S. Transalar sphenoidal encephalocele: uncommon clinical and radiological findings. Clin Radiol 1991;43:65–7. [5] Mylanus EA, Marres HA, Vlietman J, et al. Transalar sphenoidal encephalocele and respiratory distress in a neonate: a case report. Pediatrics 1999;103:E12. [6] Short J, McKinney AM, Lucato LT, et al. Transalar encephalocele associated with Wegener granulomatosis and meningeal enhancement: case report. AJNR Am J Neuroradiol 2005;26:1873–5. [7] Mulcahy MM, McMenomey SO, Talbot JM, Delashaw Jr JB. Congenital encephalocele of the medial skull base. Laryngoscope 1997;107:910–4.
Please cite this article in press as: Zoghlami A, et al. Transalar transsphenoidal meningoencephalocele presenting in the form of recurrent meningitis: Report of two cases and discussion of the diagnosis and treatment. European Annals of Otorhinolaryngology, Head and Neck diseases (2016), http://dx.doi.org/10.1016/j.anorl.2016.07.001
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[8] Rovit RL, Schechter MM, Nelson K. Spontaneous “high-pressure cerebro-spinal rhinorrhea” due to lesions obstructing flow of cerebrospinal fluid. J Neurosurgery 1969;30:406–12. [9] McLaurin RL. Encephalocele and related anomalies. In: Hoffman HJ, Epstein F, editors. Disorders of the developing nervous system: diagnosis and treatment. Blackwell scientific publications; 1986. p. 153–71. [10] Visot A, Boulin A. Les voies d’abord du sphénoide. J Neuroradiol 2003;30:258–67. [11] Zweig JL, Carrau RL, Celin SE, et al. Endoscopic repair of acquired encephaloceles, meningoceles, and meningo-encephaloceles: predictors of success. Skull Base 2002;12(3):133–9.
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[12] Falcon RT, Rivera-Serrano CM, Miranda JF, et al. Endoscopic endonasal dissection of the infratemporal fossa: anatomic relationships and importance of eustachian tube in the endoscopic skull base surgery. Laryngoscope 2011;121(1):31–41. [13] Fortes FS, Sennes LU, Carrau RL, et al. Endoscopic anatomy of the pterygopalatine fossa and the transpterygoid approach: development of a surgical instruction model. Laryngoscope 2008;118(1):44–9. [14] Hofstetter CP, Singh A, Anand VK, et al. The endoscopic, endonasal, transmaxillary transpterygoid approach to the pterygopalatine fossa, infratemporal fossa, petrous apex, and the Meckel cave. J Neurosurg 2010;113(5):967–74.
Please cite this article in press as: Zoghlami A, et al. Transalar transsphenoidal meningoencephalocele presenting in the form of recurrent meningitis: Report of two cases and discussion of the diagnosis and treatment. European Annals of Otorhinolaryngology, Head and Neck diseases (2016), http://dx.doi.org/10.1016/j.anorl.2016.07.001
ARTICLE IN PRESS
ANORL-575; No. of Pages 5
European Annals of Otorhinolaryngology, Head and Neck diseases xxx (2016) xxx–xxx
Available online at
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Case report
Transalar transsphenoidal meningoencephalocele presenting in the form of recurrent meningitis: Report of two cases and discussion of the diagnosis and treatment A. Zoghlami a , N. Bon Mardion a , F. Callonnec b , D. Dehesdin a , F. Proust c , J.-P. Marie a,∗ a
Service d’ORL-CCF, CHU de Rouen, 1, rue de Germont, 76000 Rouen, France Service d’imagerie, centre Henri-Becquerel, rue d’Amiens, 76000 Rouen, France c Service de neurochirurgie, CHU de Rouen, 1, rue de Germont, 76000 Rouen, France b
a r t i c l e
i n f o
a b s t r a c t
Keywords: Malformation Skull base Recurrent meningitis Sphenoid Encephalocele
Introduction: Skull base meningoencephaloceles are rare congenital malformations. The two cases of transalar transsphenoidal malformation reported here differ from the classical transsphenoidal meningoencephalocele. Case reports: Case 1 was a three-and-a-half-year-old boy and case 2 was a 36-year-old man. Both cases presented with clinical features of recurrent meningitis. Surgical management of case 1 was performed via an intradural infratemporal fossa craniotomy with reoperation 2 years later. In the second case, surgery was initially performed via an endonasal approach and then via pterional craniotomy. Reoperation via Sekhar’s transpetrosal approach was also a failure. Only closure of the trigeminal-pontine angle via a suboccipital retrosigmoid approach allowed repair of the defect. Discussion: Surgical access to the pterygopalatine fossa is complex due to its anatomical position and its anatomical relations with nerves and vessels. An endoscopic approach appears to be a valuable alternative to classical craniotomy. Conclusion: In the two cases reported here, neurosurgery allowed lasting closure of the defect. © 2016 Published by Elsevier Masson SAS.
1. Introduction
protrudes into the nasal cavities through the cribriform plate. Sphenomaxillary encephalocele protrudes through the sphenomaxillary fissure into the sphenomaxillary fossa. Transalar transsphenoidal encephaloceles are much more exceptional and are not described in the classical classification of transsphenoidal encephaloceles [1]. These malformations are difficult to diagnose due to their variable clinical expressions, requiring various therapeutic approaches. Surgical access to the pterygopalatine fossa is technically difficult for ENT surgeons and neurosurgeons. We report our experience in the management of this disease.
Skull base meningoencephaloceles are rare congenital malformations with an estimated incidence of 1 in 35,000 births and usually remain asymptomatic. However, they can be responsible for complications in the form of meningitis, particularly pneumococcal meningitis. Midline malformations of the skull base can be associated with abnormalities of the corpus callosum or Chiari malformation. Five anatomical types of encephalocele are distinguished: transsphenoidal, spheno-orbital, sphenoethmoidal, transethmoidal and sphenomaxillary [1]. Transsphenoidal encephalocele, the rarest form, protrudes into the sphenoidal sinus or nasopharynx through the body of the sphenoid. Spheno-orbital encephalocele passes through the sphenomaxillary fissure or the roof of the orbit. Sphenoethmoidal encephalocele protrudes through the sphenoid and posterior ethmoid cells into the nasopharynx. Transethmoidal encephalocele
∗ Corresponding author. E-mail address: [email protected] (J.-P. Marie).
2. Case 1 A three-and-a-half-year-old boy, born at term and with no notable history, presented two episodes of purulent pneumococcal meningitis with decreased susceptibility to penicillin at an interval of two months with a favourable course in response to medical treatment. In this context of recurrent meningitis, skull and brain imaging assessment was performed looking for a congenital or
http://dx.doi.org/10.1016/j.anorl.2016.07.001 1879-7296/© 2016 Published by Elsevier Masson SAS.
Please cite this article in press as: Zoghlami A, et al. Transalar transsphenoidal meningoencephalocele presenting in the form of recurrent meningitis: Report of two cases and discussion of the diagnosis and treatment. European Annals of Otorhinolaryngology, Head and Neck diseases (2016), http://dx.doi.org/10.1016/j.anorl.2016.07.001
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Fourteen months after this first operation, the patient was admitted to the paediatric ward with pneumococcal meningitis. Following a multidisciplinary discussion, it was decided to reoperate the patient via the same left infratemporal fossa craniotomy. This reoperation allowed lasting closure of the dural defect with no further recurrence of infection with a follow-up of nine years. However, the follow-up MRI showed persistence of the meningoencephalocele. Prolonged antibiotic prophylaxis with amoxicillin and an unconventional pneumococcal vaccine, Prevenar® also ensured prevention of recurrent meningitis. 3. Case 2
Fig. 1. a: computed tomography, axial section. Bone defect in the left paramedian part of the middle cranial fossa with dehiscence of the temporal fossa, left foramen ovale, pterygomaxillary fissure and cavernous sinus; b: MRI, coronal sections, T1weighted inversion-recovery sequence. Meningoencephalocele through this defect with invagination of the left temporal lobe (→) and presence of CSF clearly visible on the T2-weighted sequence ().
acquired bone and dural defect in the anterior and middle cranial fossae and petrous temporal bones. Contrast-enhanced computed tomography axial slices demonstrated a malformation of the left paramedian skull base with dehiscence of the temporal fossa, left foramen ovale, pterygomaxillary fissure and cavernous sinus (Fig. 1a). Magnetic resonance imaging was also performed and showed a meningoencephalocele protruding through the bone defect, corresponding to partial invagination of the left temporal lobe. This assessment also revealed an incidental type I Chiari malformation (Fig. 1b). Three months after medical treatment of several episodes of meningitis, surgery was performed by a neurosurgical team via a left infratemporal fossa craniotomy with neuronavigation. This approach initially allowed exposure of the left frontal and temporal regions and the meningoencephalocele was then demonstrated. The extradural portion of cerebral parenchyma was resected via an infratemporal approach and the dura was repaired and reinserted intracranially. The bone defect was repaired by muscle and fibrin sealant. The orifice situated below the cavernous sinus was lined by epicranium and maintained by fibrin sealant. At the end of the operation, the brain herniated through the craniotomy. After closure, emergency computed tomography demonstrated right parietal extradural haematoma under one of the pins of the Mayfield frame. The patient was immediately reoperated to evacuate this extradural haematoma and ensure haemostasis of the epidural artery responsible for the bleeding.
A 36-year-old man, with no history of head injury or intracranial surgery, presented three episodes of pneumococcal meningitis between May 2006 to September 2007. Clinical examination did not reveal any malformation or any signs of neurofibromatosis, but simply cerebrospinal fluid rhinorrhoea. An imaging assessment was therefore performed, comprising computed tomography of the middle and anterior cranial fossae and magnetic resonance imaging looking for a skull base malformation. CT imaging was interpreted as normal and was not contributive. CT cisternography was therefore performed with intrathecal injection of iodinated contrast agent in order to precisely localize the cerebrospinal fluid leak. Helical thin-slice CT acquisition centered on the brain was performed with a bone window setting. The CSF leak was situated on the right side in Meckel’s cave, foramen rotundum, pterygoid canal and along the second division of the trigeminal nerve (Fig. 2). MRI T2-weighted sequence revealed cystic images in the right trigeminal cisterna extending into the canal of the right pterygoid nerve as far as the right pterygopalatine fossa. A first attempt of closure of the defect demonstrated by imaging in the right pterygopalatine canal was performed via a computerassisted endoscopy-guided endonasal approach. The defect was filled with fat and fibrin sealant and the procedure was completed by lumbar drainage to ensure closure of the CSF rhinorrhoea. The patient was readmitted to hospital for purulent meningitis 3 months after the first operation. After multidisciplinary consultation, it was decided to perform right pterional craniotomy. The space in contact with the trigeminal nerve and Meckel’s cave was filled with pericranium and fibrin sealant. Postoperative clinical examination demonstrated right trigeminal nerve palsy. One year after this second operation, this patient was hospitalised for management of Streptococcus salivarius meningitis. Following this episode of recurrence, reoperation was proposed via Sekhar’s extradural lateral transpetrosal approach, which ensured closure of the CSF leak for a period of nine months, after which time the CSF rhinorrhoea recurred. A right suboccipital retrosigmoid approach to the trigeminalpontine angle was then performed with filling of the trigeminal nerve canal, allowing prolonged closure of the CSF leak. However, the patient presents permanent right peripheral facial nerve and trigeminal nerve palsy. No recurrence of CSF rhinorrhoea or meningitis has been observed with a follow-up of 18 months. 4. Discussion Transalar transsphenoidal encephalocele differs from classical transsphenoidal encephalocele, as the encephalocele passes through the greater wing of the sphenoid rather than through the body of the sphenoid. It also differs in terms of the clinical presentation. Only 6 cases of transalar transsphenoidal encephalocele, with
Please cite this article in press as: Zoghlami A, et al. Transalar transsphenoidal meningoencephalocele presenting in the form of recurrent meningitis: Report of two cases and discussion of the diagnosis and treatment. European Annals of Otorhinolaryngology, Head and Neck diseases (2016), http://dx.doi.org/10.1016/j.anorl.2016.07.001
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Fig. 2. CT cisternography, axial (a) and coronal (b) sections showing (→) the CSF leak in Meckel’s cave, foramen rotundum, pterygoid canal and along the second division of the right trigeminal nerve.
nonspecific clinical features, have been reported in the literature [2–6]. However, several symptoms are suggestive of this disease: headache, seizures, trigeminal neuralgia, sensory loss in the territory of the trigeminal nerve, neonatal respiratory distress and CSF rhinorrhoea. Both cases reported here presented several episodes of pneumococcal meningitis. In case 1, the child also presented Chiari malformation, an association that has not been previously described. Other associated malformations or concomitant diseases have also been reported in the literature [3–8]: soft palate angiomas and Wegener’s granulomatosis.
Several anatomical factors predispose to the formation of a bone and dural defect: the thin skull bones, lined by adherent dura mater on the upper surface and fragile mucosa on the lower surface and the frequency of congenital malformations related to the later development of the skull base. The sphenoid, a complex bone structure, constitutes most of the middle cranial fossa. The ossification process of this bone during intrauterine life is complex and involves nineteen distinct ossification points. The greater wing of the sphenoid is formed from the alisphenoid involving two ossification mechanisms. An initially membranous part ossifies during the
Please cite this article in press as: Zoghlami A, et al. Transalar transsphenoidal meningoencephalocele presenting in the form of recurrent meningitis: Report of two cases and discussion of the diagnosis and treatment. European Annals of Otorhinolaryngology, Head and Neck diseases (2016), http://dx.doi.org/10.1016/j.anorl.2016.07.001
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eighth week of pregnancy and forms the majority of the greater wing of the sphenoid and pterygoid process. Another originally cartilaginous part subsequently ossifies to form the middle and anterior roots of the greater wing of the sphenoid. In the first case reported here, the meningoencephalocele followed a course through the membranous portion of the greater wing of the sphenoid. In the second case, the CSF leak was located in the pterygoid process, which is also initially membranous. Other hypotheses concerning the pathogenesis of encephaloceles have been proposed. According to McLaurin et al., an encephalocele can be due to a defect of closure of the anterior neuropore at the fourth week of pregnancy [9]. An increase in intraventricular pressure may also occur during development, which would be responsible for passage of cerebral parenchyma through embryonic orifices or bony zones of least resistance. The role of cerebrospinal fluid pressure variations was discussed by Rovit et al. CSF pressure variations linked to heart beat could induce a CSF leak in a zone of least resistance [8]. Small meningoceles or encephaloceles may therefore be formed at the site of a congenital bone defect or a zone of bone weakness in response to pulsatile CSF pressure. Bone foramina gradually erode to induce cerebrospinal fluid rhinorrhoea when associated with a dural defect. Transalar meningoencephalocele is a complex disease that usually remains asymptomatic. The two cases reported here presented a history of recurrent pneumococcal meningitis. Patients with a history of recurrent meningitis should be investigated to detect a malformation or lesion of the skull base responsible for meningeal contamination. This bone and dural defect may occur in the anterior cranial fossa, middle cranial fossa or the petrosal apex. A combination of CT axial and coronal scans to demonstrate complex bone malformations and MRI T2-weighted inversion-recovery and CIS sequences to detect tissue or fluid malformations is usually sufficient to establish the diagnosis. In case 2, only CT cisternography was able to identify the site of CSF leak. CT cisternography may therefore be used as a second-line examination when CT and/or MRI are not contributive. The treatment of this little-known disease has not been clearly defined. Authors who have reported similar cases proposed various forms of treatment. Treatment decisions must be based on multidisciplinary discussion between ENT surgeons, neurosurgeons, and radiologists. The objective of surgical management is to resect the encephalocele when it contains ectopic brain tissue and to reconstruct a long-term watertight anatomical barrier, isolating the cranial fossa from the sinonasal spaces of the face. Two main types of surgical access to the sphenoid have been proposed: anterior, anterolateral or posterior craniotomies, and transfacial, transoral or transsphenoidal skull base surgery. Mixed approaches combining craniotomy and skull base surgery have also been proposed [10]. Anterior craniotomies comprise transbasal, pterional, infratemporal and orbitozygomatic infratemporal approaches. The transbasal approach is an extradural approach involving dissection of all of the anterior skull base as far as the posterior margins of the lesser wings and the tubercle of the stool. Pterional craniotomy is a unilateral anterolateral approach providing access to the roof of the orbit and the wings of the sphenoid. The infratemporal fossa approach is an intradural approach providing access to the infratemporal fossa and retrochiasmatic region. The orbitozygomatic infratemporal fossa approach is a complex approach allowing exposure of the infratemporal fossa. Posterior craniotomies essentially consist of the lateral suboccipital retrosigmoid approach, an intradural approach providing access to the middle and inferior clivus. Skull base access to the sphenoid can be achieved via a transsphenoidal approach, essentially used in pituitary disease, a
transoral approach that provides access to the clivus and craniocervical junction, Lefort I osteotomy or a unilateral or bilateral transfacial approach, possibly combined with craniotomy. Endoscopic endonasal surgery, possibly computer-assisted, has become increasingly popular over recent years. The endoscopic transpterygoid approach is a minimally invasive alternative to conventional open surgery of the pterygopalatine fossa (PPF). Endoscopic approaches have revolutionized the treatment of skull base disease. The indications, technique, type of filling material and the need for concomitant lumbar drainage remain controversial [11]. The surgical strategy depends on the aetiology and the site of the defect. Endoscopic surgery has the advantage of being less invasive than open craniotomy, thereby limiting the surgical morbidity, while providing satisfactory exposure of the skull base. Cadavre studies have allowed the development of endoscopic surgery based on a precise description of the anatomy of the pterygopalatine fossa (PPF) [12–14], as surgical access to the PPF is difficult due to its site and its complex neurovascular anatomy. Neurosurgical management of case 1 was performed via a pterional craniotomy and, after two operations, allowed filling of the bone and dural defect with a follow-up of nine years. In case 2, surgery via an endonasal approach and a transbasal extradural approach was unsuccessful. Only a suboccipital retrosigmoid approach with filling of Meckel’s cave was able to control the CSF leak, but at the price of disabling complications such as ipsilateral facial and trigeminal nerve palsy. In the two previously published cases [5,7], the patients were treated by craniotomy with resection of the encephalocele and repair of the bone defect. These patients were asymptomatic postoperatively, but follow-up was insufficient to draw any clear conclusions. 5. Conclusion Transalar meningoencephalocele is a complex and rare disease. Recurrent bacterial meningitis should raise the suspicion of a skull base malformation, requiring CT assessment, possibly completed by CT cisternography and magnetic resonance imaging. The therapeutic management of these malformations has not been clearly defined. Operative indications and the surgical approach remain controversial. Access to the sphenoid is particularly difficult due to the adjacent arteries and nerves and is associated with a risk of complications. Endoscopic surgery is a good alternative to craniotomy, which can still be used in the case of failure of endoscopic surgery. In our experience, only an intradural approach appears to allow repair of the bone and dural defect and lasting control of the CSF leak. Disclosure of interest The authors declare that they have no competing interest. References [1] Pollock JA, Newton TH, Hoyt WF. Transsphenoidal and transethmoidal encephaloceles. Radiology 1968;90:442–53. [2] Elster AD, Branch Jr CL. Transalar sphenoidal encephaloceles: clinical and radiologic findings. Radiology 1989;170:245–7. [3] Soyer P, Dobbelaere P, Reizine D, et al. Méningo-encéphalocèle transalaire associée à une angiomatose buccale. À propos d’une observation. J Neuroradiol 1990;17:222–6. [4] Soyer P, Dobbelaere P, Benoit S. Transalar sphenoidal encephalocele: uncommon clinical and radiological findings. Clin Radiol 1991;43:65–7. [5] Mylanus EA, Marres HA, Vlietman J, et al. Transalar sphenoidal encephalocele and respiratory distress in a neonate: a case report. Pediatrics 1999;103:E12. [6] Short J, McKinney AM, Lucato LT, et al. Transalar encephalocele associated with Wegener granulomatosis and meningeal enhancement: case report. AJNR Am J Neuroradiol 2005;26:1873–5. [7] Mulcahy MM, McMenomey SO, Talbot JM, Delashaw Jr JB. Congenital encephalocele of the medial skull base. Laryngoscope 1997;107:910–4.
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[12] Falcon RT, Rivera-Serrano CM, Miranda JF, et al. Endoscopic endonasal dissection of the infratemporal fossa: anatomic relationships and importance of eustachian tube in the endoscopic skull base surgery. Laryngoscope 2011;121(1):31–41. [13] Fortes FS, Sennes LU, Carrau RL, et al. Endoscopic anatomy of the pterygopalatine fossa and the transpterygoid approach: development of a surgical instruction model. Laryngoscope 2008;118(1):44–9. [14] Hofstetter CP, Singh A, Anand VK, et al. The endoscopic, endonasal, transmaxillary transpterygoid approach to the pterygopalatine fossa, infratemporal fossa, petrous apex, and the Meckel cave. J Neurosurg 2010;113(5):967–74.
Please cite this article in press as: Zoghlami A, et al. Transalar transsphenoidal meningoencephalocele presenting in the form of recurrent meningitis: Report of two cases and discussion of the diagnosis and treatment. European Annals of Otorhinolaryngology, Head and Neck diseases (2016), http://dx.doi.org/10.1016/j.anorl.2016.07.001