Volume 4, Issue 2 , Pages 66-71, March 2009
Endoscopic endonasal excision of congenital midline meningoencephalocele in a 5-month infant
Article Outline
Summary
Congenital infantile midline nasal meningoencephaloceles are rare anomalies. A 5-month-old Egyptian boy otherwise healthy presented with history of respiratory distress, difficulty in oral feeding and appearance of a mass in right nostril. The CT scan showed soft tissue density lesion filling the right nasal fossa with small bony defect in the most anterior part of anterior cranial fossa adjacent to right side of the crista galli suggesting meningoencephalocele. MRI showed the same mass criteria as on CT with fluid signal intensity. The lesion was approached and removed endonasally under general anesthesia with the use of different angles endoscopes. The mucoperiostium covering the posterior two third of the ipsilateral inferior nasal turbinate was harvested and used for repair of the defect. The patient was discharged from the hospital after 48
h of surgery and was followed up for 3 months after surgery with no reported symptoms or related surgical complication. To the best of our knowledge, this is the youngest patient reported in the literature to be treated successfully with this approach.
Keywords: Congenital, Meningoencephalocele
1. Introduction
Congenital midline nasal masses are rare anomalies. Nasal cerebral heterotopias (nasal gliomas) and nasal encephaloceles have an actual or potential central nervous system connection, and represent rare inborn malformations of the central nervous system [1], [2]. Nasal encephaloceles are herniations of the intracranial contents through a defect in the anterior skull base [3]. Nasal encephaloceles can be divided into two main groups: frontoethmoidal and basal encephaloceles [3]. Basal encephaloceles can be classified as transethmoidal, sphenoethmoidal, transsphenoidal and frontosphenoidal [3]. Frontoethmoidal and basal encephaloceles are very rare (1:5000) [3].
The pathogenesis of encephaloceles may be explained by a disturbance in the separation of the surface ectoderm and neuroectoderm in the midline just after closure of the neural folds. Diagnostic CT or MR imaging delineates the anatomy of the herniated mass [1], [2], [3].
During the past decade, the endoscopic endonasal approach for the treatment of different skull base related lesions has increased in popularity as it improved patient comfort due to its minimal invasiveness and shortened hospital stay [4], [5]. The procedure offers a panoramic view, allowing observation of all anatomic structures along the surgical route, as well as those located in skull base [4], [5].
Here we present the case of a 5 months-old Egyptian boy who suffered from a congenital encephalocele that was dealt with successively endonasally with the use of the endoscopes.
2. Case report
A 5 month-old Egyptian otherwise healthy boy was referred to our clinic with history of respiratory distress, difficulty in oral feeding and appearance of mass in right nostril. On examination a pale pink swelling was seen in the right nostril. The mass did not enlarge with crying.
The child was investigated to exclude other associated anomalies. CT scan and MRI for the head and brain were performed. The CT (Fig. 1) showed soft tissue density lesion filling the right nasal fossa. A small bony defect was seen in the most anterior part of anterior cranial fossa in the middle line and slightly to right the side of crista galli suggesting meningoencephalocele. The nasal cartilage and spine were displaced to the left and distorted in appearance. In MRI the mass showed the same criteria as on CT with fluid signal intensity (Fig. 2).
Fig. 1.
Plain axial CT scan of the head in coronal (A and B), axial (C and D) and sagittal (E) views. They showed soft tissue density lesion filling the right nasal fossa. A small bony defect was seen in the most anterior part of anterior cranial fossa in the middle line (yellow arrow) and slightly to right side adjacent to crista galli suggesting meningoencephalocele.
Fig. 2.
Non-contrast MRI of the head and brain using different pulse sequences in coronal (A–C) and sagittal (D and E) views. The mass showed the same criteria as on CT with fluid signal intensity.
2.1. Surgical procedure
The lesion was approached endonasally under general anesthesia with the use of different angles 4mm Hopkins rod endoscopes (0° and 30°). Endoscopic evaluation revealed a 1.5cm in diameter spherical soft tissue lesion arising with a broad base from the mid portion of the nasal septum. It was occupying the anterior half of right nasal fossa and covered by septal mucosa that was stretched over the lesion. The base of the lesion with the attached surrounding nasal septal mucosa was diathermied using bipolar diathermy. The fluid content of the lesion escaped inwardly during diathermy and the lesion shrunken nearly to half of its original size. The pedicle of the lesion was manipulated and excised with angled turbinate scissor. After excision there was neither CSF leak nor dural pulsation at the lesion base. Bleeding that occurred at the site of the excision was controlled by bipolar diathermy.
The mucoperiostium covering the posterior two third of the ipsilateral inferior nasal turbinate was harvested to be used for repair of the defect [5]. The turbinate tissue was fashioned with scissors and cut to a size a little larger than that of the defect. It was used to repair the defect in a manner where the turbinate mucoperiostium was laid toward the cranial site of the lesion and the covering turbinate mucosa was laid toward nasal cavity. The graft was supported in its place with gelfoam. A lumbar drain was not placed.
At the end of the procedure, light anterior nasal pack with vaseline-impregnated gauze and gentamycin ointment was inserted into right the nasal cavity to control bleeding from the operated nasal tissue, to provide temporary support for the inserted grafts and to prevent early formation intranasal synechia. Patient was kept in the hospital to apply systemic intravenous antibiotic, removal of the nasal pack after 48h of surgery and to exclude postoperative CSF leak or other complications. The child was followed up for 3 months after surgery with successful outcome (Fig. 3). The endoscopic exam of the right nasal cavity revealed a well healed graft site and no evidence of recurrence or cerebrospinal fluid leak.
Fig. 3.
Preoperative (left side) and postoperative (right side) (5 months after surgery) plain CT scan of the same case in axial (A and B), coronal (C and D) and sagittal (E and F) showing complete removal of the lesion and sealing of skull base defect. The grafted area of skull base looked in a different resolution due to either thin slices of the CT taken or due to the healing process of the grated material used (mucoperiostium of the inferior nasal turbinate).
3. Discussion
Encephaloceles are malformations of the central nervous system caused by a developmental failure in the differentiation of the surface ectoderm and neuroectoderm in the midline subsequent to closure of the neural folds [6]. Defined by the protrusion of brain tissue through an osseous midline defect in the cranium, these lesions are classified according to the location of the skull defect [6]. The occurrence of encephaloceles is variable and appears to depend on both genetic and environmental factors [7]. In countries of the Western hemisphere encephaloceles are rare (one case/40,000 population) and occur predominantly in the occipital region of the brain; in Southeast Asia encephaloceles show a relatively high incidence (one case/5000 population) [7], and are most commonly localized in the anterior region of the brain [3].
Encephaloceles are also classified according to their contents. Those containing only cerebrospinal fluid and meninges are termed craniomeningoceles; if the lesion also contains neural tissue then they are termed meningoencephaloceles [8]. The current case was meningoencephaloceles as demonstrated preoperatively by MRI, intraoperatively by CSF leakage during diathermy of the pedicle with subsequent shrinkage of the lesion and postoperative histopathological finding.
Most encephaloceles require surgical treatment to prevent damage to the surface of the herniated mass and the attendant risks of infection and further distortion of the facial anatomy that can result from the patient's growth [9]. Beside these surgical indications the case of this study was complaining of respiratory distress and difficulty in oral feeding because of the inherited nasal breathing in early life of the infant.
Traditionally, encephaloceles have been treated neurosurgically via a transcranial approach associated with the possible morbidity of a loss of sense of smell, postoperative intracerebral hemorrhage, cerebral edema, epilepsy, frontal lobe dysfunction with memory and concentration deficits [10], [11]. The advent of endoscopic sinus surgery has allowed a new intranasal approach for the treatment of basal encephaloceles, minimizing patient morbidity [4]. The current case was dealt entirely endoscopically through the ipsilateral nostril. The procedure offered a panoramic view, allowing observation of all anatomic structures along the surgical route of the herniated encephalocele. A careful use of bipolar diathermy to cauterize the pedicle of the lesion was done to avoid inadvertent injury to intracranial contents and to reduce the risk of intracranial bleeding.
Intracranial or subarachnoid communication could not be demonstrated in the current case as the intracranial connection might be lost or was very small. A pedicle directly connecting the neuroglial tissue with the subarachnoid or ventricular spaces might be detached and eventually absorbed or vestigial [9]. The incidence of bony defects noted is as high as 21% [9].
In the current work the turbinate tissue has proven to be an excellent source of donor material for successful reconstruction after encephalocele excision. It is costless, safe, soft, malleable and easy to obtain in the same set of surgery with suitable size and without side effects or complications. It is effective in sealing the surgical field defect without restriction related to the working space, which is not always comfortable and in obliteration of dead space [5].
The optimal age for repair of congenital encephaloceles is not known. The difficulties of operating in very young infants have led some surgeons to defer surgical excision until the child is older. However, in some cases the child is at risk of significant airway obstruction from the mass, leading to difficulties in feeding and failure to thrive, so that early excision becomes necessary. Schlosser [12], in 2005, reported a case of congenital intranasal encephaloceles that was repaired successfully at 23 months of age via a transnasal endoscopic approach. Hamlin and Kubba [13], in 2007, reported a successful endoscopic excision and repair of a nasal meningoencephalocoele in a 6-month-old infant. The current case and the previously mentioned two cases highlight the importance of endoscopic approaches to encephaloceles resulting in less morbidity than a traditional craniotomy.
It is important to emphasize that only in cases with meningoencephalocoele due to very narrow boney defect the surgical technique described in this work can be applied. In cases with larger boney defects of the skull base the defect should be closed in different techniques.
Continued advances in technology and skill will increase the feasibility of transnasal endoscopic skull base surgery in younger patients.
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PII: S1871-4048(08)00050-6
doi:10.1016/j.pedex.2008.06.008
© 2008 Elsevier Ireland Ltd. All rights reserved.
Volume 4, Issue 2 , Pages 66-71, March 2009
