Endoscopic excision of meningocele and meningoencephalocele-report of two cases

Meningocele and meningoencephalocele are raxe entities produced by hemiation of cranial contents at the defective axeas of the skull base, which may be congenital, spontaneous or traumatic. The condition may present as CSF rhinorrhoea, nasal obstruction or even with meningitis. Management of these basal encephaloceles with endoscopic surgery provides a direct view of the skull base and cause less morbidity compared with transcranial approach. Two cases have been reported her6, first, a meningocele presented as a case of recurrent CSF rhinorrhoea and the second one, a meningoencephalocele presented as recwrent meningitis, treated using an endoscopic procedure and reviews the literature regarding their management. Key Word: Meningocele; Meningoencephalocele; Endoscopic excision Introduction: Basal encephalocoeles are rare entities produced by herniations of cranial contents at the defective areas of the base of the skulll. They may be congenital, spontaneous or traum atic (iatrogenic or from head injury)'. Th.y may present with cerebrospinal fluid (CSF) leak, meningitis, brain abscess, nasal obstruction, factal deformity (in congenital cases)'-'. In some it may go undetected until it is noted incidentally on imaging studies7. Endoscopic surgery provides a direct view of the skull base and is associated lower morbidity rates compared with the transcranial approach in the treatment of CSF leakages'e. As the instruments progressively improve, various surgeons have recommended endoscopic surgery for the treatment of more challenging entities, such as basal encephalocoel.rl0-ra. It can also be perfomed in very young childrentt. In recent years this method has become popular among ENT surgeons and neurosurgeons. In this report, two Address for Correspondence: Dr. Sheikn Hasanur Rahman Associate Professor Dep. of Otolaryagology, BSMMU, Mobile: 01711540139 IBSMMU J 2014 ; 7 (1) : 53-57J cases, first one meningocele with recuffent CSF rhinorrhoea and second one meningoencephalocoele with recurrent meningitis, are presented and reviewed possible treatment options. Case Reports: Case 1: 1. A 45-year-old male was admitted in the Department of Otolaryngology, Bangabandhu Sheikh Mujib Medical University in April2007 with the history of clear watery discharge from right nasal cavity and right-sided nasal obstruction for 3 years. He had no history of fever, convulsion, loss of consciousness, or head injury. He was previously hospitahzedthree times, diagnosed as a case of recur:rent CSF rhinorrhoea and each time treated conservatively. Nasoendoscopic examination showed a large grayish, glistening, smooth, pulsatile mass in the right nasal cavity. A coronal computed tomography scan revealed a right-sided cystic nasal mass, deviating the septum to the opposite side, and there was bony dehiscence in the floor of anterior cranial fossa in right paramedian area. Findings of biochemical examination of nasal discharge were consistent with CSF.


Introduction:
Basal encephalocoeles are rare entities produced by herniations of cranial contents at the defective areas of the base of the skulll.They may be congenital, spontaneous or traum atic (iatrogenic or from head injury)'.Th.y may present with cerebrospinal fluid (CSF) leak, meningitis, brain abscess, nasal obstruction, factal deformity (in congenital cases)'-'.In some it may go undetected until it is noted incidentally on imaging studies7.
Endoscopic surgery provides a direct view of the skull base and is associated lower morbidity rates compared with the transcranial approach in the treatment of CSF leakages'e.As the instruments progressively improve, various surgeons have recommended endoscopic surgery for the treatment of more challenging entities, such as basal encephalocoel.rl0-ra.It can also be perfomed in very young childrentt.
In recent years this method has become popular among ENT surgeons and neurosurgeons.In this report, two Address for Correspondence: Dr. Sheikn Hasanur Rahman Associate Professor Dep. of Otolaryagology, BSMMU, Mobile: 01711540139 IBSMMU J 2014 ; 7 (1) : 53-57J cases, first one meningocele with recuffent CSF rhinor- rhoea and second one meningoencephalocoele with recur- rent meningitis, are presented and reviewed possible treatment options.

Case Reports:
Case 1: 1.A 45-year-old male was admitted in the Department of Otolaryngology, Bangabandhu Sheikh Mujib Medical University in April2007 with the history of clear watery discharge from right nasal cavity and right-sided nasal obstruction for 3 years.He had no history of fever, convulsion, loss of consciousness, or head injury.He was previously hospitahzedthree times, diagnosed as a case of recur:rent CSF rhinorrhoea and each time treated conservatively.Nasoendoscopic examination showed a large grayish, glistening, smooth, pulsatile mass in the right nasal cavity.A coronal computed tomography scan revealed a right-sided cystic nasal mass, deviating the septum to the opposite side, and there was bony dehiscence in the floor of anterior cranial fossa in right paramedian area.Findings of biochemical examination of nasal discharge were consistent with CSF.
With a diagnosis of meningocele, he underwent a endona- sal endoscopic procedure.Under general anesthesia, using nasoendoscope, the meningocele sac was identified (Fig-l).The sac was first shrinked using low voltage bipolar cautery and then redundarfipartwas dissected and resected meticulously.During the excision, cerebrospinal fluid (CSF) leak was observed.A bone defect of about 8 mm in size was identified at the cribriform plate.The defect was repaired in layers using fascia lata, and a piece of septal cartlledge by underlay technique (Fig- 2).Nasal cavity was packed first by a large piece of gelfoam and then by BIPP pack.Lumber drain was not used.
The patient was discharged from hospital on 10th postop- erative day after removing the BIPP pack, with no sign of CSF leak, infection.Follow up was done regularly by nasoendoscope and treated accordingly.There was no evidence of CSF leak or herniation through the roof of the nose till the last follow up in November 20L0.A7 -year-old boy admitted in the hospital on Janu ary 2008 with history of recurrent meningitis for last one year.He also complaint of right sided nasal obstruction for last 6 month.He was hospitahzed several times with meningitis and was treated conservatively.Nasoendoscopic examination revealed a smooth globular grayish white pulsatile mass in the right nasal cavity (Fig- 3).On aspiration clear watery fluid came out; findings of laboratory tests were consistent with CSF.Computed tomography scan showed a soft tissue mass with heterogenous enhancement in the anterior superior part of right nasal cavity.Bony dehis- cence was seen in right half of cribriform plate pushing the cris ta galhto left side.
Preoperatively it was diagnosed as a case of meningo- encephalocele , and underwent endoscopic excision.The sac was dissected and excised by using low voltage bipolar diathermy; small portion of the brain matter was also excised.Bony dehiscence was repaired by underlay technique using fascia lata and a piece of septal cartlledge 54 in layers.Nasal cavity was packed by Gelfoam and BIPP pack, which was removed after 8 days.Post operative recovery was uneventful.We didn't use lumber drain.
The patient was followed up periodically with no recur- rence of nasal mass, meningitis or CSF leak till the last follow up in Nov. 2010.The management of meningocele or meningo- encephalocele has changed dram atically with nasal endoscopic techniques.Historically, these lesions were approached with a bicoronal incision and frontal crani- otomy.Often it was necess ary apericranial flap in order to reconstruct the skull base defects3'16.
Unforfunately some disadvantages of transcranral approaches were anosmia, tntracrantal hemorrhage or edema, epilepsy, frontal lobe rctraction, and memory or concentration deficitsl6.It also has a long hospital stay, less patient's comfort and a visible scarrT-24.Furthernore, failure rates for CSF rhinorrhea can be as high as 30o/o.Many of these complications were avoided by using nasal endoscopic techniques.The endoscopic excision of intranasal encephaloceles, meningoceles, meningo- encephaloceles, and repair of cerebrospinal fluid (CSF)   leaks in adults, mostly traumatic or iatrogenic, has become the standard of caret-t.
Meningo-encephaloceles and associated CSF leaks remain a surgical challenge.Many of these lesions can be diagnosed by direct visuahzation with a nasal endoscope.High-resolution CT with contrast help to corroborate the site of origin to ascertain the extent of the skull base defect and to rule out other sinonasal and intracrantal pathology or the presence of vessels within the herniated tissue3.
MRI can complement the anatomical information provided by CT in terms of the stze and location of the stalk of the lesion and the presence of vessels within the sac.MR cisternography does not require the intrathecal administration of a contrast agent and may become the imaging modality of choice for the evaluation of CSF fisfulae.MR cisternography is noninvasive and has a reported sensitivity, specificity, and accuracy of 87oh, 57oh, and 96oh, respectively, when combined with coronal CT2s .Traditionally, CSF leaks have been managed via a craniotomy.Initially, the extracranial repair of CSF leaks involved an external ethmoidectomy approach and the use of a mucosal pedicled flap to close the CSF fistula.Subsequently, free tissue grafts followed by transnasal techniques were advocated.Microscopic transnasal techniques for the repair of CSF leaks predate endoscopic technology; however, transnasal repairs became more popular with the advent of endoscopic sinus surgery.
Since the first description of endoscopic closure of CSF leaks by Wigand in 1981, multiple reports have described a number of different grafti.ngtechniqueslO.
The choice of materials and techniques used during the endoscopic repair of CSF fistulae depends mostly on'the experience and preforence of the operating surgeon.In experienced hands, most techniques yield similar results" .The critical for all grafting techniques is that the mucosa sulrounding the defect should be removed to allow the graft to adhere firmly to the skull base.Herni- ated dura, brain, or both can be managedwith resection or reduction into the intracranial cavity.Most authors agree with transection or resection of the pedicle because encephaloceles seldom contain functional brain tissue, and the intranasal portion is considered to be contaminated28.
The inlay/underlay, onlay, and obliteration techniques have no significant differences in outcome.Typically, an underlay technique with bone or cartilage, fat, andlor muscle plugs is used for large, bony defects associated with a meningoencephalocele.In addition, various materi- als can be used to fixate the grafts andlor flaps in place, such as Surgicel, Gelfoam and Gelfilm, and fibrin glue3.Burns et al. used the endoscope to manage 42 patients with fisfulae".They supported the use of a free mucosal graft with fibrin glue for defects of the cribriform plate and roof of the ethmoid.In Zwerg et al series, fibrin glue, although subjectively helpful, did not appear to be critical to obtaining an adequate closure'.Corrrersely, it does not guararrtee success as illustrated by a meta-analysis of the literature by Hegazy et a1'0.
The aspects of perioperative management like the use of prophylactic antibiotics, the use of nasal packing, and diversion of the CSF, either with a lumb ar dratn or a VP shunt are controversial and argued in different literafures.
We used antibiotic soaked Gelfoam as fixator and Bismath Iodine paste pack and kept it for 8-10 days.Some authors prefer removing nasal pack early.We didn't use lumber drain'in our cases.In some sfudies, the authors used lumber drain after endoscopic surgery while in others, they didn't use tt''".In a study it has been found thatthere is no significant difference between using or not using lumber drain; however those with hydrocephalus requires a pennanent CSF diversion (eg.VP shurrt)'o.
Hydrocephalus and meningitis are the common causes of failure for transnasal endoscopic repair of CSF leaks with or without meningocele3.The size of a defect may be a limiting factor for endoscopic repair3, but we could draw no conclusions about this variable.

Conclusion:
Endoansal endoscopic approach is safe and effective in the management of basal meningocoele/ meningoen- c ephalo c o ele .C omp lic ati ons o f trans cr artal appr o ach c an be avoided by using this less invasive procedure.

Fig
Fig I : A meningocoele between nasal septum and middle turbinate