Successful surgical repair of progressive exophthalmos caused by a meningocele in a patient with neurofibromatosis Type 1. Case report

Clinical, radiological features and surgical strategies for 23 NF1 patients with intraorbital meningoencephalocele

Intraorbital meningoencephalocele is a rare manifestation of neurofibromatosis type 1 (NF1) caused by secondary changes in sphenoid dysplasia, and it seriously affects patients' vision and facial appearance. We retrospectively analyzed the clinical data of 23 patients with NF1 and intraorbital meningoencephalocele, summarized the surgical strategies employed, and evaluated their clinical efficacy in order to better understand its management in clinical practice, establish a reasonable surgical strategy, and assess prognosis. Before surgery, 22 patients had unilateral pulsatile exophthalmos, 18 patients had significant visual impairment, and 13 patients had ptosis associated with an orbital plexiform neurofibroma (PNF). All 23 patients underwent microsurgical craniotomy with skull base reconstruction using a soft titanium mesh. One month after surgery, the degree of exophthalmos in the 22 (95.65%) patients was significantly reduced compared with before surgery (P < 0.001), and ocular pulsation had subsided. The visual acuity did not decrease significantly (P = 0.298) compared with before surgery. Eleven (47.83%) patients received phase-II eyelid PNF resection and/or oculoplastic surgery, and the degree of ptosis was significantly reduced (P < 0.001). There was no recurrence of pulsatile exophthalmos, displacement of titanium mesh, decreased visual acuity, or increased degree of ptosis noted during follow-up. The best strategy is to reconstruct the skull base under microscopy to relieve pulsating exophthalmos and preserve existing visual function. In cases of ptosis caused by an eyelid PNF, surgical resection should be performed as soon as possible to remove the tumor, and/or oculoplastic surgery should be performed to improve the cosmetic outcome.

Orbital Meningoencephalocele and Pulsatile Proptosis: A Rare Entity

Orbital roof defects are rare congenital osseous abnormalities that cause protrusion of intracranial contents into the orbit, resulting in a condition known as the orbital meningoencephalocele, a rare cause of pulsatile proptosis. We present a case of a 25-year-old lady, presented to us with complaints of left frontal headache, left eye protrusion and double vision from the left eye for the past three months. Her higher mental functions were intact. Local examination revealed non-axial pulsatile proptosis and an outward depression of the left eyeball along with diplopia. Extraocular movements and pupillary light response were normal with no bruit or orbital tenderness. Computed tomography (CT) scan of the brain and orbit with contrast showed deficient bone on the left orbital roof and floor with left frontal gliotic brain compressing the eyeball. Magnetic resonance imaging (MRI) of the brain and orbit with contrast showed an asymmetrical deformity of the skull and left cerebral hemisphere which was bulging towards the left orbit. We planned a two-staged surgical reconstruction. The orbital roof was first reconstructed using a titanium mesh. Within two weeks of surgery her pulsatile proptosis, diplopia, and headache had considerably improved and the proptosis had resolved with no visible pulsations. She is scheduled for second stage surgery after three months for reconstruction of the orbital floor.

Pathophysiology and treatment options in trigeminal meningoceles

Trigeminal meningoceles, lateral to the maxillary nerve (V2), have seldom been reported as underlying pathology for spontaneous rhinoliquorrhea. In contrast to sphenoid meningoceles arising from a persistent lateral craniopharyngeal canal (Sternberg-Cruveilhier, medial to V2), their occurrence seems to be generated by addition of erosive processes to the constitutively thin bony shell underneath the semilunar ganglion, lateral to the round foramen (and V2). The developmental and anatomical relationships of trigeminal meningoceles to the sphenoid bone are depicted, and in a review of the literature we present the different surgical approaches employed for sealing the dura leak. In view of these techniques we discuss an unusual case of therapy-resistant rhinoliquorrhea with left-sided trigeminal meningocele involving the Meckel cave at the lateral sphenoid and reaching the superior orbital fissure and the medial orbital space. In contrast to patients who have lateral sphenoidal meningoceles with a persistent lateral craniopharyngeal canal (Sternberg-Cruveilhier), who can be treated successfully using an endoscopic transsphenoidal approach (recurrence rate 13.7%), the recurrence rate of cerebrospinal fluid (CSF) efflux for trigeminal meningoceles lies much higher (endoscopically 66%, open craniotomy 33%). The surgical strategy thus has to be chosen individually, taking into account specific anatomical situations and eventually preceding operations.

[Orbitotemporal facial involvement in type 1 neurofibromatosis (NF1)]

Plexiform neurofibromas of the orbit, sometimes extending to the temporal region and the face, are considered to be a rare but devastating and disfiguring complication of neurofibromatosis type 1. The first symptoms appear in infancy and the involvement of the orbit and the face is present in nearly all children after the age of 5. The disease is unilateral in most cases but can exceptionally involve both sides of the face. Progressive deformation of the orbital frame due to the expanding plexiform neurofibroma and buphthalmos occurs in a large proportion of cases. The associated sphenoidal dysplasia, which is thought to be, according to the most recent hypothesis, genetically determined, will inescapably increase the burden to the orbital content, cause pulsating proptosis and will endanger noble structures, finally resulting in loss of vision. Using the Jackson classification, the authors report their personal series of 22 cases (19 operated). Until now, there has been no effective medical treatment for plexiform neurofibroma and surgery remains the standard care for these patients. Controversies remain about the timing of the first operation and today most multidisciplinary teams involving plastic, maxillofacial, ophthalmologic, and neurosurgeons favor early intervention to try to minimize the secondary deformation of the orbital and facial skeleton. A number of cases of plexiform neurofibromas are illustrated within the three Jackson groups and treatment results of the rare elephantiasis neuromatosa cases are presented. Special techniques such as preoperative embolization of heavily vascularized plexiform neurofibroma are also discussed.

Computer-aided design for three-dimensional titanium mesh used for repairing skull base bone defect in pediatric neurofibromatosis type 1. A novel approach combining biomodeling and neuronavigation

BACKGROUND

Sphenoid dysplasia is a distinctive but uncommon manifestation of neurofibromatosis type 1. The absence of the sphenoid greater wing allows the temporal lobe to prolapse into the orbit resulting in temporal base encephalocele and pulsating exophthalmos. Surgical procedures are aimed at preserving vision and improving ocular movement and cosmesis. This defect can be closed using bone grafts or titanium mesh. However, the results of this procedure are often unsustainable due to bone graft resorption and graft displacement.

METHODS

In this report, we describe a novel surgical technique, combining computer-aided design, stereolithography and neuronavigation to repair a temporal base skull defect in a 16-year-old female patient with neurofibromatosis type 1. A three-dimensional model of the skull base defect and a template for graft were first constructed according to the image data, then transferred to a real-size stereolithographic biomodel using a rapid prototyping technique.

RESULTS

The final graft of titanium mesh, which was intraoperatively fabricated based on the biomodel, was precisely orientated and securely fixed to the surrounding bone under frameless navigation. Long-term follow-up result proved this repair to be effective and durable.

CONCLUSION

The approach combining computer-aided design, stereolithography and surgical navigation could help managing the complex lesions in the skull base and craniofacial area requiring rigid reconstruction.

Jugular foramen meningocoele in a patient with neurofibromatosis type 1

Objective:

We present a rare case of a jugular foramen meningocoele in a 48-year-old female, with neurofibromatosis type 1, presenting with positional vertigo. We also postulate possible underlying pathophysiological mechanisms.

Method:

We describe the imaging findings of this rare entity and review the literature on skull base meningocoeles, particularly in the context of neurofibromatosis type 1.

Results:

A computed tomography scan revealed smooth expansion of the jugular foramen. Magnetic resonance imaging showed a fluid filled lesion expanding the jugular foramen and communicating with cerebrospinal fluid of the cerebellomedullary cistern superiorly.

Conclusion:

Skull base meningocoeles are a rare entity and we believe that this is the first reported case of a meningocoele causing enlargement of the jugular foramen in a patient with neurofibromatosis type 1. The meningocoele may have resulted from a severe form of dural ectasia or from dysplastic, weakened bone at the skull base.

[Orbital meningocystocele]

Encephalocele is defined as a protrusion of cranial contents beyond the normal confines of the skull. Encephaloceles occur with an incidence of approximately 1 in 3,000-10,000 births and are categorized based on location in the skull. Orbital meningoencephalocele is a rare congenital abnormality caused by a defect of the cranio-orbital bones that usually manifests soon after birth as a soft mass associated with exophthalmos. We present a case of a giant orbital meningocele presenting as an orbital mass in a 15 months-old girl. Preoperative diagnosis was confirmed by CT-scan and magnetic resonance imaging.

Neuro-ophthalmology of the phacomatoses

The phacomatoses are a group of disorders that feature multiple hamartomas of the central and peripheral nervous system, eye, skin, and viscera. Most of these disorders have a well-defined Mendelian pattern of inheritance because of a mutation in a single gene which has been identified. In other instances, no clear patterns of inheritance or genetic susceptibility have been recognized. The combination of ocular and central nervous system manifestations in patients with phacomatoses makes neuro-ophthalmologic evaluation particularly important in diagnosis and management. This review provides an overview of the phacomatoses with emphasis on recent reports of significance to neuro-ophthalmology.

An unusual pterygopalatine meningocele associated with neurofibromatosis type 1. Case report

The authors describe an unusual meningocele of the lateral wall of the cavernous sinus and the anterior skull base in a young patient with typical stigmata of neurofibromatosis Type 1 (NF1). This lesion was discovered during evaluation for recurrent meningitis. It represented an anterior continuation of Meckel's cave into a large cerebrospinal fluid space within the lateral wall of the cavernous sinus, extending extracranially through an enlarged superior orbital fissure into the pterygopalatine fossa adjacent to the nasal cavity. It was successfully obliterated, via an intradural middle fossa approach, with fat packing and fenestration into the subarachnoid space. This meningocele most likely represents a variant of cranial nerve dural ectasia occasionally seen in individuals with NF1. It has as its basis the same mesodermal defect responsible for the more common sphenoid wing dysplasia and spinal dural ectasias identified with this condition. Involvement of the trigeminal nerve with expansion of the lateral wall of cavernous sinus has not been reported previously. The authors surmise, however, that it may be present in some cases of orbital meningocele associated with sphenoid wing dysplasia.