Absence of the greater sphenoid wing in neurofibromatosis type I: congenital or acquired: case report

The Management of Orbital Roof Fractures and Defects: A Review

PURPOSE

To explore the anatomy, etiopathogenesis, diagnosis and classification, current evidence on intervention and the surgical management of orbital roof fractures and defects (ORFD) for oculoplastic surgeons presented with such cases.

METHODS

A review of the current literature through the MEDLINE database using the following search terms: "orbital roof fracture (+treatment/management)," "orbital roof defect (+treatment/management)," "orbital roof erosion (+treatment/management)," "orbital roof repair," "orbital roof," "orbital fracture," "pediatric orbital roof (defect/fracture/erosion)," "orbital anatomy," and "orbital roof anatomy" was conducted. As relatively little has been published on this topic, inclusion criteria were broad and peer-reviewed articles judged to be of clinical importance, relevant to the aims of this review, were included. Non-English abstracts were also included if relevant. Year of publication was not a strict exclusion criterion, and older articles were judged for their suitability based on clinical importance and relevance to current practice. Additional references were obtained from citations in key articles and recommendations from the coauthors based on their areas of expertise.

RESULTS

The etiopathogenesis of ORFD varies. Classification systems have been formulated to guide management decisions and can range from conservative management to complex neurosurgery. Eyelid approaches have also been described. This review provides a summary of the evidence for each and a management framework oculoplastic surgeons can use when presented with ORFD.

CONCLUSION

Oculoplastic surgeons can be involved, either alone or as part of a multidisciplinary team, in the management of ORFD, and for some, conduct orbital approach reconstructive surgery.

"Pulsating proptosis and heavy eye syndrome precipitated by neurofibromatosis type 1: A case report"

RATIONALE

Neurofibromatosis type 1 (NF1) is a hereditary disease characterized by café-au-lait spots, peripheral neurofibromas, Lisch nodules, optic nerve glioma, and sphenoid wing dysplasia. Pulsating proptosis is associated with a sphenoid bony defect. Heavy eye syndrome is characterized by acquired esohypotropia in patients with high myopia. This study aimed to describe the presentation of pulsating proptosis and heavy eye syndrome precipitated by NF1 and its management.

PATIENT CONCERNS

A 41-year-old woman presented with progressive pulsating proptosis and hypodeviation of the right eye over the past 2 years. The axial length of the right eye was 36.81 mm. The right eye presented with esohypotropia and hypoglobus. The ocular motility examination showed limitations in all directions, especially in supraduction. Brain computed tomography revealed sphenoid wing dysplasia of the right orbit. The meningocele protruded through the orbital defect, lifting the globe. Brain magnetic resonance imaging demonstrated superior rectus muscle (SR) medial displacement and lateral rectus muscle inferior displacement. Physical examination revealed café-au-lait macules and neurofibromas on the trunk.

DIAGNOSIS

NF1 with pulsating proptosis and heavy eye syndrome.

INTERVENTIONS

The patient declined neurosurgery due to risk and economic reasons. To manage her main concern regarding cosmetics, we performed orbital floor decompression, SR resection with advancement, maximal hang-back recession of the inferior rectus muscle, and a partial Jensen's procedure.

OUTCOMES

Proptosis was reduced. The eye position became more symmetrical. The range of eye movements was also increased.

LESSONS

This case describes a rare synchronous presentation of pulsating proptosis and heavy eye syndrome precipitated by NF1. Adult-onset presentation implied a progressive process in NF1. The case also showed a different etiology from that of typical heavy eye syndrome. It reminds ophthalmologists that orbital imaging should be performed in high myopia patients with strabismus to evaluate the extraocular muscle pathway. Furthermore, the case demonstrated a management that avoided the risk and expensive cost of neurosurgery, which has not been reported.

Sphenoid Bone Pneumatisation on Lateral Cephalograms of Patients With Neurofibromatosis Type 1

BACKGROUND/AIM

Neurofibromatosis type 1 (NF1) is an autosomal dominant hereditary disease that causes tumors and many developmental disorders, e.g., cranial dysplasia. The purpose of this retrospective study was to analyse the pneumatisation of the sphenoid bone in NF1.

PATIENTS AND METHODS

The anonymised lateral cephalograms of 166 NF1 patients and 166 age- and sex-matched controls were examined for anterior-posterior sphenoid pneumatisation. The patient group analysis considered whether the patients had been affected by a facial plexiform neurofibroma (FPNF).

RESULTS

Sphenoid pneumatisation was significantly lower in NF1 patients than in controls [odds ratio (OR)=0.184; 95%CI=0.11-0.32; p<0.001]. A FPNF statistically significantly reduced sinus formation in patients (OR=0.38; p=0.002).

CONCLUSION

The condition 'NF1' has an effect on sphenoid pneumatisation. The findings are relevant for planning surgical procedures in this region and confirm current concepts to evaluate NF1 as a histogenesis control gene. The examination technique and basis of calculation presented here are easy-to-use and low-irradiation exposure instruments for screening for differences in sphenoid bone pneumatisation in defined populations.

Current concepts on ocular vascular abnormalities in the phakomatoses

BACKGROUND

Neurofibromatosis, Von Hippel Lindau disease, and tuberous sclerosis complex are classified under the term phakomatoses. They are characterized by ocular vascular abnormalities such as vascular tortuosity, corkscrew retinal vessel configuration, moyamoya-like aspect, microaneurysms, hemangioblastomas, and focal sheathing of retinal arteries, possibly due to abnormal formation, migration, and differentiation of neural crest cells. These alterations can be the first sign or the hallmark of disease and can be related to vasoproliferative tumors.

PURPOSE

Novel imaging technologies in ophthalmology, such as near-infrared reflectances and spectral domain optical coherence tomography, have improved our knowledge in the diagnosis of these pathologies. Previously undetected macular vascular alterations have been reported in phakomatoses using optical coherence tomography angiography. This review will summarize the ophthalmic vascular abnormalities and novel imaging methods in the phakomatoses.

CONCLUSION

Active research is being led into the ophthalmic management of these conditions and their complications, and owing to elevated vascular endothelial growth factor production from hemangioblastoma, hamartoma, and retinal vascular proliferative tumors, increasing interest in this line of therapy has been conducted although research is still ongoing in this area.

Sphenoid Wing Dysplasia in the Absence of Neurofibromatosis: Diagnosis and Management of a Novel Phenotype

Congenital sphenoid wing dysplasia is one of the major diagnostic criteria for neurofibromatosis type 1, and is often considered pathognomonic for the disease. Between 5% and 12% of neurofibromatosis type 1 cases have evidence of sphenoid wing dysplasia. Sequelae of this deficiency include slow expansion of the middle temporal fossa and progressive herniation of the temporal lobe into the orbital cavity, resulting in pulsatile exophthalmos. Herein, we report a patient with greater sphenoid wing agenesis and middle temporal fossa enlargement requiring transcranial orbital reconstruction in the absence of neurofibromatosis. To our knowledge, this represents a novel craniofacial phenotype of sphenoid wing agenesis in the absence of neurofibromatosis previously not described in the literature.

Craniofacial bone alterations in patients with neurofibromatosis type 1

Osseous manifestations of neurofibromatosis 1 (NF-1) occur in a minority of the affected subjects but may be because of significant clinical impairment. Typically, they involve the long bones, commonly the tibia and the fibula, the vertebrae, and the sphenoid wing. The pathogenesis of NF-1 focal osseous lesions and its possible relationships with other osseous NF-1 anomalies leading to short stature are still unknown, though it is likely that they depend on a common mechanism acting in a specific subgroup of NF-1 patients. Indeed, NF-1 gene product, neurofibromin, is expressed in all the cells that participate to bone growth: osteoblasts, osteoclasts, chondrocytes, fibroblasts, and vascular endothelial cells. Absent or low content of neurofibromin may be responsible for the osseous manifestations associated to NF-1. Among the focal NF-1 osseous anomalies, the agenesis of the sphenoid wing is of a particular interest to the neurosurgeon because of its progressive course that can be counteracted only by a surgical intervention. The sphenoid wing agenesis is regarded as a dysplasia, which is a primary bone pathology. However, its clinical progression is related to a variety of causes, commonly the development of an intraorbital plexiform neurofibroma or the extracranial protrusion of temporal lobe parenchyma and its coverings. Thus, the cranial bone defect resulting by the primary bone dysplasia is progressively accentuated by the orbit remodeling caused by the necessity of accommodating the mass effect exerted by the growing tumor or the progression of the herniated intracranial content. The aim of this paper is to review the neurosurgical and craniofacial surgical modalities to prevent the further progression of the disease by "reconstructing" the normal relationship of the orbit and the skull.

Differential gene methylation and expression of HOX transcription factor family in orbitofacial neurofibroma

Although most commonly benign, neurofibromas (NFs) can have devastating functional and cosmetic effects in addition to the possibility of malignant transformation. In orbitofacial neurofibromatosis type 1, NFs may cause progressive, disfiguring tumors of the lid, brow, temple, face and orbit. The purpose of this study was to identify biological differences between orbitofacial NFs and those occurring at other anatomic sites. We used Illumina Methylation EPIC BeadChip to study DNA methylation differences between orbitofacial NFs (N = 20) and NFs at other sites (N = 4). Global methylation differences were detected between the two groups and the top differentially methylated genes were part of the HOX (Homebox) family of transcription factors (HOXC8, HOXC4, HOXC6, HOXA6 and HOXD4), which were hypomethylated in orbitofacial NFs compared to the non-orbital NFs. Conversely, LTF (lactoferrin) was relatively hypermethylated in orbitofacial NF compared to non-orbitofacial NF. HOXC8 protein levels were higher in orbitofacial plexiform NFs (p = 0.04). We found no significant differences in the expression of HOXC4, HOXA6, or HOXD4 between the two groups. HOXC8 mRNA levels were also higher in orbitofacial NFs and HOXC8 overexpression in a non-neoplastic human Schwann cell line resulted in increased growth. In summary, we identified gene methylation and expression differences between orbitofacial NF and NFs occurring at other locations. Further investigation may be warranted, given that the HOX family of genes play an important role during development, are dysregulated in a variety of cancers, and may provide novel insights into therapeutic approaches.

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.

Sphenoid Dysplasia in Neurofibromatosis: Patterns of Presentation and Outcomes of Treatment

BACKGROUND

Sphenoid wing dysplasia in patients with neurofibromatosis type 1 may result in challenging and significant changes, including ultimately vision loss. The authors describe the radiographic patterns of sphenoid dysmorphology with time and age, and the impact of surgical intervention on preservation of vision.

METHODS

A retrospective study was performed at a single pediatric hospital, identifying subjects with neurofibromatosis type 1. Records were reviewed in their entirety for each subject, with attention to ophthalmologic evaluation. Radiographic images were digitally analyzed and scored for sphenoid transformations on a grade of 0 to 3.

RESULTS

Fifty-two subjects were identified. On initial imaging, 42.31 percent had a normal sphenoid (grade 0), 32.69 percent had an abnormal contour (grade 1), 11.54 percent had thinning (grade 2), and 13.46 percent had a gross defect (grade 3). Among the 45 subjects with serial imaging, 55.56 percent demonstrated progression of the deformity of at least one grade. Deformity progression correlated with length of imaging interval. Enucleation was noted to occur more often in subjects with a gross sphenoid defect (p < 0.0001). Of subjects identified as having a gross sphenoid defect, 26.7 percent were managed using orbitosphenoid reconstruction with titanium mesh and cranial bone graft, and 33.3 percent were managed with soft-tissue debulking and canthopexy only. Vision was more likely to be preserved with early orbitosphenoid reconstruction (p < 0.05).

CONCLUSIONS

Sphenoid dysplasia is a progressive disease. Loss of vision is associated with a gross defect, and appears to be better preserved with early orbitosphenoid reconstruction with titanium mesh and cranial bone graft.

Neuroimaging findings of extensive sphenoethmoidal dysplasia in NF1

Whereas isolated sphenoid wing dysplasia (SWD) is a well-known clinical feature in neurofibromatosis 1 (NF1), extensive cranial defects involving multiple bones have been rarely reported in this disorder. In this report, we describe the clinical course of a 20-year-old male with NF1 and an extensive cranial bone dysplasia. The large sphenoethmoidal defect was associated with transethmoidal and orbital cephalocele as well as inferolateral herniation of the frontal lobe. In spite of the large defect, the individual did not have any symptoms or complications resulting from the osteopathy. We review the current knowledge of the pathogenesis and management of cranial bone dysplasia in NF1.

Ophthalmic manifestations in neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a relatively common multisystemic inherited disease and has been extensively studied by multiple disciplines. Although genetic testing and confirmation are available, NF1 remains a clinical diagnosis. Many manifestations of NF1 involve the eye and orbit, and the ophthalmologist, therefore, plays a significant role in the diagnosis and treatment of NF1 patients. Improvements in diagnostic and imaging instruments have provided new insight to study the ophthalmic manifestations of the disease. We provide a comprehensive and up-to-date overview of the ocular and orbital manifestations of NF1.

Sphenoid dysplasia in neurofibromatosis type 1: a new technique for repair

PURPOSE

Sphenoid bone dysplasia in neurofibromatosis type 1 is characterized by progressive exophthalmos and facial disfiguration secondary to herniation of meningeal and cerebral structures. We describe a technique for reconstruction of the sphenoid defect apt at preventing or correcting the ocular globe dislocation.

METHODS

After placement of spinal cerebrospinal fluid drainage to reduce intracranial pressure, the temporal pole is posteriorly dislocated extradurally. The greater sphenoid wing defect is identified. A titanium mesh covered by lyophilized dura, modeled in a curved fashion, is interposed between the bone defect and the cerebro-meningeal structures with its convex surface over the retracted temporal pole.

RESULTS

The particular configuration of the titanium mesh allows a self-maintaining position due to the pressure exerted by the brain over its convex central part with its lateral margins consequently pushed and self-anchored against the medial and lateral walls of the temporal fossa. Screw fixation is not needed. The technique utilized in four cases proved to be reliable at the long-term clinical and neuroradiological controls (6 to 19 years).

CONCLUSION

Sphenoid bone dysplasia in NF1, resulting in proptosis and exophthalmos, is usually progressive. It can be surgically repaired using a curved titanium mesh with the convexity faced to the temporal pole that is in the opposite fashion from all the techniques previously introduced. When utilized early in life, the technique can prevent the occurrence of the orbital and facial disfiguration.

Altered cerebrospinal fluid dynamics in neurofibromatosis type l: severe arachnoid thickening in patients with neurofibromatosis type 1 may cause abnormal CSF dynamic

INTRODUCTION

The object of this study is to understand abnormal dynamic of cerebrospinal fluid (CSF) in patients with neurofibromatosis type 1 (NF1), which may cause temporal lobe herniation and bulging of temporal fossa.

METHODS

Four patients, three females and one male, with NF1 were studied retrospectively. They presented with a similar craniofacial deformity, which consisted of pulsatile exophthalmos, an enlarged bony orbit, dysplasia of the sphenoid wing with the presence of a herniation of the temporal lobe into the orbit, and a bulging temporal fossa.

RESULTS AND DISCUSSION

Surgical exploration demonstrated abnormally thickened arachnoid membrane in one case. Protruding temporal lobe, which was one of the main symptoms in NF1 patients, could be stopped by control of intracranial pressure (ICP) via programmable ventriculoperitoneal shunt (VPS) or extra ventricle drainage implantation. The dense fibrosis of the arachnoid membrane and consequent altered hemispheric CSF dynamics may cause symptoms including pulsatile exophthalmos and consequent worsening of vision, prolapse of the temporal lobe, and enlargement of the temporal fossa. This finding may not present with general features of hydrocephalus, so that delays in diagnosis often result.

CONCLUSION

For the NF1 patients with cranio-orbito-temporal deformities, prior to any surgical reconstruction, control of increased ICP (IICP) should be primarily considered.

[Pulsatile exophthalmos revealing spheno-orbital agenesis associated with Von Recklinghausen's disease]

Les manifestations ophtalmologiques au cours de la maladie de Von Recklinghausen sont rares. Seulement quelques cas ont été rapportés dans la littérature internationale. Nous rapportons un cas d'exophtalmie pulsatile révélatrice d'une agénésie sphéno-orbitaire au cours de la maladie de Von Recklinghausen.

Orbital Imaging Manifestations of Neurocutaneous Syndromes Revisited

Neurocutaneous syndromes or phakomatoses represent a heterogeneous group of multisystemic disorders involving structures of ectodermal origin. Characteristic ocular manifestations are described for individual entities that are often the first clues to the underlying diagnosis. However, opaque ocular media or involvement of retrobulbar orbit limits adequate clinical evaluation. This underlines the role of imaging, especially cross-sectional imaging modalities, such as computed tomography and magnetic resonance imaging, which offer a comprehensive evaluation of orbit and its contents. This review aims to summarize the cross-sectional imaging features of orbital manifestations of common neurocutaneous syndromes encountered in clinical practice.

Congenital Ocular Dystopia from Orbitofrontal Bone Dysplasia

BACKGROUND

Several patients with ocular dystopia and craniofacial differences have been found to have orbital dysplasia and a frontal bone defect. This deformity is characteristically different from differential diagnoses of encephalocele, sphenoid dysplasia, craniofacial dysostoses, or atypical clefting.

METHODS

The authors retrospectively reviewed the craniofacial registries of two pediatric centers for patients presenting with ocular dystopia or orbitofrontal anomalies between 2000 and 2014. The features and treatment of these patients were analyzed.

RESULTS

Four patients with congenital orbitofrontal bone dysplasia were identified, three with unilateral and one with bilateral frontal bone defects. Clinical signs of hypoglobus and vertical ocular dystopia of an average of 5.0 mm on the affected side were noted shortly after birth. The transversely oriented bony defect had an average surface area of 3.9 cm in unilateral cases and 10.7 cm in bilateral cases. Patients showed a characteristic orbital vertical elongation with an average orbital height-to-width ratio of 1.30-in excess of the average normal 1.14 by 14 percent-and inferior rim displacement. Cranial contour demonstrated frontal bossing and borderline dolichocephaly. Fronto-orbital reconstruction was performed in three patients, using cranial bone grafting to obliterate the orbital roof defect and elevate the orbital floor, which was successful in reducing ocular dystopia and preserving vision in each patient. One patient followed for 11 years postoperatively has a durable result with no surgical revision.

CONCLUSIONS

Orbitofrontal bone dysplasia has not been previously reported, and includes a frontal bone defect and ocular dystopia. Single-stage fronto-orbital reconstruction appears to adequately correct it.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Increased Ocular Pulse Amplitude Associated with Unilateral Dysgenesis of the Orbital Roof

Introduction

Two patients (one with neurofibromatosis type 1) presented with unilateral ocular pulsation.

Methods

A CT scan of the orbits revealed extensive dysgenesis of the orbital roof with herniation of the frontal lobe into the orbit in both cases. PASCAL dynamic contour tonometry was performed.

Results

The ipsilateral ocular pulse amplitude (OPA) was greater than the contralateral side, and the ocular pulse waveform morphology more closely approximated the known intracranial waveform in these patients.

Conclusions

We hypothesize that the greater OPA was due to stronger transmission of the intracranial pressure waveform amplitude and morphology in the absence of the orbital roof.

Orbital reconstruction for pulsatile exophthalmos secondary to sphenoid wing dysplasia

Sphenoid wing dysplasia or absence of the greater sphenoid wing is a rare condition that is considered pathopneumonic for neurofibromatosis type 1 (NF1). It occurs in 4% to 11% of NF1 patients, and its precise cause is unclear. Some cases appear to be congenital, while others have demonstrated it to be a progressive degeneration of the orbital wall. In about half of cases, associated adjacent neurofibromas are described. Consistently, however, the clinical sequelae is herniation of the temporal lobe into the orbit, causing progressive proptosis and pulsatile exophthalmos. Reconstruction of the orbit has traditionally been with bone grafts, but due to problems with bone resorption and recurrence, titanium plates in conjunction with bone grafts have been reported. We present a case of a 6-year-old male patient who was first diagnosed with NF1 and associated absence of the greater sphenoid wing at the age of 2. Four years later, he was referred for reconstruction after the development of pulsatile exophthalmos. Surgical management included dissection of the dura of the temporal lobe off of the periorbita and skull base reconstruction with a combination of radial-shaped titanium mesh and split calvarial bone grafts. Postoperatively, there was near immediate resolution of the pulsatile exophthalmos, and follow-up at 1 year showed no recurrence.

Ocular motility abnormalities in orbitofacial neurofibromatosis type 1

PURPOSE

To evaluate the causes of ocular motility disturbances in a group of patients with orbitofacial neurofibromatosis (OFNF) with neurofibromas on the lid, brow, face, or in the orbit from infancy or early childhood.

METHODS

The medical records of patients with OFNF from one institution were retrospectively reviewed; selected patients were reexamined.

RESULTS

A total of 45 patients with unilateral OFNF and 4 with bilateral OFNF were included. Of these, 14 had no strabismus and relatively good vision, with no ductional abnormalities on either side despite large globes, sphenoid dysplasia, and neurofibromas in the orbit and/or cavernous sinus in many. The 8 patients with comitant strabismus also had no ductional abnormalities with a similar constellation of anatomic abnormalities, but these patients all had poor vision in at least one eye. The 27 patients with incomitant strabismus all had downward displacement of the globe and limited ductions.

CONCLUSIONS

The pathologic anatomic changes associated with OFNF do not always cause ocular motility abnormalities: strabismus generally was not present when ocular motility was full and visual acuity was good. Comitant strabismus occurred in the setting of full ocular motility with reduced vision in at least one eye. Incomitant strabismus was always accompanied by reduced vision and a ductional abnormality in one or both eyes due to anatomic abnormalities of the orbit and skull.

Calvarial defects and skeletal dysplasia in patients with neurofibromatosis Type 1

OBJECT

Skull defects, including sphenoid dysplasia and calvarial defects, are rare but distinct findings in patients with neurofibromatosis Type 1 (NF1). The underlying pathophysiology is unclear. The goal of this study was to identify the clinical characteristics and natural history of skull defects in patients with NF1.

METHODS

An electronic search engine of medical records was used to identify patients with NF1 and bony skull anomalies. All clinical, radiographic, pathology, and operative reports were reviewed. The relationship between bony anomalies and significant clinical associations was evaluated. This study received institutional review board approval.

RESULTS

Twenty-one patients were identified. The mean age at NF1 diagnosis was 4.2 years. The mean age at skull defect diagnosis was 8.8 years (9.7 years in the sphenoid wing dysplasia group and 11.9 years in the calvarial defect group). Sphenoid dysplasia was associated with a plexiform neurofibroma or dural ectasia in 73.3% and 80.0% of cases, respectively. Calvarial defects were associated with a plexiform neurofibroma or dural ectasia in 66.7% and 33.3% of patients, respectively. An absence of either an associated neurofibroma or ectasia was not noted in any patient with sphenoid wing dysplasia or 25.0% of those with calvarial defects. In 6 patients, both types of skull defects presented simultaneously. Serial imaging studies were obtained for a mean follow-up time of 7.5 years (range 0.4-20.0 years). Of these patients with serial imaging, radiographic progression was found in 60% of cases of calvarial defects and 56% of cases of sphenoid wing dysplasia. Two patients underwent surgical repair of a skull defect, and both required repeat procedures.

CONCLUSIONS

The majority of skull defects in patients with NF1 were associated with an adjacent structural lesion, such as a plexiform neurofibroma or dural ectasia. This findings from this cohort also support the concept of progression in defect size in more than half of the patients. Potential mechanisms by which these secondary lesions contribute to pathogenesis of the bony defect may include changes in the bony microenvironment. A better understanding of the pathophysiology of skull defects will help guide detection, improve treatment and outcome, and may contribute to the understanding of the pathogenesis of bony lesions in NF1.

Visual loss in orbitofacial neurofibromatosis type 1

PURPOSE

On occasion, neurofibromas in neurofibromatosis type 1 may be present on the lid, brow, or face of an infant or child, a circumstance commonly referred to as "orbitofacial neurofibromatosis" (OFNF). The present study evaluates the causes and extent of visual loss in a group of patients with OFNF.

DESIGN

Case series.

PARTICIPANTS

Fifty-five patients with OFNF.

METHODS

Retrospective medical record review and reexamination of selected patients from one institution.

MAIN OUTCOME MEASURES

Visual acuity and identification of underlying cause of reduced vision.

RESULTS

Fifty patients with unilateral OFNF (23 male, 27 female, aged 4-48 years at last visit) and 5 patients with bilateral OFNF (2 male, 3 female, aged 15-43 years) had adequate information available to assess afferent visual functioning. Nine patients (4 male, 5 female, aged 4-28 years) had optic pathway glioma (OPG) in addition to OFNF. Patients were followed as long as 27 years (mean 8.4 years). Thirty-nine patients (71% of total) had visual acuity of ≤20/60 on the side of OFNF involvement (or the side of worse OFNF involvement in patients with bilateral disease). One or more causes of amblyopia were present in 29 of these patients, 19 patients had organic disease of the eye (e.g., glaucoma or retinal detachment) or the afferent system (e.g., OPG), and 12 patients had correctable refractive errors.

CONCLUSIONS

Visual loss in this OFNF cohort was common, typically profound, and usually multifactorial. Some causes of visual loss (including congenital glaucoma with buphthalmos and retinal detachment, disconjugate gaze due in part to distorted skull development causing strabismic amblyopia, and OPG) were difficult to treat adequately and tended to cause progressive, profound visual loss. Therefore, careful observation should be made during the period of visual immaturity for possible causes of amblyopia that might be treatable, such as refractive changes, occlusion of the visual axis, or congenital glaucoma. As affected individuals get older, physicians must be vigilant for the progression of optic nerve disease due to glaucoma or OPG and to the possibility that vision might be improved by refraction.

Reconstruction of skull base defects in sphenoid wing dysplasia associated with neurofibromatosis I with titanium mesh

Sphenoid wing dysplasia occurs in 3-7% of patients with neurofibromatosis type 1 (NF1). The typical radiological features are partial or complete absence of the greater wing of the sphenoid. This condition is slowly progressive and may result in temporal lobe herniation into the orbital cavity, producing pulsating exophthalmos and gross facial deformity. Thus, reconstruction of the orbit is important for both cosmetic and functional reasons. Traditional surgical treatment of sphenoid dysplasia involves split bone grafting and repair of the anterior skull base defect. However, several reports have demonstrated complications of graft resorption and recurrence of proptosis and pulsating exopthalmos. In this case series, we present two patients suffering from pulsating exophthalmos due to sphenoid dysplasia. Radiological and MRI studies demonstrated orbital enlargement and complete absence of the greater wing of the sphenoid. Surgical management of these patients involved dural defect repair, and the use of titanium mesh in conjunction with bone graft to act as a barrier between the orbit and the middle cranial fossa. The mesh was fixed by fine screws. Proptosis improved markedly post-operatively and resolved within a few weeks. Ocular pulsation subsided and remained quiescent with at least 1-year follow-up.

[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.

Associations of osseous abnormalities in Neurofibromatosis 1

The characteristic sites of Neurofibromatosis 1-associated osseous manifestations are the long bones (usually the tibia and fibula), vertebrae and sphenoid wing. Although these focal bony lesions may cause profound clinical consequences, a minority of people with NF1 are affected. However, most people with NF1 are shorter than expected for their age, gender and family. The pathogenesis of NF1 focal osteopathy and its relationship, if any, to short stature are unknown. We examined associations between the occurrence of various osseous lesions in 3377 NF1 probands from the Children's Tumor Foundation NF International Database. Using logistic regression analysis among 260 NF1 probands who had undergone radiological examination of both the spine and skull, we found associations between the occurrence of sphenoid wing and long bone osteopathy (conditional odds ratio [OR] = 6.1; 95% confidence interval [CI] = 1.7-22.3; P = 0.006) and between sphenoid wing and vertebral osteopathy (OR = 16.9; 95% CI = 5.3-53.3; P < 0.001) after adjusting for age and gender. Similar findings were observed from all 3377 NF1 probands using a multivariate probit regression model. In a separate analysis, we found lower age- and gender-standardized height in patients who had characteristic vertebral or sphenoid wing lesions than in people who did not (P < 0.05). We found no relationship between height and tibial osteopathy. We conclude that some people with NF1 are more likely to develop osseous manifestations than others and speculate that there may be a common pathogenetic mechanism responsible for the development of osseous abnormalities and that of the vertebrae and long bones.

Neurofibromin: a general outlook

Neurofibromin is a cytoplasmic protein that is predominantly expressed in neurons, Schwann cells, oligodendrocytes, astrocytes and leukocytes. It is encoded by the gene NF1, located on chromosome 17, at q11.2, and has different biochemical functions, including association to microtubules and participation in several signaling pathways. Alterations in this protein are responsible for a phacomatosis named neurofibromatosis type 1.

Absence of a sphenoid wing in neurofibromatosis type 1 disease: imaging with multidetector computed tomography

Neurofibromatosis type 1 disease is characterized by pigmented cutaneous lesions and generalized tumors of a neural crest origin and it may affect all the systems of the human body. Sphenoid dysplasia is one of the characteristics of this syndrome and it occurs in 5-10% of the cases; further, abnormalities of the sphenoid wings are often considered pathognomonic. However, complete agenesis of a sphenoid wing is very rare. We report here on an unusual case of neurofibromatosis type 1 disease with the associated absence of a sphenoid wing that was diagnosed by using multidetector computed tomography.

Clinical manifestations and management of neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder with variable expression. The complications are age specific. Neurologic complications include tumors of the peripheral nerves, nerve roots, and plexi; spinal cord compression; dural ectasias; learning disabilities; attention deficit; headaches; seizures; brain tumors; deafness; hydrocephalus; and stroke. High-intensity signals on brain magnetic resonance imaging are a frequent finding without known clinical significance. Most brain tumors are benign and asymptomatic, but malignant brain tumors occur. The major cause of death is malignancy, including brain tumors and malignant peripheral nerve sheath tumors. Management includes genetic counseling, regular eye examinations, and careful physical exams.

Decreased bone mineral density in patients with neurofibromatosis 1

Neurofibromatosis 1 (NF1) is one of the most common autosomal dominant diseases. Although there is a considerable variability in clinical expression, NF1 is almost fully penetrant in adult patients and may be associated with a variety of skeletal anomalies. Spinal deformities are the most common skeletal manifestation, with an incidence estimated from 10-25% in various studies. Some NF1 patients have a dystrophic form of scoliosis, which is characterized by early age at onset and rapid progression. Complications have been reported during spinal instrumentation of dystrophic curves due to soft, non-resistant vertebral bony tissue, suggesting that an alteration of bone quality may occur in NF1 patients. Recent studies have suggested that decreased bone mineral density (BMD) may occur among patients with NF1. We performed a cross-sectional study on 104 adults with NF1, using quantitative ultrasonometry (QUS) to investigate whether decreased BMD is a general phenomenon in NF1 patients. The data reveal that BMD, as measured by age- and gender- adjusted Z-scores, is significantly lower in NF1 patients than in the normal reference population. The decrease in BMD appears to be even more marked among NF1 patients with scoliosis that requires surgical treatment. The findings indicate that NF1 produces a generalized alteration of bone in addition to the focal osseous dysplasias of the vertebrae, tibia, and sphenoid wing that characterize this condition. The pathological mechanism underlying these bony changes remains to be elucidated.

Is osseous dysplasia a primary feature of neurofibromatosis 1 (NF1)?

Characteristic skeletal lesions are a cardinal feature of the autosomal dominant condition, neurofibromatosis 1 (NF1). The most frequently involved skeletal sites are the sphenoid wing, vertebrae, and tibia. Osseous lesions may range in severity in NF1 but are often progressive. They may lead to serious clinical consequences and be resistant to treatment. The skeletal lesions of NF1 are usually considered to be 'dysplasias', i.e. primary defects of bone, although there is no direct evidence supporting this interpretation. Moreover, it is difficult to understand why a generalized dysplasia of bone would produce focal lesions that show such a striking predisposition to only a few bones. We review the clinical and pathological features of NF1 skeletal lesions and propose that they result from an abnormal response of NF1 halpoinsufficient bone to abnormal mechanical forces rather than from a primary osseous dysplasia.

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.

Phakomatoses. Part I: Neurofibromatosis type 1: common and uncommon neuroimaging findings

Neurofibromatosis type I (NF-1) belongs to a family of diseases named phakomatoses, which are characterized by congenital malformations of ectodermal structures. Neurofibromatosis type I affects 1 in 3000 people, and has a diverse clinical presentation as well as an array of imaging findings. In this article the authors review the various neuroimaging findings present in NF-1, including abnormalities of the parenchyma, meninges, vessels, and associated neoplasms.

Suboccipital meningocele presenting as a huge retropharyngeal mass in a patient with neurofibromatosis Type 1. Case report

The authors report an extremely rare case of neurofibromatosis Type 1 (NF1) with a suboccipital meningocele presenting as a huge retropharyngeal mass. A 73-year-old woman with typical cutaneous manifestations of NF1 presented with nasal obstruction and dysphagia due to a retropharyngeal mass. Magnetic resonance imaging revealed a huge mass lesion extending from the right occipital bone defect to the retropharynx through the right paravertebral region. Computerized tomography scanning after intrathecal administration of contrast material confirmed that the mass was a meningocele protruding through a right occipital bone defect. The authors attempted to ligate this meningocele, most of which was excised via a suboccipital approach, but a second transcervical operation was required. Finally, the meningocele resolved and the patient was discharged without symptoms.

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

A case of surgical repair of progressive exophthalmos of the right eye in a 43-year-old woman with neurofibromatosis Type 1 (NF1) is presented. Preoperatively, the patient's ocular movements and visual fields were intact. Visual acuity was 20/30 on the right side and 20/20 on the left. Computerized tomography scanning demonstrated complete absence of the superolateral orbital wall on the right side with a large meningocele protruding into the right orbit. Intraoperatively, a new superolateral wall was constructed using the inner table of the left frontal bone as a bone transplant. A free galeoperiosteum flap was used for water-tight dural reconstruction. A few weeks postoperatively the patient's exophthalmos showed remarkable resolution. Her ocular movements, visual acuity, and visual fields remained unchanged. In conclusion, reconstruction of the superolateral wall and repair of a meningocele in a patient with NF1 is worthwhile and can be followed by excellent cosmetic results. More important, the patient's visual functions remain preserved.