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

Sphenoid dysplasia in patients with neurofibromatosis type 1: Clinical features and imaging findings including cerebrospinal fluid alterations

INTRODUCTION

Neurofibromatosis Type 1 (NF-1) is a genetic disorder that occurs in 1:2500-3000 live births and may involve multiple organs. An uncommon but well-known phenomena is sphenoid dysplasia, which appears in 3-11% of the patients, and may result in significant lowering of the orbit. Understanding the cause and development of this process might predict its course and its treatment.

METHODS

The records of 29 patients with PNF in the head and neck region were searched for location of the PNF and type of surgery. Photographs were studied for facial disturbances, including vertical dystopia, hypertelorism, ptosis, exophthalmos and enophthalmos. MR and CT scans were studied for the presence of PNF, aspect of the sphenoid bone, alteration in the CSF circulation, and other tumour involvement.

RESULTS

Fourteen of 29 patients with PNF in the head and neck presented with sphenoid dysplasia. All 14 patients had their PNF located in the periorbital region. Increased locoregional CSF collections were seen in almost all of these patients. Besides glioma of the optical nerve or hamartomas in the cerebrum and cerebellum, there were no other tumours found. Surgical treatment varies from simple excision to excessive debulking of the PNF, reconstruction of the orbit and even enucleation.

CONCLUSION

Although sphenoid dysplasia is uncommon in NF-1 patients, early recognition is important to prevent facial disfigurement and vision loss. Clinicians should be aware that abnormalities in the periorbital region and especially vertical dystopia might be the first sign of sphenoid dysplasia. Performing a CT or black-bone MR scan would be the next step to confirm or exclude sphenoid dysplasia and abnormal CSF dynamics.

Non-Oncological Neuroradiological Manifestations in NF1 and Their Clinical Implications

Simple Summary

Central nervous system involvement (CNS) is a common finding in Neurofibromatosis type 1 (NF1). Beside tumor-related manifestations, NF1 is also characterized by a wide spectrum of CNS alterations with variable impacts on functioning and life quality. Here, we propose an overview of non-oncological neuroradiological findings in NF1, with an insight on pathophysiological and embryological clues for a better understanding of the development of these specific alterations.

Abstract

Neurofibromatosis type 1 (NF1), the most frequent phakomatosis and one of the most common inherited tumor predisposition syndromes, is characterized by several manifestations that pervasively involve central and peripheral nervous system structures. The disorder is due to mutations in the NF1 gene, which encodes for the ubiquitous tumor suppressor protein neurofibromin; neurofibromin is highly expressed in neural crest derived tissues, where it plays a crucial role in regulating cell proliferation, differentiation, and structural organization. This review article aims to provide an overview on NF1 non-neoplastic manifestations of neuroradiological interest, involving both the central nervous system and spine. We also briefly review the most recent MRI functional findings in NF1.

Neurofibromatosis type 1-related hydrocephalus: causes and treatment considerations

The prevalence of hydrocephalus among patients with neurofibromatosis type I (NF1) is estimated to be between 1 and 13%. Most hydrocephalic causes are obstructive-aqueductal webs, chiasmatic-hypothalamic tumors, and thalamic mass effect related to NF changes. Other NF1-related conditions may mimic the clinical presentation of hydrocephalus and should be ruled out while evaluating children with headaches. These include brain tumors and moyamoya syndrome. Treatment of NF1-related hydrocephalus should be personally tailored, including tumor resection or debulking, shunts, and endoscopic procedures such as septostomy and third ventriculostomy. Despite these personalized treatments, many of the primary treatments (including shunts and endoscopic procedures) fail, and patients should be screened and followed accordingly. In the current manuscript, we review the causes of NF1-related hydrocephalus, as well as treatment options.

Assessment of the visual pathways in patients with neurofibromatosis-1 by 3S-space technique with 3-Tesla MRI

Background/aim

We aimed to evaluate the size/tortuosity of the optic nerve (ON) and the dilatation of the ON sheath (ONS) in neurofibromatosis type 1 (NF-1) patients with 3T-MRI, and to assess the usefulness of 3D-SPACE in imaging the optic pathway, ON, and ONS in NF-1 patients.

Materials and methods

Twenty consecutive NF-1 patients without optic pathway glioma (OPG) (Group 1), 16 consecutive NF-1 patients with OPG (Group 2), and 19 controls were included in this study. The thickness and tortuosity of the ON and the diameter of the ONS were measured on STIR and 3D-SPACE images.

Results

The thickness of the ON was similar in all groups on STIR images (P>0.05). The mean ONS diameter was higher in Group 2 with this sequence (P=0.009). Controls had significantly lower grades of ON tortuosity than Groups 1 and 2 (P=0.001), and Group 1 had significantly lower ON tortuosity compared to Group 2 (P=0.001). Severe tortuosity was only detected in Group 2.

Conclusion

ON tortuosity and ONS diameter were increased in NF-1 patients in the presence of OPG. High-resolution cranium imaging with the 3D-SPACE technique using 3T-MRI seems to be helpful for detection of the optic pathway morphology and pathologies in NF-1 patients.

Communicating hydrocephalus and coexisting nonenhancing tumor: An ominous sign for patients with neurofibromatosis type 1?

A 26-year-old woman with familial neurofibromatosis type 1 sustained headache that worsened for 1 month. Neuroimaging revealed a mild ventriculomegaly and nonenhancing lesion in the pons. In spite of repeated cerebrospinal fluid examinations and magnetic resonance imaging, the etiology was not determined. The affected pons markedly enlarged in the following 2 months, with extensive leptomeningeal dissemination. Biopsy through hemilaminectomy of the T9 was diagnosed as glioblastoma multiforme. Prompt histologic examination should be performed when patients with familial neurofibromatosis type 1 manifest communicating hydrocephalus coexistent with a nonenhancing tumor.

Pulsatile Proptosis due to Intraorbital Meningocele

We present a case of a 79-year-old man with a non-symptomatic pulsatile proptosis of the left eye. Magnetic resonance imaging revealed a meningocele into the left orbit due to an osseous defect in the orbital roof.