MR imaging of spinal tumors in children with neurofibromatosis 1

Three-column osteotomy versus Halo-gravity traction combined with posterior column osteotomy in the treatment of dystrophic neurofibromatosis type 1 kyphoscoliosis: a retrospective comparative cohort study

BACKGROUND

Dystrophic neurofibromatosis type I (NF1) kyphoscoliosis presents unique challenges for corrective spinal surgery due to anatomical abnormalities. To compare the radiographic and clinical outcomes of dystrophic neurofibromatosis type 1 (NF1) kyphoscoliosis patients undergoing three-column osteotomy (3CO), halo-gravity traction (HGT), or posterior column osteotomy (PCO) and to evaluate their efficacy and safety in this cohort, different treatment strategies and their associated complication rates warrant further comprehensive investigation.

METHODS

Dystrophic NF1 kyphoscoliosis were divided into 3CO, HGT, and PCO groups based on the surgical strategy. Radiographic parameters were measured preoperatively, postoperatively, and at each follow-up. Intraoperative and postoperative complications were recorded for each patient, and patient-reported outcomes were assessed using the Scoliosis Research Society-22 (SRS-22) questionnaire. Differences among the three groups were analyzed.

RESULTS

A total of 9 patients were included in the 3CO, 22 in HGT group, 95 in PCO groups, respectively. Significant differences among the three groups were found in terms of operation time (p = 0.011), estimated blood loss (p = 0.003), and number of satellite rod techniques (p = 0.013). At pre-operation, the Cobb angles of main curves were 84.3 ± 24.6° in 3CO group, 99.1 ± 24.3° in HGT group, 60.0 ± 16.8° in PCO group. At post-operation, significant post-operative improvements were found in the Cobb angles of the main curves, apical vertebral translation (AVT), segmental kyphosis (SK), and deformity angular ratio (DAR) in all three groups (p < 0.001). No significant correction loss was observed during the follow-up. Six complications were found in the 3CO group, 13 in the HGT group, and 40 in the PCO group.

CONCLUSIONS

PCO, 3CO, and HGT could be applied to dystrophic NF1 patients. The 3CO is also associated with increased perioperative complications.

LEVEL OF EVIDENCE

IV.

Multiparametric whole-body MRI of patients with neurofibromatosis type I: spectrum of imaging findings

Neurofibromatosis (NF) type I is a neuroectodermal and mesodermal dysplasia caused by a mutation of the neurofibromin tumor suppressor gene. Phenotypic features of NF1 vary, and patients develop benign peripheral nerve sheath tumors and malignant neoplasms, such as malignant peripheral nerve sheath tumor, malignant melanoma, and astrocytoma. Multiparametric whole-body MR imaging (WBMRI) plays a critical role in disease surveillance. Multiparametric MRI, typically used in prostate imaging, is a general term for a technique that includes multiple sequences, i.e. anatomic, diffusion, and Dixon-based pre- and post-contrast imaging. This article discusses the value of multiparametric WBMRI and illustrates the spectrum of whole-body lesions of NF1 in a single imaging setting. Examples of lesions include those in the skin (tumors and axillary freckling), soft tissues (benign and malignant peripheral nerve sheath tumors, visceral plexiform, and diffuse lesions), bone and joints (nutrient nerve lesions, non-ossifying fibromas, intra-articular neurofibroma, etc.), spine (acute-angled scoliosis, dural ectasia, intraspinal tumors, etc.), and brain/skull (optic nerve glioma, choroid plexus xanthogranuloma, sphenoid wing dysplasia, cerebral hamartomas, etc.). After reading this article, the reader will gain knowledge of the variety of lesions encountered with NF1 and their WBMRI appearances. Timely identification of such lesions can aid in accurate diagnosis and appropriate patient management.

Magnetic Resonance Imaging of Central Nervous System Manifestations of Type 1 Neurofibromatosis: Pictorial Review and Retrospective Study of Their Frequency in a Cohort of Patients

Background: type 1 neurofibromatosis (NF1) is the most common neurocutaneous disorder, and it is an inherited condition that causes a tumour predisposition. Central nervous system (CNS) manifestations are a significant cause of morbidity and mortality in NF1. We provide a pictorial review of neuroradiological features of NF1, with emphasis on magnetic resonance imaging (MRI), and we assess the frequency of those features on a cohort of NF1 patients. Methods: we retrospectively evaluated all patients with a diagnosis of NF1 who underwent MRI of the spine and brain in our centre over a period of almost 5 years. A total of 74 patients were enrolled, 28 males and 46 females, with a mean age of 21 ± 12.67 years. The frequency of CNS manifestations encountered in our cohort of NF1 patients was assessed and compared with the data found in other studies published in the literature. Results: many of our findings were in line with the literature, and possible interpretations for those that turned out to be different were suggested in the discussion. Conclusion: imaging plays a central role in the diagnosis and management of NF1, and the knowledge of CNS manifestations could be critical for its early detection and identification, such as for treatment planning and prognostic implications.

The management of neurofibromatosis type 1 (NF1) in children and adolescents

INTRODUCTION

Neurofibromatosis type 1 (NF1) is a rare neurogenetic disorder characterized by multiple organ system involvement and a predisposition to benign and malignant tumor development. With revised NF1 clinical criteria and the availability of germline genetic testing, there is now an opportunity to render an early diagnosis, expedite medical surveillance, and initiate treatment in a prompt and targeted manner.

AREAS COVERED

The authors review the spectrum of medical problems associated with NF1, focusing specifically on children and young adults. The age-dependent appearance of NF1-associated features is highlighted, and the currently accepted medical treatments are discussed. Additionally, future directions for optimizing the care of this unique population of children are outlined.

EXPERT OPINION

The appearance of NF1-related medical problems is age dependent, requiring surveillance for those features most likely to occur at any given age during childhood. As such, we advocate a life stage-focused screening approach beginning in infancy and continuing through the transition to adult care. With early detection, it becomes possible to promptly institute therapies and reduce patient morbidity. Importantly, with continued advancement in our understanding of disease pathogenesis, future improvements in the care of children with NF1 might incorporate improved risk assessments and more personalized molecularly targeted treatments.

Isolated Sacrococcygeal Plexiform Neurofibroma in a Child

This case report describes a 4-year-old girl with an isolated neurofibroma in the sacrococcygeal region. Although initially resembling sacrococcygeal teratoma, histopathology revealed a benign nerve sheath tumor. Wide local excision was performed, and the final diagnosis was plexiform neurofibroma. Diagnostic challenges in rare childhood tumors require stepwise evaluation and multidisciplinary team discussions.

The Role of MRI in the Diagnosis of Spinal Cord Tumors

Spinal cord tumors are uncommon, and its multiple representatives not always have pathognomonic characteristics, which poses a challenge for both patients and caring physicians. The radiologist performs an important role in recognizing these tumors, as well as in differentiating between neoplastic and non-neoplastic processes, supporting clinical and surgical decision-making in patients with spinal cord injury. Magnetic Resonance Imaging (MRI) assessment, paired with a deep understanding of the various patterns of cord involvement allied to detailed clinical data can provide a diagnosis or significantly limit the differential diagnosis in most cases. In this article, we aim to review the most common and noteworthy intramedullary and extramedullary spinal tumors, as well as some other tumoral mimics, with an emphasis on their MRI morphologic characteristics.

Consensus-Based Best Practice Guidelines for the Management of Spinal Deformity and Associated Tumors in Pediatric Neurofibromatosis Type 1: Screening and Surveillance, Surgical Intervention, and Medical Therapy

BACKGROUND

Spinal conditions, such as scoliosis and spinal tumors, are prevalent in neurofibromatosis type 1 (NF1). Despite the recognized importance of their early detection and treatment, there remain knowledge gaps in how to approach these manifestations. The purpose of this study was to utilize the experience of a multidisciplinary committee of experts to establish consensus-based best practice guidelines (BPGs) for spinal screening and surveillance, surgical intervention, and medical therapy in pediatric patients with NF1.

METHODS

Using the results of a prior systematic review, 10 key questions that required further assessment were first identified. A committee of 20 experts across medical specialties was then chosen based on their clinical experience with spinal deformity and tumors in NF1. These were 9 orthopaedic surgeons, 4 neuro-oncologists/oncologists, 3 neurosurgeons, 2 neurologists, 1 pulmonologist, and 1 clinical geneticist. An initial online survey on current practices and opinions was conducted, followed by 2 additional surveys via a formal consensus-based modified Delphi method. The final survey involved voting on agreement or disagreement with 35 recommendations. Items reaching consensus (≥70% agreement or disagreement) were included in the final BPGs.

RESULTS

Consensus was reached for 30 total recommendations on the management of spinal deformity and tumors in NF1. These were 11 recommendations on screening and surveillance, 16 on surgical intervention, and 3 on medical therapy. Five recommendations did not achieve consensus and were excluded from the BPGs.

CONCLUSION

We present a set of consensus-based BPGs comprised of 30 recommendations for spinal screening and surveillance, surgical intervention, and medical therapy in pediatric NF1.

Cauda equina thickening: an approach to MRI findings

There are many causes of cauda equina (CE) thickening on neuroimaging of the lumbar spine. The imaging features of CE thickening for the various conditions often overlap and are non-specific to clinch a definite diagnosis. Hence, the imaging findings have to be discerned in accordance with the patient's presenting history, clinical examination findings, and results from electrophysiology and laboratory studies. In this review, the authors aim to supplement the existing literature on imaging findings of CE thickening with a diagnostic framework for clinical workup. The authors also aim to familiarise readers with the interpretation of CE thickening on magnetic resonance imaging (MRI) and would like to illustrate the normal variants and pitfalls that could be mistaken for abnormal results.

Spinal screening, malignancy, medical therapy, and surgical correction of deformity in pediatric patients with neurofibromatosis type 1: a systematic review

The objective of this systematic review was to synthesize evidence regarding spinal screening recommendations, types of spinal and thoracic neurofibromatosis type 1 (NF1) tumors, medical therapy for NF1-associated neoplasms, and treatment with magnetically controlled growing rods (MCGRs) or cervical kyphosis correction in pediatric patients with NF1. We queried PubMed, Embase, Cochrane Library, Web of Science, Scopus, Clinicaltrials.gov, and medRxiv for studies reporting spinal screening recommendations, prognosis, and medical therapy for NF1-associated spinal tumors and MCGR use or cervical kyphosis correction in pediatric NF1 patients, yielding 758 publications, 33 of which were included. There is no consensus on spinal screening interval. Computed tomography is recommended for postoperative monitoring. Patients with gangliomas and spinal neurofibromas had nearly complete symptom resolution after resection. Plexiform neurofibromas were most commonly treated with resection and laminectomy; some patients reported tumor enlargement after intervention. Malignant nerve sheath tumors have high rates of metastasis even after chemoradiation and resection. MEK-inhibitors produced limited regression in tumor size. Sirolimus and thalidomide reduced tumor size but caused more severe adverse effects than MEK-inhibitors. Improvements in major curves and T1-T12 height gain were reported after MCGR intervention. Anteroposterior arthrodesis produced the greatest correction of dystrophic cervical kyphosis. There may be value in establishing standardized spinal screening protocols for pediatric NF1 patients. Surgical correction of NF1-associated spinal deformity is effective, though current medical therapies for spinal tumors have limited success. Areas for further investigation include determining appropriate screening intervals, choice of medical therapy for spinal tumors, and long-term outcomes of MCGRs. Level of Evidence: IV.

Phenotyping spinal abnormalities in patients with Neurofibromatosis type 1 using whole-body MRI

Neurofibromatosis Type 1 (NF1) has been reported to be associated with a variety of spinal abnormalities. The purpose of this study was to quantify the prevalence of spinal abnormalities in a collective of NF1 patients that is representative for the general NF1 population, to associate the co-appearance of spinal abnormalities with both NF1 and clinical symptoms and to investigate if different mutations of the NF1 gene affect the prevalence of these abnormalities. Retrospectively, 275 patients with NF1 and an age- and sex-matched collective of 262 patients were analyzed. The prevalence of spinal abnormalities was recorded. Mutational analysis of the NF1 gene was obtained in 235 NF1 patients. Associations between spinal abnormalities, clinical symptoms and genotype were investigated by binary logistic regression analysis. Prevalence of all spinal abnormalities was higher in NF1 patients than in the control group. Six characteristics of spinal abnormalities were significantly associated with NF1 (all p < 0.05). An influence of scalloping on scoliosis (OR 3.01; p = 0.002); of meningoceles (OR 7.63) and neuroforaminal tumors (OR 2.96) on scalloping, and of dural ectasia on neuroforaminal tumors (OR 1.93) was identified. Backpain and loss of motor function were associated with neuroforaminal tumors, spinal tumors and scalloping of vertebral bodies (all p < 0.05). Specific mutations of the NF1 gene were not relevantly associated with the development of spinal abnormalities. These findings can aid clinicians to improve clinical care of NF1 patients by creating awareness for co-appearences of specific spinal abnormalities and associated symptoms.

Modulation of spine fusion with BMP-2, MEK inhibitor (PD0325901), and zoledronic acid in a murine model of NF1 double inactivation

BACKGROUND

Spine fusion is a common procedure for the treatment of severe scoliosis, a frequent and challenging deformity associated with Neurofibromatosis type 1 (NF1). Moreover, deficiencies in NF1-Ras-MEK signaling affect bone formation and resorption that in turn impacts on spine fusion outcomes.

METHODS

In this study we describe a new model for AdCre virus induction of Nf1 deficiency in the spines of Nf1^flox/flox mice. The virus is delivered locally to the mouse spine in a fusion procedure induced using BMP-2. Systemic adjunctive treatment with the MEK inhibitor (MEKi) PD0325901 and the bisphosphonate zoledronic acid (ZA) were next trialed in this model.

RESULTS

AdCre delivery resulted in abundant fibrous tissue (Nf1^null +393%, P < 0.001) and decreased marrow space (Nf1^null -67%, P < 0.001) compared to controls. While this did not significantly impact on the bone volume of the fusion mass (Nf1^null -14%, P = 0.999 n.s.), the presence of fibrous tissue was anticipated to impact on the quality of spine fusion. Multinucleated TRAP + cells were observed in the fibrous tissues seen in Nf1^null spines. In Nf1^null spines, MEKi increased bone volume (+194%, P < 0.001) whereas ZA increased bone density (+10%, P < 0.002) versus BMP-2 alone. Both MEKi and ZA decreased TRAP + cells in the fibrous tissue (MEKi -62%, P < 0.01; ZA -43%, P = 0.054). No adverse effects were seen with either MEKi or ZA treatment including weight loss or signs of illness or distress that led to premature euthanasia.

CONCLUSIONS

These data not only support the utility of an AdCre-virus induced knockout spine model, but also support further investigation of MEKi and ZA as adjunctive therapies for improving BMP-2 induced spine fusion in the context of NF1.

Epidemiological and clinical burden associated with plexiform neurofibromas in pediatric neurofibromatosis type-1 (NF-1): a systematic literature review

PURPOSE

Patients with neurofibromatosis type-1 (NF-1) and associated plexiform neurofibromas (PNs) often have a high burden of illness owing to debilitating symptoms of these tumors and limited management options. To investigate this complex disease, a systematic literature review (SLR) was conducted on the epidemiology of pediatric NF-1 and associated PNs, the burden of illness, and outcomes of surgical resection of these tumors.

METHODS

Searches of MEDLINE and Embase (from database inception to October 2019) and conference proceedings (2017-2019) were performed to identify relevant studies. The review methodology was informed by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

Twenty studies were identified. Evidence confirmed NF-1 is rare but that occurrence may differ geographically. Only limited data on the birth incidence of NF-1 were identified. Prevalence estimates for pediatric NF-1 varied from one per 960 individuals (aged 17 years) to one per 5681 children (aged < 16 years) across five large registry/surveillance studies (each involving > 19,000 individuals). The prevalence of associated PNs was 0-29.6%. PNs carried increased mortality risk in pediatric NF-1 in both studies that explored this potential association. Patients with PNs reported high use of analgesics. The complication rate post-surgery for PNs was around 17-19%. The recurrence rate (18-68%) was dependent on the extent of excision achieved during surgery.

CONCLUSIONS

Data suggest NF-1 is a rare disease with increased morbidity and mortality in children with associated PNs. Surgical outcomes for PNs are often poor. These findings suggest significant unmet needs in patients with NF-1-associated PNs.

Spinal manifestations of Neurofibromatosis type 1

BACKGROUND

Neurofibromatosis type 1 (NF1) patients may present a wide spectrum of spinal pathologies. Osseous changes may lead to severe deformities with significant implications on growth and quality of life. Neurogenic tumors and soft tissue abnormalities may cause neuropathic pain and dysfunction ranging from minor paresthesias to profound motor and sensory deficits. Advanced imaging such as whole-body MRI, and volumetric tumor burden assessment have an evolving role in the evaluation and follow-up of patients with high spinal tumor load. Novel biological agents that target the hyperactivated ras pathway are currently under investigation and are reshaping current and future treatment paradigms. Surgical interventions for benign and malignant tumors, as well as deformity correction remain pivotal in treatment frameworks and require careful assessment by a dedicated multidisciplinary team.

PURPOSE

In this manuscript we review the various spinal manifestations of NF1 patients, indication for surgical intervention and oncological treatments.

Management of Proximal Thoracic Kyphoscoliosis with Early Myelopathy in a Young Adult with Neurofibromatosis Type 1: A Case Report and Review of Literature

INTRODUCTION

Neurofibromatosis (NF) 1 is associated with skeletal deformities. Scoliosis is seen in about 10-64% of NF-1 patients. NF-1 may be associated with dystrophic or non-dystrophic type of curve. There are technical difficulties in treating large dystrophic curve with proximal thoracic kyphoscoliosis in NF-1. This case report and subsequent review of literature attempts to provide a line of management for such difficult lesions.

MATERIALS AND METHODS

We present a case of 22-year-old male with NF-1 who came to us with gradually progressive upper back deformity and signs of early myelopathy for 2-3 months. The patient had a 100° proximal thoracic kyphosis and 100° scoliosis with no neurological deficit and brisk reflexes. A single stage posterior fixation with three column osteotomy at the apex of the curve was performed.

RESULTS

The kyphosis was corrected to 65° from 100, the scoliosis was corrected to 60° from 100. Clinically, the hump in the upper back was visibly reduced. At 1-year follow-up, the patient remained asymptomatic with no loss of correction and implant breakage on X-ray.

CONCLUSION

Large dystrophic proximal thoracic kyphoscoliosis is a difficult lesion to treat and can be managed with an all posterior approach, achieving good cosmetic and neurological outcomes, as demonstrated by this case.

Management of Cervical Instability as a Complication of Neurofibromatosis Type 1 in Children: A Historical Perspective With a 40-Year Experience

STUDY DESIGN

Literature review with supplementary case examples.

OBJECTIVES

The objective of this article was to review neurofibromatosis type 1 (NF1) and the associated spinal pathology with a focus on the disorder's manifestations in the immature cervical spine.

SUMMARY OF BACKGROUND DATA

NF1 is one of the most common inheritable genetic disorders. The disorder is associated with spinal deformities, long bone dysplasia, and osteoporosis. The manifestations of NF1 in the cervical spine commonly include instability secondary to kyphosis, neurofibromas, and dural ectasia.

METHODS

Literature relevant to the evaluation and management of NF1 in the cervical spine was reviewed using the PubMed/NCBI database with a focus on recent clinical studies. The review was supplemented with a historical perspective and patient cases.

RESULTS

The prevalence of NF1 cervical spine lesions is difficult to define because many patients may be asymptomatic. Symptoms of cervical kyphosis can include pain or nerve deficits but some have a surprisingly high tolerance for deformity and may have frank dislocation of one vertebral body over another (spondyloptosis) with few associated symptoms. Cervical radiographs should be obtained in patients requiring traction, surgery, or intubation, and those with neck pain or symptoms that suggest spinal neurofibromas. Patients with progressive symptoms should be offered surgery. Careful planning is required because many patients will have small, dysplastic vertebral bodies, thin posterior elements, plexiform neurofibromas, or dural ectasia. The decision to use preoperative traction will vary from patient to patient. Combined anterior-posterior fusion is recommended for most cases of severe symptomatic kyphosis, and the fusion should extend from parallel to parallel vertebrae (or six or more levels). Anterior or posterior fusion alone may be an alternative for skeletally mature patients with smaller, flexible curves.

CONCLUSIONS

Spinal deformity is the most common musculoskeletal manifestation of NF1. Cervical lesions are frequently asymptomatic, but patients with thoracolumbar scoliosis, dystrophic features, or a history of laminectomy should have the cervical spine carefully evaluated. For severe and progressive kyphotic deformities, most authors recommend a period of traction followed by a combined anterior-posterior fusion that is instrumented from parallel to parallel vertebra (or six or more levels). Close follow-up is very important because complications and progression are frequent.

A case report of cervical neurofibrosarcoma: Clinical presentation, treatment and outcome

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Malignant peripheral nerve sheath tumors are highly aggressive soft tissue sarcomas with poor prognosis.

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The recurrence rate is high.

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Complete surgical resection is the mainstay of therapy, when possible.

Introduction

Malignant peripheral nerve sheath tumors (MPNST) are highly aggressive soft tissue sarcomas in which complete surgical resection is the mainstay of therapy.

Clinical presentation

We report a case of MPNST, a 24 year old patient with right neck painful mass of 13 cm of greater dimension, skin spots, lentigos, cutaneous neurofibromas. The neck CT scan revealed a mass with liquid and soft tissues densities. Surgery was performed through right cervical Paul André incision and allowed exeresis of a hemorrhagic mass expensing on the cranial nerves X, XI, XII and the cervical sympathetic chain. Pathology analysis revealed a neurofibrosarcoma, the patient received six doses of chemotherapy. A second surgery was performed one year later after the appearance of a rapidly growing neck mass on the same site. The patient deceased in the intensive care unit one day post-op.

Discussion

Neurofibrosarcoma is a rare clinical entity most often reported as case report. This tumor takes its origin from nerve structures such as the brachial plexus, the cervical sympathetic chain and the cranial nerves and their branches. The appearance of pain, size modification or signs of nerve root compression should warn us to search for a malignant degeneration. Surgery is the base of treatment, associated to radiotherapy and chemotherapy. Vinblastin and doxorubicin were used by other authors in association to radiotherapy with complete local control of inoperable tumors. The 5-year survival is 50% in patients with a neurofibrosarcoma de novo.

Conclusion

The prognosis of neurofibrosarcoma is poor, prompting aggressive local (surgery) and systemic treatment (radiotherapy and/or chemotherapy).

Clinical Value of Multiparametric Whole-Body Magnetic Resonance Imaging over Whole-Spine Magnetic Resonance Imaging in Patients with Neurofibromatosis Type I

OBJECTIVE

To determine the clinical value of multiparametric whole-body (WBMRI) over whole-spine magnetic resonance imaging (WSMRI) in patients with neurofibromatosis type 1 (NF1).

METHODS

A consecutive series of 30 patients with known NF1 underwent WBMRI screening using anatomic, diffusion, and contrast imaging over a 30-month period. Thirteen of 30 patients also had WSMRI. Tumors were classified per location and morphology and were software segmented to determine numbers and volumes. Extra tumor burden detected by WBMRI was assessed. The comparison was made between WBMRI and WSMRI in 13 patients who had both types of scans. Enhancement characteristics were noted and 2 readers recorded apparent diffusion coefficient (ADC) in 30 patients with WBMRI scans. Interobserver performance was assessed using intraclass correlations. A 2-sample test was used for testing mean differences between tumors.

RESULTS

The age of 30 patients with WBMRI and 13 patients with WSMRI were 39.4 ± 14.4 and 41.54 ± 10.79 years (mean ± standard deviation) and male/female ratio was 1:1.73 and 1:2.25, respectively. Only 1 patient was found to have a heterogeneously enhancing lumbar paraspinal malignant peripheral nerve sheath tumor, seen on both WBMRI and WSMRI. The additional total number of tumors on WBMRI was 2766 and 2602 tumors were missed on WSMRI. The volume of tumors was 16,053 cm3 and 15,614 cm3 of tumor burden was incrementally detected on WBMRI. Mean ADC of superficial tumors was significantly lower than that of deep tumors (1.93 ± 0.39 × 10-3 mm2/second and 2.26 ± 0.56 × 10-3 mm2/second, respectively; P = 0.009), whereas no ADC differences were seen in plexiform versus discrete tumors (P = 0.64). Interobserver performance for ADC was excellent (intraclass correlation, 0.84).

CONCLUSIONS

Multiparametric WBMRI provides superior determination of tumor burden and should be considered as a preferred method for evaluation of patients with NF1.

Morphological Differences in the Vertebrae of Scoliosis Secondary to Neurofibromatosis Type 1 With and Without Paraspinal Neurofibromas

STUDY DESIGN

A retrospective study.

OBJECTIVE

Aim of the study was to investigate morphological differences in the vertebrae of scoliosis secondary to neurofibromatosis type 1 (NF1-S) with and without paraspinal neurofibromas and to identify the relationship between paraspinal neurofibromas and vertebral deformity.

SUMMARY OF BACKGROUND DATA

Scoliosis is the most common orthopedic manifestation of NF1. Erosion or infiltration of the bone by localized neurofibromas was suggested as one of the primary etiology for the vertebral deformity.

METHODS

One hundred fourteen patients with NF1-S were classified into spinal tumor (ST) group and nontumor (NT) group with respect to the presence of paraspinal neurofibromas. The curve pattern, curve magnitude, the shape and location of paraspinal neurofibromas, and various kinds of morphological changes of vertebrae were evaluated by complete radiographs were compared between the two groups to determine whether the presence of paraspinal neurofibromas could be associated with a more severe vertebral deformity.

RESULTS

The ST and NT groups included 54 patients (age, 16.8 ± 5.5 years) and 60 patients (age, 17.3 ± 4.2 years), respectively. The Cobb angles of the main curve were 72.3° ± 20.6° and 65.4° ± 19.4° for the ST and NT groups, respectively. No significant differences were observed between the two groups in age, sex ratio, and Cobb angle. There were significant differences between the ST and NT groups in apical vertebral rotation (36.8° ± 7.2° vs. 27.5° ± 6.8°; P < 0.001) and the prevalence of rotatory subluxation (66.1% vs. 35.0%; P = 0.04). Most of the paraspinal neurofibromas (70.4%) developed within the apical region, with the majority (29/38) located on the concave side.

CONCLUSION

The NF1-S patients with paraspinal neurofibromas had significantly higher prevalence of morphological changes of vertebrae. The paraspinal neurofibromas, most of which were located on the concave side of the apical region, could be associated with more severe vertebral deformities.

LEVEL OF EVIDENCE

3.

MR Imaging of the Lumbosacral Plexus: A Review of Techniques and Pathologies

The lumbosacral plexus is a complex anatomic area that serves as the conduit of innervation and sensory information to and from the lower extremities. It is formed by the ventral rami of the lumbar and sacral spine which then combine into larger nerves serving the pelvis and lower extremities. It can be a source of severe disability and morbidity for patients when afflicted with pathology. Patients may experience motor weakness, sensory loss, and/or debilitating pain. Primary neurologic processes can affect the lumbosacral plexus in both genetic and acquired conditions and typically affect the plexus and nerves symmetrically. Additionally, its unique relationship to the pelvic musculature and viscera render it vulnerable to trauma, infection, and malignancy. Such conditions are typically proceeded by a known history of trauma or established pelvic malignancy or infection. Magnetic resonance imaging is an invaluable tool for evaluation of the lumbosacral plexus due to its anatomic detail and sensitivity to pathologic changes. It can identify the cause for disability, indicate prognosis for improvement, and be a tool for delivery of interventions. Knowledge of proper MR protocols and imaging features is key for appropriate and timely diagnosis. Here we discuss the relevant anatomy of the lumbosacral plexus, appropriate imaging techniques for its evaluation, and discuss the variety of pathologies that may afflict it.

Dystrophic spinal deformities in a neurofibromatosis type 1 murine model

Despite the high prevalence and significant morbidity of spinal anomalies in neurofibromatosis type 1 (NF1), the pathogenesis of these defects remains largely unknown. Here, we present two murine models: Nf1^flox/−;PeriCre and Nf1^flox/−;Col.2.3Cre mice, which recapitulate spinal deformities seen in the human disease. Dynamic histomorphometry and microtomographic studies show recalcitrant bone remodeling and distorted bone microarchitecture within the vertebral spine of Nf1^flox/−;PeriCre and Nf1^flox/−;Col2.3Cre mice, with analogous histological features present in a human patient with dystrophic scoliosis. Intriguingly, 36–60% of Nf1^flox/−;PeriCre and Nf1^flox/−;Col2.3Cre mice exhibit segmental vertebral fusion anomalies with boney obliteration of the intervertebral disc (IVD). While analogous findings have not yet been reported in the NF1 patient population, we herein present two case reports of IVD defects and interarticular vertebral fusion in patients with NF1. Collectively, these data provide novel insights regarding the pathophysiology of dystrophic spinal anomalies in NF1, and provide impetus for future radiographic analyses of larger patient cohorts to determine whether IVD and vertebral fusion defects may have been previously overlooked or underreported in the NF1 patient population.

Combined MEK inhibition and BMP2 treatment promotes osteoblast differentiation and bone healing in Nf1Osx -/- mice

Neurofibromatosis type I (NF1) is an autosomal dominant disease with an incidence of 1/3000, caused by mutations in the NF1 gene, which encodes the RAS/GTPase-activating protein neurofibromin. Non-bone union after fracture (pseudarthrosis) in children with NF1 remains a challenging orthopedic condition to treat. Recent progress in understanding the biology of neurofibromin suggested that NF1 pseudarthrosis stems primarily from defects in the bone mesenchymal lineage and hypersensitivity of hematopoietic cells to TGFβ. However, clinically relevant pharmacological approaches to augment bone union in these patients remain limited. In this study, we report the generation of a novel conditional mutant mouse line used to model NF1 pseudoarthrosis, in which Nf1 can be ablated in an inducible fashion in osteoprogenitors of postnatal mice, thus circumventing the dwarfism associated with previous mouse models where Nf1 is ablated in embryonic mesenchymal cell lineages. An ex vivo-based cell culture approach based on the use of Nf1(flox/flox) bone marrow stromal cells showed that loss of Nf1 impairs osteoprogenitor cell differentiation in a cell-autonomous manner, independent of developmental growth plate-derived or paracrine/hormonal influences. In addition, in vitro gene expression and differentiation assays indicated that chronic ERK activation in Nf1-deficient osteoprogenitors blunts the pro-osteogenic property of BMP2, based on the observation that only combination treatment with BMP2 and MEK inhibition promoted the differentiation of Nf1-deficient osteoprogenitors. The in vivo preclinical relevance of these findings was confirmed by the improved bone healing and callus strength observed in Nf1osx (-/-) mice receiving Trametinib (a MEK inhibitor) and BMP2 released locally at the fracture site via a novel nanoparticle and polyglycidol-based delivery method. Collectively, these results provide novel evidence for a cell-autonomous role of neurofibromin in osteoprogenitor cells and insights about a novel targeted approach for the treatment of NF1 pseudoarthrosis.

Familial syndromes associated with intracranial tumours: a review

BACKGROUND

Most cancers of the central nervous system (CNS) occur sporadically in the absence of any known underlying familial disorder or multi-systemic syndrome. Several syndromes are associated with CNS malignancies, however, and their recognition has significant implications for patient management and prognosis. Patients with syndrome-associated CNS malignancies often have multiple tumours (either confined to one region or distributed throughout the body), with similar or different histology.

OBJECTIVE

This review examines syndromes that are strongly associated with CNS cancers: the phakomatosis syndromes, familial syndromes such as Li-Fraumeni and familial polyposis syndromes and dyschondroplasia.

Posterior approach for giant S1 neurofibroma in Von Recklinghausen's disease: Is total resection realistic?

Bilateral sacral neurofibromas are uncommonly seen in neurofibromatosis type 1 (NF1) also known as Von Recklinghausen's disease. They often grow to enormous dimensions before detection owing to bone scalloping. Resections of “giant” S1 neurofibromas are difficult due to the limitations of operative window in sacrum and critical functions associated with S1 nerve root. We report a case of bilateral S1 neurofibromas in a patient of NF1 where she had a giant left-sided neurofibroma with extensive bone erosion and a small fusiform neurofibroma on the right side. The tumor was excised completely on the left and near totally on the right side via posterior approach. There were no postoperative neurological deficits and the patient recovered well. Usually, complete excision harbors the chances of postoperative neurological deficits due to the eloquence of the nerve root involved and complete resection without significant morbidity seems unrealistic. However, excision of giant ones may not result in grave deficits always if the patient is neurologically intact before surgery. Also, in selected patients, only posterior approach may suffice for giant neurofibromas with extensive bone scalloping and complete removal can be attempted successfully despite narrow corridors.

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.

Clinical characteristics predicting internal neurofibromas in 357 children with neurofibromatosis-1: results from a cross-selectional study

OBJECTIVE

To identify clinical characteristics associated with internal neurofibromas in children with NF1, as a means of ensuring the early identification of patients at high risk for malignant peripheral nerve-sheath tumors developed from preexisting internal neurofibromas.

PATIENTS AND METHODS

We used data from two NF1 populations, in France and North America, respectively. The French database comprised 1083 patients meeting NIH diagnostic criteria for NF1 and the Neurofibromatosis Institute Database of North America comprised 703 patients. Patients younger than 17 years of age were eligible for our study if they had been evaluated for internal neurofibromas using computed tomography and/or magnetic resonance imaging. Clinical characteristics associated with internal neurofibromas by univariate analysis (P ≤ 0.15) were entered into a multiple logistic regression model after checking for potential interactions and confounding. Multiple imputation was used for missing values.

RESULTS

Among the 746 children in the two databases, 357 (48%) met our inclusion criteria. Their mean age was 7.7 ± 5.0 years and there were 192 (53.8%) males. Internal neurofibromas were present in 35 (9.8%) patients. Internal neurofibromas developed earlier in females than in males and their prevalence increased during adolescence. Factors independently associated with internal neurofibromas were age (OR = 1.16 [1.07-1.27]), xanthogranulomas (OR = 5.85 [2.18-15.89]) and presence of both subcutaneous and plexiform neurofibromas (OR = 6.80 [1.52-30.44]).

CONCLUSIONS

Several easily recognizable clinical characteristics indicate a high risk of internal neurofibromas in children with NF1 and, therefore, a need for very close monitoring.

Bilateral spinal neurofibromas in patients with neurofibromatosis 1

Neurofibromatosis 1 (NF1) is a neurocutaneous syndrome that can be inherited as autosomal dominant or may appear due to a de novo mutation. We present 8 patients (5 M and 3 F) with sporadic or non-familial spinal neurofibromatosis 1 (non-FSNF1) associated with bilateral spinal neurofibromas involving all of the paraspinal nerves. To our knowledge, this is the first series of such association described in the literature. Their ages ranged from 6 months to 20 years (average 9.8 years) at the time of radiological diagnosis. This presentation appears to be earlier than in familial spinal neurofibromas in NF1 (FSNF1). Predisposition to malignancy probably is greater in the non-FSNF1 type. MRI studies were performed routinely in all patients with NF1 and these were complemented with MRI enhanced with gadolinium and repeated at different ages in cases with paraspinal tumors. Coronal views provided the best evidence for the presence of neurofibromas in every spinal nerve. The size of the tumors and the clinical complications increased with advancing age in most patients. Giant plexiform tumors were often seen in the cervico-thoracic region. Malignant peripheral nerve sheath tumors (MPNST) were found in one patient with a sciatic tumor and another patient died suddenly at home without necropsy or pathological study. Voluminous paraspinal neurofibromas can be at risk for malignancy. More frequent neuroimaging studies may be necessary for an earlier detection. Early surgical treatment to anticipate the occurrence of MPNST during surveillance could be an option. Bilateral spinal neurofibromas are found in both patients who inherited the NF1 and in those due to de novo mutations.

Postpartum paraparesis from spinal neurofibroma

BACKGROUND CONTEXT

One hallmark of neurofibromatosis Type 1 (NF1) is the presence of multiple neurofibromas, which are hormonally responsive and may undergo rapid growth during periods of hormonal surge. Although spinal neurofibromas occur in up to 40% of patients with NF1, they rarely cause neurologic sequelae, especially in the young.

PURPOSE

To document a unique case of acute postpartum paraparesis in a young woman because of an extradural neurofibroma compressing the conus medullaris and discuss the possible hormonal influences related to rapid growth of this otherwise "benign" nerve sheath tumor. This case demonstrates the importance of closely monitoring patients with known NF1 for neurologic symptoms, especially during pregnancy and the postpartum period. We also seek to describe the management of this patient, which resulted in an excellent outcome.

STUDY DESIGN

Case report and literature review.

METHODS

Detailed history was obtained from the patient and her family members. All medical records, imaging studies, histopathological findings, and pertinent literature were reviewed.

RESULTS

After evaluating a 26-year-old postpartum woman with NF1 for paraparesis, magnetic resonance imaging of the lumbar spine revealed a large heterogeneously enhancing mass at the conus medullaris. She subsequently underwent resection of the mass via laminectomy. Postoperatively, the patient exhibited marked improvement in weakness and was able to ambulate with assistance 2 days later. Histopathological examination of the mass revealed a neurofibroma with strong expression of estrogen and progesterone receptors.

CONCLUSIONS

This patient had a spinal neurofibroma, which likely grew in size within the peripartum period, causing a neurologic emergency. The rapid growth of the neurofibroma may have been the result of hormonal influence of estrogen or progesterone or both. To the best of our knowledge, rapid paraparesis caused by a spinal neurofibroma has never been reported in a peripartum setting. Laminectomy with complete tumor resection is the preferred treatment for spinal neurofibromas causing acute neurologic symptoms.

Seizure, spinal schwannoma, peripheral neuropathy and pulmonary stenosis - A rare combination in a patient of Neurofibromatosis 1

Neurofibromatosis 1 (NF1) is the most common neurocutaneous syndrome. It is estimated to occur in approximately 1 out of every 3300 infants. The manifestations of this condition are diverse and can arise from almost any system in the body. The neurofibroma is the hallmark lesion of NF1 that develops from peripheral nerves. Here, we are reporting an 18-year-old girl with NF1. Clinical diagnosis was made according to the diagnostic criteria established by the National Institutes of Health Consensus Development Conference in 1987. She presented with quadriparesis due to dumbbell-shaped spinal schwannoma in the cervical region. She had history of recurrent seizures in the past, with poor scholastic performance. There were clinical and electrophysiological features of peripheral neuropathy and clinical and echocardiographical features of pulmonary stenosis. These are uncommon features of NF 1. The presence of all these features in a single patient makes it a unique case.

Neurofibromatose tipo 1: aspectos radiológicos do tórax

OBJETIVO: Identificar alterações e frequências nas radiografias simples do tórax sugestivas de neurofibromatose tipo 1 e avaliar a possibilidade de inclusão de massa no mediastino posterior como critério de diagnóstico de neurofibromatose tipo 1. MATERIAIS E MÉTODOS: Foram realizadas radiografias com técnica padrão de tórax em póstero-anterior e em perfil de 141 pacientes com neurofibromatose tipo 1, atendidos no Serviço de Radiologia do Hospital de Base e Faculdade de Medicina de São José do Rio Preto, SP. Os resultados obtidos foram avaliados por métodos não paramétricos ao nível de 0,05 de significância (p = 0,05). RESULTADOS: No presente estudo, 141 pacientes com neurofibromatose tipo 1 realizaram radiografia de tórax, sendo as alterações mais frequentes: erosão óssea das costelas (19,8%), peito escavado (12,0%), cifoescoliose (3,5%) e massas no mediastino posterior (7,1%). Esses resultados sugerem que as massas (neurofibroma e meningocele) devem ser incluídas como critério diagnóstico para neurofibromatose tipo 1, juntamente com displasia do osso esfenoide, pseudoartrose e afinamento do córtex de ossos longos, conforme definido pelo National Institutes of Health. CONCLUSÃO: A presença das massas no mediastino posterior associada às alterações ósseas características definidas pelo National Institutes of Health indicam ser um achado consistente para se considerar como critério diagnóstico da doença.

Skeletal abnormalities in neurofibromatosis type 1: approaches to therapeutic options

The skeleton is frequently affected in individuals with neurofibromatosis type 1, and some of these bone manifestations can result in significant morbidity. The natural history and pathogenesis of the skeletal abnormalities of this disorder are poorly understood and consequently therapeutic options for these manifestations are currently limited. The Children's Tumor Foundation convened an International Neurofibromatosis Type 1 Bone Abnormalities Consortium to address future directions for clinical trials in skeletal abnormalities associated with this disorder. This report reviews the clinical skeletal manifestations and available preclinical mouse models and summarizes key issues that present barriers to optimal clinical management of skeletal abnormalities in neurofibromatosis type 1. These concepts should help advance optimal clinical management of the skeletal abnormalities in this disease and address major difficulties encountered for the design of clinical trials.

Neurofibroma with increased uptake of [F-18]-fluoro-2 deoxy-d-glucose interpreted as a metastatic lesion

We report a patient with a solitary spinal neurofibroma in the posterior mediastinum interpreted as a metastatic tumor. A 46-year-old female with rectal cancer who had undergone operation and subsequent adjuvant chemotherapy two years previously was referred to our department for a follow-up whole body FDG-PET study. PET scan revealed a mass with increased uptake of FDG (SUV = 4.6) in the posterior mediastinum. MRI examination showed a dumbbell neurogenic tumor originating from the intercostal nerve at T6 level. A subsequent CT-guided biopsy demonstrated a neurofibroma.

Differential diagnosis of dumbbell lesions associated with spinal neural foraminal widening: imaging features

Computed tomography (CT) and magnetic resonance imaging (MRI) reliably demonstrate typical features of schwannomas or neurofibromas in the vast majority of dumbbell lesions responsible for neural foraminal widening. However, a large variety of unusual lesions which are causes of neural foraminal widening can also be encountered in the spinal neural foramen. Radiologic findings can be helpful in differential diagnosis of lesions of spinal neural foramen including neoplastic lesions such as benign/malign peripheral nerve sheath tumors (PNSTs), solitary bone plasmacytoma (SBP), chondroid chordoma, superior sulcus tumor, metastasis and non-neoplastic lesions such as infectious process (tuberculosis, hydatid cyst), aneurysmal bone cyst (ABC), synovial cyst, traumatic pseudomeningocele, arachnoid cyst, vertebral artery tortuosity. In this article, we discuss CT and MRI findings of dumbbell lesions which are causes of neural foraminal widening.

[Voluminous mediastinal neurofibroma in a child]

INTRODUCTION

Neurogenic tumors account for 30% of mediastinal tumors in children. The thoracic region is the most common site for neurofibromas. We report a case of a voluminous neurofibroma in a small girl.

CASE

After 8 months of paraplegia, a 4-year-old girl underwent thoracic radiography and computed tomography as well as magnetic resonance imaging of the spine. These revealed a huge mediastinal mass continuing into the vertebral canal and compressing the cord. Histological examination after surgery confirmed the diagnosis of neurofibroma. At the follow-up examination a month later, the paraplegia had resolved.

DISCUSSION

Neurofibromas may manifest as solitary tumors or may be one manifestation of neurofibromatosis. In mediastinal neurofibroma, thoracic radiography, and computed tomography can show the tumor, posterior vertebral scalloping, and enlarged neural foramina. MR imaging provides the exact anatomic location, as well as any compression and displacement caused by the tumor. This information is essential for deciding the exact extent of resection. MRI may also be helpful in postoperative management.

Spinal disorders associated with skeletal dysplasias and syndromes

Skeletal dysplasias are a heterogeneous group of disorders in which there is abnormal cartilage and bone formation, growth, and remodeling. There are more than 200 described skeletal dysplasias. Skeletal dysplasias can affect the spine in various ways, with attendant neurosurgical implications for diagnosis and treatment. Craniocervical junction abnormalities, atlantoaxial subluxation, and kyphoscoliotic deformity are among the common spinal problems that are found in certain skeletal dysplasias.

Extramedullary Intradural Spinal Tumors: A Pictorial Review

Defining the location of tumors and mass lesions of the spine in relation to the spinal cord and the dura is of the utmost importance as certain types of lesions tend to occur in certain locations. The differential diagnostic considerations will vary according to location of the mass lesion as will the treatment and prognosis of these various lesions. The category of extramedullary intradural masses includes a variety of lesions from meningiomas and nerve sheath tumors (neurofibromas, schwannomas) to less common tumors (hemangiopericytoma), metastases, benign tumors (lipoma, dermoid, epidermoid), inflammatory disorders (arachnoid adhesions, sarcoidosis), vascular lesions (spinal-dural arteriovenous fistula), and cystic lesions (perineural or Tarlov cysts). Characteristic magnetic resonance imaging findings are helpful for localization and characterization of these lesions before treatment, as well as for follow-up after treatment. We present a pictorial review of the various extramedullary intradural lesions of the spine, with pathologic correlation. We discuss imaging features that are typical for the various entities and describe various therapeutic options that are important considerations for surgical treatment of these lesions.

Imaging for spine tumors and new applications

OBJECTIVES

Discuss intramedullary, intradural/extramedullary, and extradural spinal tumors including imaging characteristics with emphasis on MR and advances in treatment.

METHODS

Literature and institutional review.

RESULTS

Spinal tumors: intramedullary, intradural/extramedullary, and extradural, comprise a wide range of histological tumors with an even wider range of clinical symptoms and prognostic features. They are relatively rare and if left untreated, can cause serious neurological deficits and disability. An accurate diagnosis is therefore crucial in determining prognosis and directing therapy. Magnetic resonance imaging (MRI) has revolutionized the diagnosis of intraspinal tumors, allowing for early detection and improved anatomical localization. Magnetic resonance has also become an integral part in staging of both primary and metastatic neoplasms of the spine for guiding therapy and is an excellent modality for follow-up. Advances in MRI (perfusion and molecular imaging) may help refine and describe these neoplasms for accurate treatment and prognosis in the future. Surveillance protocols and role of magnetic resonance are not well established.

CONCLUSIONS

Magnetic resonance plays an integral role in evaluation of spinal tumors with increasing role in staging and treatment.

[Imaging of spinal tumors]

Spinal tumors are often categorized into extradural, intradural extramedullary, or intramedullary. Although this classification represents somewhat of an overgeneralization as a lesion may reside in two compartments, it still helps to characterize spinal tumors. In the intradural, extramedullary space, primary tumors, such as neurofibroma and meningioma, are relatively common. Secondary tumors or leptomeningeal enhancement also occur. In the intramedullary space, primary tumors are far more common than secondary tumors or metastases.

Neurofibromatosis-associated nerve sheath tumors

In this paper the authors describe a patient with neurofibromatosis Type 1 (NF1) who presented with sequelae of this disease. They also review the current literature on NF1 and NF2 published between 2001 and 2005.

The method used to obtain information for the case report consisted of a family member interview and a review of the patient's chart. For the literature review the authors used the search engine Ovid Medline to identify papers published on the topic between 2001 and 2005. Neurofibromatosis Type 1 appears in approximately one in 2500 to 4000 births, is caused by a defect on 17q11.2, and results in neurofibromin inactivation. The authors reviewed the current literature with regard to the following aspects of this disease: 1) diagnostic criteria for NF1; 2) criteria for other NF1-associated manifestations; 3) malignant peripheral nerve sheath tumors (PNSTs); 4) the examination protocol for a patient with an NF1-related NST; 5) imaging findings in patients with NF1; 6) other diagnostic studies; 7) surgical and adjuvant treatment for NSTs and malignant PNSTs; and 8) hormone receptors in NF1-related tumors. Pertinent illustrations are included.

Neurofibromatosis Type 2 occurs much less frequently than NF1, that is, in one in 33,000 births. Mutations in NF2 occur on 22q12 and result in inactivation of the tumor suppressor merlin. The following data on this disease are presented: 1) diagnostic criteria for NF2; 2) criteria for other NF2 manifestations; 3) malignant PNSTs in patients with NF2; 4) examination protocol for the patient with NF2 who has an NST; and 5) imaging findings in patients with NF2. Relevant illustrations are included.

It is important that neurosurgeons be aware of the sequelae of NF1 and NF2, because they may be called on to treat these conditions.