Predictive Value and Interrater Reliability of Radiographic Factors in Neurofibromatosis Patients With Dystrophic Scoliosis

Management and surgical outcomes of dystrophic scoliosis in neurofibromatosis type 1: a systematic review

OBJECTIVE

Neurofibromatosis type 1 (NF1) dystrophic scoliosis is an early-onset, rapidly progressive multiplanar deformity. There are few studies on the surgical management of this patient population. Specifically, perioperative morbidity, instrument-related complications, and quality-of-life outcomes associated with surgical management have not been systematically evaluated. In this study, the authors aimed to perform a systematic review on the natural history, management options, and surgical outcomes in patients who underwent NF1 dystrophic scoliosis surgery.

METHODS

A PubMed search for articles with “neurofibromatosis” and either “dystrophic” or “scoliosis” in the title or abstract was performed. Articles with 10 or more patients undergoing surgery for NF1 dystrophic scoliosis were included. Data regarding indications, treatment details, morbidity, and outcomes were summarized and analyzed with descriptive statistics.

RESULTS

A total of 310 articles were identified, 48 of which were selected for full-text review; 30 studies describing 761 patients met the inclusion criteria. The mean age ranged from 7 to 22 years, and 99.7% of patients were younger than 18 years. The mean preoperative coronal Cobb angle was 75.2°, and the average correction achieved was 40.3°. The mean clinical follow-up in each study was at least 2 years (range 2.2–19 years). All patients underwent surgery with the intent of deformity correction. The scoliosis regions addressed were thoracic curves (69.6%) and thoracolumbar (11.1%) and lumbar (14.3%) regions. The authors reported on a variety of approaches: posterior-only, combined anterior-posterior, and growth-friendly surgery. For fixation techniques, 42.5% of patients were treated with hybrid constructs, 51.5% with pedicle screw–only constructs, and 6.0% with hook-based constructs. Only 0.9% of patients underwent a vertebral column resection. The nonneurological complication rate was 14.0%, primarily dural tears and wound infections. The immediate postoperative neurological deficit rate was 2.1%, and the permanent neurological deficit rate was 1.2%. Ultimately, 21.5% required revision surgery, most commonly for implant-related complications. Loss of correction in both the sagittal and coronal planes commonly occurred at follow-up. Five papers supplied validated patient-reported outcome measures, showing improvement in the mental health, self-image, and activity domains.

CONCLUSIONS

Data on the surgical outcomes of dystrophic scoliosis correction are heterogeneous and sparse. The perioperative complication rate appears to be high, although reported rates of neurological deficits appear to be lower than clinically observed and may be underreported. The incidence of implant-related failures requiring revision surgery is high. There is a great need for multicenter prospective studies of this complex type of deformity.

Management of NF-1 dystrophic scoliosis associated with rib heads dislocation into the spinal canal in neurological intact patients: a systematic literature review

PURPOSE

The management of scoliosis and kyphoscoliosis in patients with Type 1 Neurofibromatosis (NF-1) among spinal surgeons is still challenging due to the severity of the deformity especially in dystrophic deformity types. This rapid and progressive condition is likely to be associated with dislocated rib heads into the spinal canal, hence representing a real dilemma on the decision making between its resection versus not resection during the corrective surgery, especially in patients with normal neurological status. The objective of this publication is to discuss the management options in this patient population through a literature review.

METHODS

A comprehensive systematic literature search was performed for relevant studies using PubMed, Web of Science, and Scopus databases. Previous publications depicting neurologically intact patients with NF-1 and rib dislocation into the canal were reviewed. Articles reporting individual cases or case series/cohorts with patient-discriminated findings were included.

RESULTS

The data collection retrieved a total of 55 neurologically intact patients with NF-1 dystrophic scoliosis and rib penetration into the canal who underwent spinal surgery. Among them, 37 patients underwent surgery without head rib resection and 18 patients with rib excision. No patient presented postoperative neurological deficit except for one case of late postoperative neurological deterioration reported in a patient within situ fusion in which the surgeons ignored the presence of previous spinal cord compression.

CONCLUSION

Corrective surgery for patients with NF-1 and rib penetration into the canal in neurologically intact patients can be safely performed without the resection of the dislocated rib heads without a higher risk of neurological compromise.

Classification of neurofibromatosis-related dystrophic or nondystrophic scoliosis based on image features using Bilateral CNN

PURPOSE

We developed a system that can automatically classify cases of scoliosis secondary to neurofibromatosis type 1 (NF1-S) using deep learning algorithms (DLAs) and improve the accuracy and effectiveness of classification, thereby assisting surgeons with the auxiliary diagnosis.

METHODS

Comprehensive experiments in NF1 classification were performed based on a dataset consisting 211 NF1-S (131 dystrophic and 80 nondystrophic NF1-S) patients. Additionally, 100 congenital scoliosis (CS), 100 adolescent idiopathic scoliosis (AIS) patients, and 114 normal controls were used for experiments in primary classification. For identification of NF1-S with nondystrophic or dystrophic curves, we devised a novel network (i.e., Bilateral convolutional neural network [CNN]) utilizing a bilinear-like operation to discover the similar interest features between whole spine AP and lateral x-ray images. The performance of Bilateral CNN was compared with spine surgeons, conventional DLAs (i.e., VGG-16, ResNet-50, and Bilinear CNN [BCNN]), recently proposed DLAs (i.e., ShuffleNet, MobileNet, and EfficientNet), and Two-path BCNN which was the extension of BCNN using AP and lateral x-ray images as inputs.

RESULTS

In NF1 classification, our proposed Bilateral CNN with 80.36% accuracy outperformed the other seven DLAs ranging from 61.90% to 76.19% with fivefold cross-validation. It also outperformed the spine surgeons (with an average accuracy of 77.5% for the senior surgeons and 65.0% for the junior surgeons). Our method is highly generalizable due to the proposed methodology and data augmentation. Furthermore, the heatmaps extracted by Bilateral CNN showed curve pattern and morphology of ribs and vertebrae contributing most to the classification results. In primary classification, our proposed method with an accuracy of 87.92% also outperformed all the other methods with varied accuracies between 52.58% and 83.35% with fivefold cross-validation.

CONCLUSIONS

The proposed Bilateral CNN can automatically capture representative features for classifying NF1-S utilizing AP and lateral x-ray images, leading to a relatively good performance. Moreover, the proposed method can identify other spine deformities for auxiliary diagnosis.

AN ADJUNCTIVE USE OF ASFOTASE ALFA AND ZOLEDRONIC ACID AFTER SPINAL SURGERY IN NEUROFIBROMATOSIS TYPE 1 RELATED DYSTROPHIC SCOLIOSIS

Objective

Dystrophic scoliosis is a serious skeletal manifestation of neurofibromatosis 1 (NF1). The condition requires surgical intervention that is frequently associated with poor outcome due to the high rate of impaired bone healing, pseudoarthrosis, and loosening of the spinal instrumentation. New therapeutic approaches are needed to improve surgical outcomes.

Methods

Clinical, laboratory, and radiographic data are presented.

Results

A 54-year-old woman with severe NF1 related dystrophic scoliosis and 3 prior surgical interventions underwent revision of lumbar fusion with intraoperative recombinant human bone morphogenetic protein (rhBMP-2) for loosening and a fracture of the left vertical rod at the L4 pedicle screw connection. Two days after surgery, a computed tomography (CT) scan revealed a left posterior iliac periscrew fracture. Given a high risk of mechanical failure, zoledronic acid and asfotase alfa were also administered at 3 and 7 months after surgery. At 14 months after surgery, back pain improved, and a CT scan showed stable spinal fusion and a healed left posterior iliac screw fracture.

Conclusion

Combination therapy including asfotase alfa with rhBMP-2 and bisphosphonate resulted in solid arthrodesis after spinal surgery in NF1-related dystrophic scoliosis.