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

Uninstrumented fusion in cervical kyphosis due to neurofibromatosis type I: report of two paediatric cases

PURPOSE

Severe cervical kyphosis (CK) in neurofibromatosis type 1 (NF-1) is associated with a high risk for progression and neurologic impairment in children. We present our surgical technique and mid-term outcomes of uninstrumented anterior tibial strut grafting for severe CK secondary to NF-1.

METHODS

Case report. The Consensus-based Clinical Case Reporting Guideline Development (CARE) guidelines were followed.

RESULTS

Two paediatric patients (8- and 3-year-old) presented with severe CK secondary to NF-1. A halo body jacket (HV) allowed the progressive distraction of the cervical spine, avoiding neurological compromise and deformity progression. Circumferential fusion was obtained with anterior tibial strut autograft and posterior onlay bone graft. Cervical spine fusion was successfully maintained at a minimum 4-year follow-up in both patients.

CONCLUSION

In children with severe CK secondary to NF-1, cervical distraction and immobilisation with a HV followed by uninstrumented anterior tibial strut grafting and posterior bone grafting, provided spinal fusion and stability without increasing the risk of neurological injury and donor site morbidity. The reported surgical technique appears to be a valuable tool in the armamentarium of the spinal surgeon.

Surgical challenges and functional outcomes in dystrophic cervical kyphosis in Neurofibromatosis -1: an institutional experience

OBJECTIVE

Dystrophic cervical kyphosis secondary to neurofibromatosis 1 (NF1) is rarely reported. The primary objective is to highlight the clinical presentation and surgical outcomes based on clinical and biomechanical parameters. The secondary objective is to highlight the early and late complications of these surgeries.

METHODS

The hospital records of six patients operated between 2008 and 2018 were retrospectively reviewed with a minimum follow-up of 24 months. Besides demographics information, radiological findings and operative details, the outcome measures reported were neurological (MJOA score, Nurick scale), pain (VAS score) and operative complications.

RESULTS

The mean age of patients was 15.1 years (8-32 years). The average kyphotic vertebra involved-3.6 bodies (range 2-5 bodies) with four patients showing intraspinal anomaly-neurofibromas, dural ectasia. Clinically, patients improved postoperatively with-VAS (pre vs. post-: 6.6 vs. 2.6, p - < 0.05), MJOA score (pre vs. post: 10.3 vs. 13.3, p - < 0.05), Nurick grade (pre vs. post: 3.5 vs. 2.1, p - < 0.05). There was significant deformity correction from 66.8° to 20.7° (p value < 0.031), mean T1 Slope (pre vs. post - 1.8 ± 20.4 to 0.6 ± 12.8, p value - < 0.43). Mean blood loss encountered was 1800 ± 434.6 cc; however, patients with paraspinal neurofibromas reported greater blood loss. Late complications included pseudoarthrosis (1), C5 palsy (1) and junctional kyphosis (1). Vertebral dysplasia and erosions continued in all patients post-operatively.

CONCLUSIONS

Antero-posterior approach provides circumferential decompression and better sagittal balance correction. Cervical spine must be screened in all NF-1 patients and followed up regularly to assess for dystrophic changes.

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.

The MEK inhibitor selumetinib reduces spinal neurofibroma burden in patients with NF1 and plexiform neurofibromas

BACKGROUND

Spinal neurofibromas (SNFs) in neurofibromatosis type 1 (NF1) can cause progressive spinal cord compression and neurological dysfunction. The MEK inhibitor selumetinib shrinks the majority of plexiform neurofibromas (PNs) in patients with NF1. We assessed the effect of selumetinib on SNF.

METHODS

Pediatric and adult patients with NF1 and inoperable PN participating in phase 2 studies of selumetinib for PN were included in this analysis if they had SNF and serial spine magnetic resonance imaging (MRI). Selumetinib was administered orally at the recommended dose of 25 mg/m2/dose twice daily (max 50 mg b.i.d.; 1 cycle = 28 days). We qualitatively assessed the effect of selumetinib on SNF-related spinal canal distortion, cerebrospinal fluid distribution, and spinal cord deformity on MRI.

RESULTS

Twenty-four patients (18 male), median age 16.9 years (range, 6.2-60.3), had SNF, 22 of which were associated with the same nerves as the target PN assessed on the clinical trial. Twenty patients had spinal cord deformity. Twenty-three patients completed at least 12 treatment cycles to date. Eighteen patients showed subtle to a marked improvement in SNF burden, 5 remained stable, and no worsening was observed during treatment.

CONCLUSIONS

This is the first study describing the effect of selumetinib on SNF. Of 24 patients, 18 exhibited some improvement of SNF burden on imaging. These findings suggest that selumetinib may prevent the worsening of cord compression, potentially reducing the need for surgical interventions in select patients or benefitting patients who do not have a surgical option. Prospective evaluation of the clinical benefit of selumetinib for SNF is warranted.