Surgical Treatment of the Intraspinal Rib Head Dislocation in Children With Dystrophic Scoliosis Secondary to Type 1 Neurofibromatosis

Myelopathy Associated with Rapid Progression of a Dystrophic Neurofibromatosis-1 Curve - A Case Report and Review of Literature

Introduction

Thoracic myelopathy in neuro fibromatosis-1 (NF-1) is most commonly due to intra-spinal neurofibromas/dumb-bell tumors/intra-canal rib head penetration (RHP) causing cord compression. However, acute thoracic myelopathy due to rapid progression of the kyphoscoliotic curve alone in NF-1 without a significant spinal cord compression occurs very rarely. This case report discusses our experience with one such patient and we also discuss intraoperative and post-operative challenges encountered with this patient and a rare complication of hemothorax postoperatively.

Case Report

A 15-year-old male presented to the clinic after being lost to follow-up for 4 years with a rapid acute deterioration of dystrophic curve and no myelopathic symptoms (Scoliosis - 65°, Kyphosis - 77°). His subsequent examination in 6 weeks showed acute development of myelopathic gait with right ankle and extensor hallucis longus weakness. He was admitted for halo gravity traction for 6 weeks and a single-stage posterior instrumentation with excision of rib heads at the apex was planned. Postoperatively, the patient developed massive left hemothorax and loss of power in both lower limbs at day 2. He subsequently regained full power and complete resolution of myelopathic symptoms at the end of 9- month follow-up with a satisfactory alignment of spine in the follow-up X-rays.

Conclusion

Acute onset of myelopathy is a rare and uncommon finding with a rapid deterioration of dystrophic curve alone without any major spinal cord compromise. Early detection of dysplastic changes with early aggressive surgical management and deformity correction is necessary with dystrophic NF-1 curves to prevent pre-operative and post-operative morbidities.

Outcomes and Safety of Traditional Growing Rod Technique in the Treatment of Early-onset Dystrophic Scoliosis Secondary to Type 1 Neurofibromatosis With Intraspinal Rib Head Dislocation in Children

PURPOSE

The purpose of this study was to investigate the outcomes and safety of traditional growing rod (TGR) in the treatment of early-onset dystrophic scoliosis secondary to type 1 neurofibromatosis (NF1-EOS) with intraspinal rib head dislocation (IRH) in children.

METHODS

From September 2006 to June 2020, 21 patients with NF1-EOS were treated with TGR. The patients comprised 13 boys and 8 girls with a mean age of 7.1±1.5 years. Two patients had IRH-induced nerve injury [American Spinal Injury Association (ASIA) grade D]. No neurological symptoms were found in the other patients. The intraspinal rib proportion, apical vertebral rotation, apical vertebral translation, coronal main thoracic curve, trunk shift, thoracic kyphosis, lumbar lordosis, sagittal balance, and T1-S1 height were measured before and after TGR implantation and at the last follow-up. Complications were also evaluated.

RESULTS

The mean follow-up time was 3.4±2.0 years. An average of 3.1 times (range: 1 to 8 times) lengthening procedures were performed in each patient. The intraspinal rib proportion was significantly lower postoperatively than preoperatively (22±11% vs. 33±18%, respectively; P <0.001), and no significant correction loss was found at the last follow-up (24±12%, P= 0.364). Compared with the measurements before TGR implantation, the major coronal curve and T1-S1 height after TGR implantation and at the last follow-up were significantly different ( P <0.05). Significant correction of apical vertebral translation, thoracic kyphosis, lumbar lordosis, and sagittal balance were noted after TGR implantation, and no significant correction loss was found at the last follow-up ( P >0.05). Ten complications occurred in 7 patients. Two patients with nerve injury recovered after the operation. No neurological complications were found during the follow-up.

CONCLUSIONS

TGR is a safe and effective therapy for NF1-EOS with IRH where there was no direct compression of the spinal cord, which was confirmed by preoperative magnetic resonance imaging. Through this procedure, IRH could be partly removed from the spinal canal.

LEVEL OF EVIDENCE

Level III.