Vascularized fibula strut graft used in neurofibromatosis type 1-related kyphosis: a case of almost complete reversal of deformity-induced tetraparesis.

Study Design Case report. Objective The aim of this study is to describe a case of vascularized fibula strut graft implanted in the cervicothoracic spine of a patient with neurofibromatosis type 1-related progressive kyphosis. Methods A detailed history examination of the surgical procedures and the results of the follow-up after fibula strut graft implantation were performed. In addition, a review of the literature was conducted to access the incidence of similar cases with an almost complete reversal of a deformity-induced tetraparesis. Results A 37-year-old man with severe type 1 neurofibromatosis causing a collapsing kyphosis of the cervicothoracic spine presented in 2006 with progressive low cervical tetraparesis. Intervention included posterior stabilization (C5 to T5) which was extended to C3-T9 in 2008; however, the kyphosis continued to worsen. In 2009, a vascularized fibula strut graft was implanted between the inferior and superior endplates of C3 and T9. Over the following months, the patient gradually recovered motor strength and improved functional use of all limbs. In March 2011, lower limb (bilateral) and right arm strength was grade 5, with left arm strength being grade 4+. Conclusions This case report demonstrates the existence of a potential local option for the difficult problems of pseudoarthrosis, progressive spinal deformity, and cord compromise in patients with neurofibromatosis type 1-related kyphosis resulting in an almost complete reversal of deformity-induced tetraparesis.

Introduction

Progressive deformity of the vertebral column can have serious neurological and functional consequences, with neurofibromatosis among those conditions known to cause spinal degeneration that constitutes significant surgical challenges.1 As a result of neurofibromatosis-related deformity, mechanical failure of the spine may contribute to radiculopathy- or myelopathy-related outcomes such as tetraparesis or tetraplegia.1

In many instances, stabilization of the vertebral column can be achieved through posterior fixation; however, in some instances, posterior fixation is either not mechanically viable or subsequently proved inadequate through breakage. In these instances, the options for preventing on-going deformity and neurological compromise are limited, with anterior stabilization via fibula strut graft providing one such option. We report a unique case where a fibula strut graft resulted in an almost complete reversal of a deformity-induced tetraparesis.

Case Report

A 37-year-old man with severe type 1 neurofibromatosis causing a collapsing kyphoscoliosis of the cervicothoracic spine presented in 2006 with progressive low cervical tetraparesis and a partial loss of bladder and bowel function. Intervention included posterior stabilization (C5 to T5; 2006) which failed mechanically with pseudoarthrosis after 1 year. This was repeated (C3 to T9; November 2008); however, the kyphosis continued to worsen.

Further surgery to stabilize the vertebral column was indicated because of increasing tetraparesis, aiming to prevent further collapse of the vertebral column, reverse spatial compromise of the neural canal, and relieve pressure on the spinal cord (Figs. 1a, b). A fibula strut graft was performed in an attempt to stabilize the anterior aspect of the cervicothoracic spine and reverse tetraparesis.

Fig. 1

(a) Frontal preoperative image of patient's cervicothoracic spine. Frontal MRI scan of the cervical spine showing cervical translocation and lack of anterior structural support with multiple large neurofibroma. Vertebral levels are as indicated. NF, neurofibroma. (b) Sagittal preoperative image of patient's cervicothoracic spine. Sagittal MRI scan of the cervical spine showing cervical translocation and lack of anterior structural support. Vertebral levels are as indicated.

In April 2009, a vascularized fibula strut graft was performed. The harvested graft was mechanically secured between the inferior and superior endplates of C3 and T9 (Fig. 2), respectively, and the vascular pedicle anastomosed with contributions from the facial artery and vein. Postsurgery, the graft became integrated and remained vascular. Over the following months, the patient gradually recovered bladder and bowel function, motor strength, and improved functional use of all limbs. On examination (March 2011), lower limb (bilateral) and right arm strength was grade 5, with left arm strength being grade 4+.

Fig. 2

Postoperative image of fibula strut graft in-situ. Three-dimensional image reconstruction (left-lateral) showing fibula strut graft in situ (red arrow). 1. Location of anterior buttress plate for seating the fibula. 2. Previous fixation device.

Discussion

Fibula strut grafts have been used for decades as an option for anterior spinal stabilization.2 Previous reports indicating the reversal or improvement of symptoms arising from neural compromise are potential outcomes of this procedure, particularly when utilized in conjunction with other interventions such as discectomy or corpectomy.3,4 However, no previous cases of fibula strut graft implementation have reported the reversal of such significant cord compromise as seen in this patient.

This is, therefore, the first documented New Zealand case where this technique has been successfully performed in the deformed cervicothoracic spine to reverse tetraparesis and recover significant neurological function. The outcome was achieved by preventing further mechanical displacement of the vertebral column, with the successful graft surviving via patent vascular anastomosis, thereby ensuring the continued performance and integrity of the graft material. It demonstrates the existence of a potential local option for the difficult problems of pseudoarthrosis, progressive spinal deformity, and cord compromise.