Double rib penetration of the spinal canal in a patient with neurofibromatosis

Could screw/hook insertion at the apical vertebrae with rib head dislocation effectively retract the corresponding rib head from spinal canal in dystrophic scoliosis secondary to type 1 neurofibromatosis?

Background

Rib head dislocation (RHD) in dystrophic scoliosis of type 1 neurofibromatosis (DS-NF1) is a unique disorder caused by skeletal dystrophy and scoliotic instability. No particular surgical manipulation is mentioned in the literature to instruct the spine surgeons to effectively obtain more migration of the dislocated rib head without resection. The present study aimed to investigate the effectiveness of screw/hook insertion at vertebrae with RHDs on the retraction of penetrated rib head from spinal canal.

Methods

37 neurologically intact patients with DS-NF1 and concomitant 53 RHDs undergoing scoliosis surgery without rib head excision were retrospectively reviewed. We used pre and postoperative whole-spine radiographs to determine the Cobb angle and the vertebral translation (VT), and the CT scans to evaluate the intraspinal rib length (IRL) and rib-vertebral angle (RVA). The dislocated ribs were assigned into two groups according to the presence of screw/hook insertion at vertebrae with RHD: screw/hook group and non-screw/hook group.

Results

37 dislocated ribs with screws/hooks insertion at corresponding vertebrae were assigned into the screw/hook group and the remaining 16 dislocated ribs consisted of the non-screw/hook group. In the screw/hook group, the correction rates of Cobb angle and VT were significantly higher than the non-screw/hook group after surgery (58.7 ± 16.0% vs. 30.9 ± 12.4%, p = 0.003; 61.8 ± 18.8% vs. 35.1 ± 16.6%, p = 0.001; respectively). Similarly, more correction rates of IRL and RVA were found in the screw/hook group than the non-screw/hook group (63.1 ± 31.3% vs. 30.1 ± 20.7%, p = 0.008; 17.6 ± 9.7% vs. 7.2 ± 3.6%, p = 0.006; respectively). Multiple linear regression analysis revealed that the correction rates of Cobb angle, VT and RVA contributed significantly to correction of IRL (β = 0.389, 0.939 and 1.869, respectively; p = 0.019, 0.001 and 0.002, respectively).

Conclusion

Screw/hook insertion at dystrophic vertebrae with RHDs contributed significantly to the degree of retraction of penetrated rib head from spinal canal. This effectiveness is mediated by more corrections of VT and RVA.

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.

The Haleem-Marks-Botchu classification: a novel CT-based classification for intracanal rib head penetration

PURPOSE

Intracanal rib head penetration is a well-known entity in dystrophic scoliotic curves in neurofibromatosis type 1. There is potential for spinal cord injury if this is not recognised and managed appropriately. No current CT-based classification system is currently in use to quantify rib head penetration. This article aims to propose and evaluate a novel CT-based classification for rib head penetration primarily for neurofibromatosis but which can also be utilised in other conditions of rib head penetration.

MATERIALS AND METHODS

The grading was developed as four grades: normal rib head (RH) position-Grade 0, subluxed extracanal RH position-Grade 1, RH at pedicle-Grade 2, intracanal RH-Grade 3. Grade 3 was further classified depending on the head position in the canal divided into thirds. Rib head penetration into proximal third (from ipsilateral side)-Grade 3A, into the middle third-Grade 3B and into the distal third-Grade 3C. Seventy-five axial CT images of Neurofibromatosis Type 1 patients in the paediatric age group were reviewed by a radiologist and a spinal surgeon independently to assess interobserver and intraobserver agreement of the novel CT classification. Agreement analysis was performed using the weighted Kappa statistic.

RESULTS

There was substantial interobserver correlation with mean Kappa score (k = 0.8, 95% CI 0.7-0.9) and near perfect intraobserver Kappa of 1.0 (95% CI 0.9-1.0) and 0.9 (95% CI 0.9-1.0) for the two readers.

CONCLUSION

The novel CT-based classification quantifies rib head penetration which aids in management planning.

Posterior Correction Without Rib-head Resection for Patients With Neurofibromatosis Type 1, Dystrophic Scoliosis, and Rib-head Protrusion Into the Spinal Canal

STUDY DESIGN

A retrospective study.

OBJECTIVE

The objective of this study is to report the result of patients with neurofibromatosis type 1(NF-1), dystrophic scoliosis, and rib-head protrusion into the spinal canal who received posterior scoliosis correction surgery without rib-head resection.

SUMMARY OF BACKGROUND DATA

A total of 124 patients with NF-1 and dystrophic scoliosis were treated at our institution during the study period. Eight patients with a median age of 12 years had rib-head protrusion into the spinal canal and received surgery and were included in the analysis.

METHODS

All 8 patients (6 male, 2 female) were treated from 2003 to 2013 and received posterior correction with a pedicle screw-rod 3-dimensional correction system or screw-hook hybrid system. Scoliosis correction rate and percentage of spinal canal occupied by the rib head were analyzed.

RESULTS

The median patient age, number of segments fused, and follow-up duration were 12 years, 10.5, and 22.5 months, respectively. There were no surgery-related complications, and symptoms in all patients improved after surgery. The median postoperative and 1-year follow-up sagittal kyphotic angles were significantly smaller as compared with the preoperative value (28.5 and 31 vs. 62.5 degrees, P=0.012). The median postoperative coronal Cobb angle of the main thoracic curve was significantly smaller compared with the preoperative value (29 vs. 64.5 degrees, P=0.012). The median percentage of the spinal canal occupied by the intraspinal rib was significantly lower at 1-year follow-up compared with the preoperative value (23.1% vs. 28.6%, P=0.018).

CONCLUSIONS

Posterior correction without rib-head excision can provide good outcomes for patients with NF-1 and dystrophic scoliosis and rib-head protrusion into the spinal canal.

Surgical Management of Intracanal Rib Head Dislocation in Neurofibromatosis Type 1 Dystrophic Kyphoscoliosis: Report of Two Cases and Literature Review

There is still no consensus on the management of severe intracanal RH dislocation in neurofibromatosis type 1 dystrophic kyphoscoliosis. This study notes the early cord function impairment signs, reports a serious complication in a susceptible cord, identifies possible mechanisms of injury, and discusses the management of intracanal RH dislocation presented in the literature. First report is as follows: a 12-year-old female with cord compromise and preoperative neurology that underwent thoracotomy and anterior release. The RH was left in situ following a rib excision. During the posterior stage of the procedure she presented with complete loss of all IOM traces prior to any correction manoeuvres. The neurology recovered 72 h postop and the final correction and instrumented fusion were uneventfully completed 15 days postop. Second report is as follows: a 10-year-old male, whose only neurology was a provoked shock-like sensation to the lower limbs following direct pressure on the rib cage. He underwent an uneventful posterior RH excision and instrumented correction and posterior spinal fusion. In conclusion, any possible cord dysfunction sign should be sought during examination. Decompression of the spinal cord by resecting the impinging bony part, even in the absence of neurological symptoms, is advised before any attempt to release or correct the deformity.

Surgical Treatment of Dystrophic Spinal Curves Caused by Neurofibromatosis Type 1: A Retrospective Study of 26 Patients

Dystrophic scoliosis in neurofibromatosis type 1 (NF-1) is difficult to treat. The purpose of this study was to review the clinical and radiological outcome of surgical treatment of dystrophic spinal curves in NF-1, for analyzing its efficacy, safety, and possible complications.This retrospective study consisted of 26 NF-1 patients with spinal deformities treated between 2003 and 2012 in our department. Preoperative X-ray, 3D-CT, and MRI were performed to evaluate the deformities of dystrophic scoliosis accurately. All patients were treated with posterior instrumented fusion alone using screws and hooks. According to the anatomical development situation of each patient's pedicles and the transverse processes, we chose different fixations and different fixed segments. The clinical and radiological outcomes of surgical correction were evaluated postoperatively.The average preoperative kyphosis was 43° (range 15-86°). The postoperative kyphosis had an average of 20° (range 10-39°) yielding 53% correction. At final follow-up, there was an average of 4.6% correction loss. The preoperative scoliosis Cobb angle had an average of 47° (range 35-96°). The postoperative scoliosis Cobb angle had an average of 21° (range 10-37°) yielding 55% correction. At final follow-up, there was an average of 6.6% correction loss. The apical vertebral body rotation was corrected by an average of 48%. At final follow-up, the score of the SRS-30 questionnaire ranged from 97 to 135 with an average of 109.In conclusion, the deformities of dystrophic scoliosis can be accurately determine through preoperative radiolographic evaluation, which plays an important role in guiding the correction of scoliosis program development. The results of this study demonstrate that satisfactory therapeutic effects can be achieved in the dystrophic scoliosis patients by preoperative meticulous surgical plans, intraoperative careful manipulation, and hybrid instrumentation.

Posterior-only spinal fusion without rib head resection for treating type I neurofibromatosis with intra-canal rib head dislocation

OBJECTIVES

Patients with Type I neurofibromatosis scoliosis with intra-canal rib head protrusion are extremely rare. Current knowledge regarding the diagnosis and treatment for this situation are insufficient. The purpose of this study is to share our experience in the diagnosis and surgical treatments for such unique deformities.

METHODS

Six patients with Type I neurofibromatosis scoliosis with rib head dislocation into the spinal canal were diagnosed at our institution. Posterior instrumentation and spinal fusion without intra-canal rib head resection via a posterior-only approach was performed for deformity correction and rib head extraction. The efficacy and outcomes of the surgery were evaluated by measurements before, immediately and 24 months after the surgery using the following parameters: coronal spinal Cobb angle, apex rotation and kyphosis of the spine and the intra-canal rib head position. Post-operative complications, surgery time and blood loss were also evaluated.

RESULTS

Patients were followed up for at least 24 months post-operatively. The three dimensional spinal deformity was significantly improved and the intra-canal rib head was significantly extracted from the canal immediately after the surgery. At follow-up 24 months after surgery, solid fusions were achieved along the fusion segments, and the deformity corrections and rib head positions were well maintained. There were no surgery-related complications any time after the surgery.

CONCLUSIONS

Systematic examinations are needed to identify patients with Type I neurofibromatosis scoliosis with rib head dislocation into the canal who can be treated by posterior-only spinal fusion without rib head resection.