Intraspinal dislocation of the rib in neurofibromatosis: a case report

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.

Traumatic rib head subluxation through the intervertebral foramen causing spinal cord contusive injury in a cat

Case summary

A 4-year-old cat involved in a road traffic accident presented with paraparesis, which was worse on the right-hand side. Neurolocalisation was to the T3–L3 spinal cord segments. Survey radiographs showed rib fractures but no definitive diagnosis for the paraparesis. CT revealed fracture of the dorsal rim and a T9 rib subluxation through the intervertebral foramen at T8–T9. This caused a contusive spinal injury. Treatment consisted of rest and analgesia. The cat recovered well, with the owner reporting no abnormalities 5 months following the injury.

Relevance and novel information

Road traffic accidents are a common cause of injury in the cat population, with a significant number having thoracic injuries. These include rib injures such as fractures. This is the first reported case of a traumatic rib subluxation causing a contusive injury in the spinal cord of any species. Previously reported rib subluxations have been seen in humans with spinal deformities. Conservative management in this case was sufficient.

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.

Thoracic compression myelopathy due to the progression of dystrophic scoliosis, the presence of a paraspinal tumor, and high and excessive amplitude movement of the shoulder

The authors present a case of 45-year-old man with neurofibromatosis type 1 (NF-1) and thoracic scoliosis, previously undergoing fusion surgery, who developed myelopathy. This patient further complained of lightning pain when he extended and horizontally abducted the convex-side shoulder. Radiological examination revealed the progression of dystrophic scoliosis with opened spinal canals and the presence of a neurofibroma behind the spinal cord at the apical levels. Delayed development of spinal instability can occur due to dystrophy even postoperatively in patients with NF-1. After tumor resection, he had rapid recovery from myelopathy and no recurrence of radiating pain despite shoulder movement. These findings provide a speculation that high, intense amplitude movement of the shoulder toward the spinal canal causes the impingement on the neurofibroma, resulting in indirect compression of the exposed spinal cord. This is the first report describing thoracic compression myelopathy associated with paraspinal displacement of the scapula.

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.

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

BACKGROUND

Rib head penetration into the spinal canal in patients with severe kyphoscoliosis secondary to neurofibromatosis type-1 (NF-1) is extremely rare. Double rib head penetration has only been reported once earlier.

METHODS

We are reporting on an adolescent male with NF-1 and severe thoracic kyphoscoliosis with adjacent double rib head penetration into the spinal canal without neurological deficits. Only one was recognized on the initial radiographic imaging.

RESULTS

A 14-year-old with NF-1 and 74 degrees left thoracic scoliosis and 75 degrees kyphosis was treated at our institution. Preoperative computed tomography (CT) demonstrated protrusion of the left T6 rib head into the spinal canal on the convexity of the curve, compressing the spinal cord. Staged surgical procedures for resection of the rib head and correction of the spinal deformity were planned. After presumed successful resection of the penetrated rib head, a postoperative CT revealed the presence of a second adjacent left T7 rib head in the spinal canal. This was not initially recognized owing to the severe deformity and image obliquity of the CT gantry. Another procedure was performed to remove this rib head. He was then placed in halo traction until anterior and posterior spinal fusion and segmental spinal instrumentation were performed. He achieved good deformity correction and had no neurological deficits throughout his treatment.

CONCLUSIONS

Rib head protrusion into the spinal canal can occur with spine deformity in NF-1. If present, the imaging should be carefully reviewed for the possibility of an adjacent rib head penetration that may have been obscured by the limitations of CT in the context of a dysplastic spinal deformity.

LEVEL OF EVIDENCE

Level V. Case study.

Rib head protrusion into the central canal in type 1 neurofibromatosis

BACKGROUND

Intraspinal rib head dislocation is an important but under-recognized consequence of dystrophic scoliosis in patients with neurofibromatosis 1 (NF1).

OBJECTIVE

To present clinical and imaging findings of intraspinal rib head dislocation in NF1.

MATERIALS AND METHODS

We retrospectively reviewed clinical presentation, imaging, operative reports and post-operative courses in four NF1 patients with intraspinal rib head dislocation and dystrophic scoliosis. We also reviewed 17 cases from the English literature.

RESULTS

In each of our four cases of intraspinal rib head dislocation, a single rib head was dislocated on the convex apex of the curve, most often in the mid- to lower thoracic region. Cord compression occurred in half of these patients. Analysis of the literature yielded similar findings. Only three cases in the literature demonstrates the MRI appearance of this entity; most employ CT. All of our cases include both MRI and CT; we review the subtle findings on MRI.

CONCLUSION

Although intraspinal rib head dislocation is readily apparent on CT, sometimes MRI is the only cross-sectional imaging performed. It is essential that radiologists become familiar with this entity, as subtle findings have significant implications for surgical management.

Late post-operative paraparesis after rib penetration of the spinal canal in a patient with neurofibromatous scoliosis

Rib displacement into the spinal canal is a rare cause of paraplegia or paraparesis in patients affected by neurofibromatous scoliosis. We describe a case of paraparesis in a 14-year-old child affected by neurofibromatous dystrophic kyphoscoliosis, treated with combined posterior and anterior spinal arthrodesis. Seventeen days after the surgical treatment the patient developed clinical signs and symptoms of paraparesis. A CT scan showed the head of the fifth rib protruding into the spinal canal with cord compression. Rib resection and posterior cord decompression were carried out following complete neurological recovery.

Impingement of spinal cord by dislocated rib in dystrophic scoliosis secondary to neurofibromatosis type 1: radiological signs and management strategies

STUDY DESIGN

Case series.

OBJECTIVE

To define radiologic diagnosis and treatment strategies of rib dislocation to prevent serious complications during deformity surgery.

SUMMARY OF BACKGROUND DATA

Rib dislocation into the spinal canal caused by the dystrophic changes seen in scoliotic patients with neurofibromatosis type 1 (NF-1) may cause severe complications when neglected. The risk of this complication is increased by modern instrumentation techniques that produce greater correction.

METHODS

Three neurologically intact neurofibromatosis patients with scoliosis on whom rib dislocations were determined on convex side of the apical vertebrae were evaluated.

RESULTS

Three cases were operated with modern instrumentation and correction techniques either with anterior and posterior approaches with or without rib head excisions, to prevent cord injury. There were no neurologic complications postoperatively.

CONCLUSION

Apical convex rib head dislocation into the canal in NF-1 scoliotic patients can be suspected by conventional radiograms and be proven by CT and MRI. The rib dislocation is not a contraindication to deformity correction with modern spinal instrumentation techniques when preventive measures are applied.

Painful rib hump: a new clinical sign for detecting intraspinal rib displacement in scoliosis due to neurofibromatosis

BACKGROUND

Spinal cord compression and associate neurological impairment is rare in patients with scoliosis and neurofibromatosis. Common reasons are vertebral subluxation, dislocation, angulation and tumorous lesions around the spinal canal. Only twelve cases of intraspinal rib dislocation have been reported in the literature. The aim of this report is to present a case of rib penetration through neural foramen at the apex of a scoliotic curve in neurofibromatosis and to introduce a new clinical sign for its detection.

METHODS

A 13-year-old girl was evaluated for progressive left thoracic kyphoscoliotic curve due to a type I neurofibromatosis. Clinical examination revealed multiple large thoracic and abdominal "cafe-au-lait" spots, neurological impairment of the lower limbs and the presence of a thoracic gibbous that was painful to pressure at the level of the left eighth rib (Painful Rib Hump). CT-scan showed detachment and translocation of the cephalic end of the left eighth rib into the adjacent enlarged neural foramen. The M.R.I. examination of the spine showed neither cord abnormality nor neurogenic tumor.

RESULTS

The patient underwent resection of the intraspinal mobile eighth rib head and posterior spinal instrumentation and was neurologically fully recovered six months postoperatively.

CONCLUSION

Spine surgeons should be aware of intraspinal rib displacement in scoliotic curves in neurofibromatosis. Painful rib hump is a valuable diagnostic tool for this rare clinical entity.

Paraparesis after posterior spinal fusion in neurofibromatosis secondary to rib displacement: case report and literature review

In patients with neurofibromatosis, rib displacement into the spinal canal is a rare cause of paraplegia. We report a patient with paraplegia caused by rib displacement whose signs and symptoms began after posterior in situ fusion for dysplastic scoliosis. There was complete recovery after anterior decompression and resection of the rib.