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Year : 2021  |  Volume : 69  |  Issue : 6  |  Page : 1763--1766

Atlantoaxial and Subaxial Cervical Spinal Instability in Two Cases with Neurofibromatosis-Type 1

Atul Goel1, Saswat Dandpat2, Abhidha Shah2, Sagar Bhambere2, Hardik Darji2,  
1 Department of Neurosurgery, K.E.M. Hospital and Seth G.S. Medical College, Parel; Consultant Neurosurgeon, Lilavati Hospital and Research Centre, Bandra (E), Mumbai, Maharashtra, India
2 Department of Neurosurgery, K.E.M. Hospital and Seth G.S. Medical College, Parel, Mumbai, Maharashtra, India

Correspondence Address:
Dr. Atul Goel
Department of Neurosurgery, Lilavati Hospital and Research Center, Bandra, Mumbai - 400050, Maharashtra


This is a report of two patients who were diagnosed to have NF-1. The patients had severe dystrophic soft tissue and bone changes leading to craniovertebral junction and subaxial cervical spinal instability and deformity. Both the patients underwent atlantoaxial and subaxial cervical spinal stabilization. No bone, soft tissue or tumor resection was done for decompression. Both patients had gratifying clinical recovery. Follow-up in both the patients is more than 12 months.

How to cite this article:
Goel A, Dandpat S, Shah A, Bhambere S, Darji H. Atlantoaxial and Subaxial Cervical Spinal Instability in Two Cases with Neurofibromatosis-Type 1.Neurol India 2021;69:1763-1766

How to cite this URL:
Goel A, Dandpat S, Shah A, Bhambere S, Darji H. Atlantoaxial and Subaxial Cervical Spinal Instability in Two Cases with Neurofibromatosis-Type 1. Neurol India [serial online] 2021 [cited 2022 May 25 ];69:1763-1766
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Full Text

Neurofibromatosis (NF) is a multisystem autosomal dominant disorder and primarily affects cell growth of neural tissue. NF Type 1 is peripheral NF, and NF Type 2 is central NF. The dysplasia affects neuroectoderm and neuromesoderm, and consequently it affects skin, soft tissues, and bones apart from involving central nervous system. Spinal deformities have been identified with both dystrophic and nondystrophic variants of NF-1.[1],[2],[3],[4] We present our experience with two cases with NF Type 1 having dystrophic bone and soft tissue changes that were focused to the craniovertebral junction and cervical spine and led to severe craniovertebral junction and cervical spinal instability and deformity. Both patients were treated by atlantoaxial fixation and additionally underwent multilevel subaxial cervical spinal facetal fixation. No bone and soft tissue decompression or tumor resection was done. Our literature search did not locate reports of similar cases and with such form of surgical treatment.

 Material and Methods

Two patients having NF1 were surgically treated in the departments of the authors during the period December 2017–January 2019. These patients are retrospectively analyzed. Clinical profile and presenting clinical symptoms are summarized in [Table 1]. Both the patients had multiple neurofibromas and café-au-lait spots all over the body. Both patients were monitored by validated parameters that included JOA and VAS indices, both before and after surgery. Imaging included dynamic (with head in flexed, neutral and extended positions) plain radiography and CT scan and MRI. Status of the vertebral artery was evaluated on the basis of MRI and CT scan images. Dedicated angiography was not done. [Figure 1] and [Figure 2] show representative images.{Figure 1}{Figure 2}{Table 1}

Surgical procedure

The surgical position was as described by us earlier for atlantoaxial fixation. The patient was placed prone under traction with the head end of the table elevated by 30 degree. Traction helped to maintain optimum neck position during surgery, kept the head in a “floating” position that avoided pressure on the face and eyes and reduced venous congestion in the operating field. Traction assisted in reduction in the atlantoaxial instability and in the spinal deformity. Atlantoaxial fixation was done with the technique described by us earlier and is summarized here.[5],[6] Atlantoaxial joint was widely opened. Bone graft was stuffed into the articular cavity. Plate and screw atlantoaxial fixation was then done. Subaxial fixation was done by Camille's technique of transarticular screw insertion.[7] The parameters used to insert the screws were standard but were modified after assessing the real-time anatomical situation in the deformed and destructed spinal situation. After the metal instrumentation, the spinous processes were sectioned at their base and all the soft tissue interspinous and interlaminar ligaments were sharply cut. Posterior surfaces of laminae and arch of atlas were then decorticated to make them suitable host for bone graft. Cut spinous processes were shredded for bone graft. Additionally, bone graft was harvested from the iliac crest. Postoperatively, the patient was instructed to avoid all neck movements and was placed in firm cervical four-post collar for a period of 3 months. After confirming satisfactory implant positioning and evidences of bone fusion across the facets, the patients were gradually allowed normal life activities.

Follow-up after the surgical procedure was 14 and 26 months. Clinical assessment at the time of last follow-up is summarized in [Table 1]. Essentially, both the patients showed clinical recovery that was observed in the immediate postoperative period and progressed. Dynamic CT scan confirmed significant but incomplete reduction of atlantoaxial dislocation, and basilar invagination and neck deformity-related gibbus. Adequate fusion of the treated spinal segments could be observed [Figure 1]e and [Figure 2]e. There was no delayed neurological worsening. Imaging did not show any significant increase in the abnormal spinal and extraspinal soft tissue mass. Restriction of neck movements that was present even before surgery persisted but both the patients were completely relieved of the nagging pain in the nape of neck.


Although the exact incidence of spinal deformities in cases with NF-1 is difficult to speculate, it has been reported to be between 2 and 70%.[1],[2],[3],[4] Thoracic spine is more frequently involved. Clinical and radiological features and surgical treatment of nondystrophic type is essentially similar to that generally described and conducted for idiopathic spinal deformities. The spinal deformities in NF-1 are more often related to dystrophic changes in the bones, ligaments, and soft tissues. Dystrophic spinal bone alterations include vertebral body scalloping and wedging, segmental subluxation, foraminal enlargement, and defective pedicles.[1],[2],[3],[4] Soft tissue abnormalities include paraspinal and intraspinal soft tissue tumor-like formations, dural ectasia, dumbbell neurofibromas extending into intervertebral foramina and causing foraminal enlargement. Spinal deformities can be associated with multiple neurofibromas or with plexiform NF. The exact pathogenetic issue that results in such gross structural deformity is difficult to speculate. Erosion or infiltration of bone by localized neurofibromas, primary mesodermal dysplasia, osteomalacia, and related endocrine disturbances are among the presumed causes of spinal deformity. Although dysplasia of tissues does not indicate the presence of “malignant” change, it is recognized as a premalignant condition, and in the long run, the tissues are more prone to conversion into malignancy.

In both of our patients, there was marked bone destruction, spinal deformity, and evidences of instability. There was presence of soft tissue enhancing mass around the odontoid process and in the paravertebral spaces. This tissue was probably related to combination of presence of plexiform neurofibromas and to mesodermal dysplasia. The bone deformation and destruction appeared to be related both to compressive effects of the tumor and to the mesodermal dysplasia involving the bone and adjacent soft tissues. The course or development and progression of the spinal deformity are difficult to assess due to the rarity of such cases. However, limited information available on the issue suggests that the spinal deformity is present for a significant period of time and is progressive in nature.[1],[2],[3],[4],[8],[9],[10],[11],[12],[13],[14] Both decompression by removal of the tumor and compressive bone and stabilization of the spine have been accepted mode of surgical treatment.[8],[9],[10],[11],[12],[13],[14] As complete or even “radical” resection of the tumor is difficult or impossible, the optimum extent of tumor resection that is necessary remains controversial. However, it appears that resection of the part of the tumor that directly compresses and deforms the cord is mandatory.

Analysis on the basis of our study in craniovertebral junction and spinal disorders suggest that in slow progressive disorders or deformities neurological symptoms are related to subtle instability-related microtrauma rather than radiologically visible spinal deformity or neural tissue deformation. Accordingly, the aim of our surgical treatment was stabilization of the involved spinal segments rather than decompression by removal of bones and soft tissues. In both of our cases, there was atlantoaxial instability and subaxial cervical spinal instability. Surgery involved atlantoaxial and multisegmental subaxial spinal facetal fixation. Atlantoaxial fixation was done using the technique described by us earlier in 1994,[5],[6] and subaxial spinal fixation was done by transarticular facetal fixation with the technique described by Camille in 1972.[7] As discussed in our earlier publication, the levels of spinal fixation that was necessary was gauzed by the extent of cervical deformity. The entire “C” of the kyphotic segment was considered to be unstable and was included in the fixation construct. It was observed that the facets were relatively intact and less involved by the destruction unlike the other components of the vertebrae. The pedicles seemed to be most affected component of the vertebra. The facetal fixation could be done under direct vision, avoiding the need for neuronavigation or fluoroscopy during surgery. Due to limited experience of the authors, exact utility of both O-arm and navigation in such complex clinical situation cannot be adequately confirmed. The facets being the strongest part of the vertebra provided a strong ground for purchase of screws. The large size of the facets permitted alteration of site of screw insertion and trajectory as per the status of the facet. Considering the degree of spinal deformity and the status of pedicles, it appeared that other techniques that involve deployment of screws in the pedicles or use of multisegmental rods were less than optimal in the situation. Also, due to the nature of bone involvement, anterior cervical surgery that involved multisegmental plate fixation was considered to be a more difficult and less effective option. Despite this consideration, it does appear that a circumferential fixation-arthrodesis could have been an effective mode of surgical treatment in this complex clinical situation.

Our earlier report on the subject of cervical kyphosis indicates the validity of multilevel spinal fixation without any form of bone or soft tissue decompression.[15],[16] This strategy is in contrast with the other reports on the subject wherein anterior cervical multilevel corpectomies and posterior laminectomy or laminoplasty were recommended for decompression of the neural structures.[1],[2],[3],[4],[8],[9],[10],[11],[12],[13],[14]


NF-1 can be associated with spinal instability-related deformities. Spinal stabilization is the treatment.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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