SpineUniverse Case Study Library

Neurofibromatosis (NF-1) in a 15-Year-old

Patient History

The patient is a 15-year-old boy with neurofibromatosis (NF-1). At age 9, he underwent a C4-C6 laminectomy for tumor excision. In the past, the patient has had multiple NF excisions.

He fell while skateboarding and suffered transient (10 minutes) quadriplegia. The patient reports no neck pain, although examination reveals mild myelopathy. He does not want surgery.

Examination

The patient was myelopathic on reflex examination with positive Hoffman's sign and up going toes.

Images

anterior posterior x-ray, skull and cervical spine
Figure 1A. AP x-ray

lateral x-ray, cervical spine
Figure 1B. Lateral x-ray

cervical flexion x-ray
Figure 2A. Flexion x-ray

cervical extension x-ray
Figure 2B. Extension x-ray

sagittal MRI, ventral spinal cord compression at C5-C6
Figure 3. Sagittal MRI showing ventral spinal cord compression at C5-C6

axial MRI C4
Figure 4A. Axial MRI, C4

axial MRI C5
Figure 4B. Axial MRI, C5

axial MRI C2
Figure 5A. Axial MRI, C2

axial MRI C3
Figure 5B. Axial MRI, C3

axial MRI C4
Figure 5C. Axial MRI, C4

axial MRI C5-C6
Figure 5D. Axial MRI, C5-C6

axial MRI C7
Figure 5E. Axial MRI, C7

axial MRI C7
Figure 5F. Axial MRI, C7

Lateral CT scans (Figures 6A-6C).

lateral CT scan
Figure 6A

lateral CT scan
Figure 6B

lateral CT scan
Figure 6C

Diagnosis

Neurofibromatosis (NF-1), postlaminectomy with severe kyphotic deformity and myelomalacia.

Suggest Treatment

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Selected Treatment

Surgery was done in two stages on the same day:

  • Stage 1 - anterior C4-C6 corpectomies with fibular strut autograft
  • Stage 2 - C3-C7 instrumentation and fusion

lateral cervical x-ray, 2 days traction at 25#
Figure 7A. 2 days traction, 25#

lateral cervical x-ray, 4 days traction at 35#
Figure 7B. 4 days traction, 35#

postop posterior x-ray
Figure 8A. Postoperative posterior x-ray

postop lateral x-ray
Figure 8B. Postoperative lateral x-ray

Outcome

The patient is neurologically normal without any neck pain or activity limitation.

one year postop flexion x-ray
Figure 9A. One year postop, flexion x-ray

one year postop extension x-ray
Figure 9B. One year postop, extension x-ray

Case Discussion

Type I Neurofibromatosis (NF-1), also known as von Recklinghausen disease or peripheral neurofibromatosis, is an autosomal dominant disorder. Patients with NF-1 develop Schwann cell tumors called neurofibromas, pigmentation abnormalities, and spinal deformities, such as thoracolumbar scoliosis, kyphoscoliosis, and occasionally cervical spine kyphosis, as in this patient. Cervical kyphosis in NF-1 patients may develop with or without laminectomy, but cervical laminectomy at 9-years of age probably contributed to the deformity. It is fairly common for children to develop cervical kyphosis following laminectomy, and alternative techniques, such as laminoplasty or fusion, should be considered when performing laminectomy in children.

NF-1 patients with cervical spine problems may be minimally symptomatic or severely myelopathic, as in this patient. Any NF-1 patient undergoing other surgical procedures should have cervical radiographs to rule out C1-C2 instability, dural ectasia with vertebral body resorption, or cervical kyphosis. If the radiographs are suspicious, MRI, CT, and flexion-extension radiographs will further define possible lesions, such as neural tumors, spinal cord compression, dural ectasia, instability, etc.

This patient had Neurofibromatosis (NF-1) with post-laminectomy severe kyphotic deformity and myelomalacia. The history of transient quadriplegia and myelopathic signs on examination indicates spinal cord compromise and jeopardy for neurological worsening. Indications for surgery include progressive deformity or instability, neurological deficits, and failure of conservative treatment. Conservative treatment of this patient most likely will not improve myelopathy and further progressive kyphosis and neurological compromise is likely.

I agree with the author's treatment completely. Traction is quite helpful in patients with severe deformity, particularly in young children. Traction is however, not without danger. Careful monitoring of neurological status should be done as neurological deterioration may occur with traction. Surgery is less complicated if traction partially corrects the deformity prior to surgery, as done in this case. Because there is significant residual kyphosis following 4 days of traction, anterior decompression and fusion should be done first. Any attempt to reduce the deformity further without performing spinal cord decompression can result in stretching of the spinal cord and neurological deficits.

During the anterior portion of surgery, traction should be minimal and spinal cord monitoring is recommended. If the patient has intact neurologic status, multilevel discectomy and interbody fusion may be sufficient to correct the deformity, but if there is cord compression by the vertebral bodies, as in this patient, corpectomy and strut grafting is recommended.

Following corpectomy and decompression of the spinal cord, the neck can be extended to further correct the kyphotic deformity. Strut grafting is an exacting procedure, and the surgeon should be familiar with all the principles of inserting the strut graft by careful end plate preparation, countersinking the graft, traction or distraction of the cervical spine at the time of graft insertion, etc. My specific recommendation is to fashion the graft in a dome shape -- and the upper endplate is domed to the depth of 3-mm and the lower endplate is domed at 2-mm depth. The upper end of the strut graft is positioned into the dome slot first, followed by tapping the lower end of the strut graft into the lower endplate while the cervical spine is distracted about 2-mm. When the traction is discontinued, the graft should be quite secure and stable.

It is debatable whether to place anterior plate(s) in this setting. It has been documented in a biomechanics study that if posterior segmental fixation is used, there is no biomechanical advantage of additional anterior plating after corpectomy and strut grafting (1). Plating will increase operative time and there is less ability to compress with posterior instrumentation. Also, there is risk of the anterior plate loosening and other related problems. There might be an advantage to securing the graft during turning from supine to prone, but if the graft is inserted, as mentioned above, and a turning frame, such as Stryker or Jackson turning table is used, graft dislodgement during turning is rarely observed.

Anterior decompression alone and fixation alone may be sufficient in some patients undergoing corpectomy with minimal deformity and good bone stock. In some patients with cervical spondylotic myelopathy, a discectomy-corpectomy construct could be done to improve construct stability and anterior-alone fixation may be sufficient to avoid a posterior procedure (2). Postlaminectomy kyphosis is notoriously unstable with anterior fixation alone and a combined anterior and posterior fixation is therefore recommended (3).

The author should be congratulated for his careful and thoughtful approach to this patient, including preoperative traction and great surgical skills to perform a meticulous decompression, strut grafting, and posterior segmental fixation. Even though this patient is doing well following 1-year, some patients following C3-C7 fusion may develop junctional kyphosis above or below the fusion, particularly if there is residual kyphosis due to partial correction. I may have performed fusion down to T1 and perhaps up to C2 for this reason. This case is rare and technically demanding, but it illustrates many great teaching points as outlined.

References:
1. Singh K, Vaccaro, AR, Kim J, Lorenz EP, Lim TH, An HS: A Biomechanical Comparison of Cervical Spine Reconstructive Techniques Following a Multi-level Corpectomy of the Cervical Spine. Spine 28:2352-58, 2003.

2. Singh, K., Vaccaro, A. R., Kim, J., Lorenz, E. P., Lim, T. H., An, H. S.: Enhancement of stability following anterior cervical corpectomy: a biomechanical study. Spine 29:845-9, 2004.

3. Riew, K. D., Hilibrand, A. S., Palumbo, M. A., Bohlman, H. H. Anterior cervical corpectomy in patients previously managed with a laminectomy: short-term complications. J Bone Joint Surg 81:950-7, 1999.

George I Jallo MD
George I. Jallo, MD
Pediatric Neurosurgeon
John Hopkins Hospital
Baltimore, MD

Neurofibromatosis type 1, or von Recklinghausen's disease, is a neurocutaneous syndrome that affects about 1 in 4,000 people. These patients have café-au-lait spots, optic gliomas, and predisposition to scoliosis and kyphosis.

In this child, who had a previous multilevel laminectomy for a tumor, was at risk for significant injury following a minor trauma. The imaging studies demonstrated the severe C4-C6 kyphotic deformity and compression of the spinal cord. Although the child had minimal neurological symptoms, he was at a significant risk for a devastating neurological injury following a minor trauma.

The options for treatment were halo vest, anterior surgery, posterior surgery, or a combination anterior-posterior procedure. The approach in this child was the most logical treatment. He had involvement of the 3 columns and possible ligamentous laxity. In NF-1, a 360-approach would provide the safest and most durable solution to the kyphotic deformity. The addition of pre-operative traction provided a simple method for reducing the deformity prior to the definitive surgical procedure.

When considering the levels for the anterior and posterior approach, the surgeon should recognize the levels of the deformity for appropriate decompression anteriorly and the use of autologous graft. The supplemented fusion posterior spanned 1-level above and below the anterior decompression and provided the necessary fixation.

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