Anterior Cervical Foraminotomy


Chapter Preview

  • Chapter Synopsis

  • This chapter describes in detail the surgical techniques and merits of transcorporeal anterior cervical microforaminotomy for cervical radiculopathy. This procedure involves a modification of the previous anterior microforaminotomy in terms of its medial starting point and tunneling on the upper vertebral body.

  • Important Points

  • Transcorporeal anterior cervical microforaminotomy allows for direct decompression of the cervical nerve root while preserving the uncovertebral joint and intervertebral disk integrity and avoiding injury to the vertebral artery and cervical sympathetic chain.

  • Indications include cervical radiculopathy secondary to compression anterior or medial to the cervical nerve root.

  • Contraindications include bilateral foraminal stenosis, predominant axial neck pain, signs suggestive of infection, mechanical instability, and cervical myelopathy.

  • Clinical and Surgical Pearls

  • Foraminal magnetic resonance imaging and reconstructed computed tomography images perpendicular to the cervical foramen can help identify and define the foraminal disease.

  • Typically, the anterior cervical exposure to the upper vertebral body and affected disk space is approached from the side corresponding to the radiculopathy.

  • The longus colli muscle is dissected from its medial border. The starting point for microscopic drilling is just lateral to the medial margin of the longus colli muscle at the midvertebral body level heading toward the posterior tip of the uncinate process.

  • In the case of spondylotic foraminal stenosis, the ideal decompression is limited by the upper and lower pedicle and full lateral bony decompression to the transverse foramen.

  • In the case of soft disk herniation, the surgeon must excise the posterior longitudinal ligament to explore for any residual free fragments penetrating the ligament.

  • Clinical and Surgical Pitfalls

  • Care should be taken not to violate the upper vertebral end plate because that can result in late intervertebral disk collapse and narrowing.

  • Uncertainty of the sagittal orientation tends to bring about more caudally directed drilling. Usually, a 15-degree caudal angle on the sagittal plane is appropriate.

  • Tilting the patient to the proper angle can place the desired drill hole perpendicular to the ground in both the sagittal and axial planes.

  • In the case of the extruded disk, a careful search for additional extruded fragments must be performed if intraoperative findings do not confirm preoperative imaging results.

Cervical radiculopathy is mainly caused by anterior cervical disorders, including cervical disk herniation and uncovertebral osteophytes. Smith and Robinson and Cloward established the anterior approach to treat the cervical spine. In 1968, Verbiest reported using the anterolateral approach for cervical foraminal stenosis, and in 1976, Hakuba introduced the transuncodiskal approach. In 1996, Jho reported transuncal microforaminotomy, which was similar to the Hakuba technique but simpler, preserving the disk. Choi and colleagues proposed a modification of upper vertebral transcorporeal anterior cervical microforaminotomy (ACF), which starts with a drill hole at a relatively medial position compared with the previous technique. This newer concept of transcorporeal ACF offers direct decompression of the cervical nerve root while preserving the uncovertebral joint and intervertebral disk integrity and avoiding injury to the vertebral artery and the cervical sympathetic chain. The goal of this chapter is to review the preoperative and postoperative considerations, surgical technique, complications, and results of ACF procedures.

Preoperative Considerations

Eligible patients are those with persistent unilateral cervical radiculopathy and pain unresponsive to conservative treatment for longer than 6 weeks. If patients continue to have severe radicular symptoms not alleviated by opioids or have profound motor deficits, consideration for earlier operative intervention is indicated. Physical examination that shows a positive Spurling sign and weakness or sensory loss in a corresponding pain dermatome secondary to cervical radiculopathy can be expected. However, examination findings consistent with myelopathy, such as a positive Lhermitte sign or Hoffmann sign, are considered contraindications to ACF.

The required preoperative imaging study includes oblique and dynamic flexion and extension lateral radiographs, magnetic resonance imaging (MRI), and computed tomography (CT) scan. Foraminal MRI, which consists of axial MRI images obtained perpendicular to the cervical foramen, is also helpful in evaluating foraminal disorders. The extension of disk herniation or osteophytes, calcification and migration of disks, and location and variation of the vertebral artery in the transverse foramen should be checked in preparation for the operation. Axial CT scan and sagittal CT reconstruction images are useful in determining the location of the drill hole and for measuring the transcorporeal trajectory.

ACF is indicated when the history and examination confirm persistent unilateral radiculopathy that correlates with preoperative imaging studies demonstrating posterolateral disk herniation or uncovertebral osteophytes that compress the cervical nerve root anteriorly. In patients with multilevel disease or vague symptoms, electrophysiologic study, including nerve conduction velocity and electromyography, may help confirm the diagnosis. Multilevel foraminal stenosis and disk herniation are not often present and also can be indications for ACF ( Fig. 33-1 ).

FIGURE 33-1, A , Preoperative cervical magnetic resonance imaging (MRI) shows foraminal disk herniation at the C6-C7 level compressing the right C7 nerve root ( arrows ). B , Postoperative MRI shows complete removal of the herniated disk fragment and decompression of the C6-C7 neural foramen ( arrow ).

Bilateral foraminal stenosis, predominant axial neck pain, signs suggestive of infection, instability, and the presence of myelopathy are contraindications to ACF. Unilateral foraminal decompression performed in the presence of bilateral foraminal stenosis may aggravate the development of radiculopathy on the contralateral side. Axial neck pain secondary to degenerative cervical disk disease is also a contraindication to ACF. Anterior cervical diskectomy and fusion (ACDF) may be an option in patients who are not candidates for ACF.

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here