The projection of the cervical disc and uncinate process on the posterior aspect of the cervical spine

Posterior Cervical Keyhole Laminoforaminotomy: A Cadaveric Comparative Study to Evaluate Limits of Bony Resection

BACKGROUND

The posterior cervical keyhole (KH) laminoforaminotomy has been described to involve the lateral portion of cervical laminae of the upper vertebra alone (small KH) or of both upper and lower vertebrae (large KH).

OBJECTIVE

To microscopically compare the two keyhole techniques in terms of their ability to expose the corresponding cervical roots.

METHODS

Ten cadaveric specimens were operated bilaterally from C3-4 to C6-7 level to expose a total of 80 nerve roots. The large KH was applied to the left side, the small KH to the right side. The maximal length of exposed nerve roots was measured under microscope. The virtual optimal KH surface area was determined using digital software. Each root was inspected for exposure of its root and axilla.

RESULTS

The maximal exposed nerve root length on the large KH side was significantly larger than on the small KH side at C3-4, C5-6, and C6-7 levels (P = .031, P = .002, P = .003). No significance was reported for C4-5 (P = .06). We could expose right axillae in (3/40) and left axillae in (33/40; P < .001). Optimal keyhole surface areas were 37.9, 38.2, 38.7, and 46.2 mm2 in craniocaudal order.

CONCLUSION

Large KH defects involving both upper and lower laminae and facets can expose the roots to greater extent than small KH defects at C3-4, C5-6, and C6-7 levels. Large KH defects may allow better exposure of nerve roots axillae than small KH defects.

Comparison of Surgical Results between Soft Ruptured Disc and Foraminal Stenosis Patients in Posterior Cervical Laminoforaminotomy

Objective

Posterior cervical laminoforaminotomy is used to relieve cervical nerve root compression caused by a laterally herniated soft cervical disc or spondylotic spur and its several advantages and disadvantages compared with anterior cervical discectomy were reported. We compared surgical results between soft ruptured disc and foraminal stenosis in posterior cervical laminoforaminotomy.

Methods

We performed a retrospective review of 47 patients performed single level posterior cervical laminoforaminotomy for cervical radiculopathy between 2004 and 2012. We divided these patients into two groups, Group A: 27 patients for ruptured disc and Group B: 20 patients for foraminal stenosis and analyzed the demographic factors, amount of medial facetectomy, postoperative instability with neck pain and clinical outcomes.

Results

According to the modified Odom's criteria, laminoforaminotomy for the ruptured disc showed 92.6% excellent results and 7.4% good results. For the foraminal stenosis, it was 55.0% excellent and 25.0% good results, which was statistically significant. However when both groups were included, overall success rate showed 91.5%. The extent of medial facetectomy for ruptured disc (31.2%) was smaller than for stenosis (48.8%) and it was statistically significant. Thirteen patients complained of postoperative neck pain for 2 months. There was no instability on dynamic X-ray until the last follow up period and we had two cases complications (4.3%).

Conclusion

Although the extent of facetectomy for ruptured disc was smaller than it for stenosis, posterior laminoforaminotomy for the ruptured disc showed the better outcomes than foraminal stenosis.

Feasibility of Posterior Cervical Foraminotomy in Cervical Foraminal Stenosis: Prediction of Surgical Outcomes by the Foraminal Shape on Preoperative Computed Tomography

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

The aim of this study was to compare the feasibility of posterior cervical laminoforaminotomy (PCF) for V- or parallel-shaped foraminal stenosis (FS).

SUMMARY OF BACKGROUND DATA

During PCF, the need for extensive facet resection would depend on the extent of any pathology. When resection is extensive, the possibilities of instability and incomplete decompression should be considered.

METHODS

From March 2004 to March 2015, we enrolled 36 patients following single-level PCF procedures for FS. We classified patients by foraminal shape on preoperative computed tomography (CT) scan into V-shaped and parallel-shaped groups. We then compared arm and neck pain using a numeric rating scale (NRS) and clinical outcomes using Odom criteria. Radiological evaluation included dynamic X-rays for instability and CT scans for facet resection.

RESULT

We enrolled 16 and 20 patients in the V-shape and parallel-shape groups, respectively. By Odom criteria, no patient was graded fair or poor in the V group, but five patients were graded as fair and one patient as poor in the parallel group. Continued postoperative arm pain at 1 year, which was related to incomplete decompression, was significantly higher in parallel group. Only one patient complained of postoperative neck pain with an NRS >5, and another five patients sustained radiculopathy with an NRS >5. Among five patients who complained sustained radiculopathy, one patient required revision surgery for incomplete decompression. The amount of facet removal was not different significantly between groups, and no patient had postoperative instability.

CONCLUSION

Although PCF seems to be a good surgical option for V-shaped FS, we experienced worse outcomes for patients with parallel-shaped FS. We recommend that ACDF or more aggressive posterior foraminotomy be performed with fusion when presented with parallel neuroforaminal compression.

LEVEL OF EVIDENCE

4.

Posterior Cervical Microscopic Foraminotomy and Discectomy with Laser for Unilateral Radiculopathy

Surgical decompression for cervical radiculopathy includes anterior cervical discectomy and fusion, anterior or posterior cervical foraminotomy, and cervical arthroplasty after decompression. The aim of this study was to evaluate the usefulness of a CO₂ laser in posterior-approach surgery for unilateral cervical radiculopathy. From January 2006 to December 2008, 12 consecutive patients with unilateral cervical radiculopathy from either foraminal stenosis or disc herniation, which was confirmed with imaging studies, underwent posterior foraminotomy and discectomy with the use of a microscope and CO₂ laser. For annulotomy and discectomy, we used about 300 joules of CO₂ laser energy. Magnetic resonance imaging (MRI) was used to evaluate the extent of disc removal or foraminal decompression. Clinical outcome was evaluated by using visual analogue scale scores for radicular pain and Odom's criteria. For evaluation of spinal stability, cervical flexion and extension radiographs were obtained. Single-level foraminotomy was performed in 10 patients and two-level foraminotomies were performed in 2 patients. Preoperative radicular symptoms were improved immediately after surgery in all patients. No surgery-related complications developed in our cases. Postoperative MRI demonstrated effective decompression of ventral lesions and widened foraminal spaces in all cases. There was no development of cervical instability during the follow-up period. Posterior foraminotomy and discectomy using a microscope and CO₂ laser is an effective surgical tool for unilateral cervical radiculopathy caused by lateral or foraminal disc herniations or spondylotic stenosis. Long-term follow-up with radiographs showed no significant kyphotic changes or spinal instability.

Three-dimensional motion of the uncovertebral joint during head rotation

Object

The uncovertebral joints are peculiar but clinically important anatomical structures of the cervical vertebrae. In the aged or degenerative cervical spine, osteophytes arising from an uncovertebral joint can cause cervical radiculopathy, often necessitating decompression surgery. Although these joints are believed to bear some relationship to head rotation, how the uncovertebral joints work during head rotation remains unclear. The purpose of this study is to elucidate 3D motion of the uncovertebral joints during head rotation.

Methods

Study participants were 10 healthy volunteers who underwent 3D MRI of the cervical spine in 11 positions during head rotation: neutral (0°) and 15° increments to maximal head rotation on each side (left and right). Relative motions of the cervical spine were calculated by automatically superimposing a segmented 3D MR image of the vertebra in the neutral position over images of each position using the volume registration method. The 3D intervertebral motions of all 10 volunteers were standardized, and the 3D motion of uncovertebral joints was visualized on animations using data for the standardized motion. Inferred contact areas of uncovertebral joints were also calculated using a proximity mapping technique.

Results

The 3D animation of uncovertebral joints during head rotation showed that the joints alternate between contact and separation. Inferred contact areas of uncovertebral joints were situated directly lateral at the middle cervical spine and dorsolateral at the lower cervical spine. With increasing angle of rotation, inferred contact areas increased in the middle cervical spine, whereas areas in the lower cervical spine slightly decreased.

Conclusions

In this study, the 3D motions of uncovertebral joints during head rotation were depicted precisely for the first time.

Morphometrical study of uncinate processes and vertebral body of cervical spine

OBJECTIVE

The anatomical knowledge is the most important and has a direct link with success of operation in cervical spine surgery. The authors measured various cervical parameters in cadaveric dry bones and compared with previous reported results.

METHODS

We made 255 dry bones age from 19 to 72 years (mean, 42.3 years) that were obtained from 51 subjects in 100 subjects who donated their bodies. All measurements from C3-C7 levels were made using digital vernier calipers, standard goniometer, and self-made fix tool for two different cervical axes (canal and disc setting). We classified into 4 groups (uncinate process, vertebral body, lamina, and pedicle) and measured independently by two neurosurgeons for 28 parameters.

RESULTS

We analyzed 23970 measurements by mean value and standard deviations. In comparing with previous literatures, there are some different results. The mean values for uncinate process (UP) width ranged from 5.5 mm at C4 and 5 to 6.3 mm at C3 and C7 in men. Also, in women, the mean values for UP width ranged from 5.5 mm at C5 to 6.3 mm at C7. C7 was widest and C5 was most narrow than other levels. The antero-posterior length of UP tended to increase gradually from C3 to C6. The tip way, tip distance, and base distance of UP also showed increasing pattern from C3 to C7.

CONCLUSION

These measurements can provide the spinal surgeons with a starting point to address bony architectures surrounding targeted soft tissues for safeguard against unintended damages during cervical operation.

Anterior approach to disc herniation with modified anterior microforaminotomy at C7-T2: technical note

STUDY DESIGN

An easy surgical method to reach C7-Th and T1-T2 foraminal disc herniation is described.

OBJECTIVE

To describe a surgical technique that involves an anterior approach to disc herniation with inverted cone-shaped partial minicorpectomy.

SUMMARY OF BACKGROUND DATA

Anterior approaches to the cervicothoracic junction are difficult in spinal surgery because the operative area is narrow. The manubrium, the clavicles, and the slope of the vertebral bodies obstruct the view of the surgeon. The vascular and neural structures of the superior mediastinum limit the surgical approach. The thoracic duct and recurrent laryngeal nerve present risks for injury, especially with approaches from the right side. Disc herniations at the C7-T2 level are very rare. Posterior approaches at these levels are advocated because radicular symptoms occur more often than myelopathic symptoms, but anterior discectomy and fusion are generally preferred by many spinal surgeons, as these are approaches that are more intuitive.

METHODS

We review the case histories of all of our patients that underwent inverted cone-shaped partial minicorpectomy and fusion at the C7-T2 disc levels between 2000 and 2008. We applied the surgical techniques described in this manuscript.

RESULTS

The mean follow-up duration was 50 months postoperation. Physical examinations were performed and radiographs were taken at the end of the first 6 months postoperative and every 12 months thereafter. No meaningful changes were recorded on either the Visual Analog Scale or the Neck Disability Index. Cervical alignment was unchanged before and after surgery.

CONCLUSION

Minicorpectomy technique of C7 or T1 vertebra is an easy and appropriate method for treating foraminal disc herniation between the C7-T1 and T1-T2 levels.

POSTERIOR CERVICAL SPINE SURGERY FOR RADICULOPATHY

IT IS NOW common knowledge that cervical radiculopathy, frequently caused by disc herniation and/or degeneration, will often improve without surgical intervention. Only a small percentage of patients with the severity of symptoms necessitate surgical treatment. Surgery for radiculopathy is indicated for motor weakness, progressive neurological deficits, and progressive symptoms that do not improve with nonoperative treatment. Advantages and disadvantages exist for both ventral and dorsal approaches in the surgical treatment of cervical radiculopathy. Indications and results for dorsal nerve root decompression are discussed, and a review of our preferred techniques, including use of minimally invasive technology, is presented.

Small keyhole transuncal foraminotomy for unilateral cervical radiculopathy

Interbody fusion after anterior discectomy may lead to acceleration of degenerative changes at adjacent levels. Although the posterior approach preserves the motion segment, decompression of the nerve root is indirect if "hard disc prolaps" is the main cause. Recently, a technique of microsurgical anterior cervical foraminotomy for the treatment of radiculopathy with preservation of the segment mobility was published. In this study, we present this technique with several modifications.Thirteen patients - 5 men and 8 women with an average age of 49 years - with unilateral radiculopathy resistant to conservative treatment underwent microsurgical anterior foraminotomy via a small keyhole transuncal approach. The base of the uncinate process (UP) was directly drilled in the trajectory to the intervertebral foramen without destroying the disc tissue. The vertebral artery between the transverse process was not exposed. Furthermore, the functional anatomy of the uncovertebral joint remained largely intact. All patients experienced complete relief of radiating pain. A cervical collar was not used. Mean follow-up time was 19 months. The mobility of the operated segment was preserved in each patient. No instability of the cervical spine was seen. The microsurgical anterior foraminotomy via a small keyhole transuncal approach is safe, minimally invasive, and represents an effective method to treat unilateral cervical radiculopathy caused by disc prolaps and/or uncovertebral osteophytes. Additionally, the segment mobility is preserved and prevents the acceleration of degenerative changes at adjacent levels.

A review of laminoforaminotomy for the management of lateral and foraminal cervical disc herniations or spurs

BACKGROUND

Anterior versus posterior surgical management of lateral and foraminal cervical disc disease remains controversial. The key hole foraminotomy or laminoforaminotomy allows dorsal resection without the instability encountered with anterior cervical approaches, with more limited morbidity. Unilateral radiculopathy can be addressed with the laminoforaminotomy, while bilateral or multifocal radiculopathy with myelopathy may additionally require a laminectomy or laminoplasty.

METHODS

Selection of patients for laminoforaminotomy should be based upon correlation of clinical findings and neurodiagnostic (MR, CT) studies to ensure that the dorsal approaches will sufficiently address the pathology.

RESULTS

The technical completion of a laminoforaminotomy is reviewed.

CONCLUSIONS

Performing adequate preoperative MR and CT examinations allows for the selection of patients who will benefit from the "key hole" or "laminoforaminotomy" approaches to lateral and foraminal disc disease and/or spur formation.

Anatomical projection of the cervical uncinate process in ventral, ventrolateral, and posterior decompressive surgery

OBJECT

The cervical uncinate processes (UPs), their variations, and the relationships between the neurovascular structures and surrounding bone were investigated in this anatomical study. The object of this study was to highlight the important surgery-related considerations associated with ventral, ventrolateral, and posterior decompressive surgery.

METHODS

Forty-nine adult C3-7 dry bone samples were used, and 10 measurements were obtained for each vertebra. The anterior measurements involved the cervical uncinate process (UP): height, width, length, distance between its tip and vertebral foramina, interuncinate process distance, sagittal angle with the superior margin of the vertebral body (VB), VB anteroposterior diameter, and VB width. Posterior measurements involved the vertical distance between the superior border of the lamina at the lamina-facet joint and the tip of the UP, as well as the horizontal distance between the medial-most border of the superior facet and the tip of the UP. All symmetrical structures were measured bilaterally. There were no statistically significant differences between right- and left-sided measurements in this series. The height of the UP increased gradually at each segmental level between C-3 and C-7. The width of the UP did not change with segmental level (5.0 mm at C-3 compared with 5.3 mm at C-7). On average, the length of the UP was relatively constant. The distance from the tip of the UP to vertebral foramina averaged 1 mm at the C2-3 level and 1.5 mm at the C5-6 level. Interuncinate distance and VB width gradually increased and were highly variable, which appeared to be related with osteophyte formation. There was a slight gradual increase from C-3 to lower segments, and it paralleled with the midline anteroposterior diameter of the same VB. The angle between the UP and the superior margin of the VB exhibited great variety. The posterior measurements decreased gradually from C-3 to C-7.

CONCLUSIONS

Based on the data obtained in this study, a surgeon is provided with a three-dimensional orientation as well as anatomical knowledge. This knowledge also allows for a more effective neurovascular decompression by minimizing the surgery-related complications.

Microendoscopic posterior cervical foraminotomy: a cadaveric model and clinical application for cervical radiculopathy

OBJECT

Cervical radiculopathy caused by either soft herniated disc material or foraminal stenosis is a common problem. Anterior and posterior surgical approaches are commonly used to decompress the nerve root. The authors undertook a study to establish the feasibility of performing a microendoscopic posterior approach for cervical foraminotomy in the clinical setting.

METHODS

The authors performed an endoscopic posterior foraminotomy technique in which they used a rigid endoscope, in both a cadaver model and in three clinical cases, including one in which a multiple-level procedure was undertaken. Postoperatively, all patients returned to functional work status within 4 weeks. The mean length of hospitalization was 1.3 days.

CONCLUSIONS

The advantages to this technique include improved intraoperative visualization, a smaller incision, and significantly less postoperative discomfort compared with a traditional keyhole approach.

Microendoscopic posterior cervical foraminotomy: a cadaveric model and clinical application for cervical radiculopathy

Cervical radiculopathy that is caused by either soft herniated disc material or foraminal stenosis is a common problem. Anterior and posterior surgical approaches are commonly performed to decompress the nerve root. The authors describe an endoscopic posterior foraminotomy procedure in which they use a rigid endoscope, in both a cadaveric model and in three clinical cases, including a multiple level case.

Postoperatively, all patients returned to functional work status within 4 weeks. The mean length of hospitalization was 1.3 days.

The advantages of this technique include improved visualization, a smaller incision, and significantly less postoperative discomfort when compared with a matched group of patients in whom open nonendoscopic foraminotomy has been performed.