Microsurgical anatomy of the lower cervical spine and cord

Clinical significance of microsurgical excision of the posterior longitudinal ligament using a high-frequency electrosurgical excision procedure in anterior cervical discectomy and fusion

Introduction

Anterior cervical decompression and fusion surgery using traditional methods to remove the posterior longitudinal ligament often causes massive bleeding, increasing the risk of surgery. However, the use of a high-frequency electrotome under the microscope can significantly reduce bleeding and reduce the risk of surgery.

Aim

To explore the clinical significance of electrosurgical excision of the posterior longitudinal ligament in the cervical anterior approach under the microscope.

Material and methods

From December 2015 to December 2017, patients who underwent anterior cervical discectomy and fusion at our hospital were followed up. We enrolled 73 men and 50 women who were 30 to 74 years old (mean, 49.96 years). Among 67 patients in group A treated with a high-frequency electrosurgical knife under the microscope, 58 were followed up; among 73 patients in group B treated with a traditional cervical hook knife under the microscope, 65 were followed up. Clinical data, operative time, intraoperative bleeding volume, VAS score, and Japanese Orthopaedic Association (JOA) improvement rate were retrospectively analyzed.

Results

There were significant differences in the mean operative time and intraoperative bleeding volume between the two groups (p < 0.05); however, no significant differences were found in the incidence of cerebrospinal fluid leakage, JOA improvement rate at 3 months postoperatively, and VAS score at 3 months postoperatively between the two groups (p > 0.05).

Conclusions

Electrosurgical resection of the posterior longitudinal ligament of the cervical vertebrae under the microscope can significantly reduce intraoperative bleeding and shorten the operative time and has obvious advantages compared with traditional methods.

Clinical anatomy and significance of the thoracic intervertebral foramen: A cadaveric study and review of the literature

INTRODUCTION

The literature is lacking information on the anatomy and the osseous dimensions of the thoracic intervertebral foramen (IVF). We describe the anatomy of the broader area, and we proceed with morphometric data of the vertebrae and the foramina. Depiction of these features is provided with imaging and illustrations. The purpose of this paper is to survey and present the anatomy of the foramen as a whole and provide baseline statistical data.

MATERIALS AND METHODS

We review relevant literature, and we present data obtained from skeletal samples of known population and sex. One hundred and nineteen thoracic vertebrae of ten cadaveric spines from the prefecture of Eastern Macedonia and Thrace, Greece, were selected. Statistical analysis measuring the vertical height and the foraminal width of each vertebra was made in accordance with sex.

RESULTS

No statistically important differences referring to the descriptive data of both sexes were found. However, statistically, important positive correlation between the vertebral height and the foraminal width was observed, especially for men. The components of the foramen including arteries and veins passing through or neighboring it, and the spinal nerves and roots are described and depicted.

CONCLUSIONS

The osseous thoracic IVF reveals a glimpse of the in vivo structure and alterations of its width may be present in back pain and other degenerative diseases. Although it is crucial for surgeries and other interventional procedures of the thoracic spine, little is known about the precise anatomy and dimensions of this anatomical landmark.

Prognostic Factors for Postsurgical Recovery of Deltoid Palsy due to Cervical Disc Herniations

Study Design

Retrospective multicenter study.

Purpose

We aimed to investigate prognostic factors affecting postsurgical recovery of deltoid palsy due to cervical disc herniation (CDH).

Overview of Literature

Little information is available about prognostic factors affecting postsurgical recovery of deltoid palsy due to CDH.

Methods

Sixty-one patients with CDH causing deltoid palsy (less than grade 3) were included in this study: 35 soft discs and 26 hard discs. Average duration of preoperative deltoid palsy was 11.9 weeks. Thirty-two patients underwent single-level surgery, 22 two-level, four three-level, and three four-level. Patients with accompanying myelopathy, shoulder diseases, or peripheral neuropathy were excluded from the study.

Results

Deltoid palsy (2.4 grades vs. 4.5 grades, p<0.001) and radiculopathy (6.4 points vs. 2.1 points, p<0.001) significantly improved after surgery. Thirty-six of 61 patients (59%) achieved full recovery (grade 5) of deltoid palsy, with an average time of 8.4 weeks. Longer duration of preoperative deltoid palsy and more severe radiculopathy negatively affected the degree of improvement in deltoid palsy. Age, gender, number of surgery level, and disc type did not affect the degree of improvement of deltoid palsy. Contrary to our expectations, severity of preoperative deltoid palsy did not affect the degree of improvement. Due to the shorter duration of preoperative deltoid palsy, in the context of rapid referral, early surgical decompression resulted in significant recovery of more severe grades (grade 0 or 1) of deltoid palsy compared to grade 2 or 3 deltoid palsy.

Conclusions

Early surgical decompression significantly improved deltoid palsy caused by CDH, irrespective of age, gender, number of surgery level, and disc type. However, longer duration of deltoid palsy and more severe intensity of preoperative radiating pain were associated with less improvement of deltoid palsy postoperatively.

Anatomy of the spinal dorsal root entry zone: its clinical significance

BACKGROUND

The posterolateral sulcus (PLS) is an important surgical landmark, especially for DREZ (dorsal root entry zone) operations.

METHODS

The present study aimed to show the variations of the PLS using human spinal cord histological sections and report the variability in the number of dorsal rootlets of the spinal nerves in each the spinal cord segment. Further, measure the height and width of the dorsal horn on histological sections for cervical, thoracic, and lumbar levels.

RESULTS

The results of the present study showed various patterns of PLS 1.clearly present PLS, 2. short PLS, 3. absent PLS or 4. irregular PLS. Height and width measurements of the dorsal horn showed that the average width was greatest at lower cervical (0.48 ± 0.04 mm) and least at lower thoracic levels (0.41 ± 0.04 mm), whereas the average height was greatest at upper cervical (3.0 ± 0.06 mm) and smallest at lower lumbar levels (1.8 ± 0.08 mm). The average number of rootlets varied considerably, at cervical level it was 7.6 ± 1.4 mm, at thoracic 6.6 ± 0.8 mm and at lumbar 6.1 ± 0.4 mm.

CONCLUSIONS

The detailed anatomy of the variations of the PLS and the average number of rootlets at each spinal level can increase the success of regional surgery. Further, fine measurements on histological sections can give detailed knowledge on the size necessary for lesioning in DREZ operations.

Morphometric Relationship between the Cervicothoracic Cord Segments and Vertebral Bodies

Objective

The objective of this study was to investigate the morphologic characteristics between the vertebral body and the regions of the cervical and thoracic spinal cords where each rootlets branch out.

Methods

Sixteen adult cadavers (12 males and 4 females) with a mean age of 57.9 (range of 33 to 70 years old) were used in this study. The anatomical relationship between the exit points of the nerve roots from the posterior root entry zone at each spinal cord segment and their corresponding relevant vertebral bodies were also analyzed.

Results

Vertical span of the posterior root entry zone between the upper and lower rootlet originating from each spinal segment ranged from 10-12 mm. The lengths of the rootlets from their point of origin at the spinal cord to their entrance into the intervertebral foramen were 5.9 mm at the third cervical nerve root and increased to 14.5 mm at the eighth cervical nerve root. At the lower segments of the nerve roots (T3 to T12), the posterior root entry zone of the relevant nerve roots had a corresponding anatomical relationship with the vertebral body that is two segments above. The posterior root entry zones of the sixth (94%) and seventh (81%) cervical nerve roots were located at a vertebral body a segment above from relevant segment.

Conclusion

Through these investigations, a more accurate diagnosis, the establishment of a better therapeutic plan, and a decrease in surgical complications can be expected when pathologic lesions occur in the spinal cord or vertebral body.

Morphological features and clinical significance of epidural membrane in the cervical spine

STUDY DESIGN

A prospective clinical study.

OBJECTIVE

To elucidate the histomorphological features and clinical significance of the epidural membrane (EM) in the cervical spine based on operative and histological findings.

SUMMARY OF BACKGROUND DATA

The anatomical features of the EM have been mostly discussed on the basis of cadaver studies in the whole spine. However, the histomorphological features and clinical significance of the EM in the cervical spine based on operative findings have never been reported.

METHODS

Eighty-seven patients with cervical spondylotic myelopathy who had undergone an expansive open-door laminoplasty under microscopy were evaluated with a more than 2-year follow-up period. The most damaged spinal segment was determined in each patient from the preoperative neurological and image findings along with the remaining symptoms at follow-up. The morphological features of the EM were observed and recorded in each patient during decompression. For histology, specimens of common and remarkable types of the EM obtained from 16 patients were examined.

RESULTS

The age at surgery averaged 64.5 years; there were 58 men and 29 women. With regard to the most damaged spinal segment, there were 14 cases at the C3-C4 level, 37 at the C4-C5 level, 32 at the C5-C6 level, and 4 at the C6-C7 level. The EM was an adipo-fibro-vascular tissue with various histomorphologies, blending with the periradicular sheath. Some EMs showed notable findings: obstructing dural tube expansion (13 cases, 14.9%), compressing a nerve root or disturbing its mobility (4 cases, 4.6%), and the combined type (1 case, 1.1%). All of them were located at approximately the most damaged spinal segment. In addition, some EMs had interesting histological features, such as harboring many small arteries, calcified debris, and metaplastic bone fragments.

CONCLUSION

The EM can develop into remarkable structures with spondylosis and aging in patients with cervical spondylotic myelopathy, affecting surgical outcomes as well as successful decompression procedures. A sound understanding of the histomorphological features of the EM is required to obtain satisfactory surgical outcomes in the limited field afforded by minimally invasive surgery.

Useful C8 and T1 function seen immediately after a complete cervical spinal cord injury: report of 2 cases

BACKGROUND

Because of the rarity of cervicothoracic spine injuries, detailed reports on the neurologic examination after complete cord injuries are scarce. A few retrospective case series scantily documented the intrinsic hand function after C7-T1 complete cord injuries. A complete cervical cord injury with useful C8 and T1 motor function present immediately after the injury has not been reported to date.

CASE DESCRIPTION

Functional C8 and T1 motor strength at the time of the initial neurologic examination was seen in 2 cases in which a complete C7-T1 injury resulted in paraplegia. Serial neurologic examinations were performed to document useful C8 and T1 motor function and maintenance of the neurologic status after surgical treatment.

CONCLUSIONS

Patients can present with useful lower cervical root function (C8 and T1) when first seen at admission after a complete cervical cord injury. Careful neurologic examination must be performed at admission in patients with lower cervical spine injuries because useful intrinsic hand function can be present and must not be overlooked.

The use of average Pavlov ratio to predict the risk of post operative upper limb palsy after posterior cervical decompression

Study Design

A retrospective study was conducted to study the post operative upper limb palsy after laminoplasty for cervical myelopathy.

Objective

To identify a reliable and simple preoperative radiological parameter in predicting the risk of post operative upper limb palsy.

Background

Post operative upper limb palsy is one of the causes of patient dissatisfaction after surgery. There had been no simple, standard preoperative radiological parameters reliably predict the occurrence of this problem.

Materials and methods

Seventy-four patients received posterior cervical decompression from 1998 to 2008. Medical record and preoperative radiological information were evaluated. Clinical presentations of the palsy were described. The relationship between the occurrence of palsy and different preoperative radiological information is analyzed.

Results

Eighteen patients (24.3%) presented with post operative upper limb palsy. Majority of patients presented with dysesthesia (17/18) and with deficit of the C5 segment (17/18). Ten patients presented with pure dysesthesia and 8 patients presented with mixed motor-sensory deficit and dysesthesia. Multilevel involvement was exclusively presented in patients with motor weakness. A longer duration of symptom (16.7 Vs 57.2 days) was noticed in patients in the motor deficit group. Average Pavlov ratio less then 0.65 (P = 0.027, Odds Ratio = 3.68) and compression at the C3/4 in preoperative MRI image (P = 0.025, Odds Ratio = 6) were significant risk factors for development of this problem.

Conclusion

Post operative upper limb palsy is not uncommon and thorough preoperative explanation is important. There is a spectrum of clinical presentation and patients with multi-level involvement and motor deficit are associated with poorer prognosis. Average Pavlov ratio < 0.65 and compression at C3/4 segment on preoperative MRI image are simple and reliable preoperative predictor for the development of this problem.

Unusual cervical nerve root arrangement exposed during surgery: case report and review of the literature

Anatomical variations of neural structures in the cervical spine are rare and are not necessarily visible on pre-operative imaging. The authors report an unusual arrangement of neural structures identified during cervical foraminotomy. Anatomical variations of the cervical nerve roots are reviewed and their importance in neurosurgical practice is discussed.

The so-called anterior meningeal artery: an anatomic study for treatment modalities

SUMMARY

The so called anterior meningeal artery (AMA) is a branch of the vertebral artery (VA), which had been interpreted as a supplying vessel of the dura in the foramen magnum and upper cervical level. In this study, we examined the anatomy of this artery and relationships to its surrounding structures for treatment modalities. With the aid of magnification, five adult cadaveric head and neck complex and five cervical spines were examined after perfusion of the vessels with colored silicone. The AMA arose from the VA between the C2 and C3 level, and passed medially through the intrervertebral foramen anterior to the dural sheath of the third cervical nerve root. It ran upwards dorsal to the deep layer of the posterior longitudinal ligament (PLL) with anterior internal vertebral venous plexus. Rostrally, it formed an arcade above the apex of the odontoid process with its contralateral mate. The AMA gave off several tiny branches to the deep layer of the PLL, ligaments and soft tissues above the apex of the odontoid process, and vertebral bodies of the axis. At the level of the foramen magnum, it ended in several small twigs to the dura. Anastomoses between the AMA system and adjacent vessels were observed. One was directed through the hypoglossal canal to the ascending pharyngeal artery and the other was with the V3 segment of the VA. The origin and course of the two AMA, and anastomoses were symmetric. Although the AMA feeds the ventral dura of the foramen magnum, the perfusion area is larger than its name suggests, including the bony and ligamentous structures in the craniovertebral junction. Anatomical knowledge of the AMA, including its anastomoses and layer relationships to the surrounding structures, may help to perform treatment modalities in this region rationally.

Clinical analysis of cervical radiculopathy causing deltoid paralysis

In general, deltoid paralysis develops in patients with cervical disc herniation (CDH) or cervical spondylotic radiculopathy (CSR) at the level of C4/5, resulting in compression of the C5 nerve root. Therefore, little attention has been paid to CDH or CSR at other levels as the possible cause of deltoid paralysis. In addition, the surgical outcomes for deltoid paralysis have not been fully described. Fourteen patients with single-level CDH or CSR, who had undergone anterior cervical decompression and fusion for deltoid paralysis, were included in this study. The severity of deltoid paralysis was classified into five grades according to manual motor power test, and the severity of radiculopathy was recorded on a visual analog scale (zero to ten points). The degree of improvement in both the severity of deltoid paralysis and radiculopathy following surgery was evaluated. Of 14 patients, one had C3/4 CDH, four had C4/5 CDH, three had C4/5 CSR, one had C5/6 CDH, and five had C5/6 CSR. Both deltoid paralysis and radiculopathy improved significantly with surgery (2.57+/-0.51 grades vs 4.14+/-0.66, P=0.001, and 7.64+/-1.65 points vs 3.21+/-0.58, P=0.001, respectively). In conclusion, the current study demonstrates that deltoid paralysis can develop due to CDH or CSR not only C4/5, but also at the levels of C3/4 and C5/6, and that surgical decompression significantly improves the degree of deltoid paralysis due to cervical radiculopathy.

Relationship of cervical spinal rootlets and the inferior vertebral notch

The anatomic features of cervical spinal rootlets from C5 to T1 and their relationships to the inferior vertebral notches were studied. Fifteen fresh cadavers were dissected and the cervical spinal cord and spinal rootlets were exposed by posterior total laminectomy. The dorsal rootlet entry zone of each spinal root was located proximal to the inferior vertebral notch, with an increasing distance from 15 mm at C5 to 28 mm at T1. The angle sustained by the rootlets to the cord decreased from 45 degrees to 89 degrees at C5 and to 23 degrees to 41 degrees at T1. Ventral rootlet exit zones shared similar arrangements and orientations, but they could not be exposed with posterior laminectomy only. Spinal rootlets of a particular cervical spinal segment may be found medial to the pedicles or through the intervertebral foramen one level above. They may be exposed by foraminotomy or partial excision of the pedicles. The inferior vertebral notch, which is the inferior border of the pedicle, is a reliable landmark for location of the rootlets. The information is useful for safe surgical manipulation and instrumentation around the pedicles, and when reimplantation of spinal nerve roots is considered for total brachial palsy.

The anatomic relation among the nerve roots, intervertebral foramina, and intervertebral discs of the cervical spine

STUDY DESIGN

An anatomic study of the cervical intervertebral foramina, nerve roots, and intradural rootlets performed using a surgical microscope.

OBJECTIVES

To investigate the anatomy of cervical root compression, and to obtain the anatomic findings related to cervical foraminotomy for the treatment of cervical radiculopathy.

SUMMARY OF BACKGROUND DATA

Cervical foraminotomy is a procedure performed frequently for the management of cervical radiculopathy. However, anatomic studies of cervical foraminotomy have not been fully elucidated.

METHODS

In this study, 18 cadavers were obtained for the study of the cervical spine. All the soft tissues were dissected from the cervical spine. Thereafter, laminectomy and facetectomy were performed on C4 through T1 using a surgical microscope. The nerve roots and surrounding anatomic structures, including intervertebral discs and foramina, were exposed. In addition, the intradural rootlets and their intersegmental connections were observed.

RESULTS

The shape of the intervertebral foramina approximated a funnel, the entrance zone being the most narrow part and the root sleeves conical, with their takeoff points from the central dural sac being the largest part. Therefore, compression of the nerve roots occurred at the entrance zone of the intervertebral foramina. Anteriorly, compression of the nerve roots was caused by protruding discs and osteophytes of the uncovertebral region, whereas the superior articular process, the ligamentum flavum, and the periradicular fibrous tissues affected the nerve posteriorly. The C5 nerve roots were found to exit over the middle aspect of the intervertebral disc, whereas the C6 and C7 nerve roots were found to traverse the proximal part of the disc. The C8 nerve roots had little overlap with the C7-T1 disc in the intervertebral foramen. The C6 and C7 rootlets passed two disc levels in the dural sac. Also, a high incidence of the intradural connections between the dorsal rootlets of C5, C6, and C7 segments was found.

CONCLUSIONS

This study demonstrated the anatomy of the nerve roots, rootlets, and intervertebral foramina, and may aid in understanding the pathology of cervical radiculopathy. The presence of intradural connections between dorsal nerve roots and the relation between the course of the nerve root and the intervertebral disc may explain the clinical variation of symptoms resulting from-nerve root compression in the cervical spine. To perform cervical foraminotomy for cervical radiculopathy, it is necessary to understand the detailed anatomy of the intervertebral foramina thoroughly.

Endoscopic foraminotomy using MED system in cadaveric specimens

STUDY DESIGN

Four cadavers had cervical foraminotomies performed at noncontiguous levels using either the standard open technique or the microendoscopic technique.

OBJECTIVES

To evaluate the feasibility of using a minimally invasive technique for posterior decompression of cervical disc disease.

SUMMARY OF BACKGROUND DATA

Even though the anterior approach is more commonly performed for the treatment of cervical disc disease, the posterior approach has distinct advantages in selected cases of foraminal stenosis and posterolateral disc herniation. Current technique, however, requires extensive muscle dissection, and is, therefore, subject to significant morbidity.

METHODS

Each of four cadavers had posterior cervical foraminotomies performed using either the MICROENDOSCOPIC (MED) technique, or the standard open technique. Three noncontiguous levels were decompressed using one technique, and the other technique was used for the adjacent contralateral decompression. Each specimen was then evaluated with postoperative myelogram/CT and open dissection. Laminotomy size, length of root decompressed, and percentage of facet removed were measured.

RESULTS

Average vertical diameter decompression and percentage of facet removed were significantly greater for the MED technique than for the open technique. Transverse diameter of the laminotomy area and the average length of decompressed root were not significantly different between the techniques.

CONCLUSION

Posterior cervical foraminotomy, using the microendoscopic technique, is technically feasible and may be applicable to the treatment of foraminal stenosis and laterally located cervical disc herniation. Studies in live animals are currently examining techniques for hemostasis.

Magnetic resonance imaging findings in ossification of the posterior longitudinal ligament of the cervical spine

OBJECT

Because of the lack of magnetic resonance (MR) signal from cortical bones, MR imaging is inadequate for diagnosing ossified lesions in the spinal canal. However, MR imaging provides important information on spinal cord morphology and associated soft-tissue abnormality. The purpose of this study is to determine the role of MR imaging in the diagnosis and treatment of patients with ossification of the posterior longitudinal ligament (OPLL) of the cervical spine.

METHODS

The authors reviewed MR imaging findings in 42 patients with cervical OPLL who were examined with a superconducting MR imaging system. The types of OPLL reviewed included eight cases of continuous, 21 cases of segmental, and 13 cases of the mixed type. All patients were treated surgically either by anterior (26 cases) or posterior decompression (16 cases).

CONCLUSIONS

The T1-weighted images clearly demonstrated the spinal cord deformity caused by OPLL. Associated disc protrusion was found to be present at the maximum compression level in 60% of the patients in this series. The highest incidence of disc protrusion (81%) was found in patients with segmental OPLL. Intramedullary hyperintensity on T2*-weighted imaging was noted in 18 patients (43%). The neurological deficits observed in these 18 patients were significantly more severe than those observed in the other 24 patients. Postoperative MR imaging revealed improvement in the spinal cord deformity, although the intramedullary hyperintensity was still observed in most cases. The present study demonstrates the importance of associated disc protrusion in the development of myelopathy in patients with cervical OPLL. Magnetic resonance imaging findings may be used to help determine the actual levels of spinal cord compression and to suggest the method of surgical treatment.

Diagnosis of root avulsions in traumatic brachial plexus injuries: value of computerized tomography myelography and magnetic resonance imaging

Surgical management and prognosis of traction injuries of the brachial plexus depend on the accurate diagnosis of root avulsion from the spinal cord. Myelography, computerized tomography (CT) myelography, and recently magnetic resonance (MR) imaging have become the main radiological methods for preoperative diagnosis of cervical root avulsions. Most of the previous studies on the accuracy of CT myelography and MR imaging studies have correlated the radiological findings with the extraspinal surgical findings at brachial plexus surgery. Surgical experience shows that in many cases extraspinal findings diverge from intradural determinations. Consequently, only correlation with the intradural surgical findings will allow assessment of the factual accuracy of CT myelography and MR imaging studies. In a prospective study, 135 cervical roots (C5-8) were evaluated by CT myelography and/or MR imaging and further explored intradurally via a hemilaminectomy. The accuracy of the preoperative CT myelography-based diagnosis in relation to the intraoperative findings was 85%. On the other hand, MR imaging demonstrated an accuracy of only 52%. The most common reasons for false-positive or false-negative findings were: 1) partial rootlet avulsion; 2) intradural fibrosis; and 3) dural cystic lesions. Computerized tomography myelography scans using 1- to 3-mm axial slices prove to be the most reliable method to evaluate preoperatively the presence of complete or partial root avulsion in traumatic brachial plexus injuries. Because extradural judgment of cervical root avulsion can be unreliable, accurate assessment of intraspinal root avulsion enormously simplifies the decision concerning the choice of donor nerves for transplantation and/or neurotization during brachial plexus surgery.

Anatomy of intervertebral disc and pathophysiology of herniated disc disease

This discussion reviews developments in normal and abnormal disc biology over the past decade. The anatomic and biochemical structure of the disc is reviewed. Emphasis is placed on recent neurochemical changes identified in disc degeneration and disc herniation. Biomechanical considerations for the normal disc are presented. Influence of mechanical factors on disc nutrition, disc degeneration and disc herniation is reviewed. Biologic events underlying the diagnostic methods used in evaluating disorders of the intervertebral disc are presented. The biologic consequences of iatrogenic disc injury in discectomy are also discussed.