Value of magnetic resonance imaging and discography in determining the level of cervical discectomy and fusion

Prevalence and Discordance of the "Startle Response" with True Discogenic Pain According to Spine Intervention Society Guidelines for Provocation Discography: A Cohort Study

SUMMARY OF BACKGROUND DATA

The literature on cervical provocation discography (C-PD) is sparse. A "Startle Response" during C-PD is a known phenomenon that might be mistaken as an indicator of discogenic pain at the provoked disc level, but this has not been quantitatively described.

OBJECTIVES

To determine the incidence of the Startle Response and its concordance/discordance with true-positive C-PD in patients referred for surgical planning or evaluation after ruling out other axial pain generators.

METHODS

Retrospective cohort study of consecutive patients who received C-PD at an outpatient spine center. The primary outcome was the rate of discordance of the Startle Response with true-positive C-PD according to the operational criteria of the Spine Intervention Society (SIS) guidelines.

RESULTS

One hundred five discs were provoked in 36 individuals (19 female, mean age [SD] = 45.7 [10.9] years). C-PD was performed at a median of three levels (range = 1-5) with C4/5 (N = 30), C5/6 (N = 30), and C6/7 (N = 31) the most commonly evaluated. Twenty-six of 36 patients reported responses consistent with true-positive C-PD. A Startle Response was observed in 14 patients (39%, 95% confidence interval [CI] = 23-57%), and 22 of 105 (21%, 95% CI = 14-30%) provoked discs. Of the 14 patients who exhibited a Startle Response, four had negative C-PD results (29%, 95% CI = 8-58%). As assessed per disc, C-PD results were positive in 12 of the 22 (55%, 95% CI = 32-76%) provoked discs that generated a Startle Response.

CONCLUSIONS

The present data demonstrate high discordance, 45% (95% CI = 24-68%), between the Startle Response and true-positive C-PD. Clinicians should be aware of this phenomenon and take care to distinguish it from a true-positive response during C-PD, as defined by the SIS guidelines. Misinterpretation of the Startle Response as a positive C-PD result may lead to inappropriate future care decisions in a substantial proportion of patients.

Are radio-contrast agents commonly used in discography toxic to the intact intervertebral disc tissue cells?

In the literature, there have been no studies showing clear results on how radio-contrast pharmaceuticals would affect intact disc tissue cells. In this context, it was aimed to evaluate the effects of iopromide and gadoxetic acid, frequently used in the discography, on intact lumbar disc tissue in pharmaco-molecular and histopathological level. Primary cell cultures were prepared from the healthy disc tissue of the patients operated in the neurosurgery clinic. Except for the control group, the cultures were incubated with the indicated radio-contrast agents. Cell viability, toxicity and proliferation indices were tested at specific time intervals. The cell viability was quantitatively analysed. It was also visually rechecked under a fluorescence microscope with acridine orange/propidium iodide staining. Simultaneously, cell surface morphology was analysed with an inverted light microscope, while haematoxylin and eosin (H&E) staining methodology was used in the histopathological evaluations. The obtained data were evaluated statistically. Unlike the literature, iopromide or gadoxetic acid did not have any adverse effects on the cell viability, proliferation and toxicity (P < 0.05). Although this study reveals that radio-contrast pharmaceuticals used in the discography, often used in neurosurgical practice, can be safely used, it should be remembered that this study was performed in an in vitro environment.

Structural and Ultrastructural Analysis of the Cervical Discs of Young and Elderly Humans

Several studies describing the ultrastructure and extracellular matrix (ECM) of intervertebral discs (IVDs) involve animal models and specimens obtained from symptomatic individuals during surgery for degenerative disease or scoliosis, which may not necessarily correlate to changes secondary to normal aging in humans. These changes may also be segment-specific based on different load patterns throughout life. Our objective was to describe the ECM and collagen profile of cervical IVDs in young (G1 - <35 years) and elderly (G2 - >65 years) presumably-asymptomatic individuals. Thirty cervical discs per group were obtained during autopsies of presumably-asymptomatic individuals. IVDs were analyzed with MRI, a morphological grading scale, light microscopy, scanning electron microscopy (SEM) and immunohistochemistry (IHC) for collagen types I, II, III, IV, V, VI, IX and X. Macroscopic degenerative features such as loss of annulus-nucleus distinction and fissures were found in both groups and significantly more severe in G2 as expected. MRI could not detect all morphological changes when compared even with simple morphological inspection. The loose fibrocartilaginous G1 matrix was replaced by a denser ECM in G2 with predominantly cartilaginous characteristics, chondrocyte clusters and absent elastic fibers. SEM demonstrated persistence of an identifiable nucleus and Sharpey-type insertion of cervical annulus fibers even in highly-degenerated G2 specimens. All collagen types were detected in every disc sector except for collagen X, with the largest area stained by collagens II and IV. Collagen detection was significantly decreased in G2: although significant intradiscal differences were rare, changes may occur faster or earlier in the posterior annulus. These results demonstrate an extensive modification of the ECM with maintenance of basic ultrastructural features despite severe macroscopic degeneration. Collagen analysis supports there is not a "pathologic" collagen type and changes are generally similar throughout the disc. Understanding the collagen and ultrastructural substrate of degenerative changes in the human disc is an essential step in planning restorative therapies.

Assessment of nerve involvement in the lumbar spine: agreement between magnetic resonance imaging, physical examination and pain drawing findings

Background

Detection of nerve involvement originating in the spine is a primary concern in the assessment of spine symptoms. Magnetic resonance imaging (MRI) has become the diagnostic method of choice for this detection. However, the agreement between MRI and other diagnostic methods for detecting nerve involvement has not been fully evaluated. The aim of this diagnostic study was to evaluate the agreement between nerve involvement visible in MRI and findings of nerve involvement detected in a structured physical examination and a simplified pain drawing.

Methods

Sixty-one consecutive patients referred for MRI of the lumbar spine were - without knowledge of MRI findings - assessed for nerve involvement with a simplified pain drawing and a structured physical examination. Agreement between findings was calculated as overall agreement, the p value for McNemar's exact test, specificity, sensitivity, and positive and negative predictive values.

Results

MRI-visible nerve involvement was significantly less common than, and showed weak agreement with, physical examination and pain drawing findings of nerve involvement in corresponding body segments. In spine segment L4-5, where most findings of nerve involvement were detected, the mean sensitivity of MRI-visible nerve involvement to a positive neurological test in the physical examination ranged from 16-37%. The mean specificity of MRI-visible nerve involvement in the same segment ranged from 61-77%. Positive and negative predictive values of MRI-visible nerve involvement in segment L4-5 ranged from 22-78% and 28-56% respectively.

Conclusion

In patients with long-standing nerve root symptoms referred for lumbar MRI, MRI-visible nerve involvement significantly underestimates the presence of nerve involvement detected by a physical examination and a pain drawing. A structured physical examination and a simplified pain drawing may reveal that many patients with "MRI-invisible" lumbar symptoms need treatment aimed at nerve involvement. Factors other than present MRI-visible nerve involvement may be responsible for findings of nerve involvement in the physical examination and the pain drawing.

Systematic review of the incidence of discitis after cervical discography

BACKGROUND CONTEXT

Cervical discography is not uniformly used in part because of the fear of discitis. Studies report widely varying rates of this life-threatening infection.

PURPOSE

The aim of this study was to estimate the incidence of discitis after cervical discography, delineate the consequences of discitis, and identify factors that may influence this complication.

STUDY DESIGN

Meta-analysis.

METHODS

Studies pertaining to cervical discography were identified by a literature review and bibliographic search. These were screened for inclusion into the meta-analysis by two reviewers. Data were collected on a wide range of clinical and demographic variables including age, gender, morbidities, number of patients, number of discograms, use of prophylactic antibiotics, type of surgical prep, number of needles used, and the number of patients and discs infected. Primary data were used to calculate the incidence of discitis per patient and per disc.

RESULTS

Fourteen studies were included in the analysis. Both procedural details and demographic information on patients were missing from eight studies. The mean age of patients ranged from 41 to 47 years, and gender distribution varied greatly. Antibiotics use was reported in three studies. Cervical discography was complicated by postprocedural discitis in 22 of 14,133 disc injections (0.15%) and 21 of 4,804 patients (0.44%). Only one patient suffered from an infection at more than one spinal level.

CONCLUSIONS

The rate of discitis after cervical discography is relatively low. This can perhaps be further decreased by the use of prophylactic intradiscal antibiotics. Should the ability of cervical discography to improve surgical outcomes be proven, the fear of discitis should not preclude performance of disc provocation.

Cervical intradiscal radiofrequency lesioning: a feasiblity study

OBJECTIVE

The objective of this benchtop study was to establish if single site, long duration intradiscal radiofrequency (RF) at two different positions could generate adequate heating throughout the intervertebral disc to potentially ablate intradiscal nociceptors.

DESIGN

The disarticulated cervical spines from four fresh frozen cadavers were studied. Temperature recording was completed from two different positions of the RF needle. The needle was either placed in the middle of the disc in four discs, or it was inserted in the posterior quarter of the disc, in eight discs. Thermocouple measurements were made every 2 minutes from three positions: middle of the disc, posterolateral aspect of the disc, and in the anterior third of the disc.

SETTING

Fluoroscopy suite.

MATERIALS

Disarticulated cervical spine specimens.

INTERVENTIONS

Intradiscal RF lesioning in the middle and posterior portion of the cervical disc at 85 degrees C for 10 minutes.

OUTCOME MEASURES

Local temperature within the disc.

RESULTS

Lesioning in either the middle or posterior portion of the disc failed to provide sufficient temperature increases throughout the cervical disc to achieve adequate denervation.

CONCLUSIONS

As in the lumbar spine, intradiscal cervical RF provides too focal a thermal profile to effectively denervate the disc even in an ex vivo experiment. Thus, single site, long duration cervical intradiscal RF lesioning in vivo cannot be recommended.

Intra- and inter-observer reliability of MRI examination of intervertebral disc abnormalities in patients with cervical myelopathy

PURPOSE

Intervertebral cervical disc herniation (CDH) is a relatively common disorder that can coexist with degenerative changes to worsen cervicogenic myelopathy. Despite the frequent disc abnormalities found in asymptomatic populations, magnetic resonance imaging (MRI) is considered excellent at detecting cervical spine myelopathy (CSM) associated with disc abnormality. The objective of this study was to investigate the intra- and inter-observer reliability of MRI detection of CSM in subjects who also had co-existing intervertebral disc abnormalities.

MATERIALS AND METHODS

Seven experienced radiologists reviewed twice the MRI of 10 patients with clinically and/or imaging determined myelopathy. MRI assessment was performed individually, with and without operational guidelines. A Fleiss Kappa statistic was used to evaluate the intra- and inter-observer agreement.

RESULTS

The study found high intra-observer percent agreement but relatively low Kappa values on selected variables. Inter-observer reliability was also low and neither observation was improved with operational guidelines. We believe that those low values may be associated with the base rate problem of Kappa.

CONCLUSION

In conclusion, this study demonstrated high intra-observer percent agreement in MR examination for intervertebral disc abnormalities in patients with underlying cervical myelopathy, but differing levels of intra- and inter-observer Kappa agreement among seven radiologists.

Indications for surgical fusion of the cervical and lumbar motion segment

STUDY DESIGN

A literature review and the authors' clinical experience for the indication of fusion in the degenerative lumbar and cervical spine is provided.

OBJECTIVE

To establish absolute and relative criteria for the indication for fusion in the degenerative cervical and lumbar spine.

SUMMARY OF BACKGROUND DATA

Fusion in the cervical and lumbar degenerative spine is indicated under certain strict criteria. However, fusion in circumstances not meeting these criteria is controversial.

METHOD

A review of the literature and the authors' experience concerning indication and criteria of fusion in degenerative, lumbar, and cervical spine is provided.

RESULTS

Fusion for the unstable spine related to trauma, infection, and tumors is relatively accepted. However, indications for fusion for degenerative, cervical, and lumbar spine are more controversial.

CONCLUSION

Lumbar and cervical fusion in the degenerative spine is frequently performed. Certain criteria have been established when a fusion should be considered. However, even these are not universally accepted. Strict prospective studies are needed to determine when a fusion of the degenerative, cervical, and lumbar spine is indicated. Patients with severe radicular pain may be considered for surgery after a comprehensive trial of conservative management. Fusion is usually necessary after a cervical discectomy, especially when spondylosis or osteophytic compression is present. Lumbar fusion is rarely indicated for routine discectomy. In patients with mechanical back or neck pain, surgery should only be considered after conservative measures have been exhausted and a radiographic abnormality is present at the symptomatic level, perhaps with pain concordant with discographic findings. Careful patient selection is the key to obtaining favorable surgical outcomes. In many cases, the goal may be a return to functionality rather than achieving a completely asymptomatic state.

Provocative discography: Current status

Low back pain is a common clinical problem that may be due to a variety of causes, including disc disease. Provocative discography is an imaging-guided procedure in which a contrast agent is injected into the nucleus pulposus of the disc. Despite its controversial history, it remains the only imaging technique that provides both anatomical and functional information about a diseased disc. Disc morphology is usually assessed on either radiographs or computed tomography (CT), or both. Functional evaluation of the disc consists of pain provocation and careful assessment of the patient's response to pain. As provocative discography is an invasive procedure, it should not be used as a screening study in patients with back pain. It should instead be reserved for carefully- selected patients whose painful symptoms cannot be explained by findings on non-invasive imaging modalities such as magnetic resonance imaging or CT, and who are not responsive to conservative measures. Discography is helpful in selection of patients and disc levels to be operated upon. Careful application of indications and meticulous technique are however required if a successful outcome is to be expected.