Soft cervical disc herniation. Influence of cervical spinal canal measurements on development of neurologic symptoms

Pathophysiology of cervical myelopathy (Review)

Cervical myelopathy is a well-described medulla spinalis syndrome characterized by sensory disorders, such as pain, numbness, or paresthesia in the limbs, and motor disorders, such as muscle weakness, gait difficulties, spasticity, or hyperreflexia. If left untreated, cervical myelopathy can significantly affect the quality of life of patients, while in severe cases, it can cause disability or even quadriplegia. Cervical myelopathy is the final stage of spinal cord insult and can result from transgene dysplasias of the spinal cord, and acute or chronic injuries. Spondylosis is a common, multifactor cause of cervical myelopathy and affects various elements of the spine. The development of spondylotic changes in the spine is gradual during the patient's life and the symptoms are presented at a late stage, when significant damage has already been inflicted on the spinal cord. Spondylosis is widely considered a condition affecting the middle aged and elderly. Given the fact that the population is gradually becoming older, in the near future, clinicians may have to face an increased number of patients with spondylotic myelopathy.

Establishment of parameters for congenital thoracic stenosis: a study of 700 postmortem specimens

BACKGROUND

Congenital thoracic stenosis (CTS) occurs when the bony anatomy of the canal is smaller than expected in the general population. The diagnosis currently is made based on the clinical impression from subjective radiographic studies, and the normal values for CTS have not been established.

QUESTIONS/PURPOSES

We provided a statistical definition for CTS based on objective measurements of thoracic spine specimens and explored parameters that might predict CTS.

METHODS

We selected 700 adult skeletal specimens from the Hamann-Todd Collection in the Cleveland Museum of Natural History (Cleveland, OH, USA). We used calipers to measure the sagittal canal diameter (SCD), interpedicle distance (IPD), and pedicle length (PL). At each level, canal area was calculated using a geometric formula, a standard distribution was created, and values two SDs below the mean were considered congenitally stenotic. Corresponding values of SCD and IPD of the stenotic specimens were studied. The values of SCD and IPD predicting CTS with highest sensitivity and specificity were tabulated.

RESULTS

At each level, CTS was defined as: T1, 160 mm(2); T2, 135 mm(2); T3, 131 mm(2); T4, 130 mm(2), T5, 129 mm(2), T6, 127 mm(2); T7, 127 mm(2); T8, 129 mm(2); T9, 130 mm(2); T10, 132 mm(2); T11, 140 mm(2); and T12, 173 mm(2). A SCD less than 15 mm and an IPD less than 18.5 mm were predictive of CTS at each level with sensitivities and specificities of 80% to 100%.

CONCLUSIONS

We statistically defined CTS at each level. A SCD less than 15 mm or IPD less than 18.5 mm predicted the presence of CTS at all levels.

CLINICAL RELEVANCE

In a symptomatic patient, on routine radiologic examination, a physician should suspect stenosis of the thoracic canal if the SCD and IPD are less than 15 and 18.5 mm respectively. As a spinal deformity surgeon, the canal area is especially relevant when considering a possible canal intrusion by implants.

Establishment of parameters for congenital stenosis of the cervical spine: an anatomic descriptive analysis of 1,066 cadaveric specimens

PURPOSE

Congenital cervical stenosis (CCS) occurs when the bony anatomy of the cervical canal is smaller than expected in the general population predisposing an individual to symptomatic neural compression. No studies have defined CCS based on the normal population. The diagnosis is currently made based on clinical impression from radiographic studies. The aim of this study is to establish parameters that are associated with CCS, based on anatomic measurements on a large sample of skeletal specimens.

METHODS

From the Hamann-Todd collection at the Cleveland Museum of Natural History, 1,066 skeletal specimens were selected. Digital calipers were used to measure the sagittal canal diameter (SCD), interpedicular distance (IPD), and pedicle length. Canal area at each level was calculated using a geometric formula. A standard distribution was created and values that were 2 SD below mean were considered as congenitally stenotic. An analysis of deviance was performed to identify parameters that were associated with CCS. Regression analysis was used to determine odds ratios (OR) for CCS using these parameters.

RESULTS

CCS was defined at each level as: C3/4 = 1.82 cm(2), C4/5 = 1.80 cm(2), C5/6 = 1.84 cm(2), C6/7 = 1.89 cm(2), C7/T1 = 1.88 cm(2). Values of SCD < 13 mm and IPD < 22.5 mm were associated with CCS and yielded sensitivities and specificities of 88-100 % at each level. Logistic regression demonstrated a significant association between these parameters and presence of CCS with OR > 18 at each level.

CONCLUSIONS

Based on our study of a large population of adult skeletal specimens, we have defined CCS at each level. Values of SCD < 13 mm and IPD < 23 mm are strongly associated with the presence of CCS at all levels.

Endogenous-lesioned cervical disc herniation: a retrospective review of 9 cases

The purpose of this study was to analyze the pathogenic mechanisms, clinical presentation, and surgical treatment of cervical disc herniation without external trauma. Between 2004 and 2008, 9 patients with cervical disc herniation and no antecedent history of trauma were diagnosed with cervical disc herniation and underwent surgical decompression. Pathogenic mechanisms, clinical presentation, surgical treatment, and prognosis were analyzed retrospectively. In 6 patients, herniation resulted from excessive neck motion rather than from external trauma. An injury from this source is termed an endogenous-lesioned injury. Patients exhibited neurologic symptoms of compression of the cervical spinal cord or nerve roots. In the other 3 patients, no clear cause for the herniation was recorded, but all patients had a desk job with long periods of head-down neck flexion posture. After surgery, all patients experienced a reduction in their symptoms and an uneventful recovery. Cervical disc herniation can occur in the absence of trauma. Surgical decompression is effective at reducing symptoms in these patients, similar to other patients with cervical disc herniation. Surgical treatment may be considered for this disorder when the herniation becomes symptomatic.

Computerized tomographic morphometric analysis of the cervical spine

Background:

Detailed knowledge of cervical canal and transverse foramens’ morphometry is critical for understanding the pathology of certain diseases and for proper preoperative planning. Lateral x-rays do not provide the necessary accuracy. A retrospective morphometric study of the cervical canal was performed at the authors’ institution to measure mean dimensions of sagittal canal diameter (SCD), right and left transverse foramens’ sagittal (SFD) and transverse (TFD) diameters and minimum distance between spinal canal and transverse foramens (dSC-TF) for each level of the cervical spine from C1-C7, using computerized tomographic scans, in 100 patients from the archives of the Emergency Room.

Results:

Significant differences for SCD were detected between C1 and the other levels of the cervical spine for both male and female patients. For the transverse foramen, significant differences in sagittal diameters were detected at C3, C4, C5 levels. For transverse diameters, significant differences at C3 and C4 levels. A significant difference of the distance between the transverse spinal foramen and the cervical canal was measured between left and right side at the level of C3. This difference was equally observed to male and female subjects.

Conclusion:

CT scan can replace older conventional radiography techniques by providing more accurate measurements on anatomical elements of the cervical spine that could facilitate diagnosis and preoperative planning, thus avoiding possible trauma to the vertebral arteries during tissue dissection and instrument application.

Ethnic differences in pedicle and bony spinal canal dimensions calculated from computed tomography of the cervical spine: a review of the English-language literature

PURPOSE

The aims of this study were to review published data on pedicle dimensions and bony spinal canal diameters calculated from CT examinations of the cervical spine through the English-language literature and analyze these data for ethnic disparities and similarities.

MATERIALS AND METHODS

The authors reviewed the literature on "pedicle" and "spinal canal" by conducting a bibliographic search using PubMed, Ovid MEDLINE, and Science Direct from January 1985 to December 2010. After evaluating all of the selected abstracts, we ultimately selected 19 studies involving living subjects: 12 studies on pedicle dimensions and 7 on spinal canal diameters. The four parameters, pedicle width (PW), pedicle transverse angle (PTA), anterior-posterior diameter of the spinal canal (APD), and transverse diameter of the spinal canal (TD), were analyzed at the relevant levels from C3 to C7. In addition, the values for pedicle dimensions and spinal canal diameters in the European/American populations were compared using the data from Asian populations as a baseline.

RESULTS

The smallest mean PW was found at C4 in the male (5.1 mm) and female populations (4.1 mm); the largest mean PW was found at C7 in both male (7.7 mm) and female populations (7 mm). The PW in males was greater than in females at the majority of levels. The smallest mean PTA was found at C7 in both male (33.4°) and female populations (33°); the largest mean PTA was found at C4 in both male (53.2°) and female populations (52.1°). The overall PW, PTA, APD, and TD ratio of European/American to Asian populations was 91.4-98.8, 99.6-106.2, 110.7-122, and 100-108.3 %, respectively.

CONCLUSION

Although our cervical spine CT data were suggestive of possible ethnic differences in spinal canal morphology, our analysis failed to identify significant ethnic disparity in pedicle dimensions despite potential differences in physique between populations.

Cervical myelopathy due to single level prolapsed disc and spondylosis: a comparative study on outcome between two groups

This article describes a retrospective study on myelopathy, induced by monosegmental prolapsed disc and spondylosis. To assess pre- and postoperative clinical and radiological findings related to myelopathy, and factors influencing the outcome, 20 disc herniation (group A) and 11 spondylosis patients (group B) were studied. Average duration of myelopathy in groups A and B were 3 and 8.7 months, respectively. Anterior decompression and fusion were performed. Pre- and postoperative clinical and radiological findings and outcomes were assessed. Average preoperative disc heights were 85.9% of normal in group A and 72.7% in group B. Average anteroposterior canal diameter and Pavlov ratio at diseased level were 13.9 mm and 0.81 in group A, respectively, and 12.1 mm and 0.78 in group B. Five group A (25.0%) and four group B cases (36.4%) had radiculopathy. Cord compressions among 20 group A patients were median in seven and paramedian in 13. In the 11 group B patients, nine were median and two were paramedian. High signal intensity was observed in 19 group A and ten group B patients. Postoperative regression of T(2)-weighted high signal intensity in 14 group A (73.7%) and two group B patients (20.0%) was observed. Preoperative JOA scores in groups A and B were 10.3 and 12.8, respectively, which became 66.2 and 22.5 postoperatively. Neurological recovery was poorer in group B than in group A. Outcome was influenced by chronicity of myelopathy.

Prevalence of concurrent lumbar and cervical arthrosis: an anatomic study of cadaveric specimens

STUDY DESIGN

An anatomic, epidemiologic study of lumbar and cervical arthrosis in cadaveric spines.

OBJECTIVE

Determine the prevalence of combined lumbar and cervical arthrosis in a large population sample and examine its association with age, sex, and race.

SUMMARY OF BACKGROUND DATA

Lumbar and cervical arthrosis are common radiographic findings, which have both been linked to pain. However, the prevalence of and temporal relationship between combined lumbar and cervical arthrosis has not been defined.

METHODS

The lumbar and cervical segments from 234 cadaveric spines were examined by a single investigator for evidence of endplate and facet arthrosis. Arthrosis at each endplate and facet was graded on a continuum from 0 to IV. Race, age at death, and sex of each specimen was recorded.Stepwise multiple linear regression was used to analyze any association between race, age, sex, lumbar arthrosis, and cervical arthrosis. Factors with P-values <0.05 remained in the analysis. T tests for matched samples were used to analyze any difference between the mean lumbar and cervical arthrosis severity among patients within the same decades of life.

RESULTS

Concurrent lumbar and cervical arthrosis was present in 80% of the study population. Stepwise multiple linear regression revealed significant (P < 0.01) associations between lumbar arthrosis and cervical arthrosis and between age and cervical arthrosis. Race and sex did not correlate with lumbar or cervical arthrosis. In addition, patients in age groups 20 to 29, 30 to 39, 40 to 49, 50 to 59, 60 to 69, 70 to 79, and 80 to 89 demonstrated more severe (P < 0.01) lumbar arthrosis in comparison to cervical arthrosis.

CONCLUSION

Concurrent lumbar and cervical arthrosis is a common condition. Lumbar arthrosis and advancing age are associated with cervical arthrosis independent of race and sex. Lumbar arthrosis precedes cervical arthrosis. These findings suggest an underlying systemic component for spinal osteoarthritis.

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.

Myelography using flat panel volumetric computed tomography: a comparative study in patients with lumbar spinal stenosis

STUDY DESIGN

The technical feasibility of flat panel volumetric computed tomography (FPVCT) for lumbar myelographic imaging was evaluated in 20 patients and compared with multislice computed tomography (MSCT).

OBJECTIVE

The purpose of this study was to determine the feasibility and sensitivity of FPVCT for myelographic imaging in lumbar spinal stenosis.

SUMMARY AND BACKGROUND DATA

In the diagnosis of spinal stenosis, myelography and myelo-computed tomography (PCT) have been performed routinely for nearly 30 years. Rotational angiography is a new technique initially developed to visualize vessels but also allowing multiplanar reconstructed (MPR) CT images. The spatial resolution of FPCVT is even higher than in current MSCT. To date, this technique has not been evaluated for use in myelography.

METHODS

In 20 patients referred for CT for evaluation of low back pain, lumbar myelography was performed on a biplane angiography system equipped with flat panel detectors. FPVCT was provided from a volume data set out of a rotational acquisition and compared with MSCT performed on a 4-slice CT scanner. Hereby, for a total of 100 disc levels (range from L1-L2 to L5-S1), the narrowest dural cross-sectional diameter (D-CSD) and the dural cross-sectional area (D-CSA) referred to MSCT and FPVCT were calculated.

RESULTS

Mean D-CSD and C-CSA for all disc levels as measured by MSCT was 9.26 +/- 3.0 mm and 63.2 +/- 10.8 mm, respectively. Compared with D-CSD and C-CSA measured by FPVCT, there was no statistically significant difference (9.48 +/- 2.9 mm and 64.7 +/- 11.2 mm, respectively; P > 0.89). The most pronounced lumbar spinal stenosis was seen on L4/5 level with D-CSD of 6.6 +/- 3.6 mm and 6.8 +/- 3.2 mm and D-CSA of 53.7 +/- 14.7 mm and 55.0 +/- 14.3 mm, respectively.

CONCLUSION

In all patients, the diagnostic quality of the reconstructed FPVCT slice images is comparable to those acquired by MSCT. Using FPVCT, radiographic myelography and postmyelographic computed tomography can be performed with less radiation in a single session at the same imaging system.

Evaluation of the internal vertebral venous plexus, vertebral canal, dural sac, and vertebral body via nonselective computed tomographic venography in the cervical vertebral column in healthy dogs

OBJECTIVE

To evaluate nonselective computed tomographic (CT) venography for evaluating the cervical internal vertebral venous plexus (IVVP), define the diameter and area dimensions of the IVVP, and determine the relationship between dimensions of the cervical IVVP and other vertebral components in medium-sized dogs. Animals-6 healthy dogs that weighed 18 to 27 kg. Procedure-Helical CT scans were performed from C1 to C7 before and after IV injection of contrast medium (480 mg of iodine/kg) and a continuous infusion (240 mg of iodine/kg). Image data were transferred to a CT workstation, and measurements were performed on displayed transverse images. Diameter and area measurements of the vertebral canal, dural sac, IVVP, and vertebral body were obtained at C3 to C7.

RESULTS

Opacification of vertebral venous structures was achieved in all dogs with no adverse reactions. Sagittal diameters of the IVVP for C3 to C7 ranged from 0.6 to 3.2 mm. Transverse diameters ranged from 2.32 to 5.74 mm. The IVVP area represented 12.4% of the mean vertebral canal transverse area and 30.61% of the mean vertebral epidural space area. Area measurements of the IVVP were significantly correlated with vertebral canal area and dural sac area.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that nonselective CT venography is a safe, sensitive method for performing morphometric assessments of the cervical IVVP in dogs. Findings support the theory that there may be a physiologic or developmental relationship between cervical vertebral canal components.

Degenerative disorders of the lumbar and cervical spine

Degenerative disorders in the spine are normal, age-related phenomena and largely asymptomatic in most cases. Conservative management of lumbar and cervical spondylosis is the mainstay of treatment, and most patients with symptomatic degenerative changes respond appropriately with nonsurgical management. Surgical intervention can be considered an appropriate and viable option when conservative measures have failed. Treatment options should always be directed toward the specific nature and location of the patient's individual pathology. Although current standards in the surgical management of lumbar and cervical degenerative disorders include discectomy, neural decompression, and instrumented spinal arthrodesis, new approaches that address this often-challenging clinical entity are on the horizon.

Neural space integrity of the lower cervical spine: effect of anterior lesions

STUDY DESIGN

A repeated measures study design was used to evaluate intervertebral foramen and spinal canal neural space integrity subsequent to sequential surgical anterior lesions of the lower cervical spine in a human cadaver model.

OBJECTIVE

To investigate the degree to which sequential ablation of anterior vertebral elements places the neural structures at risk of injury.

SUMMARY OF BACKGROUND DATA

Classic instability management utilizing functional-structural criteria has been widely examined associating specific lesions or pathologies to a degree of mechanical instability. Unfortunately, these studies have not assessed the neuroprotective role of the vertebral column.

METHODS

Eight human cadaveric lower cervical spines were instrumented with transducers to measure geometrical changes in the intervertebral foramen and spinal canal. Sequential lesions were performed anteriorly on the anterior and middle column structures (C4-C5 disc and C5 vertebra), and their effects on neural space integrity and range of motion were measured under physiologic loading.

RESULTS

Range of motion significantly increased with successively more destructive lesions, whereas the spinal canal exhibited few changes. Intervertebral foramen integrity was statistically reduced for corpectomy (66% intact), hemivertebrectomy (62% intact) and full vertebrectomy (57% intact) lesions when loaded in concomitant extension and ipsilateral bending (4 Nm).

CONCLUSIONS

Lesions more extensive than a surgical discectomy have significant effects on the cervical neural foramens specifically when the spine is placed in extension, ipsilateral bending, and coupled ipsilateral bending and extension. Our study establishes a quantitative relationship between the risk of neural structure compression and anterior lesions of the spinal column under physiologic loading.

MR Image–based Grading of Lumbar Nerve Root Compromise due to Disk Herniation: Reliability Study with Surgical Correlation

A system for grading lumbar nerve root compromise (no compromise, contact of disk material with nerve root, deviation of nerve root, and compression of nerve root) was tested in the interpretation of routine magnetic resonance images of 500 lumbar nerve roots in 250 symptomatic patients. Intra- and interobserver reliability was assessed for three independent observers. In the 94 nerve roots evaluated at surgery, surgical grading was correlated with image-based grading. kappa statistics indicated substantial agreement between different readings by the same observer and between different observers (for intraobserver agreement, kappa = 0.72-0.77; for interobserver agreement, kappa = 0.62-0.67). Correlation of image-based grading with surgical grading was high (r = 0.86). The image-based grading system enabled reliable evaluation and reporting of nerve root compromise.

Imaging of the spine and nerve roots

Advances in imaging have greatly improved the ability to display spine anatomy and pathology. This article describes the imaging findings in degenerative, traumatic, infectious, and neoplastic disease. Anatomic information, however, must be tempered by an understanding of asymptomatic disease and interpreted in the context of the clinical syndrome.

Neural space integrity of the lower cervical spine: effect of normal range of motion

STUDY DESIGN

An experimental investigation of intervertebral foramen and spinal canal neural space integrity was performed throughout physiologic range of motion of the lower cervical spine in intact human cadaver specimens.

OBJECTIVE

To investigate cervical positions that might place the neural tissues of the spine in heightened risk of injury. To meet this objective the following hypotheses were tested: 1) spinal canal integrity varies with specific normal range of motion positions of the lower cervical spine, and 2) intervertebral foramen integrity is dependent on and unique for different physiologic positions of the lower cervical spine.

SUMMARY OF BACKGROUND DATA

Cervical spine injuries are frequently associated with compressive damage to neurologic tissues and consequently poor clinical outcomes. Neurologic injury typically occurs from disc, ligamentous, or bony occlusion of the spinal canal and intervertebral foraminal spaces dynamically during an injury event or with abnormal alignment and position after the injury event. Prior studies have shown pressure and geometric changes in cervical spine neural spaces in certain cervical spine positions. However, to the authors' knowledge, this is the first research effort aimed at elucidating the integrity of the cervical spine neural spaces throughout the normal physiologic range of motion.

METHODS

The authors instrumented 17 fresh-frozen unembalmed cadaveric human cervical spines (C3-C7) with specially designed intervertebral foramen occlusion transducers and a spinal canal occlusion transducer. The specimens were loaded with pure bending moments to produce simulated physiologic motions of the lower cervical spine. The resulting occlusion profiles for the intervertebral foramen and spinal canal were recorded along with the 6-degree of freedom position of the cervical spine. Because these occlusion measurements describe the ability of the spine to preserve the space for the neural structures, the authors define this neuroprotective role of the vertebral column as neural space integrity.

RESULTS

The range of motion developed experimentally in this study compared well with published reports of normal cervical motion. Thus, subsequent changes in neural space integrity may be regarded as resulting from normal human cervical spine motion. No significant change in the spinal canal space was detected for any physiologic motion; however, intervertebral foramen integrity was significantly altered in extension, ipsilateral bending, combined ipsilateral bending and extension, and combined contralateral bending with extension when compared with intact upright neutral position.

CONCLUSIONS

This study defines the range of neural space integrity associated with simulated physiologic motion of the lower cervical spine in an experimental setting. This information may be useful in comparing neural space changes in pathologic conditions and may enhance refinement of neurologic injury prevention strategies.