Diameter Of Cervical Spinal Canal Research Articles

CT correlation of spinal canal diameter with pedicle size for safer posterior cervical pedicle screw fixation.

Utilizing computed tomography (CT) studies, we correlated cervical spinal canal diameters (SCDs) with pedicle size between the C3 and C7 levels to more safely perform posterior cervical surgery. We retrospectively analyzed CT studies for 71 patients with cranial or spinal disorders and correlated the cervical SCD with the pedicle outer width (POW) between the C3 and C7 levels. Patients were divided into normal (SCD ≥12 mm at any level, n = 30) and stenosis groups (SCD <12 mm at any level, n = 41). C7 exhibited the largest SCD and POW values, while C3 and C4 exhibited the smallest SCD and POW values. Moderate correlations (r = 0.3, P = 0.002) were observed at the C3 and C4 levels but no significant correlations were observed from the C5 to C7 levels. For SCD values, the normal group demonstrated significantly greater values between the C3 and C7 levels versus the stenosis group. For POW values, only the C4 level differed significantly between the two groups (P = 0.014, Mann-Whitney U-test). Preoperative pedicle size evaluation remains an essential manoeuvre before performing cervical C3-C7 pedicle screw placement. In 71 cervical CT studies, we found no consistent correlation between POW and SCD values, indicating that it is difficult to estimate POW values based on spinal canal size.

Morphometric study of cervical spinal canal and transverse foramen diameter using computed tomography: Sex difference and relationship to age in Turkish population.

Accurate and detailed spinal canal diameter transverse foraminal morphometry measurements are essential for understanding spinal column-related diseases and surgical planning, especially for transpedicular screw fixation. This is especially because lateral cervical radiographs do not provide accurate measurements. This retrospective study was conducted to measure the dimensions of the transverse foramen sagittal and transverse diameter (TFD), spinal canal diameter, the distance of the spinal canal from the transverse foramina at the C1 to C7 cervical level, and the anteroposterior and TFDs in the Turkish population. A total of 150 patients who underwent cervical spine computed tomographic imaging with a 1:1 gender ratio were enrolled in the study. The sagittal and TFDs of the spinal canal, the distance of the spinal canal from the transverse foramen, and anteroposterior and TFDs in both right and left sides for all cervical levels C1 to C7. Foramina transversal diameters were measured using imaging tools of the imaging software in the radiology unit. The mean age of the study group was 47.99 ± 18.65 (range, 18-80) years. The majority of the distances of the spinal canal from the transverse foramen and antero-posterior (AP) & transverse (T) diameters for cervical vertebrae were significantly higher in male patients (P < .05). However, between age groups, a few measurements were found significantly different. Some of the distances of the spinal canal from the transverse foramen were significantly higher on the right side whereas all AP & T diameters were significantly higher on the left side in both male and female patients (P < .05). Almost all measurements were significantly higher on the left side for younger patients (<65 years) whereas only AP & T diameters were significantly higher on the left side for older patients (>65 years) (P < .05). Computed tomographic imaging is better than conventional radiographs for the preoperative evaluation of the cervical spine and for a better understanding of cervical spine morphometry. Care must be taken during transpedicular screw fixation, especially in female subjects, more so at the C2, C4, and C6 levels due to decreased distance of the spinal canal from the transverse foramina.

Fiberoptic bronchoscopy versus video laryngoscopy guided intubation in patients with craniovertebral junction instability: A cinefluroscopic comparison.

Background: Manipulation during endotracheal intubation in patients with craniovertebral junction (CVJ) anomalies may cause neurological deterioration due to underlying instability. Fiberoptic-bronchoscopy (FOB) is better than video laryngoscope (VL) for minimizing cervical spine movement during intubation. However, evidence suggesting superiority of FOB in patients with CVJ instability is lacking. We prospectively compared dynamic movements of the upper cervical spine during intubation using FOB with VL in patients with CVJ anomalies.Methods: A prospective, randomized, and clinical trial was conducted in 62 patients of American Society of Anaesthesiologist Grade I-II aged between 12 and 65 years with CVJ anomalies. Patients were randomized for intubation under general anesthesia with either VL or FOB. The intubation process was done with application of skeletal traction and recorded cinefluroscopically. The dynamic interrelationship of bony landmarks (horizontal, vertical, and diagonal distances between fixed points on posterior C1 and C2) was analyzed to indirectly calculate alteration of the upper cervical spinal canal diameter (at CVJ). Atlanto-dental interval (ADI) was calculated wherever possible.Results: The alteration in canal diameter (using bony landmarks) at CVJ during intubation was not significant with the use of either VL or FOB (P > 0.05). In 41 patients, where ADI could be measured, ADI was reduced (increased spinal canal diameter) in a greater number of patients in VL group when compared to FOB group (P < 0.05).Conclusion: Using rigid skull traction, intubation under general anesthesia with VL offers similar advantage as FOB in terms of the spinal kinematics in patients with CVJ anomalies/instability. Nevertheless, greater number of patients intubated with VL may have an advantage of increased cervical spinal canal diameter when compared to FOB.

Prevalence of cervical anterior and posterior spondylolisthesis and its association with degenerative cervical myelopathy in a general population

The purpose of this study was to examine the prevalence of cervical spondylolisthesis according to age and vertebral level and its association with degenerative cervical myelopathy (DCM). This study included 959 participants (319 men and 640 women; mean age, 66.4 years) in the Wakayama Spine Study from 2008 to 2010. The outcome measures were cervical spinal canal (CSC) diameter at C5 level on plain radiographs, the degree of cervical spondylosis using the Kellgren-Lawrence (KL) grade, cervical cord compression on sagittal T2-weighted magnetic resonance imaging, and physical signs related to DCM. The prevalence of cervical anterior and posterior spondylolisthesis was investigated in men and women by age. In addition, logistic regression analysis determined the association between CSC diameter, posterior spondylolisthesis, and clinical DCM after overall adjustment for age, sex, and body mass index. The prevalence of anterior spondylolisthesis was 6.0% in men and 6.3% in women, and that of posterior spondylolisthesis was 13.2% and 8.9%, respectively. In addition, posterior spondylolisthesis prevalence increased with age in both sexes. Logistic regression analysis revealed that developmental canal stenosis (≤13 mm) and cervical posterior spondylolisthesis are independent significant predictive factors for DCM. The prevalence of degenerative cervical posterior spondylolisthesis was increasing with age and more frequent in men than in women. Narrow canal and degenerative cervical posterior spondylolisthesis on X-ray may be useful in predicting or diagnosing DCM.

CT morphometric analysis of the cervical spinal canal with special reference to the correlation with the vertebral level

BackgroundNarrowness of the spinal canal is associated with the development of cervical myelopathy. While studies have addressed the sagittal diameter of the cervical spinal canal, few evaluated the correlation between the size of the spinal canal and the vertebral level. We addressed this issue. MethodsOur retrospective study included 102 patients with cranial or spinal disorders. We examined the correlation between the cervical spinal canal diameter (SCD) at C1 to C7 and the inner anteroposterior diameter (IAPD) of the atlas on CT images. ResultsAt C1, the SCD was largest, at C4 it was smallest. While there was a strong correlation between the IAPD and the SCD at C1 (r = 0.8), the correlation between the size of the atlas and the SCD at C4 to C7 was weak (r = 0.2–0.3). We divided our patients into a normal group (n = 34, SCD ≥ 12 mm at any levels) and a stenosis group (n = 68, SCD < 12 mm at all levels). The mean SCD at C2 to C7 was significantly larger in the normal group. There was no significant difference between the two groups with respect to the IAPD and the SCD at C1. ConclusionsThe size of the subaxial spine does not necessarily affect the size of the atlas. The pathophysiology of spinal canal stenosis should be considered separately at the C1- and the subaxial level.

Measurement of cervical spinal canal diameter by radiographs to study the degree of cervical spinal canal stenosis in an Indian population; Predictive value of Torgs ratio to assess cervical spinal canal stenosis

Cervical myelopathy a debilitating degenerative condition occurs due to cervical spinal canal stenosis, the incidence of which increases significantly with age and is more common above the age of 50 years. Imaging of the spinal canal is an indispensable procedure for evaluation of cervical myelopathy and standard lateral radiographs remain the recommended initial imaging study of choice. The present study was undertaken to measure the cervical spinal canal diameter by lateral radiographs of the cervical spine and to study the degree of cervical spinal canal stenosis in symptomatic patients and asymptomatic cases. The canal body ratio and its reliability to assess cervical spinal canal stenosis and risk of cervical myelopathy was evaluated.In this study 200 cases who presented to the radiology department for radiographs of cervical spine, were divided into symptomatic and asymptomatic cases and were grouped age wise. Measurements of the cervical vertebral body and cervical spinal canal were taken. Torg ratio was assessed. The measurements were analyzed statistically and results tabulated.Cervical spinal canal diameter was lower in symptomatic cases as compared to asymptomatic cases across all age groups and the lowest value was measured at C3 level. All the symptomatic cases had Torg ratio of less than 0.82, and that of C3 was lowest. The data analysis showed the sensitivity of the Torg ratio as 100%. 40% of patients above 50 years were symptomatic and had cervical spinal canal stenosis on lateral radiographs.Our results suggest that plain films can estimate the cervical spinal canal midsagittal diameter and be used as a first step examination for the evaluation of cervical spinal stenosis. The importance of canal body ratio in lateral cervical radiographs for determining the stenosis of cervical spinal canal is confirmed.

Do universal critical spine dimensions exist

The effective spinal canal diameter is the fundamental index which will determine whether a patient of any compressive cervical spine pathology will get neurological deficit or not. So we analysed this index in our subset of population. 180 subjects with normal or near normal cervical spine magnetic resonance imaging were included. Antero-posterior diameter and transverse diameter of spinal canal from C3 to C7 was measured. Similarly spinal cord antero-posterior and transverse diameters were measured. Space available for cord was calculated at each of these levels in both sexes as the difference between the antero-posterior diameter of the spinal canal and that of the spinal cord. The mean value with standard deviation of cervical spinal canal diameter antero-posterior diameter at C3, C4, C5, C6 and C7 was 13.69±1.248, 13.34±1.186, 13.15±1.233, 13.12±1.275 and 13.73±1.226 mm respectively. The spinal cord antero-posterior diameter at the same level was 7.61±0.728, 7.58±0.677, 7.40±0.653, 7.12±0.657 and 6.69±0.622 mm respectively. The mean cervical spinal canal diameter of the local population in our region is different from the rest of the country. This has two implications; first the ancestral lineage is matching with some remote races of the world for which a detailed study may be needed. Secondly the dimension at which we call critical stenosis may be different in the region as compared with the rest of the country.

Morphometric analysis of cervical spinal canal diameter, transverse foramen, and pedicle width using computed tomography in Indian population.

Accurate and detailed measurements of spinal canal diameter (SCD) and transverse foraminal morphometry are essential for understanding spinal column-related diseases and for surgical planning, especially for transpedicular screw fixation. This is especially because lateral cervical radiographs do not provide accurate measurements. This study was conducted to measure the dimensions of the transverse foramen sagittal and transverse diameters (SFD, TFD), SCD, and the distance of spinal canal from the transverse foramina (dSC-TF) at C1-C7 level in the Indian population. The study population comprised 84 male and 42 female subjects. The mean age of the study group was 44.63 years (range, 19-81 years). A retrospective study was conducted, and data were collected and analyzed for patients who underwent cervical spine computed tomography (CT) imaging for various reasons. One hundred and twenty-six patients were included in the study. Detailed readings were taken at all levels from C1-C7 for SCD, SFD, TFD, and dSc-TF. Values for male and female subjects were separately calculated and compared. For both the groups, the widest SCD were measured at the C1 level and the narrowest SCD at the C4 level. The narrowest SFD was measured at C7 for both male and female subjects on the right and left sides. The widest SFD was measured at C1 both for male and female subjects on the right and left side. The narrowest TFD on the left side was measured at C7 for male and at C1 for female subjects. The narrowest mean distance of dSC-TF was found to be at C4 for both male and female subjects on both left and right side. The computed tomographic (CT) imaging is better than conventional radiographs for the preoperative evaluation of cervical spine and for better understanding cervical spine morphometry. Care must be taken during transpedicular screw fixation, especially in female subjects, more so at the C2, C4, and C6 levels due to a decrease in the distance of dSC-TF.

Clinical characteristics of acute central cervical spinal cord injury with only upper extremity involvement and with both upper and lower extremity involvement

Objective To compare and analyze the clinical characteristics of acute central cervical spinal cord injury with only upper extremity involvement and with both upper and lower extremity involvement. Methods A retrospective case control study was made on clinical data of 76 patients with acute central cervical spinal cord injury hospitalized from January 2010 to December 2013. Nerve injury involved was only upper extremity in 39 patients (upper extremity group), but both upper and lower extremities in 37 patients (upper-and lower-extremity group). In upper extremity group, there were 35 males and four females, age was 21-80 years [(52.5±13.4)years], injury resulted from traffic accidents in 24 patients, ground-level falls in eight, high-level falls in six and heavy-object hit in one, and level of injury was C3/4in 16 patients, C4/5in 14 and C5/6in nine. In upper- and lower-extremity group, there were 30 males and seven females, age was 36-78 years [(59.6±9.7)years], injury resulted from traffic accidents in 16 patients, ground-level falls in 11, high-level falls in seven and heavy-object hit in three, and level of injury was C3/4in nine patients, C4/5in 18 and C5/6in 10. Sagittal diameter of the cervical spinal canal, maximal canal compromise, maximal spinal cord compression, degenerating factors of the cervical spine and treatment protocols were determined. Upper extremity function was assessed with the American spinal injury association (ASIA) score. Results There were significant differences between upper extremity group and upper- and lower-extremity group in sagittal diameter of the cervical spinal canal [(7.5±1.5)mm ∶(6.8±1.2)mm], maximal canal compromise [(28.9±9.6)% ∶(34.9±10.6)%], ASIA score at admission[(31.6±11.8)points ∶(22.7±11.3)points)] and ASIA score at last follow-up [(46.2±4.2)points ∶(40.2±4.0)points](P 0.05). Lower prevalence of posterior osteophyte of the vertebral body was noted in upper extremity group than upper- and lower-extremity group (15% ∶51%) (P<0.01). Twenty patients (49%) in upper extremity group were surgically treated, while 31 patients (84%) in upper-and lower-extremity group (P<0.05). Conclusions Compared to acute central cervical spinal cord injury with both upper and lower extremity involvement, the injury with only upper extremity involvement is much common in younger patients and is characterized by lowered frequency of osteophyte, large buffer space, mild nerve damage, preferred non-operation treatment and good prognosis. Key words: Spinal cord injuries; Magnetic resonance imaging; Neurological status

Roentgenographic and computerized tomography based morphometric analysis of cervical spinal canal diameters to establish normative measurements in an Indian population.

Compressive cervical myelopathy secondary to degenerative changes in the cervical spine is a common cause of neurologic morbidity in the elderly. Identification of canal stenosis and addressing it surgically in addition to the obvious compressive lesions is essential to obtain satisfactory results. We attempt to define the saggital and transverse diameters in a normal adult population presenting at our centre with head injuries. We found that the values were lower than those reported in comparable studies for a western population, and also that the dimensions in women are significantly lower than in men.

Anterior slip phenomenon of the vertebrae after corpectomy surgery and its clinical significance

To investigate the anterior slip phenomenon of the vertebrae after corpectomy surgery and its clinical significance. The clinical data of 164 patients with cervical spondylotic myelopathy treated from January 2010 to April 2013 were retrospectively analyzed. There were 88 males and 76 females, aged from 38 to 74 years old with the mean of 56.2 years. Among them, 31 cases for C₄ corpectomy, 87 cases for C₅ corpectomy, 46 cases for C₆ corpectomy. Preoperative and postoperative distance of posterior wall of vertebral canal to the line of adjacent upper vertebral bodies anterosuperior border and lower vertebral bodies anteroinferior border was measured by CT in cervical sagittal middle layer scanning as the center, anterior slip degree of the vertebrae after operation was evaluated. The fast clustering method was used, the vertebral shift distance as variable, according to the size of the forward distance, 90 cases classified as group 1(forward greatly group), and the 74 cases classified as group 2(forwad short group). The relationships on the anterior slip of the vertebrae and cervical curvature, surgical segment were analyzed. Japanese Orthopaedic Association (JOA) scores and its improvement rate were observed before and after operation, and the relationships on the anterior slip of the vertebrae and sagittal plane diagonal diameter of spinal canal, clinical effect were analyzed. All the patients were followed up from 12 to 48 months with an average of 29.5 months. All operative vertebrae occurred anterior slip with different degree after corpectomy surgery, the maximum was 3.52 mm and minimum was 1.12 mm, with an average of (2.14±1.02) mm. According to the clustering method, the anterior slip distance with (3.07±0.21) mm classified as forward greatly group(90 cases, 54.9%) and the anterior slip distance with (1.55±0.32) mm classified as forwad short group(74 cases, 45.1%). There was no significant difference between anterior slip distance and operation segments(χ²=0.01, P=0.996). Cervical curvature index and anterior slip distance of operated vertebra had a positive correlation (r=0.724). The incidence of reduction of the diagonal diameter of cervical spinal canal in forward greatly group was higher than that of forwad short group(χ²=4.45, P=0.035). The patients with unsatisfactory efficacy appeared obvious anterior slip of the vertebrae after corpectomy than the patients with satisfactory efficacy(P<0.05). Corpectomy of the cervical spine can result in vertebral forward displacement trend, and obvious displacement may cause the secondary compression of the spinal cord.

Kinematic analysis of cervical spine canal diameter and its association with grade of degeneration.

To investigate the cervical spinal canal diameters variance under positional MRI, and also the relationship between cervical canal diameter variance rate and grade of degeneration. From January 2013 to January 2015, a consecutive of 273 symptomatic patients (166 males and 207 females) with an average age of 44.6years (range 21-89years) underwent positional cervical MRI. T2-weighted sagittal images of 1638 cervical intervertebral discs from 273 subjects were classified into five grades. The canal diameter and canal diameter variance rate at three positions and their comparison among five grade of degeneration were evaluated. The measurements were tabulated and analyzed using SPSS. 13.0. p values less than 0.05 were considered to indicate a statistically significant difference. The sagittal cervical canal diameter at the C5/6 level were the smallest compared with the other levels regardless of neutral, flexion or extension positions, C5/6 level had the largest canal diameter variance rate in both flexion and extension (8.14∓0.38 and 7.81∓0.31%, respectively), second was C4/5 level (7.65∓0.39 and 7.67∓0.32%, respectively). A total of 1638 discs were classified into 5 groups, each level showed the similar tendency that no matter what position, with the increasing grade of degenerative disc degree, spine canal diameter decreased gradually. For C5/6 under extension and flexion position, significant difference was also noted between grade 2 and 3; For C4/5 under extension position, significant difference existed between grade 1 and 2, grade 1 and 3, while under flexion position, significant difference existed between grade 2 and 4, and the results also showed no significant difference at the same degree of degeneration on both levels between extension and flexion position. C5/6 and C4/5 is of higher risk of suffering SCI than other levels, C4/5 level predispose SCI at earlier stage than C5/6, patients presenting with intermediate signal and slight decreased disc height on T2 weighted MRI at C4/5 level should be paid attention.

Cervical spinal canal narrowing in idiopathic syringomyelia.

The cervical spine in Chiari I patient with syringomyelia has significantly different anteroposterior diameters than it does in Chiari I patients without syringomyelia. We tested the hypothesis that patients with idiopathic syringomyelia (IS) also have abnormal cervical spinal canal diameters. The finding in both groups may relate to the pathogenesis of syringomyelia. Local institutional review boards approved this retrospective study. Patients with IS were compared to age-matched controls with normal sagittal spine MR. All subjects had T1-weighted spin-echo (500/20) and T2-weighted fast spin-echo (2000/90) sagittal cervical spine images at 1.5T. Readers blinded to demographic data and study hypothesis measured anteroposterior diameters at each cervical level. The spinal canal diameters were compared with a Mann-Whitney U test. The overall difference was assessed with a Friedman test. Seventeen subjects were read by two reviewers to assess inter-rater reliability. Fifty IS patients with 50 age-matched controls were studied. IS subjects had one or more syrinxes varying from 1 to 19 spinal segments. Spinal canal diameters narrowed from C1 to C3 and then enlarged from C5 to C7 in both groups. Diameters from C2 to C4 were narrower in the IS group (p < 0.005) than in controls. The ratio of the C3 to the C7 diameters was also smaller (p = 0.004) in IS than controls. Collectively, the spinal canal diameters in the IS were significantly different from controls (Friedman test p < 0.0001). Patients with IS have abnormally narrow upper and mid cervical spinal canal diameters and greater positive tapering between C3 and C7.

The Evaluation and Observation of "Hidden" Hypertrophy of Cervical Ligamentum Flavum, Cervical Canal, and Related Factors Using Kinetic Magnetic Resonance Imaging.

Study Design Retrospective cohort study. Objective The objective was to measure the change of flavum ligament diameter during positional changes of the cervical spine using kinetic magnetic resonance imaging (MRI) and to examine the correlational diameter changes of the flavum ligament, disk bulging, and the spinal canal from extension to flexion positions. Methods One hundred eight-nine patients underwent kinetic MRI in neutral, extension, and flexion positions. The diameters of cervical ligamentum flavum, disk bulging, and cervical spinal canal and the disk degeneration grade and Cobb angles were measured from C2–C3 to C7–T1. Results In all, 1,134 cervical spinal segments from 189 patients were included. There was a 0.26 ± 0.85-mm average increase in the diameter of the ligamentum flavum from flexion to extension, and 62.70% of the segments had increased ligamentum flavum diameter from flexion to extension. For all segments of the 189 patients, the cervical spinal canal diameters had an average decrease at the disk level of 0.56 ± 1.21 mm from flexion to extension. For all segments with cervical spinal canal narrowing ≥1 mm from flexion to extension view, the ligamentum flavum diameters at C3–C4 to C5–C6 had significant increases compared with patients with spinal canal narrowing < 1 mm (p < 0.05). For patients with ligamentum flavum hypertrophy of ≥1 mm from the flexion to extension view, the cervical spinal canal diameters at C2–C3, C4–C5, and C5–C6 had significant decreases compared with patients with ligamentum flavum hypertrophy of <1 mm (p < 0.05). Conclusion The “hidden” hypertrophy of ligamentum flavum was significant at C4–C5 and C5–C6 and significantly contributes to the stenosis of cervical spinal canal in the extension position.

Transcranial magnetic stimulation but not MRI predicts long-term clinical status in cervical spondylosis: a case series.

Case series. To compare transcranial magnetic stimulation (TMS) and magnetic resonance imaging (MRI) findings between patients who underwent surgery for cervical spondylotic myelopathy and those with spondylosis who were not operated upon, and to correlate these findings with clinical functionality at follow-up. Private practice. Of 16 consecutive patients with cervical spondylosis 8 underwent surgery (group I) and 8 were treated conservatively (group II). We compared TMS and MRI findings between these groups and we correlated central motor conduction times (CMCTs) and MRI-measured sagittal and parasagittal diameters of the spinal canal at baseline evaluation, with clinical functionality at 2-year follow-up. Group I CMCTs at the lower limbs correlated significantly with modified-JoA 2 years post surgery (r=-0.71, P<0.05), but MRI-measured diameters did not. In group II baseline TMS was unrevealing, contrary to significant spinal stenosis disclosed by MRI. The condition of none of these patients deteriorated at 2 years. CMCTs at the lower limbs, but not cervical spinal canal diameters, correlate with long-term functional outcome following surgical or conservative treatment.

Hyperextension injury of the cervical spine with central cord syndrome.

Traumatic central cord syndrome (TCCS) is the most commonly encountered type of incomplete spinal cord injury. TCCS typically occurs in patients over the age of 50 with a narrow spinal canal and follows an acute hyperextension injury of the cervical spine. Here, we report on the demographics of TCCS patients, their clinical course and outcomes, and the factors that may have influenced these outcomes. We conducted a retrospective folder review of patients who presented to our facility between January 2004 and December 2008 following hyperextension injury of the cervical spine and with the clinical manifestations of a central cord syndrome. Patient details were obtained from the acute spinal cord injury register at Groote Schuur Hospital and the patient folders, radiographs and magnetic resonance imaging films were reviewed. Predetermined data points were identified, tabulated and analysed, with only information from the injury-related admission being included. An ASIA motor score of ≥60 on admission or discharge correlated with an 80 % chance of being able to walk at discharge from hospital. An ASIA motor score of ≤50 on admission correlated with an 80 % chance of not walking at discharge. An ASIA motor score of ≤50 at discharge meant a patient was not only unable to walk, but required placement in a spinal injury rehabilitation centre. Further, if a patient had a cervical spinal canal diameter of ≥8 mm they had a 50 % chance of clinical improvement and nearly 80 % chance of a functional outcome. The Groote Schuur Hospital patient population differs from the international norm, particularly with respect to age and mechanism of injury. The ASIA motor score and cervical spine canal diameter proved to be useful predictors of outcome. Within our patient group, timing of surgery did not appear to influence the outcome.

The prevalence of cervical myelopathy among subjects with narrow cervical spinal canal in a population-based magnetic resonance imaging study: the Wakayama Spine Study

Background contextA narrow cervical spinal canal (CSC) is a well-known risk factor for cervical myelopathy (CM). However, no epidemiologic data of the CSC based on a population-based cohort are available. PurposeThe purpose of the study was to investigate the age-related differences in CSC diameters on plain radiographs and to examine the associated magnetic resonance imaging (MRI) abnormalities including cervical cord compression and increased signal intensity (ISI) as well as the clinical CM with the narrow CSC. Study design/settingThis was a cross-sectional study. Participant sampleData were obtained from the baseline survey of the Wakayama Spine Study that was performed from 2008 to 2010 in a western part of Japan. Finally, a total of 959 subjects (319 men and 640 women; mean age, 66.4 years) were included. Outcome measuresThe outcome measures included in the study were the CSC diameter at C5 level on plain radiographs, cervical cord compression and ISI on sagittal T2-weighted MRI, and physical signs related to CM (eg, the Hoffmann reflex, hyperreflexia of the patellar tendon, the Babinski reflex, sensory and motor function, and bowel/bladder symptoms). MethodsThe age-related differences of CSC diameters in men and women were investigated by descriptive statistics. The prevalence of MRI abnormalities and clinical CM was compared among the groups divided by the CSC diameter (less than 13, 13–15, and 15 mm or more). In addition, a logistic regression analysis was performed to determine the association of the CSC diameter with cervical cord compression/clinical CM after overall adjustment for age, sex, and body mass index. ResultsThe CSC diameter was narrower with increasing age in both men and women. The prevalence of cervical cord compression, ISI, and the clinical CM was significantly higher in the narrower CSC group. The prevalence of cervical cord compression, ISI, and CM among subjects with CSC diameter less than 13 mm was 38.0%, 5.4%, and 10.1%, respectively. In the logistic model, the CSC diameter was a significant predictive factor for the clinical CM (p<.0001). ConclusionsThis study firstly confirmed the age-related differences in CSC diameters and the significant association of the narrow CSC diameter with CM in a population-based cohort.

Experimental study on pathogenesis of syringomyelia

Objective To establish an animal model of SM in rabbits and research it's pathogenesis.Methods 16 rabbits were randomly divided into experimental group and control group,all animals were perfomed microsurgery via suboccipital midline approach.The core of pencil (diameter 0.5 mm,length 6 mm) was planted into spinal central canal via its opening in experimental group.MRI were carried out preoperation and 2,4,6,8 weeks after operation.All rabbits were executed after 8 weeks and spinal cord histological examinations were perfomed.Results The diameter of cervical spinal central canal were (0.505±0.046) mm in experimental group and (0.304 ±0.045) mm in control group,which have significance difference (t =8.787,P ＜ 0.05).The MRIT2 weighted sagittal films showed the linear high signal shadow at middle of cervical spinal cord 2 ～4 weeks after operation in experimental group and the linear high signal shadow became wider and longer in 6 ～ 8 weeks.Conclusion The SM model in rabbits were established successfully via mechanical obstruction of the opening of spinal central canal.The pathogenesis of SM pitients may be obstruction of the opening of spinal central canal caused by defferent kinds of elements. Key words: Syringomyelia; Chiari malformation; Central canal of spinal cord ; Animal model; Pathogenesis

The Torg-Pavlov ratio for the prediction of acute spinal cord injury after a minor trauma to the cervical spine

Background contextAcute cervical spinal cord injury (SCI) has been observed in some patients after a minor trauma to the cervical spine. The discrepancy between the severity of the trauma and the clinical symptoms has been attributed to spinal canal stenosis. However, to date, there is no universally established radiological parameter for identifying critical spinal stenosis in these patients. The spinal canal–to–vertebral body ratio (Torg-Pavlov ratio) has been proposed for assessing developmental spinal canal stenosis. The relevance of the Torg-Pavlov ratio for predicting the occurrence and severity of acute cervical SCI after a minor trauma to the cervical spine has not yet been established. PurposeTo investigate the Torg-Pavlov ratio values of the cervical spine in patients suffering from acute cervical SCI after a minor trauma to the cervical spine and the use of the Torg-Pavlov ratio for identifying patients at risk of cervical SCI and predicting the severity and course of symptoms. Study design/settingRetrospective radiological study of consecutive patients. Patient sampleForty-five patients suffering from acute cervical SCI and 68 patients showing no neurologic symptoms after a minor trauma to the cervical spine. Outcome measuresMidvertebral sagittal cervical spinal canal diameter and the sagittal vertebral body diameter. Calculation of the Torg-Pavlov ratio values. MethodsConventional lateral radiographs of the cervical spine (C3–C7) were analyzed to determine the Torg-Pavlov ratio values. Receiver operating characteristic curves were calculated for evaluating the classification accuracy of the Torg-Pavlov ratio for predicting SCI. ResultsThe Torg-Pavlov ratio values in the SCI group were significantly (p<.04) smaller compared with that in the control group. A Torg-Pavlov ratio cutoff value of 0.7 yielded the greatest positive likelihood ratio for predicting the occurrence of SCI. However, there were no significant differences in the Torg-Pavlov ratio values between the different American Spinal Injury Association Impairment Score groups and between patients with complete, partial, and no recovery of symptoms. ConclusionsDevelopmental cervical spinal canal stenosis assessed by the Torg-Pavlov ratio was characteristic for patients suffering from acute cervical SCI after a minor trauma to the cervical spine. Patients at risk of SCI after a minor trauma to the cervical spine can be identified by applying a Torg-Pavlov ratio cutoff value of 0.7. Other factors in addition to the spinal canal–to–vertebral body ratio affect the severity and course of symptoms as a result of cervical SCI.

Measurement of volume-occupying rate of cervical spinal canal and its role in cervical spondylotic myelopathy

To compare volume-occupying rate of cervical spinal canal between patients with cervical spondylotic myelopathy (CSM) and normal subjects, and to investigate its significance in cervical spine disease. Spiral computed tomography (CT) scan (C4-C6 cervical spine unit) was performed in 20 normal subjects and 36 cases of CSM at a neutral position, and data were transferred to the Advantage Workstation Version 4.2 for assessment. Bony canal area and fibrous canal area in each cross section, and sagittal diameters of cervical spinal canal and cervical spinal body were measured. Volume-occupying rate of cervical spinal canal was calculated using MATLAB. Cervical spinal canal ratio and effective cervical spinal canal ratio were calculated, and Japanese Orthopaedic Association score was used to assess cervical spinal cord function. Volume-occupying rate of cervical spinal canal at a neutral position was significantly higher in CSM patients as compared to normal subjects (P<0.01). There was no correlation between cervical spinal canal ratio and JOA score in CSM patients, with a Pearson's correlation coefficient of 0.171 (P>0.05). However, sagittal diameter of secondary cervical spinal canal, effective cervical spinal canal ratio and volume-occupying rate of cervical spinal canal were significantly associated to JOA score, with Pearson's coefficient correlations of 0.439 (P<0.05), 0.491 (P<0.05) and -0.613 (P<0.01), respectively. Volume-occupying rate of cervical spinal canal is an objective reflection of compression on cervical spine and spinal cord, and it is associated with cervical spinal cord function. These suggest that it may play a significant role in predicting the development of CSM.