Congenital Stenosis of the Spine-A Cross-Sectional Study of 1019 Whole-Spine Computed Tomography Scans to Determine Prevalence and Association Among Multilevel, Tandem, and Triple Region Stenosis.

BACKGOUND: Patients with congenital stenosis of the spine (CSS) present with clinical symptoms at an early age and fewer degenerative hypertrophic changes than the more common degenerative cohort. Literature is lacking in the true prevalence of CSS affecting the 3 segments of the spine in isolation, as well as in tandem in the Indian subcontinent. METHODS: Anteroposterior spinal canal diameter in axial plane computed tomography at the midvertebral level was measured in asymptomatic patients with whole-spine computed tomography. Spinal canal stenosis was defined as a diameter of <12 mm for the cervical region, <12 mm for the thoracic region, and <13 mm for the lumbar region. Single-level and multilevel stenosis, as well as tandem and triple-region stenosis, were evaluated. RESULTS: The results show the prevalence of CSS as 16.6%, 11.5%, and 20.1% involving the cervical, thoracic, and lumbar spine, respectively. Single-level stenosis affected 90.6%, 94%, and 79.8% of the patients with cervical, thoracic, and lumbar CSS, respectively. Tandem stenosis affected 10.4% of the population (n = 104), with cervicolumbar stenosis being the most prevalent (n = 51, 5%). The presence of CSS in any one segment of the spine was significantly associated with the presence of stenosis at one of the other segments (P < 0.05). Triple-region stenosis was seen in 0.3% (n = 3) patients. CONCLUSIONS: The prevalence of cervical, thoracic, lumbar and tandem stenosis from our study is established at 16.6%, 11.5%, 20.1%, and 10.4%. Additionally, our study demonstrates the association between stenosis of the different regions of the spine.

Thoracolumbar stenosis and neurologic symptoms: Quantitative MRI in achondroplasia.

BACKGROUND AND PURPOSE: Whole-spine magnetic resonance imaging (MRI) studies, to identify structural abnormalities associated with the development of symptomatic spinal stenosis in achondroplasia. METHODS: Forty-two subjects with achondroplasia were grouped into four age-related categories. Congenital spinal deformities (vertebral body and disc height, interpedicular distance), acquired spinal degenerative changes, thoracic kyphotic (TK) angle, thoracolumbar kyphotic (TLK) angle, spinal canal widths were evaluated by MRI. RESULTS: Patients in the first three groups were asymptomatic and younger (group 1: 4.4 ± 0.78 years; group 2: 8.18 ± 0.60 years; group 3: 10.95 ± 0.93 years) than the symptomatic group (group 4: 23 ± 1.30 years). Patients showed height of vertebral bodies, whole canal width, and average lumbar interpedicular distance reduced. Discs degeneration was more pronounced in the lumbar region and in symptomatic adult patients. TK and TLK angles showed a positive correlation with age (p < .05, r = .42; p < .05, r = .41), whereas thoracic and thoracolumbar canal width had a negative correlation (p < .05, r = -.69; p < .05, r = -.58). A negative correlation between lumbar discs degeneration and canal width was found only at L1-L3 level (p < .05, r = -.35). At L1-L3, the canal width cutoff value of .59 allowed the differentiation between asymptomatic and symptomatic patients (area under the curve of .966, p < .0001). CONCLUSION: In achondroplasia, the spinal canal narrowing, due to accelerated degenerative changes, is a predisposing factor of symptomatic lumbar spinal stenosis. Lumbar canal MRI is a helpful tool to detect the risk of the development of neurological symptoms; in adult patients, a stenosis higher than 60% of upper lumbar canal could be a critical value for the onset of neurological symptoms.

Surgical Outcomes in Patients with Congenital Cervical Spinal Stenosis.

OBJECTIVE: To evaluate the differences in surgical outcomes of patients with cervical spondylotic myelopathy with and without congenital cervical spinal stenosis (CCSS). METHODS: Institutional review board approval was obtained to conduct a retrospective chart review of patients with cervical spondylotic myelopathy who underwent decompression and fusion surgeries from 2010-2016 at a single institution. CCSS was identified using the Torg-Pavlov ratio on lateral cervical radiographs. Pre- and postoperative outcome measures were assessed using the modified Japanese Orthopedic Association (mJOA) and the EuroQol 5-dimension questionnaire (EQ-5D). RESULTS: Of 208 patients, Torg-Pavlov ratio identified 85 patients with CCSS. There were no significant differences between the CCSS patient and control patient groups in EuroQol 5-dimension questionnaire and mJOA scores at all 4 designated time points in the study (preoperative, earliest postoperative, 6 month postoperative, and 1 year postoperative). Although not statistically significantly, there was a notable trend for patients with CCSS to be less likely to have mJOA-defined severe myelopathy at the postoperative (odds ratio [OR], 0.75; P = 0.38), 6 month postoperative (OR, 0.66; P = 0.20), and 1 year postoperative (OR, 0.64; P = 0.14) time points. CONCLUSIONS: Postoperatively, compared with non-CCSS patients, patients with congenital cervical stenosis reported equal quality of life for all markers. Our findings suggest that in patients with CCSS and relatively mild symptoms of myelopathy, equal consideration should be given for surgical intervention. The findings of this study warrant further large-scale, multi-institutional investigation to further understand the generalizability of these surgical outcome results.

Progressive hemiparesis due to spino-laminar anomaly of the axis-a case report and literature review.

Introduction: Some of the most common developmental malformations of the axis include anomalies of the odontoid, for example, hypoplasia or aplasia. Isolated anomalies of the posterior arch of the axis rarely occur. This study reports a unique case of congenital anomaly of the neural arch of the axis vertebra, which manifested clinically as progressive hemiparesis. Case presentation: A 33-year-old man presented with progressive weakness of the right upper and lower limbs that had lasted 18 months. The patient reported loss of right-hand dexterity in the 6 months period before he consulted us. Plain radiographs, computed tomography (CT), and magnetic resonance imaging (MRI) revealed C5-C6 block vertebra, primary canal stenosis and spino-laminar anomaly of the axis, along with invagination of the lamina into the canal causing severe cord compression. Discussion: The anomalous posterior element of the axis was excised, and the cord was decompressed. The presence of congenital stenosis and block vertebrae at the C5-C6 level necessitated decompression and instrumentation between C2-C6. Simultaneous occurrence of a posterior arch anomaly, primary canal stenosis, and block vertebra has not been previously described. A cervical spine anomaly presenting as hemiparesis is uncommon in clinical practice. Information enabling clinicians to identify causative anomaly and determine the appropriate surgical intervention is useful, and can facilitate a good clinical outcome.

Comparative morphometric analysis of congenital and acquired lumbar spinal stenosis.

Lumbar spinal stenosis is one of the primary causes of low back pain and is one of the primary causes of spinal surgery. Lumbar spinal stenosis is classified as congenital, acquired and a combination of both. Although the symptoms of both groups are similar, their etiology and radiographic features demonstrate some differences. Our aim to compare morphological characteristics of congenital and acquired lumbar spinal. We have reviewed CT and T2 weighted MRI images of 100 lumbar spinal stenosis patients operated between the years of 2014-2018 in our clinic. For each patient; pedicle length, facet joint angles, the degree of facet tropism, the lateral recess height and ligamentum flavum thickening have been determined. In patients within the congenital lumbar spinal stenosis, pedicle length has significantly found to be shorter than the "acquired" group. There is no significant difference between the facet joint angles of neither group and the facet tropism degrees in many of the patients appear to be similar and "no type". No significant difference has been found in the statistical distribution of lateral recess height and thickening of ligamentum flavum in acquired lumbar spinal stenosis and congenital lumbar spinal stenosis patient groups. As a result of the evaluations of facet joint angles of both groups, more sagittalized facet joints are related to the development of congenital and acquired lumbar spinal stenosis. As a result of our study, we think that facet joint angle and tropism type is not a distinctive factor in congenital and acquired lumbar spinal stenosis etiology.

Ossification of the Ligamentum Flavum at the Thoracic and Lumbar Region in an Achondroplastic Patient.

BACKGROUND: Achondroplasia, a genetic disorder of bone growth, produces specific clinical features of the extremities and spine. Spinal stenosis, seen in patients with achondroplasia, is a congenital disorder related to premature fusion of the pedicles to the lamina. It can be caused by ossification of the ligamentum flavum, which is rare in patients with achondroplasia. CASE DESCRIPTION: We report a rare congenital spinal stenosis with ossification of the ligamentum flavum and thoracolumbar kyphosis deformity in a 24-year-old man with dwarfism and achondroplasia. He was treated with posterior instrumentation and decompression with a wide laminectomy. CONCLUSIONS: Treatment of the deformity and the rare condition of ligamentum flavum in a patient with achondroplasia resulted in improved neurologic status and symptoms. To our knowledge, this is the first case report including treatment for both the deformity and thoracic and lumbar ossified ligamentum flavum lesion in a patient with achondroplasia.

Size Matters: Which Adolescent Patients Are Most Likely to Require Surgical Decompression for Lumbar Disk Herniations?

BACKGROUND: Lumbar herniated nucleus pulposis (HNP) occurs infrequently in the pediatric/adolescent population. A minority of patients with radicular symptoms fail to improve with conservative management and require discectomy. The authors hypothesize that children who ultimately require surgical intervention have an underlying lumbar stenosis predisposing them to continued symptoms. METHODS: Pediatric patients with a lumbar HNP on advanced imaging were retrospectively identified at a tertiary pediatric orthopaedic institution. Patients with spondylolisthesis, fractures, previous spine surgery, or structural thoracolumbar scoliosis were excluded. On sagittal magnetic resonance imagings, measurements were taken of the L4 and L5 vertebral body diameters (VBD) and canal diameters (CD) by 2 independent reviewers. Statistical analysis was performed using 2 sample T tests followed by logistic regression analysis. This was utilized to identify significant associations between CD and need for surgical decompression. RESULTS: A total of 76 patients (37 males/39 females) were identified with a lumbar HNP from 2001 to 2016. Eleven patients underwent discectomy. Sixty-five patients were managed conservatively. Age at magnetic resonance imaging was not different between groups (15.1±1.7 vs. 14.9±2.2 y, P=0.82). VBD at L4 and L5 were not different between groups (P=0.2 and 0.36, respectively). The reviewers had fair to good (0.584-0.854) interrater reliability correlation coefficients. CD was decreased in the surgically treated cohort at L4 (11.6±1.6 vs. 14.2±2.1 mm, P=0.0002) and at L5 (10.1±1.3 vs. 14.2±2.2 mm, P<0.00001). The ratio of CD:VBD was lower in the surgically treated group at L4 (0.36±0.06 vs. 0.46±0.08, P=0.0002) and L5 (0.31±0.68 vs. 0.45±0.08, P<0.00001). Patients with a L4 CD<12.6 mm were 18.8× more likely to require surgical decompression. 100% of patients with a L5 CD<12.36 mm ultimately underwent surgical decompression. CONCLUSIONS: Adolescent patients with congenital lumbar stenosis that develop a lumbar HNP are significantly more likely to require surgical decompression to relieve persistent radicular symptoms. A L4 CD<12.6 mm and a L5 CD<12.36 mm were highly correlated with the need for decompression. LEVEL OF EVIDENCE: Level III-prognostic study.

Radiographic Cobb Angle: A Feature of Congenital Lumbar Spine Stenosis.

PURPOSE: A low cost, reproducible radiographic method of diagnosing congenital lumbar spinal stenosis (CLSS) is lacking. We hypothesized that the Cobb angle for lumbar lordosis would be smaller in patients with CLSS, based on observations in our spine clinic patient population. Here, we compared lumbar lordosis Cobb angles with the radiographic ratio method in patients with normal spine imaging, degenerative spinal stenosis, and with CLSS. MATERIALS AND METHODS: Orthopedic surgeons categorized patients with low back pain as "Normal," "Degenerative spinal stenosis," and "CLSS" based on clinical presentation and findings on lumbar magnetic resonance imaging. We included 30 patients from each cohort who had undergone lateral lumbar spine radiographs and lumbar magnetic resonance imaging. For each lateral radiograph, 2 measurement methods were used (1) 4-line lumbosacral Cobb angle between L2-S1 and (2) the ratio of the anteroposterior vertebral body diameter and spinal canal anteroposterior diameter at the L3 level. We performed logistic regression analyses of CLSS prediction by Cobb angle vs the ratio method in all three cohorts. Covariates included age, gender, and body mass index. RESULTS: The radiographic Cobb angles were smaller in CLSS patients when compared to the degenerative disease and normal cohorts: a smaller radiographic Cobb angle showed higher odds ratio (OR) of predicting CLSS diagnosis compared to the radiographic ratio when compared with degenerative disease (OR = 0.28; 95% CI: 0.11-0.78, P = 0.01) and when compared with the normal cohort (OR = 0.46; 95% CI: 0.24-0.92, P = 0.03). Radiographic ratio measurements showed no difference between the three cohorts (P = 0.12). CLSS was associated with male gender (P = 0.04), younger age (P = 0.01), and higher body mass index (P = 0.01). CONCLUSION: The radiographic Cobb angle method for lumbar lordosis may be useful for raising the possibility of CLSS as the diagnosis.

Dural ectasia associated with Mounier-Kuhn syndrome: a novel association in the context of spinal stenosis.

We present the case of a patient undergoing lumbar spine decompression for stenosis with a history of Mounier-Kuhn syndrome. The patient presented with axial lumbar spine pain over 6 months with progressive radicular pain to the left L3 dermatome. MRI confirmed spinal stenosis at L3/4 level with associated dural ectasia. The patient had an uneventful spinal decompression with resolution of radicular symptoms and axial spine pain. Dural ectasia poses a significant risk when operating on the lumbosacral spine. Larger cerebrospinal fluid volumes and a capacious dural canal can result in anaesthetic and orthopaedic complications such as inadequate spinal anaesthesia, complicated epidural analgesia, intraoperative dural tears and difficult pedicle screw insertion due to narrow pedicles. This is the first case in the literature detailing the association between dural ectasia and Mounier-Kuhn syndrome. We recommend adequate spinal imaging in patients with Mounier-Kuhn syndrome to exclude dural ectasia prior to undergoing lumbosacral spinal procedures.

Stability-preserving decompression in degenerative versus congenital spinal stenosis: demographic patterns and patient outcomes.

BACKGROUND CONTEXT: Although lumbar spinal stenosis often presents as a degenerative condition (degenerative stenosis [DS]), some patients present with symptoms from lifelong narrowing of the spinal canal. These patients have congenital stenosis (CS) and present with symptoms of stenosis at a younger age. Patients with CS often have a distinct pathophysiology with fewer degenerative changes but present with multilevel involvement. In the setting of neurologic symptoms, decompression alone while preserving stability has been proposed for both patient populations. PURPOSE: The purpose of this study is to evaluate if the different etiology for narrowing in CS and DS results in a different natural history of pain progression, different locations requiring decompression, and different outcomes following a stability-preserving decompression procedure. STUDY DESIGN/SETTING: This study used a retrospective cohort study patient sample: We retrospectively reviewed consecutive patients of a single surgeon with DS or CS who underwent surgical decompression without fusion between 2008 and 2014. Patients were excluded if they had undergone a previous lumbar surgical procedure (decompression or fusion) or follow-up less than 12 months. OUTCOME MEASURES: Pre- and postoperative clinical outcome scores including visual analogue scale (VAS) and Oswestry Disability Index (ODI) were recorded. Postoperatively, data were collected regarding complications, the presence of new radicular or myelopathic symptoms, and necessity of reoperation in the lumbar spine. METHODS: Demographic information included age, sex, body mass index, smoking status, and Charleston Comorbidity Index (CCI). Preoperative clinical symptoms as well as the presence of lower extremity radiculopathy and claudication were evaluated. Patients were determined to have a diagnosis of CS by the treating surgeon if primary radiographs revealed shortened pedicles and decreased cross-sectional area of the spinal canal as detailed by previous studies. Binary outcomes were compared between congenital and degenerative cohorts using bivariate and multivariate logistic regression. Multivariate regressions controlled for baseline patient and operative characteristics. RESULTS: The average age of the DS cohort was 66.7±10.7 years, whereas for the CS group, it was 47.1±9.2 years. Average follow-up was 27.6 months. The patients with DS had significantly more comorbidities as shown by the CCI score (2.8±1.6 vs. 0.5±0.6); p<.001) and the American Society of Anesthesiologists (ASA) score ≥3 (52.8% vs. 11.1%; p<.001). Patients with CS presented with higher VAS back (8.0 vs. 5.1; p=.008) and leg (7.9 vs. 4.5; p<.001) scores. Patients with DS presented with significantly greater duration of preoperative back pain and leg pain (42.7 vs. 30.5 months; p=.042). Postoperatively, there were no significant differences in VAS back, leg, or ODI scores. However, a trend toward a lower VAS leg score was present in the patients with CS when compared with patients with DS (2.6±3.0 vs. 4.2±3.2; p<.117). Both patient groups experienced similar levels of symptomatic relief and improvement in VAS and ODI scores. There were no significant differences in new-onset radicular symptoms requiring conservative treatment or reoperation. In both groups combined, 81.9% of patients reported resolution of lower extremity symptoms at final follow-up. Overall, 20.6% of patients experienced new lower-extremity radicular symptoms after a period of resolution of symptoms postoperatively. There were significantly more reoperations following surgical decompression in patients with DS (13.9% vs. 2.8%; p=.02). CONCLUSIONS: Patients with CS and patients with DS respond well to decompression alone, without a supplemental fusion, despite differences in pain experience and presentation. The localization of pathology requiring decompression is similar. The patients with DS were more susceptible to require another operation resulting in a fusion, which confirms the theory that initial microinstability can progress in DS, but is likely not part of the disease process in CS. At just over 2 years after decompression, patients with CS may not need to be treated by a fusion in the setting of lower back pain; however, longer-term follow up is necessary to further assess these outcomes.

Is cervical disc arthroplasty good for congenital cervical stenosis?

OBJECTIVE Cervical disc arthroplasty (CDA) has been demonstrated to be as safe and effective as anterior cervical discectomy and fusion (ACDF) in the management of 1- and 2-level degenerative disc disease (DDD). However, there has been a lack of data to address the fundamental discrepancy between the two surgeries (CDA vs ACDF), and preservation versus elimination of motion, in the management of cervical myelopathy associated with congenital cervical stenosis (CCS). Although younger patients tend to benefit more from motion preservation, it is uncertain if CCS caused by multilevel DDD can be treated safely with CDA. METHODS Consecutive patients who underwent 3-level anterior cervical discectomy were retrospectively reviewed. Inclusion criteria were age less than 50 years, CCS (Pavlov ratio ≤ 0.82), symptomatic myelopathy correlated with DDD, and stenosis limited to 3 levels of the subaxial cervical (C3-7) spine. Exclusion criteria were ossification of the posterior longitudinal ligament, previous posterior decompression surgery (e.g., laminoplasty or laminectomy), osteoporosis, previous trauma, or other rheumatic diseases that might have caused the cervical myelopathy. All these patients who underwent 3-level discectomy were divided into 2 groups according to the strategies of management: preservation or elimination of motion (the hybrid-CDA group and the ACDF group). The hybrid-CDA group underwent 2-level CDA plus 1-level ACDF, whereas the ACDF group underwent 3-level ACDF. Clinical assessment was measured by the visual analog scales (VAS) for neck and arm pain, Japanese Orthopaedic Association (JOA) scores, and Nurick grades. Radiographic outcomes were measured using dynamic radiographs for evaluation of range of motion (ROM). RESULTS Thirty-seven patients, with a mean (± SD) age of 44.57 ± 5.10 years, were included in the final analysis. There was a male predominance in this series (78.4%, 29 male patients), and the mean follow-up duration was 2.37 ± 1.60 years. There were 20 patients in the hybrid-CDA group, and 17 in the ACDF group. Both groups demonstrated similar clinical improvement at 2 years' follow-up. These patients with 3-level stenosis experienced significant improvement after either type of surgery (hybrid-CDA and ACDF). There were no significant differences between the 2 groups at each of the follow-up visits postoperatively. The preoperative ROM over the operated subaxial levels was similar between both groups (21.9° vs 21.67°; p = 0.94). Postoperatively, the hybrid-CDA group had significantly greater ROM (10.65° vs 2.19°; p < 0.001) than the ACDF group. Complications, adverse events, and reoperations in both groups were similarly low. CONCLUSIONS Hybrid-CDA yielded similar clinical improvement to 3-level ACDF in patients with myelopathy caused by CCS. In this relatively young group of patients, hybrid-CDA demonstrated significantly more ROM than 3-level ACDF without adjacent-segment disease (ASD) at 2 years' follow-up. Therefore, hybrid-CDA appears to be an acceptable option in the management of CCS. The strategy of motion preservation yielded similar improvements of cervical myelopathy to motion elimination (i.e., ACDF) in patients with CCS, while the theoretical benefit of reducing ASD required further validation.

Comparison of morphology between patients with and without developmental spinal canal stenosis to inform the feasibility of C1 lateral mass screw insertion in the atlas.

BACKGROUND: C1 lateral mass screws are increasingly being used as an effective anchoring system. Insufficient posterior arch height increases difficulty of inserting the screws using the Tan method. The general aim of our retrospective cross-sectional study was to clarify the atlas morphology of patients with developmental spinal canal stenosis to evaluate the usefulness of the Tan method. METHODS: A computed tomography myelogram was performed in 85 Japanese patients presenting with spinal disorders. The following morphological measures at the level of the atlas were obtained: anterior-posterior length (APL), medial-lateral width (MLW), lateral mass transverse diameter (LMTD), dural sac area (DSA), spinal cord area (SCA), lateral mass height (LMH), lateral mass width (LMW), lateral mass length (LML), posterior arch length (PAL), posterior lamina height (PLH), and posterior vertebral groove height (PVGH). Patients were classified into two groups: patients with developmental spinal canal stenosis (DCS), identified by a longitudinal diameter of the spinal canal <12 mm and patients without developmental spinal canal stenosis (NDCS), identified by a longitudinal diameter of the spinal canal ≥12 mm. Measures obtained on the computed tomography images were compared between the two groups. RESULTS: Among the 85 patients in our study group, developmental spinal stenosis was identified in 47 patients. The APL, DSA, PAL and PVGH measurements were significantly smaller among the 47 patients in the DCS group, compared to the 38 patients in the NDCS group (p < 0.01). The mean height of the PVGH was <4.0 mm in 63.5% of the total study group. CONCLUSIONS: The normally inserted C1 lateral mass screws have a diameter of 3.5-4.0 mm, and hence, the Tan method require a posterior arch height that exceeds this value. Our study provides evidence of a narrower posterior arch in Japanese individuals with developmental spinal canal stenosis. Therefore, the safe use of the Tan method to insert C1 lateral mass screws may be limited in Japanese individuals with developmental spinal canal stenosis.

A novel MRI classification system for congenital functional lumbar spinal stenosis predicts the risk for tandem cervical spinal stenosis.

PURPOSE: The purpose of this study was to develop a simple and clinically useful morphological classification system for congenital lumbar spinal stenosis using sagittal MRI, allowing clinicians to recognize patterns of lumbar congenital stenosis quickly and be able to screen these patients for tandem cervical stenosis. METHODS: Forty-four subjects with an MRI of both the cervical and lumbar spine were included. On the lumbar spine MRI, the sagittal canal morphology was classified as one of three types: Type I normal, Type II partially narrow, Type III globally narrow. For the cervical spine, the Torg-Pavlov ratio on X-ray and the cervical spinal canal width on MRI were measured. Kruskal-Wallis analysis was done to determine if there was a relationship between the sagittal morphology of the lumbar spinal canal and the presence of cervical spinal stenosis. RESULTS: Subjects with a type III globally narrow lumbar spinal canal had a significantly lower cervical Torg-Pavlov ratio and smaller cervical spinal canal width than those with a type I normal lumbar spinal canal. CONCLUSION: A type III lumbar spinal canal is a globally narrow canal characterized by a lack of spinal fluid around the conus. This was defined as "functional lumbar spinal stenosis" and is associated with an increased incidence of tandem cervical spinal stenosis.

Cervical canal stenosis and adjacent segment degeneration after anterior cervical arthrodesis.

PURPOSE: Adjacent segment degeneration (ASD) is known to occur after anterior cervical arthrodesis. However, it is not known whether cervical canal stenosis enhances the risk of ASD. The purpose of this study was to explore whether congenital stenosis could be used as a predictor of ASD after anterior cervical decompression and fusion (ACDF). METHODS: We enrolled 141 patients who had undergone ACDF for cervical myelopathy and/or radiculopathy, and had at least 6 years of follow-up. In standard radiographs of cervical spine in lateral view, bony congenital stenosis was evaluated and all patients were divided into two groups: stenosis (n = 63) and non-stenosis (n = 78). Radiographic ASD was assessed according to the criteria of Kellgren and Lawrence and correlated with symptomatic ASD. Clinical and radiological parameters were compared between the groups. The primary outcome was the rate of radiographic ASD after initial ACDF. The incidence of symptomatic ASD was assessed by Kaplan-Meier method. RESULTS: Radiographic ASD and symptomatic ASD developed in 46.8 % and 18.4 % of all patients, respectively. There was a significant association between congenital stenosis and radiographic ASD. The area under the receiver operating characteristic curve of preoperative anteroposterior (AP) diameter of cervical canal for predicting radiographic ASD was 0.756. 13.0 mm was the cutoff value of preoperative AP diameter of cervical canal predicting radiographic ASD. Kaplan-Meier analysis predicted a disease-free survival rate of symptomatic ASD in 97.2 % of patients at 5 years and 78.0 % at 10 years after ACDF. There was no significant difference in survival rates of the adjacent segment between the two groups via log-rank analysis (P = 0.102). CONCLUSION: Congenital stenosis can increase the rate of radiographic ASD after initial ACDF. The cutoff value of 13.0 mm for preoperative AP diameter of cervical canal had the highest validity for predicting radiographic ASD.

The morphological and clinical significance of developmental cervical stenosis.

PURPOSE: To investigate the difference of intra-dural space for spinal cord in magnetic resonance imaging between patients with and without developmental cervical stenosis and its clinical significance. METHODS: 445 patients with cervical spondylotic myelopathy who had decompression surgeries were recruited. Based on their lateral radiographs, they were divided into stenosis and non-stenosis groups. On the magnetic resonance images, the ratio of the sagittal diameter of the dural sac to that of the vertebral body was measured and calculated as MRI Pavlov ratio at mid-vertebral level on sagittal images, and the ratio of the transverse area of the spinal cord to that of the dural sac was measured and calculated as occupation ratio on axial images from C3 to C7. The two ratios were compared between the two groups. We examined the correlations of the Pavlov ratio and the MRI Pavlov ratio between different vertebral levels. The correlation between the Pavlov ratio of each level and its corresponding MRI Pavlov ratio was also examined. The stenosis group was further divided into space-reserving and non-space-reserving subgroups based on their occupation ratios; then, clinical parameters were compared between the two subgroups to determine the clinical significance of the reserving space. RESULTS: The MRI Pavlov ratio of the stenosis group was significantly smaller at C3-C7 (P < 0.001), while the occupation ratio was larger without significance. The Pavlov and MRI Pavlov ratios were correlated significantly at different levels (P < 0.001). The Pavlov ratio correlated significantly with its corresponding MRI Pavlov ratio at each level (P < 0.001). For space-reserving subgroup, the recovery rate was lower (P < 0.05) than that for non-space-reserving group, and was higher in anterior approach than that in posterior approach (P < 0.05). CONCLUSIONS: Developmental cervical stenosis is associated with a smaller sagittal diameter of dural sac, but does not lead to a significant decrease of intra-dural space available for the cord. For patients with normal intra-dural space, the recovery after anterior decompression surgery was better.

Defining hyoplasia of the atlas: a cadaveric study.

STUDY DESIGN: Cadaveric study. OBJECTIVE: To define congenital hypoplasia of the atlas. SUMMARY OF BACKGROUND DATA: Little has been written about hypoplasia of the atlas and it is usually described in the setting of other skeletal dysplasias or syndromes. METHODS: A total of 543 cervical spine specimens were randomly selected from the Hamann-Todd collection. Sagittal and coronal diameters of the atlas, axis, and C3 (when available), and the dens diameter were measured using digital calipers. Correction for modern size and radiographical magnification was performed. Hypoplasia of the atlas was defined as the lowest 2.5% of measurements. The correlation between inner sagittal diameters at C1 and C3 was calculated. RESULTS: The mean C1 inner sagittal diameter was 30.8 ± 2.4 mm (range, 23.5-38.1 mm). We defined C1 hypoplasia as an inner sagittal diameter value representing the smallest 2.5% of subjects. Because the mean was 30.8 mm, hypoplasia was defined as a diameter of ≤26.1 mm or less. Correcting for size and magnification of radiographs, hypoplasia is defined as an inner sagittal diameter of the atlas of 28.9 mm. Approximately 10% of cases had a dens that occupied more than 40% of the spinal canal at C1, thus not following Steel's Rule of Thirds. There was only a moderate correlation between the spinal canal diameter at C1 and at C3 (r = 0.483, N = 345; P < 0.001). CONCLUSION: With an inner sagittal diameter of 26 mm or less, one may describe the atlas as hypoplastic. Ten percent of the specimens had an odontoid process that occupied more than 40% of the spinal canal at C1. There was little correlation between the inner sagittal diameter at C1 and the diameter at C3. LEVEL OF EVIDENCE: N/A.

Anatomic radiological variations in developmental lumbar spinal stenosis: a prospective, control-matched comparative analysis.

BACKGROUND CONTEXT: Developmental lumbar spinal stenosis is a maldevelopment of the dorsal spinal elements involving short pedicles and a trefoil bony spinal canal that increases the likelihood of neural compression at an earlier age. PURPOSE: To identify radiographically the anatomic variations caused by the maldevelopment of the infrequently characterized dorsal spinal elements. STUDY DESIGN: A prospective, control-matched comparative analysis. METHODS: Magnetic resonance imaging (MRI) and anteroposterior (AP) plain radiographs of 66 patients (mean age, 40.7 years) selected and randomized prospectively and compared with images of 45, age- and gender-matched control subjects. Variables assessed included spinal canal cross-sectional area (CSA), thecal sac AP and transverse canal diameters (CSA), and interpedicular distance. All were expressed in ratios with vertebral body diameter (VBD), interlaminar angle, stenosis grade, and MRI evidence of disc degeneration. RESULTS: In the stenosis cohort, global pathology and multilevel involvement with L3, L4, and L5 segments were involved more commonly and severely. Severe stenosis, at L1, L2, and S1 occurs infrequently. Multivariate analysis demonstrated a statistically significant reduction in spinal canal CSA-to-vertebral body CSA ratio, AP spinal canal diameter-to-VBD ratio on axial and sagittal magnetic resonance images, and plain radiograph interpedicular distance-to-VBD ratio at all levels. Interlaminar angle and the transverse spinal canal diameter-to-VBD ratio were reduced significantly in the stenosed cohort at all levels, except L1. No statistically significant difference regarding the incidence of disc degeneration on MRI between the two cohorts, as well as thecal sac CSA-to-spinal canal CSA ratios across all levels were observed, except for L3 and S1 (p<.05). CONCLUSIONS: Three spinal canal morphologies were identified: (1) "flattened" canal with predominantly reduced spinal canal AP diameter, (2) spinal canal with predominantly reduced interlaminar angle, and (3) global reduction of all canal parameters. Early age at presentation and subtle spondylosis, although typical, should not be considered the identifying, differentiating factors.

Spinal cord compression in pseudohypoparathyroidism.

BACKGROUND CONTEXT: Spinal cord compression associated with pseudohypoparathyroidism (PHP) is an increasingly reported sequelae of the underlying metabolic syndrome. The association of neurologic dysfunction with PHP is not well appreciated. We believe this to be secondary to a combination of underlying congenital stenosis, manifest by short pedicles secondary to premature physeal closure, and hypertrophic ossification of the vertebral bony and ligamentous complexes. PURPOSE: The purpose of this case report is to review the case of spinal stenosis in a child with PHP Type Ia. We are aware of only eight published reports of patients with PHP Type Ia and spinal stenosis-there are only two previously known cases of pediatric spinal stenosis secondary to PHP. STUDY DESIGN/SETTING: This is a case report detailing the symptoms, diagnosis, interventions, complications, and ultimate outcomes of a pediatric patient undergoing spinal decompression and fusion for symptomatic stenosis secondary to PHP Type Ia. Literature search was reviewed regarding the reports of spinal stenosis and PHP, and the results are culminated and discussed. PATIENT SAMPLE: We report on a 14-year-old obese male with PHP and progressive lower extremity weakness secondary to congenital spinal stenosis. Examination revealed functional upper extremities with spastic paraplegia of bilateral lower extremities. The patient's neurologic function was cautiously monitored, but he deteriorated to a bed-bound state, preoperatively. METHODS: The patient's chart was reviewed, summarized, and presented. Literature was searched using cross-reference of PHP and the terms "spinal stenosis," "myelopathy", "myelopathic," and "spinal cord compression." All relevant case reports were reviewed, and the results are discussed herein. RESULTS: The patient underwent decompression and instrumented fusion of T2-T11. He improved significantly with regard to lower extremity function, achieving unassisted ambulation function after extensive rehabilitation. Results from surgical decompression in previously reported cases are mixed, ranging from full recovery to iatrogenic paraplegia. CONCLUSIONS: The association of neurologic dysfunction with PHP is not well appreciated. It is important to highlight this rare association. Surgical decompression in patients with PHP yields mixed results but may be of greatest efficacy in younger patients who receive early intervention.

Is congenital bony stenosis of the cervical spine associated with congenital bony stenosis of the thoracic spine? An anatomic study of 1072 human cadaveric specimens.

SUMMARY OF BACKGROUND DATA: Tandem stenosis of the cervical and lumbar spine is known to occur in 5% of individuals with symptomatic neural compression in one region. However, the prevalence of concurrent cervical and thoracic stenosis is not known. Whether this relationship is due to an increased risk of degenerative disease in these individuals, or whether this finding is due to the tandem presence of a congenitally small cervical and thoracic canal is unknown. OBJECTIVES: To determine the prevalence of concurrent thoracic and cervical stenosis and whether the presence of stenosis in the cervical spine is associated with stenosis in the thoracic spine. STUDY DESIGN: A morphoanatomic study of the cervical and thoracic cadaveric spines. METHODS: A total of 1072 adult skeletal specimens from the Hamann-Todd Collection in the Cleveland Museum of Natural History were selected. Canal area at each level was also calculated using a geometric formula. A standard distribution for each level was created, and values that were 2 SD below mean were considered as being congenitally stenotic. Linear regression analysis was used to determine the association between the additive canal areas at all levels in the cervical and thoracic spine and to determine the association between the number of stenotic levels in the cervical and thoracic spine. Logistic regression was used to calculate odds ratios for concurrent cervical and thoracic stenosis. RESULTS: The prevalence of concurrent cervical and thoracic stenosis is 1%. A positive association was found between the additive areas of all cervical and thoracic levels (P<0.01). No association, however, was found between the number of stenotic thoracic and cervical levels (P=0.689). Log regression demonstrated no significant association (odds ratio <1) between stenosis in the thoracic and cervical spine. CONCLUSIONS: The area changes in the cervical spine correlate with area variations in the thoracic spine and the severity of stenosis in the thoracic spine increases as the levels of stenosis increase in the cervical spine. The presence of tandem cervical and thoracic stenosis does seem to be, in part, related to the tandem presence of a congenitally small cervical and thoracic canal.

Cervical spinal cord contusion in professional athletes: a case series with implications for return to play.

STUDY DESIGN: Retrospective case series. OBJECTIVE: This report provides long-term follow-up on athletes who have sustained a cervical spinal cord contusion. Their magnetic resonance (MR) image is correlated with clinical signs and symptoms. Mechanism of injury and a hypothesis of etiology are reported. SUMMARY OF BACKGROUND DATA: Current return-to-play criteria for athletes who sustain a cervical cord contusion are based on expert opinion only. Decision making for this clinical situation in athletes carries significant clinical, legal, and economic ramifications. The natural history, clinical correlation, and effect of surgery for athletic cervical cord contusions have not been established. The mechanism of injury for this entity has historically emphasized axial loading. METHODS: The case histories, physical examination, and MR images were reviewed for 4 professional athletes. All athletes had documented cervical cord contusions. None of the athletes had an acute disc herniation, fracture, instability, or focal cord compression. All athletes were contacted by telephone to assess symptoms at a minimum follow-up of 2 years after injury. RESULTS: All 4 athletes had congenital stenosis, defined as lack of CSF signal around the cord on an MR image. All underwent anterior fusions at the level of their contusion. In follow-up, 2 athletes developed new contusions: one more than 5 years later, adjacent to a fusion; and 1, 2 years later, not adjacent to his previous fusion. No athlete developed permanent neurological sequelae. The presence of a contusion did not correlate with athletes' signs and symptoms. The mechanism of injury was hyperextension. CONCLUSION: It is hypothesized that the horizontal facet orientation of the C3-C4 level, congenital stenosis, and relative hypermobility in extension are the contributing factors in the cause of this clinical entity. An anterior fusion at the C3-C4 level seems to be the most reliable method of preventing or delaying the return of symptoms. Return-to-play guidelines should emphasize the athletes' history of symptoms in context with their MR image because there is poor correlation between the finding of a contusion and the clinical presentation. Recurrence of symptoms is common and the long-term consequences of repeated episodes remain unknown.