Why the patients with Hirayama disease have abnormal cervical sagittal alignment? A radiological measurement analysis of posterior cervical extensors

Purpose To explore the relationship between the strength of posterior cervical extensors (PCEs) and cervical sagittal alignment in Hirayama disease (HD) patients. Methods We analyzed the (magnetic resonance imaging) MRI T2WI and X-rays of 60 HD patients who visited Huashan Hospital from June 2017 to February 2020. Symptoms of these patients include adolescent onset, manifestation of unilateral upper limb muscle weakness and muscle atrophy of the forearm and hand. MRI images were used to measure (the cross-sectional area) CSA of cervical PCEs. The ratio of muscle CSA to vertebral body areas at the same level is defined as R-CSA. Cervical sagittal alignment includes the C2–7 Cobb angle, T1 slope and C2–7 sagittal vertical axis (SVA). The geometric center of the C3–6 vertebral body was determined using the line connecting the C2 inferior endplate and the C7 upper endplate. When located behind the line, it is defined as a “local kyphotic deformity.” The number of vertebral bodies involved in kyphotic deformity was determined by measuring the local kyphosis angle (LKA). Spearman correlation analysis (α = 0.05) was used to determine the relationship between R-CSA and sagittal parameters. ROC curves were used to analyze the sensitivity and specificity of relevant variables. Results Spearman correlation test revealed that R-CSA negatively correlated with T1S (S = 0.34, r = 0.34, p = 0.01) and LKA (S = 0.44, r = 0.5, p = 0.01), but did not correlate with the C2-C7 Cobb angle (S = 0.20, p = 0.12) or C2-C7 SVA (S = − 0.17, p = 0.46). (p < 0.05). ROC curve analysis showed that the areas under the curve (AUCs) of the T1 slope and LKA was 0.6696 and 0.7646, respectively. T1 slope, cutoff value: 17.2°; sensitivity: 0.5806; specificity: 0.7241; p < 0.05. LKA: cutoff value: − 14°; sensitivity: 1; specificity: 0.5333; p < 0.05. Conclusions In patients with Hirayama disease, the strength of posterior cervical extensors and cervical sagittal alignment are closely related. The local kyphosis angle can be used as a reference for the strength of posterior cervical extensors. These results indicate the weakness of PCEs, which may predispose the cervical spine of HD patients to a less stable situation. Therefore, patients with Hirayama disease should strengthen the exercise of the PCEs.

Novel Method for Evaluation of Sagittal Spinal Alignment Using Cluster Analysis of Slope of Each Vertebra.

Background: The parameters of sagittal spinal alignment proposed to date measure only the specific sectional angle or the specific sectional distance of the entire spine. To evaluate the alignment of the entire spine without segmentation, we sought to measure and analyze the slope of each vertebral body from skull to pelvis. The purpose of this study was to confirm the effectiveness of this novel analytic method for the evaluation of spinal alignment that considers the slope of each spinal vertebra using graph and cluster analysis.Methods: Every spinal slope from McGregor’s slope to the sacral slope of 88 patients who underwent standing whole spine radiography was measured. Subsequently, we conducted cluster analysis of each spinal slope to understand the characteristics of sagittal alignment.Results: Cluster analysis of whole spinal slopes did not provide useful results in this study because the number of cases per cluster was small due to the large number of parameters. Therefore, we focused the cluster analysis on only the cervical spine slopes. Then, we categorized cervical alignment into four groups (named Normal, Mismatch, Straight, and Sigmoid) based on the results of the cluster analysis. Patients in the Normal and Mismatch groups were older and had lower lumbar apex (L4), apparent lordo-kyphosis around the thoracolumbar junction, and high thoracic kyphosis (TK). Patients in the straight and sigmoid groups were younger, had a higher lumbar apex (L3), flat thoracolumbar junction, and low TK. There was no significant difference between the four groups with respect to pelvic incidence (PI) or pelvic tilt (PT).Conclusion: We proposed a novel method for visually understanding sagittal alignment. Using this analysis method, differences and similarities of sagittal alignment between each group can be easily identified. More detailed analysis of the whole spine may be possible by increasing the number of cases.

Association between diffuse idiopathic skeletal hyperostosis and thoracic kyphosis in patients with cervical myelopathy: a retrospective observational study

Background Diffuse idiopathic skeletal hyperostosis (DISH) is a structural abnormality of the thoracic spine that is known to impair posture. However, the relationship between DISH and sagittal balance in the whole spine is unclear. The aims of this study were to investigate the prevalence of DISH in patients with cervical myelopathy caused by cervical ossification of the posterior longitudinal ligament (OPLL) or cervical spondylosis and to compare sagittal alignment of the spine between patients with and without DISH. Methods A total of 103 consecutive patients with a diagnosis of cervical myelopathy due to cervical OPLL or spondylosis were retrospectively enrolled in this single-center study. DISH was defined as an ossified lesion that was seen to be completely bridging at least four contiguous adjacent vertebral bodies in the thoracic spine on computed tomography scans. Cervical and spinopelvic sagittal parameters were measured in whole spine radiographs. Results The study population included 28 cases with DISH [DISH (+) group] and 75 without DISH [DISH (−) group]. OPLL was more prevalent in the DISH (+) group than in the DISH (−) group; however, there were no significant differences in other clinical findings. Propensity score matching produced 26 pairs. C7 slope, C2-7 sagittal vertical axis (C-SVA), whole thoracic kyphotic angles, upper thoracic kyphosis, and T5-T12 thoracic kyphosis values were significant higher in the DISH (+) group than in the DISH (−) group. There was no significant between-group difference in the other sagittal spinopelvic parameters. Conclusions This study is the first to compare sagittal alignment in patients with cervical myelopathy according to whether or not they have DISH. Patients with DISH are more likely to have excessive kyphosis in the thoracic spine, a high C7 slope, and a high C2-7 SVA.

Upper Thoracic Spine Fractures Outcomes and Complications in King Abdul-Aziz Medical City, Riyadh

Introduction: Upper thoracic spine fractures (T1-T6) are not uncommon. They are often high-energy injuries complicated by multiple life-threatening comorbidities. There is a controversial discussion in the literature regarding the treatment choices. Thoracic pedicle screw fixation has replaced all other fixation techniques for its success rate and safety. Despite the number of studies discussing upper thoracic spine fractures, data on literature reporting postoperative complications are deficient. The aim of the study was to assess, in a series of patients, the impact of traumatic upper thoracic fractures on sagittal alignment, the incidence of possible complications, and the effect of associated injuries. Methodology: This retrospective chart review study included all adult cases diagnosed as traumatic upper thoracic spine fractures in KAMC in Riyadh. Data were obtained from the computerized database. The information reviewed included fracture characteristics, associated injuries, pre- and postoperative neurological status and sagittal alignment, follow-up duration, and the presence of complications. Result: A total of 19 patients were included in the study. Of them, 17 (89.5%) were injured secondary to a motor vehicle accident. There were three patients with a fixation level crossing the CT junction, more blood loss and procedure time was noticed with these cases. There was a notable improvement in upper thoracic kyphosis by 9º when measuring pre- and postop fracture Cobb's angle. The mean preop angle was 28.98 and the mean postop was 20.76. Of all the 19 cases involved in the study, 3 patients had developed surgical site infection as a complication. No other complication was reviewed. Conclusion: It is well-known in the literature that the correction of kyphosis and the absence of residual deformity postoperatively are indicators of the success and safety of the procedure used. Our findings correspond to the literature discussion that the current practice in managing traumatic upper thoracic spine fracture in KAMC in Riyadh is relatively safe and effective. Yet, further studies are needed to elaborate more on the relationship between the presence of other injuries and patients’ factors and postoperative outcomes.