Impact of cervical sagittal parameters on axial neck pain in patients with cervical kyphosis

Is cervical sagittal alignment associated with pain and disability in myofascial pain syndrome?: A cross-sectional study

OBJECTIVE

To elucidate the role of cervical sagittal alignment in the pathophysiology of cervical myofascial pain syndrome(MFPS) and its impact on pain levels and disability status among patients.

METHODS

This prospective cross-sectional study included participants aged 18-64 years experiencing neck pain for more than 3 months and diagnosed with MFPS. Cervical sagittal parameters (C0-2 cervical lordosis(CL) angle, C2-7 CL angle, cervical sagittal vertical axis (cSVA), T1 slope, T1 slope minus CL mismatch(T1S-CL), and cervical tilt) were measured using Surgimap software by an expert physiatrist. Pain levels were assessed using the Numerical Pain Rating Scale(NRS), and neck disability was evaluated using the Neck Bournemouth Questionnaire(NBQ).

RESULTS

Out of 200 initially assessed participants with cervical MFPS, 133 were included after excluding ineligible individuals. The mean age of the participants was 35.3±8.2 years. Participants categorized by pain severity (moderate vs. severe) showed no significant differences in cervical range of motion, C0-2 angle, cSVA, T1 slope and T1S-CL. However, significant differences were observed in C2-7 angle (p=0.008), cervical tilt (p=0.006), and NBQ scores (p<0.001) between the two pain severity groups. Grouping based on T1S-CL compliance showed no significant differences in pain and disability effects. Correlation analysis revealed weak negative correlations between pain levels and C2-7 Cobb angle (p=0.009, r=0.226) as well as cervical tilt (p=0.005, r=0.243). No correlations were found between cervical sagittal parameters and NBQ scores.

CONCLUSIONS

Decreased C2-7 CL angle and cervical tilt angle are associated with increased pain levels; however, cervical sagittal alignment was not found to be associated with disability.

Safety and Efficacy of Combined Imbrication Axle Reconstruction and Z-Type Titanium Plate Fixation for Hinge Fracture Displacement During Open-Door Laminoplasty

BACKGROUND

 Open-door laminoplasty is a classical decompression method used to treat cervical spondylotic myelopathy. However, hinge fracture displacement (HFD) is a common occurrence during this procedure. The current study aimed to investigate the safety and efficacy of a combined imbrication axle reconstruction and Z-type titanium plate fixation method for HFD during open-door laminoplasty.

METHODS

 In total, 617 patients with cervical spondylotic myelopathy who underwent C3-C7 open-door laminoplasty from March 2015 to October 2018 were included in this retrospective study. Overall, 73 patients developed HFD during surgery. Of these, 43 underwent combined imbrication axle reconstruction and Z-type titanium plate fixation (IRZF group) and 30 underwent traditional titanium plate fixation (TF group). Data such as the operative time, intraoperative blood loss volume, and distribution of fractured hinges were recorded. Both groups were compared in terms of improvement in neurologic function, cervical curvature index, hinge fusion rate, incidence of C5 palsy, severity of axial symptoms, and development of complications.

RESULTS

 The operative time and intraoperative blood loss were slightly higher in the IRZF group than in the TF group; however, the differences were not significant (p > 0.05). Furthermore, there was no significant difference between the groups in terms of the number of fractured segments and the distribution of fractured hinges (p > 0.05). The cervical curvature index did not decline in the two groups (p > 0.05). The IRZF group had a higher hinge fusion rate than the TF group at 3 (79.6 vs. 57.1%) and 12 (93.9 vs. 74.3%) months postoperatively (p < 0.05). There was no significant difference in the incidence of C5 palsy between the two groups (9.3 vs. 6.7%; p > 0.05). However, the TF group had more severe axial symptoms than the IRZF group (p < 0.05). The neurologic function of the two groups increased postoperatively as per the Japanese Orthopaedic Association scoring system (p < 0.05). Nevertheless, there was no significant difference in terms of neurologic function at any observational time point (p > 0.05). One patient in the TF group with hinge nonunion underwent laminectomy due to lamina displacement into the spinal canal and nerve root compression.

CONCLUSION

 In patients with HFD, IRZF facilitates a more intimate contact between the lamina and the lateral mass and, therefore, achieves fractured hinge fusion without additional surgical trauma. This technical improvement can significantly promote neurologic recovery, decrease the severity of axial symptoms, and prevent the development of spinal cord or nerve root recompression.

Quantitatively assessing the effect of cervical sagittal alignment on dynamic intervertebral kinematics by video-fluoroscopy technique

BACKGROUND

Cervical sagittal alignment is crucial for distributing the head load to lower cervical segments and maintaining normal cervical spine function, but its biomechanical effect on the cervical spine was not fully elucidated.

OBJECTIVE

To investigate the effect of cervical sagittal alignment on dynamic intervertebral kinematics.

DESIGN

Cross-sectional study.

METHODS

Healthy participants without neck pain were recruited and divided into lordosis, straight and kyphosis groups according to the C2-C7 Cobb angle at the neutral position. The anti-directional and total joint motions were extracted across 10 epochs of dynamic cervical flexion and extension movements.

RESULTS

/findings: The overall anti-directional joint motion during flexion is larger in the kyphosis group when compared with the lordosis group (p = 0.021), while the range of flexion is smaller in the kyphosis group than that in the lordosis group (p = 0.017). The C2/C3 anti-directional joint motion during extension in the straight group is larger than that in the lordosis group (p = 0016). The range of extension in the kyphosis group (p < 0.001) and the straight group (p = 0.002) are larger than that in the lordosis group. The increased range of extension in the kyphosis and straight groups were mainly from the C3/C4, C4/C5, and C5/C6 joints(p < 0.05).

CONCLUSION

Changes in cervical sagittal alignment alter both the quality and quantity of the individual joint motions. More adjustments are required by the cervical joints to complete neck movements with the loss of lordosis. The lordotic curvature is a relatively effort-saving mode for the cervical spine from a biomechanical perspective.

Comparison of the Effects of Posterior Cervical Fixation or Posterior Cervical Fixation Extending to the Upper Thoracic Region on Cervical Sagittal Alignment

OBJECTIVE

For degenerative diseases accompanied by cervical malalignment, the starting and ending points of fixation for better cervical sagittal alignment and clinical results are not as clear as the thoracolumbar region. In this study we aimed to compare the effects of posterior subaxial cervical fixation (PSCF), posterior cervical fixation extending to the upper thoracic region and posterior upper cervical fixation extending to the upper thoracic region on cervical sagittal alignment.

METHODS

Sixty-three patients who underwent posterior cervical and cervical-up thoracic fixation were retrospectively analyzed in a comparative study. The procedures that we performed from May 2019 to March 2022 on these 63 patients were: (1) C3-C6 group-posterior subaxial cervical fixation; (2) Subaxial-T2 group-posterior subaxial cervicothoracic fixation (PSCTF); (3) C2-T2 upper thoracic posterior fixation group. The C3-C6 group had 27 patients, Subaxial-T2 group had 24, and C2-T2 group had 12. We determined the minimum follow-up period as 12 months. C0-2, C2-7 lordosis angle, sagittal vertical axis (SVA), C2 slope, C7 slope, T1 slope, cervical slope, neck slope, and thoracic inlet angle (TIA) measurements were made in three patient groups. Comparatively, cervical sagittal alignment was evaluated.

RESULT

In the C2-T2 group, a significant increase in C2-C7 lordosis, decrease in C2 slope, and increase in TS-CL were observed. Significant C2-C7 lordosis decrease, C2 slope increase, and TS-CL decrease were observed in the C3-C6 group. A significant increase in C2-C7 lordosis and a decrease in C2 slope were observed in the subaxial-T2 group. No significant change was observed in the TS-CL angle.

CONCLUSION

In cervical degenerative disorders accompanied by cervical malalignment, we recommend the C2-T2 fixation method, which provides the desired C2-C7 lordosis, SVA within the normal range, and the best Neck Disability Index results.

Comparative Analysis of Postoperative Sagittal Balance in Expansive Open-Door Laminoplasty versus Laminectomy with Fusion for Multilevel Ossification of Posterior Longitudinal Ligament: A Retrospective Study

BACKGROUND This single-center study included 80 patients with multilevel cervical ossification of the posterior longitudinal ligament (OPLL) and aimed to compare postoperative sagittal balance following treatment with expansive open-door laminoplasty (LP) vs total laminectomy with fusion (LF). MATERIAL AND METHODS Data of 80 patients with multilevel OPLL treated with LP vs LF between January 2017 and January 2022 were retrospectively analyzed. The basic data, cervical sagittal parameters, and clinical outcomes of the patients were counted in the preoperative and postoperative periods, and complications were recorded. Forty patients underwent LP and 40 underwent LF. Cervical sagittal parameters were compared between and within the 2 groups. Clinical outcomes and complications were compared between the 2 groups. RESULTS At last follow-up, the postoperative C2-C7 Cobb angel, T1 slope (T1S), and C7 slope (C7S) were significantly higher in the LF group than in the LP group (P<0.001). C2-C7 SVA (cSVA) was slightly higher in the LF group (P>0.05) and significantly higher in the LP group (P<0.05). The incidence of postoperative complications in the LP group was significantly lower than in the LF group (P=0.02). The postoperative scores on the Visual Analog Scale (VAS), Neck Disability Index (NDI), and Japanese Orthopedic Association (JOA) were significantly improved in both groups (P<0.001). CONCLUSIONS Both procedures had good outcomes in neurological improvement. After posterior surgery, the cervical vertebrae all showed a tilting forward. Compared to LP, LF may change cervical balance in Cobb angel, T1S. LF has better efficacy in improving cervical lordosis compared with LP. Patients with high T1 slope after surgery may has more axial pain.

Correlations between Sagittal Parameters and Functional Scores in 65-Year-Old Osteoporotic Females with Vertebral Body Fracture under Low-Energy Mechanism

Background: Vertebral compression fractures (VCFs) are the most common fragility fractures associated with low-energy injury mechanisms in postmenopausal women with osteoporosis. No clear consensus is currently available on the optimal timing for surgical intervention in specific cases. Methods: This study examined the correlations between sagittal parameters, functional scores, and the appropriate timing for surgical intervention during the recovery stage in patients with osteoporosis with thoracolumbar (TL) vertebral body fractures. A total of 161 women aged ≥ 65 years with osteoporosis were included in the study. Spinal sagittal parameters from standing plain films and functional outcomes as the Oswestry disability index (ODI) and the visual analogue scale (VAS) were collected. Results: We found that TL junction Cobb angle was significantly correlated with ODI > 30 (p < 0.001) and VAS > 6 (p < 0.001) and the discriminative values for predicting ODI > 30 and VAS > 6 were a TL kyphotic angle of 14.5° and 13.5°, respectively. Among women aged ≥ 65 years with osteoporosis, the back pain and functional impairment observed within 6 months following a compression fracture are associated with a greater TL kyphosis angle. Conclusions: This suggests that a more proactive approach may be necessary when addressing the conditions of these patients.

Odontoid incidence: a constant cervical anatomical feature evident in standing plain radiographs and supine magnetic resonance images

OBJECTIVE

To assess whether there is a difference between measurements of odontoid incidence (OI) and other cervical sagittal parameters by X-ray radiography and those by supine magnetic resonance imaging (MRI).

METHODS

Standing X-ray and supine MRI images of 42 healthy subjects were retrospectively analyzed. Surgimap software was employed to measure cervical sagittal parameters including OI, odontoid tilt (OT), C2 slope (C2S), C0-2 angle, C2-7 angle, T1 slope (T1S) and T1S-cervical lordosis (CL). Paired samples t-test was applied to determine the difference between parameters measured by standing X-ray and those by supine MRI. In addition, the statistical correlation between the parameters were compared. The prediction of CL was performed and validated using the formula CL = 0.36 × OI - 0.67 × OT - 0.69 × T1S.

RESULTS

Significant correlations and differences were found between cervical sagittal parameters determined by X-ray and those by MRI. OI was verified to be a constant anatomic parameter and the formula CL = 0.36 × OI - 0.67 × OT - 0.69 × T1S can be used to predict CL in cervical sagittal parameters.

CONCLUSIONS

OI is verified as a constant anatomic parameter, demonstrating the necessity of a combined assessment of cervical sagittal balance by using standing X-ray and supine MRI. The formula CL = 0.36 × OI - 0.67 × OT - 0.69 × T1S can be applied to predict CL in cervical sagittal parameters.

A novel rapid measurement method of cervical sagittal parameters based on the integrated inclinometer of a smartphone: a validity and reliability study

Objectives: A new method was introduced using a smartphone's integrated inclinometer for rapid measurement of sagittal cervical parameters. The present study aims to compare the validity and reliability of the proposed method.Methods: We retrospectively reviewed 120 patients with cervical spondylosis treated at our hospital. The C0-2 Cobb angle, C2-7 Cobb angle, T1-slope (T1S), and neck tilt (NT) were selected as representative sagittal angles for this study. Two methods, the smartphone's integrated inclinometer and picture archiving and communication system (PACS), were used to measure these four representative angles. Validity, reliability, and measurement times were recorded and compared.Results: The representative parameters (C0-2 Cobb angle, C2-7 Cobb angle, T1S, and NT), the ICC was 0.957 (0.939-0.970), 0.971 (0.958-0.979), 0.974 (0.963-0.982) and 0.949 (0.927-0.964) for validity respectively. For the aforementioned representative parameters, the ICC values were 0.972 (0.960-0.980), 0.979 (0.969-0.985), 0.972 (0.959-0.980), 0.942 (0.917-0.959) for intraobserver reliability respectively. For the representative parameters mentioned above, the ICC values were 0.947 (0.926-0.963), 0.964 (0.949-0.975), 0.956 (0.938-0.969), 0.916 (0.881-0.940) for interobserver reliability respectively. For the validity of the representative parameters mentioned above, the Bland-Altman plot displayed a mean difference of 0.2, 0.1, 0.1, and 0.4°with a 95% CI of 4.3, 4.5, 3.4, and 4.1°, respectively. The measurement by smartphone's integrated inclinometer (46.31 ± 3.99 s) was significantly quicker than that by PACS (69.48 ± 3.25 s) according to independent-samples T test (p < 0.001).Conclusion: This novel smartphone measurement based on the integrated inclinometer is accurate and reliable for measuring cervical sagittal parameters rapidly and conveniently.

Prevalence and risk factors of occupational neck pain in Chinese male fighter pilots: a cross-sectional study based on questionnaire and cervical sagittal alignment

Background

Neck pain (NP) is a common musculoskeletal disorder among fighter pilots and has become a rising concern due to its detrimental impact on military combat effectiveness. The occurrence of NP is influenced by a variety of factors, but less attention has been paid to the association of NP with demographic, occupational, and cervical sagittal characteristics in this group. This study aimed to investigate the prevalence and risk factors of NP in Chinese male fighter pilots using a questionnaire and cervical sagittal measurements.

Methods

Demographic and flight-related data, as well as musculoskeletal pain information, were gathered from Chinese male fighter pilots via a self-report questionnaire. Cervical sagittal parameters were measured and subtypes were classified using standardized lateral cervical radiographs. Differences in various factors between the case and control groups were analyzed using t-tests or chi-square tests. Binary logistic regressions were conducted to explore potential risk factors contributing to NP. Predictors were presented as crude odds ratios (CORs) and adjusted odds ratios (AORs), along with their respective 95% confidence intervals (CIs).

Results

A total of 185 male fighter pilots were included in this cross-sectional study. Among them, 96 (51.9%) reported experiencing NP within the previous 12 months. The multivariate regression analysis revealed that continuous flight training (AOR: 4.695, 95% CI: 2.226-9.901, p < 0.001), shoulder pain (AOR: 11.891, 95% CI: 4.671-30.268, p < 0.001), and low back pain (AOR: 3.452, 95% CI: 1.600-7.446, p = 0.002) were significantly associated with NP.

Conclusion

The high 12-month prevalence of NP among Chinese male fighter pilots confirms the existence of this growing problem. Continuous flight training, shoulder pain, and low back pain have significant negative effects on pilots' neck health. Effective strategies are necessary to establish appropriate training schedules to reduce NP, and a more holistic perspective on musculoskeletal protection is needed. Given that spinal integrated balance and compensatory mechanisms may maintain individuals in a subclinical state, predicting the incidence of NP in fighter pilots based solely on sagittal characteristics in the cervical region may be inadequate.

Relationship between C2 slope with sagittal parameters and clinical function of degenerative cervical kyphosis

PURPOSE

To explore the relationship between C2 slope with sagittal parameters and clinical function of degenerative cervical kyphosis (DCK).

METHODS

A retrospective analysis of 127 patients with degenerative cervical spondylosis treated in our spinal deformity center from January 2019 to June 2022. Patients were categorized into two groups and compared based on C2-7 angle (C2-7 ≥ 5° as kyphosis group, C2-7 < 5° as lordosis group). Pearson correlation or Spearman correlation was used to analyze the relationship between C2S and conventional radiological parameters and health -related quality-of-life (HRQOL) outcomes as measured by the EuroQol 5 dimension questionnaire (EQ5D), NRS, and the neck disability index (NDI). The cutoff value of C2S was determined by a receiver operating characteristic (ROC) curve.

RESULTS

There were 127 patients who met inclusion criteria (79 men and 48 women). Average 56.00 ± 10.27 years old (range 31-81 years old). C2S of kyphosis group is higher than non-kyphosis group. Aggravating cervical kyphosis increases cSVA positively. For all patients, C2S demonstrated a significant correlation with the O-C2 angle, C2-7 angle, cSVA, and TS-CL (p < 0.05). NRS, NDI and EQ5D-VAS scores revealed a significant correlation with C2S and cSVA (p < 0.01). For the subgroup of patients presenting with DCK, ROC curves demonstrated the cutoff values of C2S as 26.3°, and 30.5°, according to a cSVA of 40 mm, and severe disability expressed by NDI, respectively.

CONCLUSION

On the basis of retaining the consistency of cranio-cervical and cervico-thoracic structure, C2S can better analyze the sagittal alignment of DCK patients than TS-CL and has good practicability in clinical application and HRQOL evaluation.

Factors related to T1 slope: spinopelvic balance and thoracic compensation

OBJECTIVE

To identify factors associated with T1 slope (T1S).

METHODS

A total of 215 patients over 18 years old who underwent whole-spine X-rays to evaluate lower back pain were enrolled in this study. T1S, pelvic tilt (PT), sacral slope (SS), pelvic incidence (PI), thoracic kyphosis (TK), lumbar lordosis (LL), cervical lordosis (CL), thoracolumbar kyphosis (TLK), and sagittal vertical axis (SVA) were measured. Patients were divided into balance, compensatory balance, thoracic compensation, and thoracic decompensation groups.

RESULTS

TK (p < 0.001), SVA (p < 0.001), and CL (p = 0.020) were significantly related to high T1S. The balance group had the smallest PT, largest SS and largest LL of the four groups (p < 0.001). The thoracic compensation group had the smallest TK of all groups (p < 0.001). There was no significant difference in T1S between the balance and thoracic compensation groups (p = 0.099). The thoracic decompensation group had a larger T1S than the balance group (p = 0.023).

CONCLUSIONS

Caudal spine segments had a sequential effect on cranial spine segments. T1S reflected the compensation ability of the spine. The absence of balance tended to increase the T1S. Pelvic posterior rotation and thoracic compensation were two crucial factors protecting against increased T1S in patients with ASD.

Quantitatively biomechanical response analysis of posterior musculature reconstruction in cervical single-door laminoplasty

BACKGROUND AND OBJECTIVE

The current trend of laminoplasty is developing toward the goal of muscle preservation and minimum tissue damage. Given this, muscle-preserving techniques in cervical single-door laminoplasty have been modified with protecting the spinous processes at the sites of C2 and/or C7 muscle attachment and reconstruct the posterior musculature in recent years. To date, no study has reported the effect of preserving the posterior musculature during the reconstruction. The purpose of this study is to quantitatively evaluate the biomechanical effect of multiple modified single-door laminoplasty procedures for restoring stability and reducing response level on the cervical spine.

METHODS

Different cervical laminoplasty models were established for evaluating kinematics and response simulations based on a detailed finite element (FE) head-neck active model (HNAM), including ① C3 - C7 laminoplasty (LP_C37), ② C3 - C6 laminoplasty with C7 spinous process preservation (LP_C36), ③ C3 laminectomy hybrid decompression with C4 - C6 laminoplasty (LT_C3 + LP_C46) and ④ C3 - C7 laminoplasty with unilateral musculature preservation (LP_C37 + UMP). The laminoplasty model was validated by the global range of motion (ROM) and percentage changes relative to the intact state. The C2 - T1 ROM, axial muscle tensile force, and stress/strain levels of functional spinal units were compared among the different laminoplasty groups. The obtained effects were further analysed by comparison with a review of clinical data on cervical laminoplasty scenarios.

RESULTS

Analysis of the locations of concentration of muscle load showed that the C2 muscle attachment sustained more tensile loading than the C7 muscle attachment, primarily in flexion-extension (FE) and in lateral bending (LB) and axial rotation (AR), respectively. Simulated results further quantified that LP_C36 primarily produced 10% decreases in LB and AR modes relative to LP_C37. Compared with LP_C36, LT_C3 + LP_C46 resulted in approximately 30% decreases in FE motion; LP C37 + UMP also showed a similar trend. Additionally, when compared to LP_C37, LT_C3 + LP_C46 and LP C37 + UMP reduced the peak stress level at the intervertebral disc by at most 2-fold as well as the peak strain level of the facet joint capsule by 2-3-fold. All these findings were well correlated with the result of clinical studies comparing modified laminoplasty and classic laminoplasty.

CONCLUSIONS

Modified muscle-preserving laminoplasty is superior to classic laminoplasty due to the biomechanical effect of the posterior musculature reconstruction, with a retained postoperative ROM and loading response levels of the functional spinal units. More motion-sparing is beneficial for increasing cervical stability, which probably accelerates the recovery of postoperative neck movement and reduces the risk of the complication for eventual kyphosis and axial pain. Surgeons are encouraged to make every effort to preserve the attachment of the C2 whenever feasible in laminoplasty.

Analysis of risk factors of axial neck pain in posterior cervical single-door laminoplasty from the perspective of cervical sagittal plane

Objective

We carried out this study to explore the possible relationship between the cervical sagittal parameters in radiological images and axial neck pain (ANP) for patients who had underwent posterior cervical single-door laminoplasty.

Method

141 patients were enrolled in the study from January 2018 to January 2021, among which 38 were enrolled into the ANP group and 103 were enrolled into the non-ANP group. C2–7 Cobb angle, C2–7 sagittal vertex axis (SVA), thoracic inlet angle, neck tilt, and T1 slope were measured using computed tomography. Spearman correlation tests were used to analyze the possible correlation between radiological parameters and ANP. Logistic regression was carried out to analyze the potential risk factor for the occurrence of ANP. Receiver operating characteristic (ROC) curve and area under the ROC curve were used to evaluate the significant result and the optimal diagnostic value.

Results

As for radiographic parameters in the sagittal plane, the results suggested that only T1 slope and C2–7 SVA were statistically different between the ANP and non-ANP group (p = 0.001 and p = 0.047). Patients whose surgery involved the C2 spinous process demonstrated severe ANP symptoms than patients in the non-ANP group (p = 0.003). The Spearman correlation test showed that no statistical differences were found between visual analog scale (VAS) and radiological morphology parameters and only C2 involvement was found to correlate with postoperative VAS with respect to surgery. Logistic multivariate regression analysis demonstrated that only C2 involvement and T1 slope were significantly different when C2–7 SVA, T1 slope, C2 involvement together were included into consideration, with p values of 0.01 and 0.001.

Conclusion

According to our research, C2 involvement and greater T1 slope were independent risk factors of ANP for the patients who underwent laminoplasty of cervical spine.

Posture and Health: Are the Biomechanical Postural Evaluation and the Postural Evaluation Questionnaire Comparable to and Predictive of the Digitized Biometrics Examination?

Background: Postural tone alterations are expressions of myofascial and, therefore, of structural, visceral, and emotional disorders. To prevent these disorders, this study proposes a quantitative investigation method which administers a postural evaluation questionnaire and a postural biomechanical evaluation to 100 healthy subjects. Methods: The reliability of the method is studied by comparing both assessments with digitized biometrics. In addition, 50 subjects undergo the biomechanical evaluation form twice, by four different operators, to study the intraoperative repeatability. Results: The results show a satisfactory overlap between the results obtained with the postural evaluation questionnaire and the postural biomechanical evaluation compared to computerized biometrics. Furthermore, intraoperative repeatability in the use of the biomechanical evaluation form is demonstrated thanks to a minimal margin of error. Conclusions: This experience suggests the importance of undertaking this path in both the curative and the preventive sphere on a large scale and on different types of people who easily, and even unknowingly, may face dysfunctional syndromes, not only structural and myofascial but also consequently of the entire body’s homeostasis.