Evaluation of MM spinal stability scoring system
MM is characterized by the accumulation of clonal plasma cells in bone marrow (BM), the secretion of monoclonal immunoglobulins, and the presence of osteolytic bone lesions, which involve multifactorial problems. How to protect the spine and improve the quality of life of patients with routine chemotherapy in the hematology department is an important issue. It is necessary to evaluate the stability of the spine to develop interventions and determine prescriptions. At present, methods for evaluating the stability of the spine in individuals with primary tumors and metastatic cancer already exist, but no methods have been reported for the evaluation of spinal stability in individuals with multiple myeloma. Based on the clinical features of multiple myeloma, this study established a method for assessing the stability of a MM spine. It should be emphasized that the evaluation of spinal stability is one of the assessments in the course of diagnosis and treatment of MM patients. It may be the most difficult assessment for physicians who are not spinal surgeons. Therefore, constructing a simple and easy to learn scoring system is our main research topic.
The spine requires stability to ensure its degree of movements without pain and prevent neurological dysfunction and abnormal angulation . Spinal stability depends on the integrity of the static structure and function of its components (bones, ligaments, intervertebral discs, facet joints, etc.), the dynamic structures of the muscles, the structure of the nervous system and the functional integrity. Spinal instability caused by tumors is mainly due to the destruction of the bone structure, and other structures are for the most part normal; this condition is quite distinct from those of spinal degenerative instability (with mainly affects ligaments and intervertebral discs a causes changes in facet joints) and traumatic spinal instability (which leads to bone, ligament, and muscle damage or fractures). Similarly, it is not the same as spinal instability caused by neuromuscular disease. Because multiple myeloma is predominantly characterized by osteolytic lesions, osteogenesis and mixed bone changes do not occur. Therefore, it is not appropriate to evaluate the stability of the spine in individuals with multiple myeloma by using methods for assessing the spinal stability of individuals with primary tumors and spinal metastases.
SOSG defines spinal instability as a loss of functional integrity of the spine. Potential instability of the spine is an intermediate state between stability and instability, which is also a significant factor affecting the clinical decision-making process of treatment for individuals with a spinal disease and tumors. There is no consensus on the definition of potential instability , but the importance of the underlying spinal instability with multiple myeloma is noticeable. A surgical intervention can be performed for the spinal nerve compression caused by multiple myeloma spinal lesions [5–8, 14–16]. For MM patients without neurological deficits, it is of great clinical significance to evaluate the stability of the spine, detect spinal instability, determine whether it is accompanied by spinal cord and neurological dysfunction, and prevent spinal instability caused by pathological fractures and the deterioration of neurological symptoms.
Clinical Significance Of Mm Spine Stability Evaluation
The purpose of the MM spine stability assessment is to guide clinical decision making and should be characterized by effectiveness, repeatability, reliability, and maneuverability. Most importantly, it should promote multidisciplinary cooperation and communication between spine surgeons and hematologists. Currently, the SINS score is an internationally accepted method for assessing tumor-related spinal stability. The scoring system was established on the basis of six aspects, including tumor location, degree of pain, type of bone destruction, imaging changes in the spinal line, degree of vertebral collapse and posterior lateral involvement as determined by the SOSG in 2010. Daryl R et al. analyzed the reliability and effectiveness of the SINS scoring system, which is considered to have good prediction accuracy. The specificity and sensitivity of the SINS scoring system in predicting spinal instability were 79.5% and 95.7%, respectively. Fisher et al. have shown that the SINS scoring system is highly reliable; of 629 patients with spinal instability or potential instability, 621 had SINS scores > 7 , and most of them were potentially unstable. Mauricio Campos et al. also obtained similar results for the study of the repeatability and reliability of the SINS scoring system.
Despite the recognition of the specificity and sensitivity of the SINS scoring system, there is still a lack of relevant large-scale prospective studies. Moreover, the scoring system only evaluates the stability of local lesions without considering the general status of the patient. In previous literature, some scholars used the SINS scoring system to evaluate the spinal stability of patients with multiple myeloma, but the sensitivity of multiple myeloma to chemotherapy and radiotherapy and its clinical features were not considered. Therefore, the SINS scoring system still has some limitations when used in the MM population. MM tends to occur in the elderly population, and some patients have spinal degeneration, ankylosing spondylitis and other diseases. The number of tumor infiltrating segments was large, and almost all cases involved osteolytic destruction. MM directly destroys the bone, causing the rigidity of the spine to decrease. In addition, multiple segments are involved in the course of MM, so MM is more likely to cause spinal instability or increase the tumor-related instability on the basis of the original degenerative instability of the spine. These factors are closely related to the evaluation of MM spine stability; however, the SINS scoring system does not take these factors into consideration. Therefore, SINS may not be fully suitable for MM patients.
The lesion location of the tumor affects the stability of the spine. The risk of instability is the largest in the transitional sites of the spine, with the highest score weighting in these areas; the next largest risk of instability is in the active areas, while the weightings of the semiactive region composed of T3-T10 and the fixed region composed of S2-S5 were low.
Although pain is not the only symptom of spinal instability that is caused by tumors, it plays an important role in assessing the instability of the spine. Pain caused by spinal instability can be aggravated by exercise and relieved by bed rest, which is related to the destruction of the spinal structure. As the disease progresses, most patients with MM may feel pain in the chest and lower back, which are caused by local tumor infiltration and spinal instability. Pain associated with tumor invasion can be effectively controlled by chemotherapy, while pain caused by instability cannot be relieved after chemotherapy. Therefore, we rated the pain according to the location and severity of the pain. We evaluated postchemotherapy pain caused by spinal instability, which was different from the pain assessed in the SINS scoring system.
Many studies have indicated that skeletal system-related destruction includes osteolytic lesions and bone pain in patients with MM. Moreover, osteolytic lesions are important factors causing structural instability, and the risk of vertebral collapse caused by osteolytic lesions is higher than that caused by osteoblastic lesions.
Unlike spinal metastatic and primary tumors, which may occur with osteogenesis or osteolytic lesions, this indicator showed no significant differences in the MM spinal stability assessment, which is different from the results of the SINS scoring system.
In general, changes in the physiological curvature or abnormalities often lead to instability of the spine. Malformations may occur gradually, which may be the cumulative effect of multiple lesions. Since vertebral compression fractures caused by multiple myeloma are mostly accompanied by multiple fractures, kyphosis, and spinal degeneration due to advanced age, the scoring system includes the patient's spinal curvature as an indicator. In addition, degenerative changes in the spine (spondylolisthesis/displacement greater than 1 degree, disc herniation less than 1 degree, bone spurs, bony fusion or no lesion) were also assessed separately as first-level indicators; this method of assessment was different from that of the SINS scoring system.
Number Of Involved Segments
More than one segment of the spine was involved in MM. Moreover, a greater number of segments involved in the vertebral compression fracture corresponded to a greater probability of spinal instability, so we considered the number of affected segments as a primary indicator. It should be noted that spinal compression fractures may not be continuous in many situations, and the doctor may evaluate the stability of the corresponding site based on the fracture, which was not mentioned in the previous SINS scoring system.
Sudden neurological dysfunction may occur in patients with MM during treatment, including compression of the spinal cord caused by direct tumor infiltration of the spinal canal and neurological changes due to vertebral instability, which can be distinguished by imaging examinations. In contrast to the SINS scoring system, this scoring system excluded neurological dysfunction caused by intraspinal lesions and assessed neurological changes due to spinal instability based on the Frankel score.
Applicability of the spinal stability assessment for multiple myeloma patients
This scoring system was based on the above indicators and was used to guide the clinical treatment of individuals with MM. The most important clinical contributions of the system are its ability to evaluate patients with MM and provide specific interventions according to the scores to minimize the serious consequences of spinal instability for improving the quality of life of patients. Notably, the spine stability score is a part of the assessment of the stability of a patient's spine. BMI, daily activity, bone quality, and history of previous spinal surgery may also affect the stability of the spine. Special considerations are needed in an overall evaluation of a patient. In guiding treatment, the timing of interventions may change as the disease becomes less invasive. Stability is a part of the assessment when making a surgical treatment decision. The general health, prognosis, neurological function, and decisions of patients must also be taken into consideration.