ABSTRACT
Objective:To analyze the prevalence and distribution characteristics of diffuse idiopathic skeletal hyperostosis (DISH) in hospitalized patients with thoracic ossification of the ligamentum flavum (TOLF).Methods:The clinical records of 132 consecutive TOLF patients from January 2018 to June 2019 were retrospectively studied. DISH was identified by the preoperative X-ray and CT and its prevalence was calculated. The prevalence of patients with different genders, different age groups and different ossification types was compared. The segmental distribution of DISH and the distribution in the upper (T 1-T 4), middle (T 5-T 8), and lower thoracic spine (T 9-T 12) were analyzed. Ossification degree of DISH was evaluated based on the Meta scoring system. The demographic characteristics (age, gender, BMI, etc.) were compared between DISH and non-DISH group. Results:Forty-nine patients was diagnosed as DISH with the prevalence of 37.1% in all included cases. The prevalence was about twice as high in male (46.3%) than in female (23.1%) ( χ2=8.806, P=0.003). The prevalence in the age groups of <40, 40-49, 50-59, 60-69 and ≥70 years was 20.0%, 28.0%, 34.4%, 44.0%, and 66.7%, respectively. The prevalence in long-segment TOLF patients (45.1%) was significantly higher than that in short-segment TOLF patients (24.0%) ( χ2=5.937, P=0.015). DISH most frequently affected T 8,9 levels (91.8%). The total number and mean number of ossified segments were 365 and 7.4, respectively. Ossification lesions in the upper, middle, lower thoracic spine accounted for 26.03%, 40.54%, and 33.15%, respectively. Grade I, grade II, and grade III ossification accounted for 21.4%, 28.5% and 50.1%, respectively. The mean age of the DISH group was older than the non-DISH group ( t=2.024, P=0.045). The proportion of male patients in the DISH group was significantly higher than that in the non-DISH group ( χ2=8.806, P=0.003). The average height and weight in the DISH group were significantly greater than those in the non-DISH group ( t=2.564, P=0.012; t=2.191, P=0.030), whereas no significant differences in BMI and constituent ratio of concurrent diabetes, cardiac disease, hypertension between two groups were observed. Conclusion:The prevalence of DISH in patients with TOLF is 37.1%. Male, elderly and long-segment TOLF patients are associated with higher prevalence. DISH frequently occurs in the middle and lower thoracic spine, and T 8,9 is the common affected segment. Ossification lesions may develop with age. Demographic characteristics of DISH group differ, to some extent, from those of non-DISH group.
ABSTRACT
Ossification of posterior longitudinal ligament (OPLL) and ossification of ligamentum flavum (OLF) are clinically common heterotopic ossification diseases, which are the main causes of cervical and thoracic spinal stenosis and spinal cord injury. In some cases, OPLL and OLF may involve multiple spinal sites, individually or concurrently, increasing the difficulty of clinical diagnosis and treatment. This review initially attempts to define this specific ossification phenomenon as Tandem ossification of intraspinal ligaments (TOIL). It refers to a kind of severe spinal ligament ossification diseases caused by multiple factors, that OPLL and OLF occur alone or in combination at two or more sites of the cervical, thoracic, or lumbar spine with five or more ossified segments, progressively compressing the spinal cord or nerves, thereby resulting in a series of complex clinical symptoms. The prevalence of TOIL remains unknown, but its clinical detection rate is relatively high, and the most common TOIL is cervical OPLL combined with thoracic OPLL or/and OLF. Moreover, occurrence and development of TOIL involve many factors and its definitepathogenesis is not clear. Damage of upper and lower motor neurons can occur simultaneously in TOIL patients so that their clinical symptoms and signs often interfere with each other. TOIL has various forms, complex imaging features, and no uniform diagnostic and localization diagnostic criteria, which may easily lead to missed diagnosis and misdiagnosis. It is recommended that TOIL is identified by the typical symptoms and signs as the basis, CT three-dimensional reconstruction and MRI signs as the reference, and combination of the possible risk factors and clinical experience. Currently, surgical decompression for responsible lesions is the only effective treatment for symptomatic TOIL. However, domestic and foreign scholars still have great arguments on the optimal surgical strategy of TOIL. No consensus has been reached on how to determine the operating segment and the extent of decompression, which surgical approach and technique to be adopted, and when to select staged or one-stage combined surgery. Therefore, this review summarizes and discusses the current status and progress of the clinical characteristics and surgical strategies of TOIL through searching the relevant literature, to provide a reference for clinicians to diagnose and treat TOIL.
ABSTRACT
Thoracic ossification of ligament flavum (TOLF) is a pathological process of heterotopic bone formation from ligamentum flavum tissue, which is the most common cause of thoracic spinal stenosis and thoracic myelopathy. Imaging examination is the predominant measure for localization and qualitative diagnosis for TOLF. Various TOLF classification systems have been reported currently, based on its morphology, distribution, configuration of compressed spinal cord or its association with peripheral tissue structures. However, there has been no unified classification due to confusing clinical applications. Therefore, we conducted a review to summarize TOLF classification systems and to evaluate the reliability of these classification systems and the diagnostic accuracy of various imaging modalities. As demonstrated in literatures, the diagnostic accuracy of radiography and the reliability of related classification were low. CT-based Sato classification (lateral, extended, enlarged, fused, tuberous) and Kuh classification (unilateral, bilateral, bridging), MRI-based Kuh classification (round, beak) and Chen Zhongqiang classification (isolated, skipping, continuous), Muthukumar classification combined with dural ossification (Tram track sign, Comma sign) elaborated ossification characteristics from different angles and dimensions. These classification systems were clinically significant in pathogenesis implication, risk assessment, treatment guidance and prognosis judgement, which showed high diagnostic accuracy and reliability. Combining multi-dimension and multi-level parameters of CT and MRI will play an important role in the diagnosis, treatment and new classification research of TOLF.