Factors related to long-term outcome after decompressive surgery for ossification of the ligamentum flavum of the thoracic spine

Abstract

<jats:p content-type="fine-print"><jats:italic>Object.</jats:italic> Factors related to long-term surgical outcome of thoracic myelopathy caused by ossification of the ligamentum flavum (OLF) have not been fully investigated. To evaluate these factors, the authors reviewed medical records obtained in patients who had undergone decompressive surgery for thoracic OLF.</jats:p> <jats:p content-type="fine-print"><jats:italic>Methods.</jats:italic> Thirty-four patients in whom decompressive surgery was performed for thoracic OLF (mean follow-up period 8 years) were recruited. Fourteen patients underwent simultaneous decompressive surgery for cervical or lumbar lesions. Patient age, duration of symptoms, OLF type, dural adhesion, neurological status classified by the Japanese Orthopaedic Association (JOA) scale before and after surgery (1 month postoperatively and at final follow up), and recovery rate were reviewed. The ossified ligamentum flavum was classified into five types according to Sato's classification by assessing preoperative computerized tomography scans. The mean preoperative JOA score (5) was significantly improved at 1 month after surgery (7.1) and at final follow up (7.9) (p &lt; 0.05). Recovery rates at 1 month and at final follow up were 34.6 and 44.2%, respectively. No significant correlations were found between age, OLF type, and neurological status before and after surgery. In patients with dural adhesion, which was observed in cases of larger-type OLF (p &lt; 0.02), lower JOA scores were observed compared with those in patients without dural adhesion both preoperatively and at 1 month after surgery (p &lt; 0.05) but not at the final follow-up examination. Higher JOA scores and recovery rates were demonstrated in patients who had undergone simultaneous surgery than in those who had not undergone simultaneous surgery at 1 month (p &lt; 0.05) but not at the final follow up. Using multiple regression analysis, the authors identified the duration of preoperative symptoms as the most important predictor of a high JOA score and recovery rate at the final follow up.</jats:p> <jats:p content-type="fine-print"><jats:italic>Conclusions.</jats:italic> Duration of preoperative symptoms represents the most important predictor of long-term surgeryrelated outcome in patients treated for thoracic OLF. The type of ossified ligamentum flavum, dural adhesion, and simultaneous surgery for coexistent cervical or lumbar lesions do not appear to influence the long-term postoperative prognosis.</jats:p>

Contributing factors affecting the prognosis surgical outcome for thoracic OLF

“…Early diagnosis and treatment are important for the postoperative functional prognosis. It is reported that the persistence of residual spasticity at follow-up may be due to irreversible changes within the cord that is caused by the significant cord compression and the delay between the onset of initial symptoms and surgical decompression [2,9,12,14]. In our series, the symptom duration was not related to the surgical outcome statistically, but, especially the short symptom duration, less than 6 months, was a relatively favorable factor to the surgical outcome.…”

“…In our series, the symptom duration was not related to the surgical outcome statistically, but, especially the short symptom duration, less than 6 months, was a relatively favorable factor to the surgical outcome. Miyakoshi et al [9] classified the thoracic OLF into five types according to the range and morphological features of the ossification depicted on the preoperative CT scans at the narrowest spinal level: lateral, extended, enlarged, fused, and tuberous. They reported that there were no correlations observed between the types of OLF and preoperative neurological status or postoperative prognosis.…”

Clinical characteristics and surgical outcome of thoracic myelopathy caused by ossification of the ligamentum flavum: a retrospective analysis of 85 cases

“…In addition, it has been reported Clinical characteristics and surgical outcome of TM caused by OLF Z Li et al that the location of OLF is less vulnerable in mobile segments such as the cervical and lumbar vertebra than in the thoracic vertebrae. 26,30,40,55,56 This phenomenon gives us insight about the pathogenetic mechanism of OLF. On the basis of the literature review, we hypothesized that biomechanical and anatomical factors might have a key role in thoracic OLF progression.…”

“…Furthermore, lamina treated with laminoplasty may return to the preoperative position, the surgical procedure is relatively complicated and the long-term effect is less reliable than that of the surgical technique reported here. 56,65 As we all know, each surgical procedure has its own complications. Dural tears and CSF leakage are the most common complications of thoracic OLF surgery and can lead to CSF pseudocyst, respiratory obstruction, wound dehiscence and meningitis.…”

“…A high-intensity signal in the spinal cord on T2-weighted MRI is thought to indicate edema, demyelination, myelomalacia, cavitation or necrosis and related to the severity of the myelopathy. 56,[59][60][61] However, MRI alone is insufficient for the diagnosis of OLF because a low-intensity signal on T1-and T2-weighted sequences is indistinguishable from that corresponding to a hypertrophic ligamentum flavum. Consequently, as we have performed in our study, preoperative whole-spine MRI combined with CT are recommended to establish an accurate diagnosis and to determine the extent of surgical procedure.…”