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Surgical Results of Thoracic Myelopathy with Ossification of the Yellow Ligament.
Abstract
We reviewed the surgical results of 18 patients suffering from thoracic myelopathy caused by ossification of the yellow ligament (OYL) and investigated the factors affecting postoperative results. The percentage of clinical recovery, which was calculated from the JOA score before and after surgery, averaged 54.9%. Factors investigated were age at surgery, delay of surgery after onset of symptoms, JOA score before surgery and percentage of narrowing of spinal canal calculated from CT myelography. Correlation between percentage of clinical recovery and these factors were analyzed. There was a significant negative correlation between the percentage of clinical recovery and delay of surgery. No significant correlation was found between the other factors. Therefore, we recommend early diagnosis and early surgery without delay.
... Age or sex does not correlate with RR as reported [3,5,7,8,10,12,13,16,17], except one study [1] reporting correlation of age with RR. Kojima [30] reported good postoperative recovery in younger patients despite severe involvement indicating good plasticity of spinal neurons. ...
... Preoperative duration of symptoms significantly correlates with recovery and indicates the importance of early operative intervention to achieve better result. Eight studies [1,5,[8][9][10][11][12]16] support this observation, though same number of studies [2-4, 7, 13-15, 17] are against it. The latter observation may be due to either delay in surgery after onset of symptoms causing irreversible cord changes unlikely to affect recovery significantly or due to small sample size causing type 2 error. ...
... Out of 17 studies [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] reporting factors affecting outcome, only four studies [10,12,15,16] used MRA to identify prognostic factors. Our study is unique due to four reasons: ...
Despite good posterior decompression of thoracic myelopathy due to ossification of ligamentum flavum (OLF), recovery varies widely from 25 to 100%. Neurological status on presentation also varies widely in different patients. We, therefore retrospectively studied relation of various clinical and magnetic resonance imaging (MRI) parameters with preoperative neurological status and postoperative recovery in 25 patients who underwent decompressive laminectomy for thoracic myelopathy due to OLF. Patients were assessed using leg-trunk-bladder scores of JOA scale and recovery rate (RR) was calculated as RR = postoperative score - preoperative score/11 - preoperative score × 100. With Pearson's correlation, postoperative recovery rate (RR) significantly correlated with preoperative duration of symptoms, JOA score, sensory JOA score, canal grade, dural canal-body ratio (DCBR), intramedullary signal size (ISS), and intramedullary signal type (IST) on MRI. On MRI, two types of signal changes were identified: normal in T1/hyperintense in T2 representing cord edema and hypointense in T1/hyperintense in T2 representing cystic changes indicating lesser and higher grades, respectively. Presence or absence of signal changes did not correlate with postoperative recovery; but whenever present, ISS greater than 15 mm significantly compromised recovery. Multiple regression analysis (MRA) identified preoperative duration of symptoms and preoperative ISS as significant predictors of postoperative outcome. Based on MRA, we formulated a multiple regression equation to predict RR as Predicted RR = 83.4 + (0.1 × age in years) - (0.7 × preoperative duration of symptoms in months) + (1.5 × preoperative JOA score) + (0.2 × preoperative canal grade in percentage) - (2.5 × ISS in mm) - (1.5 × IST in grade). Though age, preoperative anal sensations, spasticity, canal grade, DCBR, ISS, and IST significantly correlated with preoperative neurological status, MRA identified ISS as most important factor determining preoperative neurological status. Preoperative duration of symptoms and developmentally narrow canal had no influence on preoperative neurological status. Patients with developmentally narrow canal showed significant correlation with younger age at onset of myelopathy. To conclude, only independent factor determining preoperative neurological status is ISS. Predictors of postoperative recovery are preoperative duration of symptoms and ISS. Postoperative recovery can be predicted by formulated equation.
... The ligamentum flavum is a yellowish elastic ligament extending form second cervical vertebra to the S1 segment of sacrum consisting of 80% elastin (5) . The ligament is in the dorsal portion of the spinal canal, proximal insertion of ligamentum flavum is the ventral part of cranial lamina extending to the dorsal part of caudal lamina and extending to the capsules of facet joints and the posterior aspects of the neural foramina and is separated from the dura mater by epidural fat (9). ...
... For thoracic ossified ligamentum flavum fenestration or complete laminectomy are usually performed. The ossified ligament should be removed carefully taking care of ossified dura matter which usually concurs (5) . This ossification of LF was reported to occur in up to 20% of Japanese individuals >65 years old and many reports viewed it as a normal feature of the ageing Asian spine (12) . ...
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