title: Thoracic myelopathy due to ossification of ligamentum flavum: a retrospective analysis of predictors of surgical outcome and factors affecting preoperative neurological status.
abstract: 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.
authors.affiliation: Indian Spinal Injuries Centre, Sector-C, Vasant kunj, New Delhi, India. amishsanghvi@rediffmail.com
authors.forename: Amish V
authors.initials: AV
authors.lastname: Sanghvi
authors.forename: Harvinder Singh
authors.initials: HS
authors.lastname: Chhabra
authors.forename: Amrithlal A
authors.initials: AA
authors.lastname: Mascarenhas
authors.forename: Vivek K
authors.initials: VK
authors.lastname: Mittal
authors.forename: Gururaj M
authors.initials: GM
authors.lastname: Sangondimath
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D007796:Laminectomy; D017843:Ligamentum Flavum / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009999:Ossification, Heterotopic / Q000150:complications / Q000601:surgery*; D011184:Postoperative Period; D011379:Prognosis; D012044:Regression Analysis; D012189:Retrospective Studies; D013117:Spinal Cord Compression / Q000209:etiology / Q000473:pathology / Q000601:surgery*; D013904:Thoracic Vertebrae / Q000473:pathology / Q000601:surgery*; D016896:Treatment Outcome
references.citation: Eur J Radiol. 1998 Nov;29(1):76-82
references.pmid: 9934562
references.citation: Spine J. 2003 Jan-Feb;3(1):33-45
references.pmid: 14589243
references.citation: Neurol India. 2002 Sep;50(3):286-9
references.pmid: 12391454
references.citation: J Neurosurg. 2003 Oct;99(3 Suppl):251-6
references.pmid: 14563141
references.citation: Acta Neurochir (Wien). 2001 Aug;143(8):775-82
references.pmid: 11678398
references.citation: Spine (Phila Pa 1976). 1991 Mar;16(3):280-7
references.pmid: 1902988
references.citation: J Spinal Disord Tech. 2004 Oct;17(5):401-4
references.pmid: 15385880
references.citation: J Bone Joint Surg Br. 1995 Jan;77(1):131-3
references.pmid: 7822370
references.citation: J Spinal Disord Tech. 2008 Apr;21(2):116-9
references.pmid: 18391716
references.citation: Practitioner. 1964 Apr;192:540-2
references.pmid: 14143329
references.citation: Int Orthop. 1992;16(1):75-9
references.pmid: 1572777
references.citation: Neurosurgery. 1990 Feb;26(2):217-26 discussion 226-7
references.pmid: 2308669
references.citation: Neurosurgery. 1990 Oct;27(4):638-40
references.pmid: 2234372
references.citation: Spine (Phila Pa 1976). 2001 Mar 1;26(5):558-66
references.pmid: 11242384
references.citation: J Neurosurg Spine. 2005 Jan;2(1):34-9
references.pmid: 15658124
references.citation: Spine (Phila Pa 1976). 2002 Jun 15;27(12):E308-12
references.pmid: 12065995
references.citation: Joint Bone Spine. 2007 Dec;74(6):600-5
references.pmid: 17888708
references.citation: Spine (Phila Pa 1976). 2005 Jul 15;30(14):E400-5
references.pmid: 16025016
references.citation: Eur Spine J. 2006 Apr;15(4):485-91
references.pmid: 15902507
references.citation: Eur Spine J. 2008 Oct;17(10):1277-88
references.pmid: 18704517
references.citation: J Neurosurg. 1988 Feb;68(2):217-22
references.pmid: 3339437
references.citation: Spinal Cord. 2001 Jul;39(7):362-9
references.pmid: 11464309
references.citation: Spine (Phila Pa 1976). 1997 Mar 15;22(6):710-5
references.pmid: 9089946
references.citation: J Neurosurg. 2001 Apr;94(2 Suppl):221-6
references.pmid: 11302624
references.citation: J Neurosurg Spine. 2008 Oct;9(4):358-62
references.pmid: 18939922
references.citation: J Neurosurg Spine. 2006 Aug;5(2):133-9
references.pmid: 16925079
references.citation: J Neurosurg Spine. 2005 Nov;3(5):348-54
references.pmid: 16302628
references.citation: J Neurosurg. 2003 Sep;99(2 Suppl):157-61
references.pmid: 12956457
references.citation: J Korean Neurosurg Soc. 2009 Sep;46(3):189-94
references.pmid: 19844616
references.citation: J Neurotrauma. 2011 Aug;28(8):1431-43
references.pmid: 19831845