Clinical analysis of thoracic ossified ligamentum flavum without ventral compressive lesion

Abstract

The aim of this study was to analyze the clinical characteristics of thoracic ossified ligamentum flavum (OLF) and to elucidate prognostic factors as well as effective surgical treatment modality. The authors analyzed 106 thoracic OLF cases retrospectively from January 1999 to December 2008. The operative (n = 40) and the non-operative group (n = 66) were diagnosed by magnetic resonance imaging (MRI) and/or computed tomography (CT) imaging. We excluded cases exhibiting ventral compressive lesions causing subarachnoid space effacement in thoracic vertebrae as well as those with a coexisting cervical compressive myelopathy. Those in the operative group were treated with decompressive laminectomy as well as resection of OLF. The preoperative neurologic status and postoperative outcomes of patients, as indicated by their modified Japanese Orthopedic Association (mJOA) scores and recovery rate (RR), Modic changes, the axial (fused or non-fused) and sagittal (omega or beak) configurations of OLF, and the ratios of the cross-sectional area (CSA) and anteroposterior diameter (APD) of the most compressed level were studied. The most commonly affected segment was the T10-11 vertebral body level (n = 49, 27.1%) and the least affected segment was the T7-8 level (n = 1, 0.6%). The ratios of the CSA in non-fused and fused types were 77.3 and 59.3% (p < 0.001). When Modic changes were present with OLF, initial mJOA score was found to be significantly lower than those without Modic change (7.62 vs. 9.09, p = 0.033). Neurological status improved after decompressive laminectomy without fusion (preoperative vs. last mJOA; 7.1 ± 2.01 vs. 8.57 ± 1.91, p < 0.001). However, one patient exhibited transient deterioration of her neurological status after surgery. In the axial configuration, fused-type OLF revealed a significant risk for a decreased postoperative mJOA score (0-7, severe and moderate) (Odds ratio: 5.54, χ (2) = 4.41, p = 0.036, 95% CI: 1.014-30.256). The results indicated that the new categorization of axial-type of OLF is a helpful predictor of postoperative patient outcome and fused type was related with poor prognosis. In OLF cases free from ventral lesions compressing the spinal cord, decompressive laminectomy is enough for successful surgical outcome. Therefore, early surgical treatment will be considered in cases with fused-type OLF compressing spinal cord even though they do not have myelopathic symptoms.

Outcomes and Complications Following Laminectomy Alone for Thoracic Myelopathy due to Ossified Ligamentum Flavum

“…Early neurological deficit that manifested immediately after surgery was reported in three studies. 17,18,23 The incidence was 5.0% (4/80) and the pooled estimate was 5.7% (95% CI, 2.2–14.3%, I 2 = 0%). Late neurological deterioration that did not occur immediately after surgery was reported in one study in six out of 24 patients.…”

“…The incidence of dural tear was reported in all six studies. 1,16–19,23 The cumulative incidence of dural tears was 17.5% (24/137), and the pooled proportion estimate was 18.4% (95% CI, 12.6–26.1; I 2 = 0%).…”

“…The neurological deficit fully resolved following evacuation of the hematoma. 17 Yoon et al 23 reported one transient episode of neurological deficit that resolved without any evidence of long-term sequelae; however, they did not comment on the possible underlying etiology of the neurological deficit. Liao et al 18 described two episodes of transient neurological deterioration that occurred following unintended intraoperative spinal cord manipulations.…”

Treatment strategies for the surgical complications of thoracic spinal stenosis: a retrospective analysis of two hundred and eighty three cases

“…Nerve-root injury is comparatively rare during surgical treatment of thoracic spinal stenosis, and single nerve-root injury does not have serious consequences [17,18]. Nerveroot injury occurred in seven patients in our series: two were due to traction during posterior discectomy, three to irritation caused by the Kerrison rongeur, one to incorrect use of the drill and one to incorrect use of the bone knife during partial resection of the facet joint.…”

A Rare Case of Ossification of Ligamentum Flavum presenting as Dorsal Myelopathy in Achondroplasia

“…Recent studies indicate that the development of OPLL is associated with certain genetic factors [10,11] which may also play a specific role in the origin of OLF (12). The lower thoracic spine (T9-12) is the most frequently affected, while the mid-thoracic spine (T5-8) is rarely affected [13]. CT and MRI are the two most common diagnostic modalities with CT being the more sensitive tool for diagnosis [12].…”