This study evaluated the sensitivity and specificity of LUS in the management of lumbosacral spinal dysraphisms by using the MRI as the standard reference. The sensitivity of LUS in detecting a thickened filum was 77.8% preoperatively and 62.5% postoperatively, with a specificity of 100%. The sensitivity and specificity of detecting conus level, solid masses, and cystic masses were 100%.
Azzoni et al. found LUS in comparison with MRI was highly specific but not very sensitive. The images were similar, easily comparable, and often identical to the MRI results, although MRI was certainly more sensitive. The advantages of sonography are non-invasiveness, lower cost, availability, simplicity, rapidity of the examination, and its specificity. Indications for its use are lumbosacral skin abnormalities and neurological disorders caused by malformations . Chern et al. found the sensitivity of LUS in comparison with MRI 76.9% in detecting low-lying tethered cord. The diagnostic value of SUS has been shown to be equal to MRI . Rohrschneider et al. found that LUS exactly correlated with MRI in 32 of 38 cases. In five cases, LUS detected the main abnormality but MRI gave additional information. Wherever LUS is normal, MRI is also normal. LUS had a sensitivity of 100%. Therefore, LUS may be used as a primary screening tool, with MRI being performed in any case where LUS revealed abnormalities . Dhingani et al. reported that 79.31% of cases showed full agreement between LUS and MRI examinations and 20.69% partial agreement. LUS can be used as the initial modality for evaluation of spinal dysraphism as well as for screening of suspected cases . Hughes et al. reported 40% full agreement between LUS and MRI examinations, 47% partial agreement, 13% no agreement, and 90% agreement in low-lying cord location . Kommana et al. concluded that ultrasound and MRI are adjuvant in the evaluation of spinal dysraphism. MRI is excellent in characterizing the soft tissue spinal anomalies of dysraphism, whereas ultrasound is an excellent initial imaging modality in infants for evaluation of dysraphism .
Ultrasound is used in this study not only as a preoperative screening but also as an intraoperative screening for adequacy of surgical exposure, confirming preoperative diagnosis and detection of the relationship between the tethered cord and the surrounding tissue through echogenicity differentiation between the spinal cord and other tissues (plane of demarcation). Also, ultrasound was used on the postoperative follow-up evaluation of untethering and repair by detecting cord regression and postoperative presence of any lesion. Gerscovich et al. concluded that in patients who have a spinal defect or interlaminar space allowing visualization of the lumbosacral spinal canal, ultrasound can provide similar information to that obtained with magnetic resonance imaging with no need for sedation and at a low cost. Ultrasound seems more sensitive than magnetic resonance imaging in the detection of cord adhesions, which is particularly relevant in the diagnosis of tethering .
In this study, in post-operative follow-up, three cases presented with wound healing problems (two cases with erythema on either side of the incision, in areas of tension, one case with subcutaneous collection). Two cases presented with CSF leak managed conservatively.