gms | German Medical Science

Objective: In cases of multisegmental cervical stenosis and an obtained lordotic angle dorsal decompression of the spinal cord is a useful approach. This prospective study was performed to evaluate whether intraoperative ultrasonography might provide additional information to verify the sufficiency of spinal cord decompression.

Method: After completion of decompression the width of the subdural space at the cranial and caudal site was measured by intraoperative ultrasound in axial and sagittal reconstruction and compared to data obtained by postoperative T2-weighted MRI. Clinical outcome and symptoms of myelopathy were assessed by Odom and McCormick score.

Results: From July 2011 to April 2014 a total of 31 patients (18 male, 13 female; mean 72.8 y) received one- (n=25) or two-level (n=6) laminectomy for cervical stenosis. The mean follow-up was 6.3 months (range: 0 - 38 mo). At last follow-up 14/31 patients (45.2%) reported either complete recovery or minimal persistent symptoms, 14/31 patients (45.2%) a relief of some symptoms and 3/31 patients (9.7%) reported no improvement or worsening according to the Odom outcome score. No clinical or radiological signs of instability were seen. McCormick myelopathy score was significantly improved in 16/31 patients (p=0.012, Mann-Whitney). After decompression there were no significant differences of diameter of the subdural space measured by sonography and MRI, whether at the cranial or caudal edge of the decompression, nor at the ventral or dorsal site of the spinal cord, both measured in axial and sagittal plane (all average values 1.6 - 2.2 mm; p>0.05; t-test). Overall, the mean difference of width of the subdural space (sonography vs. MRI) was 9.6 % (0 - 32%), assuming a high correlation of the results of both imaging modalities. Complications (3/31, 9%) included one, our first patient, for revision due to insufficient decompression, presumably due to initially missing experience in handling or interpretation of sonographic imaging.

Conclusions: The diameters of the cervical subdural space after decompression showed a high correlation between intraoperative sonography compared to postoperative MRI. Ultrasound imaging proved to be a fast, reliable, precise and safe tool to verify sufficient decompression of the spinal cord, however with a user's learning curve. This technique offers the opportunity for an immediate correction of insufficient decompression without contraindications or complications related to ist use.