Thoracic discectomy by posterior pedicle-sparing, transfacet approach with real-time intraoperative ultrasonography

Object. Symptomatic thoracic disc herniations (TDHs) are relatively uncommon, and the technical challenges of resecting the offending disc are formidable due to the location of spinal cord that has relatively poor perfusion characteristics within a narrow canal. The majority of disc herniations are long-standing calcified discs that can be adherent to the ventral dura. Real-time intraoperative ultrasound (RIOUS) visualization of the spinal cord during the retraction and resection of the disc greatly enhances the safety and efficacy of disc resection. The authors have adopted the posterior laminectomy with pedicle-sparing transfacet approach with real-time ultrasound guidance in their practice, and they present the clinical outcome in their patients to illustrate the safety profile of this technique. Methods. Sixteen consecutive patients undergoing operative management of TDHs were identified from the authors' database. All patients underwent microdiscectomy through a posterior transfacet pedicle-sparing approach under RIOUS. Outcomes and complications were retrospectively assessed in this patient series. Clinical records and pre- and postoperative imaging studies were scrutinized to assess levels and types of disc herniation, blood loss, surgical time, pre- and postoperative Nurick grades, Japanese Orthopaedic Association (JOA) scores, and complications. Results. All patients had single-level symptomatic TDHs. The patients presented with symptoms including thoracic myelopathy, axial back pain, urinary symptoms, and thoracic radiculopathy. Thoracic disc herniations involved levels T2-3 to T12-L1. Discs were classified as central or paracentral, and as calcified or noncalcified. All discs were successfully removed with no incidence of neural injury or CSF leak. The mean estimated blood loss was 523 ml, and the mean surgical time was 159 minutes. Nurick grades improved on average from 3.3 to 1.6. The mean JOA scores improved from 5.7 to 8.3 out of 11. The mean Hirabayashi recovery rate of the JOA score was 57%. All patients reported improvement in symptoms compared with preoperative status except for 1 patient with an American Spinal Injury Association Grade A spinal cord injury prior to surgery. The average duration of follow-up was 10.5 months. One patient developed postoperative wound infection that required additional operative debridement and revision of hardware. Conclusions. Thoracic discectomy via a posterior pedicle-sparing transfacet approach is an adequate method of managing herniations at any thoracic level. The safety of the operation is significantly enhanced by the use of realtime intraoperative ultrasonography.