Multi-slice spiral CT 3-dimensional reconstruction tech-nique to treat multi-segmental degenerative spinal steno-sis with traumatic instability of lower cervical spine

Objective: To study the feasibility of multi-slice spiral computed tomography (MSCT) 3-dimensional reconstruc-tion technique in assisting cervical pedicle screw fixation (PSF) and double-door laminoplasty to treat multi-segmen-tal degenerative spinal stenosis with traumatic instability (MDSTI) of lower cervical spine.Methods: From September 2006 to August 2007, PSF combined with double-door laminoplasty was performed in 9 patients with MDSTI of lower cervical spine. MSCT 3-dimensional reconstruction techniques, including volume rendering (VR) and multi-planar reconstruction (MPR), were used to assist preoperative diagnosis and measurement to guide the procedure. MPR was performed after operation. In coronal view, the degree of screw perforation was mea-sured precisely and the different positions of pedicle screws were divided into three grades according to Richter's method. In axial view, the canal sagittal diameter and trans-verse area of every laminoplasty level were measured.Results: Nine patients with MDSTI of lower cervical spine underwent PSF (total 44 screws). According to the classification of Richter, 72.7% (32/44) was in Grade 1 and 27.3% (12/44) was in Grade 2. No screw perforation occurred in Grade 3 and no screw revision was done for misplacement.No iatrogenic damage was observed. Double-door laminoplasty was performed in total 42 volumes. The post-operative sagittal diameter and transverse area of cervical spinal canal were significantly increased (P<0.05). The confi-dence intervals of mean increased ratio were 23.43%-40.65% in sagittal diameter and 23.18%-42.07% in transverse area. Six months after laminoplasty, based on MSCT axial view, complete union between "open door" and allograft bone was obtained in 76.19% of volumes (32/42), and allograft bone was absorbed partly in 23.81% (10/42). A solid union in bilateral gutters was achieved in all cases. They were followed up from 6 months to 1 year (mean 7.8 months). Post-operative neural function recovery in two cases improved 2 ASIA grade, 5 cases improved 1 grade and 2 cases remained the same as preoperative grade. No cases had lower ASIA grade.Conclusion: Assisted with MSCT 3-dimensional re-construction technique, PSF combined with double-door laminoplasty can be performed more safely and effectively to treat patients with MDSTI of lower cervical spine.