1. 1 Iatrogenic Foraminal Stenosis after Cervical Pedicle Screw Fixation Akiyoshi Yamazaki, Kei Watanabe, Keiichi Katsumi, Masayuki Ohashi Spine Center, Dept. of Orthop. Surg., Niigata Central Hospital, Niigata, Japan EuroSpine 2010 Sept. 15 - 17, Vienna, Austria

2. 2 Purposes CT- based navigation has remarkably decreased the neurovascular injuries directly attributable to pedicle screw (PS) insertion. On the other hand, iatrogenic foraminal stenosis (FS) which is not directly attributable to screw insertion has been reported. Purposes are to investigate the clinical features of nerve root palsy due to FS after PS fixation and to discuss on its mechanism and preventive measures.

3. 3 Materials and Methods 2005 - 2009 PS fixation ranging from C4/5 to C7/T1 7/ 38 pts (18%), 6 men, 1 woman 9 roots (C5: 6, C6: 1, C8: 2) Age: avg 60 y.o. (36 - 76) N. of fused seg.: avg 3 (1 - 4) Diagnosis: CSMR 5 pts, CSM 2 pts Comorbidity: CP 2 pts, RA 1 pt, TSM 1 pt FU period: avg 10 m (5 ‐ 18)

4. Operative procedure ① PS insertion Fluoroscopy: 1 pt in the early phase CT-based Navigation: 6 pts ② Decompression ③ Rod application With correction of alignment: 5 roots Without correction of alignment : 4 roots 4

5. RESULTS Foraminotomy at the 1st op: 4 roots (Group A) Foraminotomy at the 2nd op: 4 roots (Group B) No foraminotomy: 1 root 5 0 1 2 3 4 5 PrePostFU C5 MMT Group A 0 1 2 3 4 5 PrePostFU C6 C5 C8 MMT Group B

6. 6 mm Deg. Without correction (4 roots) Reduction of anterior translation Reduction of kyphosis With correction (5 roots) Kyphosis: avg 6.3 deg. (Pre), 1.0 deg. (FU) Anterior translation: avg 0.3 mm (Pre), -0.6 mm (FU)

7. 4 5 4 5 4 5 4 5 LR 4/5 Case 4 76 y.o. woman CSM, RA (group B) Kyphosis decreased with Rt. C5 palsy Fully recovered after C4/5 foraminotomy

8. 8 7/17/17/17/1 7 1 7 1 R L R L 7/17/1 7 1 7 1 R L RL 7/1 Case 5 59 y.o. man CSM, TSM (group B) Complete paraplegia, VRD

9. 9 L 7 1 7 1 R L 7/1 Case 5 59 y.o. man CSM, TSM (group B) Without correction, blt. Intrinsic m. paralyzed. Partially recovered after blt. foraminotomy. Post. translation increased by 1mm. C7/ T1 blt. foraminal stenosis! RL

10. 10 4 5 4 5 R L 4/5 RL R R Case 7 65 y.o. man CSMR, CP (group A) Deterioration of C5 palsy even after blt. C4/5 foraminotomy Kyphosis decreased by 5 deg. Ant. translation (3mm) disappeared

11. DISCUSSION 11 This study –C5, 6, 8 palsy, 7/ 38pts (18%), 9 roots –Additional foraminotomy in 4 roots –Fully recovered in only 2 roots; no good prognosis –Posterior translation in 3 roots without correction –Palsy deteriorated in 4 roots even after foraminotomy –Difficult to predict the risk –Foraminotomy, then fixation; not sufficient –Foraminotomy, fixation, then reassurance of decompression would be necessary

12. Prophylactic foraminotomy For what degree of FS should be prophylactically decompressed? How much of correction of kyphosis or ant. translation would be allowed after prophylactic foraminotomy? 12 None of the authors has any potential conflict of interest.