Neurological outcome and management of pedicle screws misplaced totally within the spinal canal.

STUDY DESIGN: This study reports 9 cases referred to our institution after surgical correction of adolescent idiopathic scoliosis and pedicle screws misplaced totally within the spinal canal.

OBJECTIVE: To assess the neurological outcome associated with pedicle screws misplaced totally within the spinal canal.

SUMMARY OF BACKGROUND DATA: The prevalence of neurological complications from misplaced pedicle screws might be under-reported, and optimal management of pedicle screws misplaced totally within the spinal canal remains unclear.

METHODS: Nine cases with pedicle screws misplaced totally within the spinal canal during posterior surgery for adolescent idiopathic scoliosis were reviewed. All cases presented at least 1 medially misplaced pedicle screw, with spinal canal intrusion greater than pedicle screw diameter, that is, completely within the spinal canal. Percentage of spinal canal intrusion was measured from computed tomographic scans.

RESULTS: Spinal canal intrusion varied from 21% to 61%. In 2 patients, misplacement of pedicle screws was recognized intraoperatively and all implants were removed. They both had motor deficits from which 1 patient recovered completely. Two patients had early postoperative postural headache that disappeared after removal of the misplaced screw. Five patients had uneventful early postoperative course. One of these developed a Brown-Sequard syndrome 2 years after surgery and underwent complete implant removal. Another patient developed left thoracic paresthesia 3 years after surgery, and complete implant removal was performed. Two neurologically intact patients had uneventful implant removal after infection. The last patient refused implant removal and remained asymptomatic 5 years after surgery.

CONCLUSION: Improper pedicle screw placement can lead to neurological complications appearing early or late (after 2 yr). Late neurological complications were associated with screw loosening in 2 cases. The authors strongly recommend removal of any pedicle screw misplaced totally within the spinal canal due to the risk of early or late neurological complications, regardless of the severity of spinal canal intrusion.