Iatrogenic Foraminal Stenosis after Cervical Pedicle Screw Fixation

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
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
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

• PS insertion
• Fluoroscopy 1 pt in the early phase
• CT-based Navigation 6 pts
• Decompression
• Rod application
• With correction of alignment 5 roots
• Without correction of alignment 4 roots

5
RESULTS

• Foraminotomy at the 1st op 4 roots (Group A)
• Foraminotomy at the 2nd op 4 roots (Group B)
• No foraminotomy 1 root

Group A
Group B
6

• Kyphosis avg 6.3 deg. (Pre), 1.0 deg. (FU)
• Anterior translation avg 0.3 mm (Pre), -0.6 mm
  (FU)

Deg.
Reduction of kyphosis
With correction (5 roots)
Without correction (4 roots)
mm
Reduction of anterior translation
7
Case 4 76 y.o. woman CSM, RA (group B)
4
4
4
4
5
5
5
5
4/5
L
R

• Fully recovered after
• C4/5 foraminotomy

Kyphosis decreased with Rt. C5 palsy
8
7
7
1
1
7/1
7/1
R
L
R
L
Case 5 59 y.o. man CSM, TSM (group B)
7
7
1
1
7/1
L
R
R
L
Complete paraplegia, VRD
9
Case 5 59 y.o. man CSM, TSM (group B)
Post. translation increased by 1mm. C7/ T1 blt.
foraminal stenosis!
R
L
Without correction, blt. Intrinsic m.
paralyzed. Partially recovered after blt.
foraminotomy.
L
10
Case 7 65 y.o. man CSMR, CP (group A)
4
4
5
5
4/5
R
R
L
Kyphosis decreased by 5 deg. Ant. translation
(3mm) disappeared
4/5
R
R
L
Deterioration of C5 palsy even after blt. C4/5
foraminotomy
11
DISCUSSION

• 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?

None of the authors has any potential conflict of
interest.