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Iatrogenic Foraminal Stenosis after Iatrogenic Foraminal Stenosis after Cervical Pedicle Screw FixationCervical Pedicle Screw Fixation

Akiyoshi Yamazaki, Kei Watanabe, Keiichi Katsumi, Masayuki Ohashi

Spine Center, Dept. of Orthop. Surg., Niigata Central Hospital, Niigata, Japan

EuroSpine 2010Sept. 15 - 17, Vienna, Austria

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PurposesPurposes

• 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.

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Materials and Methods 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)

Operative procedureOperative procedure

① PS insertion Fluoroscopy: 1 pt in the early phase CT-based Navigation: 6 pts

② Decompression③ Rod application

With correction of alignment: 5 roots Without correction of alignment : 4 roots

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RESULTSRESULTS

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

5

012345

Pre Post FU

C5C5C5C5

MMT

Group A

012345

Pre Post FU

C6C5C8C8

MMT

Group B

6

0

2

4

6

8

10

12

14

0 1 2 3

C6C5C5C5C5C8C8C5C5

mm

Deg.

Without correction (4 Without correction (4 roots)roots)

Reduction of anterior translationReduction of anterior translationReduction of anterior translationReduction of anterior translation

Red

uctio

n o

f R

edu

ction

of

kyph

osis

kyph

osis With correction (5 roots)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)

45

454

5

45

LR4/5

Case 4 76 y.o. woman CSM, RACase 4 76 y.o. woman CSM, RA 　　　　　　　　　　　　　　 (group B)(group B)

Kyphosis decreased with Rt. C5 palsyKyphosis decreased with Rt. C5 palsy

Fully recovered after

C4/5 foraminotomy

7

1

71

R L

R L

7/1

Case 5 59 y.o. man CSM, TSM Case 5 59 y.o. man CSM, TSM 　　(group B) (group B)

Complete paraplegia, VRD

9

7

1

7

1

R L7/1

Case 5 59 y.o. man CSM, TSM Case 5 59 y.o. man CSM, TSM 　　(group B) (group B)

Without correction, blt. Intrinsic m. paralyzed.Partially recovered after blt. foraminotomy.

Post. translation increased by 1mm.C7/ T1 blt. foraminal stenosis!

R L

10

45

45

R L4/5

R L

R

R4/5

Case 7 65 y.o. man CSMR, CP (group A) 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. Kyphosis decreased by 5 deg. Ant. translation (3mm) disappearedAnt. translation (3mm) disappeared

DISCUSSIONDISCUSSION

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• 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

Prophylactic foraminotomyProphylactic 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?

12None of the authors has any potential conflict of interest.