Radiographic Risk Factors for Unfavourable Outcomes after
Percutaneous Interlaminar Endoscopic Lumbar Discectomy
at L4-5 LevelJong-chul Chung, MD, Eun-kyung Kim, RN, In-sun Jeong, RN,
Woo-sung Sun, MD, Byeong-wook Hwang, MD, PhD, Hyung-dong Kim, MD, PhD.
Department of Neurosurgery, Bumin Hospital, Busan, Korea
Backgrounds
• Endoscopic interlaminar approach is still more challenging above L4-5 level
• Endoscopic working sheath inserted in narrow interlaminar space can cause dysesthesia or motor weakness.
• This study investigated the radiographic variables related to the interlaminar working zone.
Radiographic risk factor for unfavorable outcome after PIELD at L4-5. Chung et al.
Choi et al. 2006 Operative Neurosurgery
Materials : PEILD at L4-5 levelRadiographic risk factor for unfavorable outcome after PIELD at L4-5. Chung et al.
• Fully endoscopic interlaminar approach– FHD Rigid scope (OD 6.3mm, WchD 3.7mm, OA 30º, WL 125mm, TL 205mm )– Ligamentum flavum splitted and spared– Except for cases with laminotomy
• Jan.2015 – Jul.2016• 34 patients (M:F = 23:11)• Mean age: 49.6 years (19-74)• Mean follow-up : 14.2 months (12-27)• Type of disc protrusion 6%
9%
26%
15%
44% sup.migration
huge rupture
inf.migration
central
paracentral
Methods : Plain radiographyRadiographic risk factor for unfavorable outcome after PIELD at L4-5. Chung et al.
• ILH : Interlaminar space height on anteroposterior radiography• ILW : Interlaminar space width on anteroposterior radiography• ISDf : Interspinous distance of flexion lateral radiography • ISDe : Interspinous distance of extension lateral radiography• ISDd : distance difference between dynamic radiography
ISDf
ISDe
ISDd = IDSf - ISDe
FLEXION EXTENSION
ILH
ILW
AP
Methods : Computed tomographyRadiographic risk factor for unfavorable outcome after PIELD at L4-5. Chung et al.
• SLA : Sublaminar angle of L4 level on sagittal CT image• ILDs : Interlaminar distance at ipsilateral lateral margin of dura on sagittal CT • ILDc : Interlaminar distance at ipsilateral lateral margin of dura on coronal CT
ILDc
ILDs
SLA
midlineparamedian
Results: OverallRadiographic risk factor for unfavorable outcome after PIELD at L4-5. Chung et al.
• Pain score (VAS)
Ave VAS leg 7.7(6-10) → 2.2(1-5) Ave VAS back 3.9(0-8) → 2.1(0-5)
• Group I : Favorable outcome group• Group II : Unfavorable outcome group
– Persistent dysesthesia : 3 patients– Aggravated motor weakness : 2 patients
Group I Group II
Group I Group II
Results: IL height & widthRadiographic risk factor for unfavorable outcome after PIELD at L4-5. Chung et al.
ILW
ILH
ILH
ILW
ILH (mm) 13.7±3.2 12.7±3.0ILW (mm) 23.1±3.7 20.5±6.3
※ P>.05
Results: IL height & widthRadiographic risk factor for unfavorable outcome after PIELD at L4-5. Chung et al.
ISDf
ISDe
ISDd = IDSf - ISDe
FLEXION EXTENSION
ISDf ISDe ISDd
ISDd (mm) 9.4±4.3 3.3±2.5 P<.05 0.630 (95%CI, 0.933-0.996)
ISDf (mm) 14.4±4.9 9.1±3.2
ISDe (mm) 5.3±4.8 5.7±5.1
Results: IL distance, & SLARadiographic risk factor for unfavorable outcome after PIELD at L4-5. Chung et al.
ILDc
ILDs
SLA
midlineparamedian
ILDcILDsSLA
SLA ( º) 24.8±8.6 20.6±3.4
ILDc (mm) 9.2±2.9 5.4±3.1 P<.05 0.635 (95%CI, 0.408-0.989)
ILDs (mm) 10.3±2.9 7.7±4.2
DiscussionRadiographic risk factor for unfavorable outcome after PIELD at L4-5. Chung et al.
• L45 interalminar space can be widened in flexion position.
• ISDd, and ILDc were significant parameters for planning PIELD.
• In cases of narrower and unexpandable interlaminar space, laminotomy or laminoplasty by advanced endoscopic instruments should be required.
ISDf
ISDe
ISDd = IDSf - ISDe
FLEXION EXTENSION
ILDc
paramedian