1. Review of LIF and role of neurography in XLIF
Chad Cox, MD
Ryan Murtagh, MD, MBA
Juan Uribe, MD
Summer Decker, PhD
Jonathan Ford, PhD
University of South Florida
College of Medicine
Tampa, FL

2. Spine surgery – the “LIF’s”
Number of approaches for Lumbar Interbody Fusion(LIF) including
ALIF – Anterior lumbar interbody fusion
PLIF – Posterior lumbar interbody fusion
TLIF – Transforaminal lumbar interbody fusion
XLIF – eXtreme lateral lumbar interbody fusion
OLIF – oblique lateral lumbar interbody fusion (save for another day)
Bottom line: Don’t know what it is?!? Call it a LIF

3. Anterior Lumbar Interbody Fusion
The good
Great restoration of height, discectomy, lot of room to work in, can use plate (obviate 360o fusion), good lordosis if needed
The bad
Invasive, requires access surgeon

4. Anterior LIF: Surgical Technique

5. ALIF

6. Posterior Lumbar Interbody Fusion
The good
Less invasive than ALIF, decent discectomy and access to disc space
The bad
Requires laminectomy (often w posterior stabilization too), work around thecal sac and nerve roots

7. PLIF

8. Posterior LIF: Surgical Technique

9. PLIF on MRI

10. X-ray of PLIF

11. PLIF on CT

12. Transforaminal Lumbar Interbody Fusion
The good
Even less invasive (oblique approach with inferior facetectomy and laminectomy)
The bad
Least surface exposure for fusion, harder to introduce lordosis, leaves patient unstable (needs posterior fusion)

13. Transforaminal LIF: Surgical Technique
1-access the level through a trans-psoas approach
2-discectomy
3-distraction and test spacer
4-spacer
5-lateral butressing screws

14. TLIF

15. TLIF on CT

16. TLIF on MRI

17. Extreme Lumbar Interbody Fusion
Aka Lateral trans-psoas Lumbar Interbody Fusion ( LLIF)
The good
Less invasive, good increase in disc height for canal decompression. Useful for deformity surgery.
The bad
Risk to peritoneum and retroperitoneal structures, including nerves in lumbosacral plexus, resulting from direct injury or excessive retraction
Result is iliopsoas/quadricep weakness as well as groin and thigh paresthesias/numbness

18. XLIF
Posterior annulus left intact
Passes through psoas

19. Extreme Lateral LIF: Surgical Technique
Lumbar plexus resides in the posterior 1/3 of the psoas muscle
1-access the level through a trans-psoas approach
2-discectomy
3-distraction and test spacer
4-spacer
5-lateral butressing screws

20. XLIF

21. Complications of XLIF
Complications result from approach through psoas/lumbar plexus
Thigh paresthesia or dysesthesia, usually in anterior cutaneous branch of femoral nerve
Tormenti et al found paresthesias in 6/8 patients
5 of the 6 had persistent sx at 1 yr
Two patients had motor sx’s. One resolved immediately post op, other persisted to 3 mos.
Dakwar – transient paresthesia in 3/25 (12%) – resolved by 3 mos.
Knight et al – 10%, also transient

22. Lumbosacral plexus

23. How do surgeons avoid?
Use known landmarks, correlated with anatomic specimens
Use intra-op monitoring
XLIF® from Nuvasive® has directional neuromonitoring
Others, like DLIF® don’t
Neurography could be an alternative to reduce complicaions.

24. “safe zones” Dakwar, et al
Genitofemoral n. course, risk of injury in these zones at these levels
Zone IV contains all parts of LS plexus except genitofemoral n.

25. Neurography
Established imaging technique typically done using heavily T2 weighted fat-saturation technique
Can be done centrally (lumbosacral plexus) and peripherally (nerves of extremities)

26. Normal femoral nerves (arrows) and illioinguinal nerves (arrowheads)
Normal anatomy
Normal femoral nerves (arrows) and illioinguinal nerves (arrowheads)
Soldatos, T. High Resolution 3-T MR Neurography of the Lumbosacral Plexus. Radiographics, 2013.

27. Neurography paper Recent article by Quinn, et al, in Spine 2015
Did MRI neurogram and showed variability in position of “LS plexus” A-P relative to L4-5 disc.
Focus of their paper on L4-5 because important NV structures are in working zone for XLIF in up to 44%

28. Variability - Moro’s zones
Quinn, et al right side plexus (more variable)
Zone 2 – 8.6%%
Zone 3 – 42.9 %
Zone 4 – 45.7%
Zone 5 – 2.9%
Quinn, et al, left side plexus
Zone 2 – 5.7%
Zone 3 – 54.3 %
Zone 4 – 40%

29. DIY
Soldatos, T. High Resolution 3-T MR Neurography of the Lumbosacral Plexus. Radiographics, 2013.

30. Our Study
We have selected a cohort of ten patients to have neurography followed by XLIF. We will compare these patient’s complication rate with more traditional intraoperative monitoring.
Goal: Reduce the complication rate of paresthesia and weakness with neurography.
Thus far, five patients have underwent neurography before surgery.
All five patients had no abnormalities on neurological exam immediately post operative or at 6 week follow up.

31. Combining neurogram and T2 FSE using Osirix®
The obturator nerve is the more posterior nerve. The Femoral nerve is more anterior in orientation.

32. Using Vitrea® L4 L5

33. Mimics 18.0 (Materialise)
Left Lateral
Right Lateral

34. Mimics, different pt.
Left Lateral: The white arrow is pointing to the left femoral nerve.
Right Lateral: The white arrow is pointing to the right femoral nerve.

35. Mimics Different Patient
The white arrows are labeling the bilateral femoral nerves.

36. Summary XLIF is very important and a very popular procedure because:
Less surgery time — XLIF can be completed in as little as an hour.
It is minimally invasive so less blood loss and scarring.
Less pain — Because the surgeon is able to access the intervertebral disc space from the patient's side, XLIF does not disrupt sensitive back muscles, bones or ligaments. Shorter hospital stay — In some cases, XLIF requires only an overnight hospital stay.
Quicker return to normal activity — Patients usually walk the day of surgery, although full recovery takes a couple of months, compared to approximately six months for traditional procedures

37. Summary The biggest drawback of XLIF is nerve damage
Landmarks/intraoperative monitoring are useful but still the complication rate is high.
Neurography could play an important role in this approach
The consensus is still out rather neurography will become part of preprocedural planning, but our early results are promising.