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

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

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

Anterior LIF: Surgical Technique

ALIF

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

PLIF

Posterior LIF: Surgical Technique

PLIF on MRI

X-ray of PLIF

PLIF on CT

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)

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

TLIF

TLIF on CT

TLIF on MRI

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

XLIF Posterior annulus left intact Passes through psoas

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

XLIF

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

Lumbosacral plexus

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.

“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.

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

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.

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%

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%

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

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.

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

Using Vitrea® L4 L5

Mimics 18.0 (Materialise) Left Lateral Right Lateral

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.

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

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

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.