Mini-invasive fenestration of the lumbar spine through a transspinous approach Pr Olivier GILLE Spinal Unit University Hospital Bordeaux France

Central stenosis The lamina The lamina –Its proximal part

lateral recess stenosis

foraminal stenosis

Lumbar fenestration described by Pr Senegas 1976 Alterations of erector spinae muscles following a posterior lumbar surgery

Assessment of erector spinae muscles Measurement of muscular strength with force measuring devices Measurement of muscular strength with force measuring devices Measurement of the electromyographic signal Measurement of the electromyographic signal Measurement of the cross-sectional area (CSA) of the muscles Measurement of the cross-sectional area (CSA) of the muscles –Ultrasound studies –CT scans –MRI Measurement of signal density (CT scans) or signal intensity (MRI) Measurement of signal density (CT scans) or signal intensity (MRI)

Assessment of muscles using MRI Measurement of muscle area on axial slides Measurement of muscle area on axial slides –Barker Spine –Parkkola Spine –Dangaria. Spine muscle signal intensity muscle signal intensity –Visual assessment –Salminen. J Spinal Disord. 1993; Parkkola R, Spine –Region of interest (ROI) in the muscle –Gejo Spine 1999 –Kim Spine 2005

Measurement of the muscle contractile component cross- section area (CCSA) Area measurement by surrounding the muscle Area measurement by surrounding the muscle signal intensity determination of the contractile tissue signal intensity determination of the contractile tissue –Using 4 ROI in plain muscular zone In collaboration with the biomechanics Laboratory of ENSAM, Paris

Measurement of the muscle contractile component cross- section area (CCSA)

Following a posterior surgery Pre operative MRI Post operative MRI

On proximal slide On proximal slide

TC TNC Postop Preop

CCSA NCCSA Pre operative MRI Post operative MRI Alterations of erector spinae muscles following a posterior lumbar surgery

Following a posterior lumbar surgery the contractile component of the erector spinae muscles decreases of 25% the contractile component of the erector spinae muscles decreases of 25% O.Gille, JM Vital. Erector spinae muscle changes on MRI following lumbar surgery through a posterior approach. Spine, 2008

LUMBAR SPINOUS PROCESS-SPLITING LAMINECTOMY WATANABE, 2006

CHIMNEY SUBLAMINAR DECOMPRESSION LIN, 2006

CHO : « Marmot technique », J. Neurosurgery Spine 2007

No high rate of improvement Long time surgery Technically difficult Long learning curve “Blind” surgery High risk of nerve root or dural tear

Step 1: Length spinous process measurement on preop MRI

Step 2: Spinous process osteotomy using a straight osteotom (3 mm security) Step 3: Osteotomy at the base of the spinous process performing with a curved osteotom. Step 5: The decompressive procedure can be continue as usual Step 4: Osteotomy of the distal part of the lamina using a curved osteotom L4 L5

Optical magnification Optical magnification Head light Head light Operative time < 30 mn Operative time < 30 mn No blood loss No blood loss

15 patients 15 patients Lumbar canal stenosis Lumbar canal stenosis –One level preop and 3 months postop MRI preop and 3 months postop MRI –Quality of decompression –Assessment of muscle changes

Measurement of the cross-sectional area of the spinal canal (T2 sequence) PreopPostop

PreopPostop

Results Preop spinal canal area : 0.8 cm² Postop spinal canal area : 2.1 cm²

Measurement of the MULTIFIDUS AND LONGISSIMUS contractile component cross-section area (CCSA) (T1 sequence) PreopPostop

Measurement of the MULTIFIDUS AND LONGISSIMUS contractile component cross-section area (CCSA) (T1 sequence) PreopPostop

Results Following a transspinous approach : Following a transspinous approach : –the contractile component of the erector spinae muscles decrease less than 5% (Mean 4.8)

Conclusion Advantages of fenestration through transspinous approach: Technically simple Technically simple Minimal soft tissues injury Minimal soft tissues injury Short time surgery (< 30 mn) Short time surgery (< 30 mn) Excellent working space and visualization Excellent working space and visualization Less bleeding Less bleeding Less postoperative pain ? Less postoperative pain ? Limits: Difficulties for repairing a dural tear Difficulties for repairing a dural tear