PMC7298322_01
A. patient positioned on a prone position on the operating table. The patient is awake, only mildly sedated, waiting for the local anesthesia and the procedure to start. B. Preoperative sagittal (left) and axial (right) T2-weighted lumbar MRI scan showing a right L3-L4 paramedian disc herniation caudally migrated. C. Three-months postoperative T2-weighted lumbar MRI scan shows the satisfactory outcome of the procedure and the lack of signal intensity suggestive for pedicle damage or fracture.
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Preoperative MRI showed a paramedian, down-migrated, L3-L4 disc herniation (Fig. 1, B). FETD was planned. From a prone position (Fig. 1, A), the patient underwent the procedure under monitored and local anesthesia (local infiltration with a 50/50 mixture of lidocaine 2% and physiological solution). Late postoperative MRI showed satisfactory decompression (Fig. 1, C) and no sign of additional instability or fractures.
Form upper left to lower left on clockwork disposition, and from number 1 to 5, AP (left) and lateral (right) radiograms of sequential steps of the transpedicular discectomy procedure. Descriptions on the right side.
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Using intermittent fluoroscopic guidance, alternating between lateral and anterior-posterior views, an 18-gauge needle was advanced until reaching the lateral border of the right L4 peduncle (Fig. 2,1). The smallest dilatator (green guiding rod, outer diameter: 1.8 mm) was hammered inside the right L4 pedicle (Fig. 2,2). The instrument position was kept under radiographic control while continuously switching from lateral to AP views (Fig. 2,3). We then inserted the endoscope working cannula (8.0 mm in outer diameter) and the camera (Fig. 2,4).
Sagittal (A), axial (B), and oblique 3-dimensional (C) pictorial representation of different access routes for spinal surgery procedures. Comparison between endoscopic transforaminal, endoscopic transpedicular, and pedicle screw surgery.
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The trajectory was forced towards the medial wall of the pedicle to access the intracanal space (Fig. 3) After radiographic confirmation of the trajectory, the hole in the pedicle was increased with subsequential dilatators and reamers (outer diameters: from 3 to 7 mm).
A. medial pedicle wall access to the spinal canal. Endoscopic first look: visible the herniated fragment (*: herniated disc fragment). B.nerve roots floating freely in the spinal canal after herniated fragment retrieval. C. spinal canal inspection with a probe for additional fragments search.
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The herniated fragment was clearly visible (Fig. 4, A). The decompression was considered successful when we saw the nerve root pulsating freely in the epidural space (Fig. 4, B), after having checked the intraspinal space for additional fragments (Fig. 4, C).