Chapter 26 Selective Percutaneous Posterolateral Endoscopic Lumbar Nuclectomy

Kyung-Hoon Kim, MD, PhD, Hyeon-Jung Lee, MD, PhD

A percutaneous endoscopic lumbar discectomy (PELD) through a posterolateral approach is one of many newly developed minimally invasive spine surgery (MISS) techniques. These techniques require only a small skin incision, present less traumatic sequelae to the muscles, epidural space, and neural tissues passing through the intervertebral foramen, and allow an early recovery after the procedure.

The three distinct mechanisms for pain relief by selective percutaneous posterolateral endoscopic lumbar discectomy are a manageable bulk decompression under direct endoscopic visualization and fluoroscope guidance, dilution of inflammatory peptides through continuous irrigation, and denervation of ingrown nerves by means of radiofrequency and laser (Fig. 26-1).

Figure 26–1 The three distinct mechanisms of pain relief after endoscopic discectomy are decompression under direct endoscopic visualization and fluoroscopic guidance, continuous irrigation to dilute inflammatory peptides, and denervation of sensory nerve endings by means of radiofrequency and laser ablation.

Selective chromoendoscopy (Table 26.1) in spine surgery is based on using the specific indicator (a blue color) of indigo carmine that is highly reactive with acidic extracellular matrix in degenerated nucleus pulposus. There is strong evidence for the usefulness of applying indigo carmine for selective endoscopic intervertebral nuclectomy in degenerated nucleus. However, there is no strict difference between normal aging and degeneration in the intervertebral disc (IVD), and an acidic condition of the IVD does not always indicate a pathologic condition. Removal of all blue-colored nucleus pulposus ensures the removal of all degenerated nucleus pulposus, whether or not the IVD is pathologically degraded. To remove the neural compression of herniated nucleus, decompression must become the primary purpose. Therefore, selective nuclectomy must be performed only when the targeted herniated nucleus turned blue in the posterior third of the IVD during chromoendoscopy.

Table 26.1 Concept of Selective Percutaneous Posterolateral Endoscopic Lumbar Nuclectomy

Selective	Blue-stained degenerated acid nucleus pulposus
Percutaneous	A small incision, not open
Posterolateral	Minimization of muscle trauma, with passage through the intervertebral foramen
Endoscopic	Under direct visualization
Nuclectomy	Targeted third of posterior herniated nucleus under fluoroscopic guidance

Complications

The informed consent discussion with the patient should include the following possible complications and their management (Table 26.2):

The surgeon may be unable to access the involved area owing to a high iliac crest, especially in men, or because of an extremely narrow intervertebral disc space. This situation is rare but would require the surgeon to change to an interlaminar approach.

Transient dysesthesia (sunburn syndrome), lasting about 4 weeks, can be caused by searching for the structures during the approach, or by decompressing and detaching the protruded disc from adhesion with the neural component. Selective dorsal ganglion block and gabapentin medication can be prescribed in these cases.

Lumbar plexopathy can be caused by blunt trauma from approaching too close to the midline (within 8 cm). This complication can be prevented by keeping at least 10 cm from the midline. Lumbar plexopathy is verified by electromyography and nerve conduction velocity measurements and is treated with selective dorsal ganglion block and gabapentin medication when necessary.

Superficial or deep-layer hematoma in the can occur in the subcutaneous tissue or between the psoas major and psoas minor muscles, respectively. Compression is necessary for superficial hematoma; observation by magnetic resonance imaging for absorption of blood is required for deep-layer hematoma.

Further instability can result from the procedure in patients with spondylolisthesis and disc herniation. This instability would be repaired through percutaneous external pedicle screw fixation.

Table 26.2 Potential Complications, Their Causes, and Their Management

Potential Complication	Cause(s)	Management
Inability to access the involved area	A high iliac crest, especially in men An extremely narrow intervertebral disc space	Requires conversion to an interlaminar approach
Transient dysesthesia (sunburn syndrome)	Intraoperative probing for the structures Detachment of a protruded disc from adhesion	Gabapentin and/or selective dorsal root ganglion block
Lumbar plexopathy	Blunt trauma by an approach that is too near the midline, i.e., within 8 cm	Confirmed by electromyography and nerve conduction testing Gabapentin and/or lumbar plexus block
Superficial or deep-layer hematoma	Occurs in the subcutaneous tissue or between the psoasas major and minor muscles	Superficial hematoma requires compression Deep-layer hematoma requires observation by magnetic resonance imaging for confirmation of absorption of blood
Aggravation of instability	In patients with spondylolisthesis combined with disc herniation	Percutaneous external pedicle screw fixation