7 Surgical Techniques in Percutaneous E ndoscopic Cervical Diskectomy

10.1055/b-0034-82083

7 Surgical Techniques in Percutaneous E ndoscopic Cervical Diskectomy

The successful use of percutaneous endoscopic cervical diskectomy has been reported by several authors.1–3 The techniques used are summarized in this chapter.

Surgical Technique

Anesthesia

Performed under local anesthesia
Neuroleptanalgesia (intravenous injection of fentanyl, 50 mg, and intramuscular injection of midazolam, 3 mg) along with 1% lidocaine

Position

Supine on radiolucent table
The neck is slightly extended by placement of a towel roll under the shoulder blade.
The head can be stabilized by applying a plaster tape across the forehead.
A plastic tent is placed over the patient’s face to prevent a feeling of suff ocation and also for ease of communication during the procedure.
The shoulders are pulled down and the arms are fixed to the sides of the table for better viewing ( Figs. 7.1 and 7.2 ).

Procedure

The level and midline are marked with the help of a Carm fluoroscope ( Fig. 7.3 ).
For lower cervical levels the C-arm may have to be tilted obliquely for better visualization.
The anterior cervical skin is painted and draped.
Lidocaine (1%) is infiltrated into the skin and subcutaneous tissue at the entry site.
For foraminal disk herniation approach from the contralateral side is preferable, whereas for a midline disk herniation entry from the right side is better for a right-handed surgeon.
The carotid pulse is palpated by the left hand.
The tracheoesophageal complex is then pushed by the fingernail while the anterior part of the cervical vertebra is felt ( Fig. 7.4 ).
The anatomy of the tracheoesophageal complex helps in retracting both esophagus and trachea together.
The shift of the complex is confirmed under fluoroscopy.
An 18-gauge needle is inserted into the interval created.
Further advancement of the needle past the skin, subcutaneous tissue, and up to the anterior margin of the disk space is done under fluoroscopic guidance ( Figs. 7.5 and 7.6 ).
The disk is penetrated between the longus colli m uscles.
This helps prevent bleeding and any sympathetic injury because the sympathetic chain is located medially in the lower cervical segments ( Fig. 7.7 ).
The stylet is advanced up to the center of the disk, then diskography is performed with 0.5 mL of a mixture of radiopaque dye, normal saline, and indigo carmine dye in the ratio 2:2:1.
Diskography helps to confirm the disk space and to identify the stained herniated nucleus pulposus during diskectomy ( Figs. 7.8 and 7.9 ).
Then a guide wire is passed through the needle and the needle is withdrawn.
While the needle is withdrawn, the guide wire should be firmly held to prevent slippage of the wire; otherwise the steps may have to be repeated ( Figs. 7.10 and 7.11 ).
A 5-mm transverse incision is placed on the skin and underlying subcutaneous tissue.
Serial dilators are passed over the guide wire from 1 to 4 mm until final placement of the obturator ( Fig. 7.12 ).
If the space between the tracheoesophageal complex in the middle and the carotid artery on the lateral side is wide, the obturator can be directly passed over the guide wire.
A 5-mm working cannula is passed over the obturator and the obturator is removed; the final position is determined depending on the pathology ( Figs. 7.13, 7.14, and 7.15 ).
For central disk herniation the tip of the working cannula should be in the midline on the anteroposterior (AP) view,
For foraminal herniation the tip should be directed toward the respective foramen in the AP view ( Figs. 7.16, 7.17, 7.18, 7.19, and 7.20 ).

**Fig. 7.1** The patient’s position is shown using the plastic tent and stabilization of both the shoulders after pulling down. **(A)** Cranial view. **(B)** Lateral view.

**Fig. 7.2** The patient is positioned supine with slight neck e xtension.

**Fig. 7.3** Skin markings are done under fluoroscopy.

**Fig. 7.4** **(A)** The trachea and esophagus are moved gently by the surgeon. **(B)** Illustration showing safe needle insertion into the created interval. **(C)** C-arm view showing the insertion of the needle while pushing the tracheoesophageal complex toward the opposite side; one can confirm this movement by looking at the tracheal air shadow moving away (*arrows*) as it is being pushed by the surgeon’s fingers.

**Fig. 7.5** C-arm view showing insertion of 18-gauge spinal needle under constant C-arm guidance. Continuous fluoroscopy is very important in percutaneous endoscopic cervical diskectomy to avoid injury to important structures of the neck.

**Fig. 7.6** Spinal needle insertion. The needle is advanced past the skin, subcutaneous tissue, and up to the anterior margin of the disk space under fluoroscopic guidance.

**Fig. 7.7** C-arm AP view shows the puncture of the disk space with the spinal needle in the midline between the two longus colli.

**Fig. 7.8** **(A)** Diskography is performed with a mixture of indigo car-mine and radiopaque dye and normal saline. **(B)** Note the epidural leakage of the dye through the annular tear into the foramen on the AP view (*arrow*).

**Fig. 7.9** In the lateral view, note the leakage and upward migration (*arrows*), thus implying the direction and noncontained nature of disk herniation.

**Fig. 7.10** **(A)** The insertion of the guide wire and removal of the spinal needle are shown. Note the surgeon’s right hand is keeping the guide wire stable for any inadvertent withdrawal while the left hand is removing the spinal needle gradually with gentle rotatory movements. **(B,C)** Serial C-arm lateral views are necessary to confirm the placement of the guide wire inside the disk and removal of the spinal needle.

In the lateral view the tip of the working cannula is advanced by gentle tapping up to the posterior vertebral line. If required minimal disk removal can be done by forceps under fluoroscopic guidance.
A 4-mm endoscope is passed through the working cannula; it has a 1.9-mm central working channel and two additional ports ( Fig. 7.21 ).
The central port is for the forceps/laser, whereas the additional ports are for input and output of irrigation.
Irrigation is done by cold saline to which intravenous cephazolin and epinephrine are added for hemostasis and to prevent infection ( Fig. 7.22 ).
Initial location of the fragment may be difficult; a side-firing holmium:yttrium-aluminum-garnet (Ho:YAG) laser is useful. It helps to ablate the annulus and create an opening for the advancement of the scope to locate the fragment.
The cannula is advanced posteriorly to locate the inter-canalicular fragments if required, using the laser and grasping with the forceps.
Sometimes the posterior end plates are narrow due to osteophytes; the laser can be used to ablate the vertebral margins also.
The advantage of the laser is also that the penetration depth in continuous irrigation is less than 1 mm, so there is less chance of neural damage. Also it is side firing and thus avoids direct trauma to the tissues ( Figs. 7.23, 7.24, and 7.25 ).

**Fig. 7.11** Guide wire insertion: A guide wire is passed through the needle and the needle is withdrawn.

**Fig. 7.12** Dilation and obturator placement. Serial dilators are passed over the guide wire from 1 to 4 mm until reaching the final location of the obturator.

**Fig. 7.13** C-arm view shows the insertion of serial dilators over the guide wire to create a working path for the subsequent insertion of a working cannula.

**Fig. 7.14** Direct insertion of the obturator over the guide wire.

**Fig. 7.15 (A–E)** Serial C-arm lateral views showing the insertion of the obturator over the guide wire. **(F)** C-arm AP view showing the midline position of the obturator. A midline puncture of the disk and subsequent insertion of the obturator and working cannula provide for flexibility of shifting the working cannula sideways, if required. If the working cannula is angled directly toward the foramen right from the beginning, it is very difficult to shift the working cannula medially for successful removal of a combined foraminal and paramedian disk herniation. On the other hand, a midline insertion of the cannula can provide for easy manipulation and orientation of the working cannula.

**Fig. 7.16 (A–D)** Serial C-arm views showing the insertion of the working cannula over the blunt-tip, tapered obturator.

**Fig. 7.17 (A,B)** Lateral views showing the proper position of the working cannula and the removal of the obturator.

**Fig. 7.18** Creation of a working space with fluoroscopic forceps for better subsequent visualization with the endoscope.

**Fig. 7.19** In the C-arm images, the position of the tip of the working cannula has been pushed to lie in the posterior one fourth of the disk. **(A)** In the AP view, the tip of the working cannula is facing toward the opposite foramen. **(B)** Note the difference in cannula position as compared with the figure showing a midline position of the obturator.

**Fig. 7.20** The introduction of the working channel endo-scope through the working cannula. The central channel is for introduction of the instruments, and the two channels on the sides are used for input and output of the irrigation fluid.

**Fig. 7.21** Insertion of the endoscope.

**Fig. 7.22** First view on introduction of the endoscope showing the blue-stained nucleus pulposus lying within the confines of the disk space surrounded by the annulus fibrosus.

**Fig. 7.23** **(A)** Laser release of the annulus fibers to create space for further advancement of the working cannula. After lasing, we can see a part of the blue-stained herniated disk tissue **(B)**, which is removed with the grasping forceps (C, D).

**Fig. 7.24** **(A)** After the cannula is advanced further, we can see the two end plates at the posterior corner of the disk space. **(B)** Difficulty in opening the forceps to grasp the herniated fragment due to close position of the two end plates. (C, D) Use of the laser on end plates to create space for insertion of the forceps.

**Fig. 7.25 (A,B)** Further lasing of the posterior lip of the end plates, especially toward the foraminal side (12 o’clock is medial, 3 o’clock is cranial, 6 o’clock is lateral, and 9 o’clock is caudal). **(C,D)** Note the widened space between end plates.

The fragment freed from the annulus and fibrotic adhesions can be easily grasped with the help of forceps and removed ( Figs. 7.26, 7.27, 7.28, 7.29, 7.30, and 7.31 ).
Some bleeding may ensue after the fragment removal, which can be controlled by continuous irrigation and usually stops by itself.
Laser can be used for ablation of free fragments too small to be removed by forceps.
Laser is also used for ablation of osteophytes and painful nociceptors of the posterior annulus.
The adequacy of decompression can be checked by the free course of the nerve root/dural pulsations.
The patient’s symptoms are assessed, and hand compression hemostasis is done on the skin entry site after removing the scope and the working cannula.
A single stitch is taken, and the patient is discharged the same day with oral analgesics and antibiotics.

**Fig. 7.26** Further release of the annular layers for mobilization of the blue-stained herniated fragment is shown. **(A)** Laser on the thick annulus layer. **(B)** The thick annular layer being split open by the laser beam. **(C)** Laser is used for lateral release of the annulus to mobilize the foraminal fragment. **(D)** The blue-stained herniated fragment lying in the foraminal location can be seen clearly now, free from its surrounding annular anchorage. The fragment is ready to be grasped and removed with the grasping forceps.

**Fig. 7.27** Fluoroscopic view showing the position of the laser tip during annular release of the foraminal fragment.

**Fig. 7.28** **(A)** The herniated foraminal fragment being grasped with the endoscopic grasping forceps. **(B)** The fragment being gently pulled away with the forceps. **(C)** Some bleeding coming from the epidural space after the removal of the fragment. **(D)** With continuous saline irrigation, the bleeding is controlled and one can see the empty space left behind after the removal of the herniated fragment. One can see a small remnant disk fragment along with the fibers of the posterior longitudinal ligament from the 10 to the 2 o’clock position. These can be ablated with laser to complete the decompression.

**Fig. 7.29** C-arm views showing the position of the forceps jaws inside the foramen during removal of the herniated fragments lying in the foramen. **(A)** Oblique view. **(B)** Lateral view. **(C)** AP view.

**Fig. 7.30** The use of laser on the annular nociceptor and remnant small nuclear fragments and posterior longitudinal ligament after the main herniated fragments have been removed.

**Fig. 7.31** The complete decompressed nerve root.

References

1. Choi G, Lee SH. The Textbook of Spine. Korean Spinal Neurosurgery Society; 2008:1173–1185 2. Lee SH, Lee JH, Choi WC, Jung B, Mehta R. Anterior minimally invasive approaches for the cervical spine. Orthop Clin North Am 2007;38:327–337 3. Ruetten S, Komp M, Merk H, Godolias G. Full-endoscopic cervical posterior foraminotomy for the operation of lateral disc herniations using 5.9-mm endoscopes: a prospective, randomized, controlled study. Spine (Phila Pa 1976) 2008;33:940–948

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