Fig. 1. Minimally
invasive spine surgery instruments: minicurettes, discectome probe, discectomy
dilator/cannula/trephine, cutter forceps, grasper forceps, and endoscopes.
Percutaneous Microdecompressive Endoscopic Cervical Discectomy with Laser Thermodiskoplasty
JOHN C. CHIU, M.D., THOMAS J. CLIFFORD, M.D., MARK GREENSPAN, M.D., RICHARD C. RICHLEY, M.D., GEORGE LOHMAN, M.D., AND ROMULO B. SISON, P.A.
Keywords: percutaneous microdecompressive endoscopic cervical discectomy, laser thermodiskoplasty, minimally invasive surgery
Presented in part at the Annual Meeting of the American Association of Neurological Surgeons in Philadelphia, PA on April 6, 1 998.
From the California Center for Minimally Invasive Spine Surgery, Thousand Oaks, California. Address reprint requests to John C. Chiu, M.D., 2100 Lynn Road, Thousand Oaks, CA 91360
Purpose: To study the surgical outcome of outpatient percutaneous microdecompressive endoscopic cervical discectomy with lower energy laser for shrinkage of disc material (thermodiskoplasty). Method: Since 1994, 200 patients with herniated cervical discs presented with unilateral radicular pain. The diagnosis was confirmed by MRI or CT and EMG.
Results: At an average follow up of 25 months, 94.5% of the cases had good to excellent results. Eleven patients (5.5%) remained symptomatic with persistent neck and upper extremity pain associated with paresthesias. There were no significant postoperative complications. Average time to return to work was 10 days. Conclusions: Percutaneous microdecompressive endoscopic cervical discectomy with laser thermodiskoplasty has proven to be a safe and efficacious minimally invasive procedure.
Conventional open cervical discectomy with or without bony fusion is considered the standard treatment for cervical disc protrusion (1). However, open discectomy with fusion is associated with significant local inflammation, graft donor site pain, and a lengthy period of convalescence (2,3). In contrast, percutaneous microdecompressive endoscopic cervical discectomy (4) is minimally invasive and offers decreased morbidity with no bone graft to cause secondary symptoms and shortened recuperation. The purpose of this study is to evaluate the surgical outcome of outpatient percutaneous microdecompressive endoscopic cervical discectomy with lower energy laser for shrinkage of disc material (thermodiskoplasty).
Patient population. Since 1994, 200 consecutive patients with 360 non-extruded cervical disc herniations ranged from 26 to 72 years of age. The levels of involvement were one at C2-3, 34 at C3-4, 92 at C4-5, 1 04 at C5-6, 1 27 at C6-7, and 2 at C7-T1 The indications for surgery were: 1) neck pain with radiation down the arm, 2) symptoms and signs of sensory loss, tingling, numbness, muscle weakness, and/or decreased deep tendon reflexes, 3) MRI or CT findings of nonextruded disc herniation consistent with the signs and symptoms, 4) positive electromyography and/or nerve conduction studies, and 5) no improvement after 1 2 weeks of conservative therapy.
Preoperatively, all of the patients were on trials of anti-inflammatory agents. Thirty cases (1 5%) were treated with epidural steroid injections, 25 (12.5%) with oral steroids, 74 (37%) with muscle relaxants, 35 (17.5%) with aspirin, 10 (0.5%) with tranquilizers, and 64 (32%) with narcotics or prescription analgesics
The contraindications to surgical intervention were: 1) acute or progressive degenerative spinal cord disease, 2) neurological or vascular pathologies mimicking a herniated disc, 3) advanced spondylosis with disc space narrowing, 4)significant bony spurs that could block percutaneous entry into the disc space, 5)cervical spinal canal stenosis or lateral recess stenosis, and 6) an extruded disc or free fragment.
Surgical technique. Under local or general anesthesia, the patient was placed in a supine position with the neck extended by a rolled towel under the shoulders. A soft strap was placed over the forehead for stabilization. The shoulders were gently distracted downward with tape. Carm fluoroscopy was used in AP and lateral planes to direct the placement of a spinal needle onto the disc surface. Initially, at the point of entry adjacent to the medial border of the right sternocleidomastoid muscle, firm pressure was applied digitally in the space between the muscle and the trachea and pointed toward the vertebral surface. The larynx and trachea were displaced medially and the carotid artery laterally. The esophagus may be made more prominent with the insertion of an endotracheal tube. The pulse of the carotid artery may be augmented with sympathomimetics. The anterior cervical spine was palpated with the fingertips, and an #18-gauge spinal needle was passed into the disc space. The position was confirmed fluoroscopically.
A 2-3 mm skin incision was made, and a narrow guide wire was passed through the needle, which was then removed. A blunt trocar was introduced over the guide wire down to the interspace followed by a cannula. A trephine inserted through the cannula cut the annulus in a circular fashion. Minicurettes loosened and removed disc material prior to introduction of the discectome with a suction-irrigation system and a guillotine-cutting blade (Fig. 1). The instruments included a probe, grasper forceps, and laser fiber (Fig.2). Movement in a critical fan sweep maneuver, a 25° rocking excursion of the cannula hub from side to side increased the removal up to a 50° cone-shaped area within the disc space(Fig. 3). The procedure was closely monitored with the fluoroscope (Fig. 4) and an endoscope (Fig. 5). The holmium: yttriumaluminum-garnet laser with right angle or side-fire probe facilitated the discectomy (Fig. 6). In addition, nonablative levels of holmium laser energy (500 joules) or thermodiskoplasty added shrinking of collagen and fibrocartilage; and the tightening effect further decompressed and hardened the herniated cervical disc. (Table 2)
| Cervical | Single Stage |
Postoperative MRI evaluation showed changes in disc space (Fig. 7B) compared to preoperative study (Fig. 7A). Follow up averaged two years with a range of 9 to 45 months. Eleven patients (5.5%) had persistent slight to mild neck and upper extremity pain that required analgesic medication, while 189 (94.5%) had good to excellent recovery with minimal or no pain and resumption of a fully active lifestyle. There were no postoperative complications of wound infection or arterial or nerve compromise. Of the 1 98 cases (99%) demonstrating muscle spasm preoperatively, 6 (3%) continued to be symptomatic with some neck stiffness. Of the 200 patients (1 00%) reporting dermatome specific numbness of the upper extremities and manifesting decreased pain and touch sensation, 8 (4%) reported persistent numbness and tingling, and 6 (3%) had occasional diminished feeling without objective findings on neurological examination. The average time before returning to work was 1 0 days with a range of 3 days to 4 weeks.
| Symptom | ||
| Severe neck pain | ||
| Mild neck pain | ||
| Required analgesics | ||
| Muscle weakness | ||
| Muscle spasm | ||
| Persistent numbness |
The current trend of evolution of all spinal surgery has been toward less invasive techniques. In 1 964, Smith (5,6) introduced chymopapain chemonucleolysis to treat herniated nucleus pulposus. Hijikata (7) and Onik et al (8) described percutaneous lumbar discectomy. Ascher (9) and Sherk (10) then reported laser discectomy.
Key (11) first described the pathologic findings of two cases of cord compression by "intervertebral substance" in 1 838. Historically, in the 1 800's and early 1 900's, reports of cervical chondromas of the cervical spine were presented. Stookey (12) described the clinical symptoms and anatomic location of cervical disc herniation in 1928. Subsequently, in 1934 Mixter and Barr (13) further implicated cervical disc protrusions. The standard surgical approach to discs in the upper spine was posterior cervical laminectomy before 1950. Bailey and Badgley (14), Cloward (2, 3), Smith and Robinson (15) popularized the anterior approach with interbody fusion in the 1950's. Hirsch (1) in 1960, then Robertson (16) in 1973, recommended cervical discectomy without fusion; similar results and success rates were reported. Fukushima (26) introduced the ventriculofiber in 1973 and further set the foundation for percutaneous endoscopic cervical discectomy (27).
The advancements in miniaturization of microsurgical instrumentation, fiber optics, improved fluoroscopic imaging, high-resolution digital video imaging endoscopy, accumulated experience in percutaneous lumbar discectomy (4,17-22), and laser application (9,10,23-25) have all facilitated the development of percutaneous endoscopic decompressive cervical discectomy. The development of rigid and flexible endoscopes has provided better visualization of the spinal canal and disc anatomy.
Since 1995, holmium laser at nonablative levels of energy was added to our standard protocol for percutaneous discectomy. At lower energy settings (500 joules), contraction of tissue occurs as a photocoagulation effect or laser thermodiskoplasty. Previously, surgery on joint ligaments, the skin, and the retina has utilized this innovative technique for therapeutic purposes. Our methodology applies this idea to intradiscal surgery and completes the triad of surgical objectives: lowering intradiscal pressure, debulking the disc, and shrinking the fibrocartilage.
Our success rate of 94.5% reflects careful patient selection, thorough diagnostic evaluation by MRI, CT, and electromyography, and careful correlation with signs and symptoms. Prior success rates reported in the literature (28,29) vary between 40% and 77%. Percutaneous endoscopic microdecompressive cervical discectomy with laser thermodiskoplasty has been safe and efficacious. The minimally invasive outpatient procedure has lead to less morbidity, rapid recovery, and significant economic savings.
The holmium laser probe (side-fire) was developed by Trimedyne, P.O. Box 57001, Irvine, CA 92619.
Fig. 1. Minimally
invasive spine surgery instruments: minicurettes, discectome probe, discectomy
dilator/cannula/trephine, cutter forceps, grasper forceps, and endoscopes.
Fig. 2: Endoscopic view of three
instruments working inside a disk.
Fig. 3. A. Advanced 3-channel
endoscope (left), and B. 3-tip probe (right) to make procedure more efficient
and faster.
Fig. 4. Critical fan sweep maneuver
in cone shape
Fig. 5. X-rays of
curette (upper left), cutter (upper right), grasper (lower left), and discectome
(lower right) in disc space
Fig. 6 A. Endoscopic views of grasper
removing disc material, and B. note defects left following discectomy and
debulking
Fig. 7 A. Posterior
protrusion of disc, and B. Note shrinkage and tightening of disc material.