Use of the operating microscope anterior cervical discectomy without fusion. KEY WORDS 9 cervical discectomy 9 fusion 9 intervertebral disc

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1 Use of the operating microscope anterior cervical discectomy without fusion in HAL L. HANKINSON, M.D., AND CHARLES B. WILSON, M.D. Department of Neurological Surgery, University of California School of Medicine, San Francisco, California The authors report their experience using the operating microscope in 52 anterior cervical discectomies without fusion. They found long-term results highly satisfactory, even in difficult cases with multiple-level disease, and complications from bone grafting were obviated. They highly recommend this approach for radicular, nonradicular, or myelopathic symptoms. KEY WORDS 9 cervical discectomy 9 fusion 9 intervertebral disc s INCE the advent of the anterior approach to cervical disc disease, several techniques for this procedure have been described by both orthopedic and neurological surgeons. In the last 5 years, we have adopted with some modifications the method advocated by Hirsch, et al., 5 Boldrey, ~ Susen," and, most recently, Murphey and Gado. 8 Extending anterior cervical discectomy without interbody fusion to include extensive osteophyte removal, we have performed 52 operations on 5 patients. The results of these procedures are the subject of this report. Clinical Material and Methods Summary of Patients Fifty-two operations were performed on 5 patients with cervical disc disease during the period April, 969, to March, 974. All operations were carried out by or under the direct supervision of one surgeon (CBW). The patients ranged in age from to 76 years; were males and 20 females. The diagnosis in was acute cervical disc herniation, and in 8 degenerative cervical disc disease or cervical spondylosis. Symptoms varied in duration from month to 6 years. Radicular symptoms, characterized by pain or neurological deficit, were seen in 40 patients, Nonradicular pain was present in 45, and myelopathy was evident in 2. Preoperatively, all patients had plain x-ray films of the cervical spine, with or without flexion and extension views. Findings in 50 were considered abnormal; of the 49 who had myelograms, 4 showed abnormalities. The only discogram done was positive; eight of nine patients had a positive electromyogram. All patients had previously received conservative therapy. Nine had had a prior operation; six of these patients had had cervical laminectomies. Twenty-five had a history of trauma. 452 J. Neurosurg. / Volume 4 / October, 975

2 Anterior cervical discectomy without fusion TABLE Operated levels in 5 patients Levels Operated No. of Cases single 25 C-4 2 C4-5 C5-6 4 C6-7 6 two 6 C-4, C4-5 C4-5, C5-6 6 C5-6, C6-7 9 three 7 C-4, C4-5, C5-6 C4-5, C5-6, C6-7 6 four C-4, C4-5, C5-6, C6-7 total 5 portion of disc and anterior osteophyte, if present, is removed with a rongeur. The opening into the interspace need be no wider than 0 mm, with columns of disc preserved on both sides. The most difficult interspace is ordinarily done first, should the operation involve multiple levels. The operating microscope is then brought into the field and, using the air turbine drill with an angled adaptor and suction irrigation, the surgeon drills away a portion of the superior and inferior vertebral bodies to provide 5 to 6 mm of vertical exposure. This is done in such a fashion that the drilling is carried more laterally as the posterior aspect of the body is approached (Fig. ); thus, the entire disc is not removed. Drilling is augmented by curettage as necessary to remove disc material and widen exposure. When posterior cortical bone is reached, drilling is terminated and dissection proceeds with the angled-up curettes. These instruments and the excellent light of the microscope allow extensive removal of posterior and lateral osteophytes under direct vision. When the cord and roots are free from impingement, hemostasis is obtained, and the wound is closed without a drain. Often, although not always, the posterior longitudinal ligament is opened and the dura is inspected directly. F~G. I. Sketch illustrating bone removal and technique of root decompression. We operated on 90 levels; their distribution among patients is shown in Table. Postoperatively most patients required no external support, and only a very few needed more support than a soft collar. Technique The anterior cervical spine is approached in the standard fashion, usually from the right side. Appropriate levels are localized by x-ray study and exposure maintained with two Cloward self-retaining retractors. An incision is made in the disc with a No. 5 blade and a Results We were extremely gratified with the smooth postoperative course exhibited by all but a few patients. The postoperative stay varied from to 8 days, with one exception. The average hospital period was about 8 days following operation; however, in many it was 4 to 6 days. One man was hospitalized for 07 days; this patient had a Chiari Type I malformation and hydrocephalus, and developed shunt obstruction and meningitis during his hospitalization. Operative complications are listed in Table 2. One patient who underwent a four-level operation had to have further osteophyte removal at C6-7 before the pain was resolved. Patients with Horner's syndrome, recurrent laryngeal palsy, and new radicular pain improved gradually. In one case, brachial plexitis was diagnosed after standard diagnostic studies failed to reveal a cause for postoperative pain and weakness. At this writing ( month postoperatively), the condi- J. Neurosurg. / Volume 4 / October,

3 H. L. Hankinson and C. B. Wilson TABLE 2 tion is clearing. The other complications, including in- interscapular pain, were transient. for cervical disc disease With two exceptions, all patients have been Complications occurring in 52 operations followed by office examination or questionnaire, question- Complication No. of Cases and in many cases, both. The follow-up neck and interscapular pain 5 period varied from 4 months to 5 years. dysphagia Results from our last six patients are not in in- pulmonary congestion 2 cluded eluded in this study because the follow-up new radicular pain 2 period is currently too brief. transient Horner's Homer's syndrome 2 A questionnaire was sent to the first 9 recurrent laryngeal palsy* palsy wound hematoma patients in the series; this method was chosen brachial plexitis l to remove the influence of the surgeon in the discitis I response. Thirty of these 9 responded, and exacerbation of pain requiring the results are presented in Table. Twentyeight patients said that they were helped by Twentyreoperation * This patient had had previous anterior discectomy the operation. Fifteen of the 0 have returned and fusion (Cloward). to the same level of work as prior to the onset of disability. Table 4 summarizes the surgeon's sur- clinical impressions during follow-up visits. According to the grading system of TABLE Results ofquestionnaire returned by 0 patients Odom, et a/.,7 al.fl of 5 patients followed in this way were considered to have excellent or good surgical outcomes. Nine of 2 patients with myelopathy myr were Patient Classification followed by office examination. One had an Response to Acute Disc Cervical excellent result, five good, two satisfactory, Questionnaire Herniation Spondylosis and one poor. (0) (20) Murphey and Gado d ~ reported radiographic presence ofoverall overall benefit evidence of fusion in 72% of 8 cases in which yes 9 9 discectomy had been performed at a single no estimated percentage of level. They stated that neither incomplete fusion nor failure of osteophyte resolution 00% 70 I precluded a good clinical result. This has also fuoverall benefit 90%-00% 7o-00 % 4 8 been our observation in those patients who 75%-90% ~o 2 2 Vo have had postoperative radiographs. 50%-75% o0 8 <50% <50~o We recently performed a repeat myelography for suspected disease at an adjacent myelog- level in a patient year postoperatively. Figure 2 demonstrates the absence of posterior osteophytes at the previously TABLE 4 operated levels (C5-6, C6-7) in comparison with her preoperative myelogram. Flexion Clinical follow-up evaluations in 5 patients related to number ofoperated operated levels and extension films demonstrated minimal movement at the operated interspaces. No. Levels Results Operated Excellent Good Satisfactory Poor Discussion cervical spondylosis At least four methods of anterior cervical discectomy with subsequent fusion have been 2 -- described for the treatment of cervical disc disease.l.a.b.lo,,9,~ Each method has distinguished 6 acute disc herniation proponents, and excellent results have been reported with each procedure The origin of the concept that a stable fusion fu- is necessary to relieve the symptoms caused by cervical spondylosis, particularly 454 J. Neurosurg. / Volume 4 / October, 975

Anterior cervical discectomy without fusion FIG. 2. Left." Myelogram showing extensive degenerative disease before a C5-6, C6--7 discectomy was performed.

Walker 2 stated that when pain is primarily the result of disc degeneration, fusion may be the most important factor in relieving the pain.

4 Anterior cervical discectomy without fusion FIG. 2. Left." Myelogram showing extensive degenerative disease before a C5-6, C6--7 discectomy was performed. Right: Myelogram year postoperatively shows absence of osteophytes at operated levels. pain, is nebulous. Walker 2 stated that when pain is primarily the result of disc degeneration, fusion may be the most important factor in relieving the pain. This idea may, in part, be attributed to the improvement experienced by many patients after immobilization in a brace or collar. Riley, et al, 8 reported good or excellent results with one- or two-level fusions in 72% of their series in which Smith-Robinson fusions were done for neck, shoulder, arm, hand, or interscapular pain. However, their results were not nearly as good when no union occurred, as was the case in 4% of 66 interspaces. Simmons, et al., '~ reported an 80.8% good or excellent result when they used a keystoneshaped fusion. With this method, the authors encountered no instance of nonunion. Several papers describe the use of anterior cervical discectomy without fusion for the relief of radicular pain, discogenic pain, and myelopathy. 2.5,6, The results compare favorably with those obtained by fusion, and the procedure is distinguished by its simplicity and lack of complications. Discectomy without fusion has several advantages. The major advantage is that complications associated with fusion, especially at multiple levels, are avoided. These include nonunion, ejection or absorption of the graft, painful iliac scar or meralgia paraesthetica, and donor site hematoma or infection. Other advantages include the reduction of time and technical difficulty of the operation. One of the authors (CBW) had used the Cloward dowel procedure almost exclusively for several years. The operating microscope has introduced a new dimension to spinal as well as to intracranial neurosurgery. We have been extremely satisfied with the results of the operation and especially with the technical advantages afforded by the microscope. We have found this procedure to be superior to fusion methods except in special cases, which often involve trauma and an unstable cervical spine. The operating microscope has enabled us to remove safely and under direct vision extensive posterior and lateral osteophytes. In part because of the safety of magnification and good lighting, we do not hesitate to operate for myelopathy from this approach. Despite reports to the contrary, 4 it is possible to decompress the cord anteriorly, and only rarely do we recommend laminectomy for cervical disc disease. The operation seems especially well suited for multiple-level disease; of the three patients operated at four levels, the results were considered good in two and satisfactory in the third. At three levels, six of seven patients had a good or excellent result. Lack of problems with instability, even in four-level operations, is attributable to the minimal removal of bone and the widespread spon- J. Neurosurg. / Volume 4 / October,

5 H. L. Hankinson and C. B. Wilson dylosis that exists in spines with multiple-level disease. Neither postoperative interspace settling with resulting radicular symptoms nor persistent neck pain has been a serious problem. However, one patient did develop postoperative radiculopathy at the same level contralateral to his originally symptomatic arm. Thorough curettage of both foramina will prevent this postoperative complication. Patients sometimes complain of more interscapular pain than we had noted after interbody fusion. This usually subsides spontaneously and is attributed to postoperative narrowing of the interspace. Finally, the postoperative course is usually benign, as shown by the average postoperative hospital period. After hospitalization, external stabilization is rarely necessary and wound problems are virtually unknown. References. Bailey RW, Badgley CE: Stabilization of the cervical spine by anterior fusion. J Bone Joint Surg (Am) 42: , Boldrey EB: Anterior cervical decompression (without fusion). Presented at the American Academy of Neurologic Surgery, Key Biscayne, Florida, 964. Cloward RB: The anterior approach for removal of ruptured cervical discs. J Neurosurg 5:602-67, Epstein JA, Carras LA, Lavine LS, et al: The importance of removing osteophytes as part of the surgical treatment of myeloradiculopathy in cervical spondylosis. J Neurosurg 0: , Hirsch L, Wickbom I, LidstrSm A, et al: Cervical disc resection: a follow-up of myelographic and surgical procedure. J Bone Joint Surg (Am) 46:8-82, Murphey MG, Gado M: Anterior cervical discectomy without interbody bone graft. J Neurosurg 7:7-74, Odom GL, Finney W, Woodhall B: Cervical disc lesions. JAMA 66: 2-28, Riley LH, Robinson RA, Johnson KA, et al: The results of anterior interbody fusion of the cervical spine. Review of 9 consecutive cases. J Neurosnrg 0:27-, Robinson RA, Smith GW: Anterolateral disc removal and interbody fusion for cervical disc syndrome. Bull Johns Hopkins Hosp 96:22-224, 955 (Abstract) 0. Simmons EH, Bhalla SK, Butt WP: Anterior cervical discectomy and fusion. A clinical and biomechanical study with eight-year followup. J Bone Joint Surg (Br) 5:225-27, 969. Susen AF: Simple anterior cervical discectomy without fusion. Presented at the American Academy of Neurologic Surgery, San Francisco, California, Walker E: The development of the anterior surgical approach for cervical disk lesions. J Med Assoc Georgia 58:7-2, 969 This work was supported in part by NINDS Training Grant 559. Address reprint requests to: Charles B. Wilson, M.D., Department of Neurological Surgery, University of California School of Medicine, San Francisco, California J. Neurosurg. / Volume 4 / October, 975

Anterior cervical discectomy without bone graft DONALD H. WILSON, M.D., AND DWIGHT D. CAMPBELL, M.D.

J Neurosurg 47:551-555, 1977 Anterior cervical discectomy without bone graft Report of 71 cases DONALD H. WILSON, M.D., AND DWIGHT D. CAMPBELL, M.D. Department of Neurosurgery, Dartmouth-Hitchcock Medical