AAOS & ABOS Spine Surgery MCQs (Set 3): Spinal Trauma, Degenerative Conditions, Scoliosis

Boden and associates' article presents compelling evidence that patients with rheumatoid arthritis and neurologic deterioration in C1-2 instability are more likely to achieve some improvement if the posterior atlanto-dens interval is greater than 10 mm on preoperative studies. All the patients in their series who had neurologic deterioration and a preoperative posterior atlanto-dens interval of greater than 14 mm achieved complete motor recovery. Boden SD, Dodge LD, Bohlman HH, et al: Rheumatoid arthritis of the cervical spine: A long-term analysis with predictors of paralysis and recovery. J Bone Joint Surg Am 1993;75:1282-1297. Boden SD, Clark CR: Rheumatoid arthritis of the cervical spine, in Clark CR (ed): The Cervical Spine, ed 3. Philadelphia, PA, Lippincott Raven, 1998, pp 755-764.

Patients with a degenerative spondylolisthesis and severe stenosis who have failed appropriate nonsurgical management are candidates for surgical intervention. Most studies show good to excellent results in more than 85% of patients after lumbar decompression for stenosis. Atlas and associates found that at 8- to 10-year follow-up, leg pain relief and back-related functional status were greater in those patients opting for surgical treatment of the stenosis. Similarly, the decision to fuse a spondylolisthetic segment has been supported in the literature. Herkowitz and Kurz compared decompressive laminectomy alone and decompressive laminectomy with intertransverse arthrodesis in 50 patients with single-level spinal stenosis and degenerative spondylolisthesis. They demonstrated good to excellent results in 90% of the fused group compared to 44% in the nonfusion group. The decision to include instrumentation during the fusion is more controversial. Whereas the use of instrumentation has shown to improve fusion rates, it has not been conclusively shown to improve the overall clinical outcomes of patients. Atlas SJ, Keller RB, Wu YA, et al: Long-term outcomes of surgical and nonsurgical management of lumbar spinal stenosis: 8 to 10 year results from the Maine lumbar spine study. Spine 2005;30:936-943. Herkowitz HN, Kurz LT: Degenerative lumbar spondylolisthesis with spinal stenosis: A prospective study comparing decompression with decompression and intratransverse process arthrodesis. J Bone Joint Surg Am 1991;73:802-808.

Dickman and associates classified injuries of the transverse atlantal ligament into two categories. Type I injuries are disruptions through the substance of the ligament itself. Type II injuries render the transverse ligament physiologically incompetent through fractures and avulsions involving the tubercle of insertion of the transverse ligament on the C1 lateral mass. Type I injuries are incapable of healing without supplemental internal fixation. Type II injuries can be treated with a rigid cervical orthosis with a success rate of 74%. Surgery may be required for type II injures that fail to heal with 3 to 4 months of nonsurgical management. Findlay JM: Injuries involving the transverse atlantal ligament: Classification and treatment guidelines based upon experience with 39 injuries. Neurosurgery 1996;39:210.

Unilateral sacralization of the fifth lumbar vertebra was first described by Bertolotti in 1917. Bertolotti's syndrome is present in 12% to 21% of the population. The altered biomechanics have been postulated to cause low back pain by placing increased stress on the adjacent cephalad disk, thus contributing to accelerated degenerative disk disease at this level. It has also been found that the neoarticulation between the enlarged transverse process and the sacrum and/or ilium may be a source of neural impingement on the exited L5 nerve root and results in radicular pain syndrome. Brault and associates reported on a case treated surgically at the Mayo Clinic, in which the pain generator was found to be the contralateral facet joint. Brault JS, Smith J, Currier BL: Partial lumbosacral transitional vertebra resection for contralateral facetogenic pain. Spine 2001;26:226-229. Quinlan JF, Duke D, Eustace S: Bertolotti's syndrome: A cause of back pain in young people. J Bone Joint Surg Br 2006;88:1183-1186.

The rate of symptomatic degeneration at an adjacent segment warranting either decompression or arthrodesis was predicted to be 16.5% at 5 years and 36.1% at 10 years based on a Kaplan-Meier analysis.

The standard practice in the pharmacologic treatment of a spinal cord injury in the United States has been the administration of methylprednisolone with an initial bolus of 30 mg/kg followed by 5.4 mg/kg for 24 hours, in accordance with the findings of the second and third National Acute Spinal Cord Injury Studies (NASCIS). Although the studies have subsequently drawn criticism for their methodology and outcomes, it has been generally accepted that beneficial neurologic outcomes were anticipated in patients who were able to start the protocol within 8 hours of their initial injury. Further improvement was noted in patients receiving the methylprednisolone within 3 hours of their injury and continuing an infusion for 48 hours. In this patient, who is outside the 8-hour treatment window, no studies have supported starting the methylprednisolone protocol at this time. Braken MB, Shepard MJ, Holford TR, et al: Administration of methylprednisolone for 24 or 48 hours or tirilazad mesylate for 48 hours in the treatment of acute spinal cord injury: Results of the third National Acute Spinal Cord Injury Randomized Controlled Trial. National Acute Spinal Cord Injury Study. JAMA 1997;277:1597-1604.

The patient has obvious signs of progressive myelopathy. Based on her significant physical examination findings, nonsurgical management will not significantly impact her outcome. Cervical decompression alone is contraindicated in patients with cervical kyphosis such as seen here. Anterior cervical fusion is the best option. Emery SE, Bohlman HH, Bolesta MJ, et al: Anterior cervical decompression and arthrodesis for the treatment of cervical spondylotic myelopathy: Two to seventeen-year follow-up. J Bone Joint Surg Am 1998;80:941-951. Ferguson RJ, Caplan LR: Cervical spondylotic myelopathy. Neurol Clin 1985;3:373-382.

The structure illustrated is the sympathetic chain viewed from an anterolateral view of the lower lumbar spine. It descends along the anterolateral aspect of the spine into the pelvis closely adherent to the vertebral column. The spinal nerves, including L5, can be seen exiting from the foramen. The ureters descend from the kidneys and cross anterior to the iliac vessels to the bladder. Onibokun A, Khoo LT, Holly L: Anterior retroperitoneal approach to the lumbar spine, in Kim DH, Henn JS, Vaccaro AR, et al (eds): Surgical Anatomy and Techniques to the Spine. Philadelphia, PA, Saunders Elsevier, 2006, pp 101-105.

The most predictable positive outcome from spinal surgery due to a cauda equina syndrome is early surgical intervention before any significant neurologic deficit develops. Meta-analysis studies demonstrate that surgical intervention more than 48 hours after the onset of cauda equina syndrome show an increased risk for poor outcomes. Ahn UM, Ahn NU, Buchowski JM, et al: Cauda equina syndrome secondary to lumbar disc herniation: A meta-analysis of surgical outcomes. Spine 2000;25:1515-1522.

The radiograph shows significant prevertebral soft-tissue swelling following a two-level anterior cervical diskectomy and fusion. The incidence of dysphagia 2 years after anterior cervical spine surgery is 13.6%. Risk factors for long-term dysphagia after anterior cervical spine surgery include gender, revision surgeries, and multilevel surgeries. The use of instrumentation, higher levels, or corpectomy versus diskectomy did not significantly increase the prevalence of dysphagia. Lee and associates demonstrated that while dysphagia after anterior cervical spine surgery is a common early finding, it generally decreases significantly by 6 months with nonsurgical management. A minority of patients experience moderate or severe symptoms by 6 months after the procedure. Female gender and multiple surgical levels have been identified as risk factors for the development of postoperative dysphagia. Lee MJ, Bazaz R, Furey CG, et al: Risk factors for dysphagia after anterior cervical spine surgery: A two-year prospective cohort study. Spine J 2007;7:141-147.

The proposed mechanisms by which steroids such as methylprednisolone are thought to prevent neurologic deterioration by limiting secondary insult, include: decreasing the area of ischemia in the cord, reducing TNF-alpha expression and NF-kB binding activity, decreasing free radical oxidation and thus stabilizing cell and lysosomal membranes, and checking the influx of calcium into the injured cells, thus reducing cord edema. Slucky AV: Pathomechanics of spinal cord injury. Spine: State Art Rev 1999;13:409-417.

Cigarette smoking has been directly linked to pseudarthrosis in spinal fusions. The direct mechanism of action is diminished revascularization of cancellous bone graft. Additionally, a smaller area of revascularization is seen in these grafts, as well as an increased area of necrosis. Increased activity of osteoblasts would result in more bone production. Increased activity of osteocytes would not affect the fusion because osteocytes are mature bone cells.

In a study of 427 patients undergoing cervical spine surgery, 12 patients demonstrated substantial or complete loss of amplitude of the tceMEPs. Ten of those patients had complete reversal of the loss following prompt intraoperative intervention. SSEP monitoring failed to identify any changes in one of the two patients that awoke with a new motor deficit. SSEP changes lagged behind the tceMEP changes in patients in which major changes were detected by both modalities. TceMEP monitoring was 100% sensitive and 100% specific. SSEP monitoring was only 25% sensitive and 100% specific.

In general, a previously healthy patient with an acute onset of nontraumatic lower back pain does not need diagnostic imaging before proceeding with therapeutic treatment. In the absence of any "red flags" during the history and physical examination, such as trauma or constitutional symptoms (ie, fevers, chills, weight loss), the appropriate treatment for acute onset lower back pain is purely symptomatic treatment including limited analgesics and early range of motion. Diagnostic imaging is not necessary unless the initial treatment is unsuccessful and symptoms are prolonged. Miller and associates suggested that the use of radiographs can lead to better patient satisfaction but not necessarily better outcomes. Miller P, Kendrick D, Bentley E, et al: Cost effectiveness of lumbar spine radiographs in primary care patients with low back pain. Spine 2002;27:2291-2297.

Denis divided the sacrum into three zones: zone 1 represents the lateral ala, zone 2 represents the foramina, and zone 3 represents the central canal. A fracture is classified according to its most medial extension. Those in zone 3 are typically bursting-type fractures or fracture-dislocations and are most prone to neurologic sequelae. Denis F, Davis S, Comfort T: Sacral fractures: An important problem. A retrospective analysis of 236 cases. Clin Orthop Relat Res 1988;227:67-81.

The indications of bisphosphonate therapy in breast cancer patients range from the correction of hypercalcemia to the prevention of cancer treatment-induced bone loss. Bisphosphonates reduce metastatic bone pain in at least 50% of patients and can reduce the frequency of skeletal-related events by 30% to 40%. Osteonecrosis of the jaw could occur in up to 2.5% of breast cancer patients during long-term bisphosphonate therapy.

The patient sustained an incomplete spinal cord injury known as central cord syndrome. Central cord syndrome characteristically has disproportionate involvement of the upper extremities with the lower extremities being relatively spared. It is most commonly seen after cervical injuries in elderly patients with spondylosis and spinal stenosis, often without fracture. Penrod and associates noted that 23 of 59 patients with central cord syndrome (ASIA C and D) ultimately walked. The poorest prognosis, however, was in ASIA C patients older than age 50, in which only 40% walked. Penrod LE, Hegde SK, Ditunno JF Jr: Age effect on prognosis for functional recovery in acute, traumatic central cord syndrome. Arch Phys Med Rehab 1990;71:963-968.

In the patient who is neurologically intact or has an incomplete injury from a cervical facet dislocation, a closed reduction with weighted tong traction is appropriate when the patient is awake, alert, and cooperative. Although there is a risk that a cervical facet dislocation could occur with an underlying cervical disk herniation, Vaccaro and associates have shown that closed reduction can be safely carried out in the awake, responsive patient. Closed reduction can be performed in the emergency department with traction with skull tongs or a halo ring. A slow stepwise application of weight is added until a reduction is achieved. Any worsening of the neurologic status of the patient requires immediate termination of the closed reduction and further diagnostic imaging before proceeding with further treatment. Vaccaro AR, Falatyn SP, Flanders AE, et al: Magnetic resonance evaluation of the intervertebral disc, spinal ligaments, and spinal cord before and after closed traction reduction of cervical spine dislocations. Spine 1999;24:1210-1217. Hart RA: Cervical facet dislocation: When is magnetic resonance imaging indicated? Spine 2002;27:116-117.

In the initial assessment of acute low back pain in adults, no diagnostic testing is indicated during the first 4 weeks in the absence of "red flags" for a serious underlying condition. The purpose of the initial assessment of acute low back pain in adults is to rule out serious underlying conditions presenting as low back pain. The Agency for Healthcare Policy and Research, in its 1994 clinical practice guideline, identified four serious conditions that may present with low back pain, including fracture, tumor, infection, and cauda equina syndrome. This patient has five "red flags" for a spinal tumor as a possible etiology of his low back pain, including age of older than 50 years, constitutional symptoms (recent weight loss), pain worse when supine, severe nighttime pain, and a history of cancer. Of these, his history of cancer is most significant, as greater than 90% of spinal tumors are metastatic. In order of frequency, breast, prostate, lung, and kidney make up approximately 80% of all secondary spread to the spine. In the presence of "red flags" for tumor or infection, it is recommended that the clinician obtain a CBC count, ESR, and a urinalysis. If these are within normal limits and suspicions still remain, consider consultation or seek further evidence with a bone scan, radiographs, or additional laboratory studies. Negative radiographs alone are insufficient to rule out disease. If radiographs are positive, the anatomy can be better defined with MRI. Agency for Health Care Policy and Research, Bigos SJ (ed): Acute Low Back Problems in Adults. Rockville, MD, US Department of Health and Human Services, AHCPR Publication 95-0642, Clinical Practice Guideline #14, 1994.

Continuous fluoroscopy and cine radiography expose the patient and personnel to markedly increased levels of direct and scatter radiation exposure. Continuous fluoroscopy should be limited to only what is absolutely needed for safe completion of the procedure. By orienting the cathode ray tube beneath the patient and placing the image intensifier as close as clinically possible to the patient, scatter radiation exposure to the personnel is minimized.

The MRI scans reveal a large postoperative hematoma causing significant thecal compression. An epidural hematoma with neurologic deficit is a surgical emergency requiring immediate evacuation of the hematoma. Although the incidence of postoperative epidural hematomas is rare, the consequences of a missed diagnosis can be catastrophic. Early recognition and evacuation are essential in preserving or restoring neurologic function. Uribe and associates attributed delayed postoperative hematomas to previous multiple lumbar surgeries as a possible contributing factor. Yi S, Yoon do H, Kim KN, et al: Postoperative spinal epidural hematoma: Risk factor and clinical outcome. Yonsei Med J 2006;47:326-332.

Although the spinal canal has been penetrated, the lateral masses are intact bilaterally with only partial destruction of the vertebral body and penetration of the lamina on one side, thus the cervical spine is not unstable and surgical stabilization is not indicated. Dural repair is not indicated since there is no external cerebrospinal fluid leakage. Surgical treatment should be based on the need to treat extraspinal pathology only. Bono CM, Heary RF: Gunshot wounds to the spine. Spine J 2004;4:230-240.

Symptomatic herniations of the thoracic spine are much less common than those of the cervical or lumbar region. They tend to occur most commonly during the third to fifth decades of life and although they can be found at all levels, they are most common in the lower third near the thoracolumbar region. Posterior laminectomy and disk excision has the highest rate of neurologic deterioration and is not recommended. Multiple studies have shown that herniated thoracic disks can be found at one or more levels in 40% of asymptomatic individuals. Shah RP, Grauer JN: Thoracoscopic excision of thoracic herniated disc, in Vaccaro AR, Bono CM (eds): Minimally Invasive Spine Surgery. New York, NY, Informa Healthcare, 2007, pp 73-80.

Patient safety and prevention of medical errors is a major focus of recent national advocacy groups. Analysis has shown that the most common sentinel event in spine surgery is surgery on the wrong level. Therefore, it is recommended that every patient have the surgical site signed, the level of surgery marked intraoperatively, and a radiograph taken. Surgery on the wrong level is most likely to occur in single-level decompressive procedures. Wong DA, Watters WC III: To err is human: Quality and safety issues in spine care. Spine 2007;32:S2-S8.

Posterior screw fixation of the upper cervical spine has gained a great deal of popularity due to its stable fixation, obviating the use of halo vest immobilization, and its high fusion rates. The use of screws in this location, however, has introduced a whole new set of potential complications. Vertebral artery injury is one of the most feared complications associated with screws in the C1/C2 region. This structure, however, is lateral and posterior at the C2 level and then penetrates the foramen transversarium of C1 to lie cephalad to the arch of C1 before entering the foramen magnum. It is the internal carotid artery that lies immediately anterior to the arch of C1 that is particularly at risk by anterior penetration of C1 lateral mass or C1-C2 transarticular screws as demonstrated by Currier and associates. The internal carotid artery lies posterior to the pharynx. The external carotid artery and the glossopharyngeal nerve are not at risk with this method of fixation. Currier BL, Todd LT, Maus TP, et al: Anatomic relationship of the internal carotid artery to the C1 vertebra: A case report of cervical reconstruction for chordoma and pilot study to assess the risk of screw fixation of the atlas. Spine 2003;28:E461-E467. Grant JC: Grant's Atlas of Anatomy, ed 6. Baltimore, MD, Williams & Wilkins, 1972.