6. Spine MCQs

Exclusion and inclusion criteria for studies on interspinous process decompression varied somewhat, but cauda equina syndrome was the only exclusion criteria listed in both major studies cited. All of the other choices did not represent exclusion criteria in either study.

The patient has spinal stenosis and degenerative spondylolisthesis. Laminectomy and posterior spinal fusion have been demonstrated to be superior to both nonsurgical management and laminectomy without fusion in prospective randomized studies. The effect of instrumentation on improvement of clinical outcomes remains a matter of debate. This patient has exhausted physical therapy approaches per the history. Epidural steroid injections have not been shown to significantly alter the natural history of patients with degenerative lumbar spinal stenosis and spondylolisthesis. While minimal access decompression has been described, percutaneous endoscopic diskectomy would be more appropriate for a disk herniation.

It has been traditionally taught that a left-sided approach to the anterior cervical spine is associated with a lower incidence of injury compared to the right-sided approach. This is due in part to the anatomic differences in the path the recurrent laryngeal nerve (RLN) takes on the right as compared to the left. Both nerves ascend in the tracheoesophageal groove after branching off the vagus nerve in the upper thorax. The left-sided RLN loops around the aortic arch and stays relatively medial as compared to the right-sided RLN which loops around the right subclavian artery and is somewhat more lateral at this point, and therefore is theoretically more vulnerable as it ascends toward the larynx before becoming protected in the tracheoesophageal groove. Furthermore, the variant of a nonrecurrent inferior laryngeal nerve branching directly off the vagus nerve at the level of the midcervical spine is much more common on the right than the left. Despite this reasoning, there has been no clinical evidence to suggest that laterality of approach for anterior cervical surgery makes any difference in the incidence of vocal cord paralysis. Furthermore, two recent studies have shown that the incidence of RLN injury and vocal cord paralysis is equal with either side of approach.

DISCUSSION: Surgical open reduction may increase the neurologic deficit if a disk herniation exists. Evidence from animal studies suggests that rapid decompression of the spinal cord may improve recovery. Serially increasing traction weight to reduce the dislocation has been shown to be safe when used in patients who are awake. Indications for MRI include patients who are unable to cooperate with serial examinations, the need for open reduction, and progression of deficit during awake reduction. REFERENCES: Delamarter RB, Sherman J, Carr JB: Pathophysiology of spinal cord injury: Recovery after immediate and delayed decompression. J Bone Joint Surg Am 1995;77:1042-1049. Star AM, Jones AA, Cotler JM, Balderston RA, Sinha R: Immediate closed reduction of cervical spine dislocations using traction. Spine 1990;15:1068-1072. Eismont FJ, Arena MJ, Green BA: Extrusion of an intervertebral disc associated with traumatic subluxation or dislocation of cervical facets: Case report. J Bone Joint Surg Am 1991;73:1555-1560.

DISCUSSION: Kayanja and associates, in a number of biomechanical studies, showed that in a kyphotic spine the strain is located at the apex of the deformity, the force is transmitted to the superior adjacent vertebrae, and that realignment and cement augmentation effectively normalize the load transfer. REFERENCES: Kayanja MM, Ferrara LA, Lieberman IH: Distribution of anterior cortical shear strain after a thoracic wedge compression fracture. Spine J 2004;4:76-87. Kayanja MM, Togawa D, Lieberman IH: Biomechanical changes after the augmentation of experimental osteoporotic vertebral compression fractures in the cadaveric thoracic spine. Spine J 2005;5:55-63. Kayanja MM, Schlenk R, Togawa D, et al: The biomechanics of 1, 2, and 3 levels of vertebral augmentation with polymethylmethacrylate in multilevel spinal segments. Spine 2006;31:769-774. Kayanja M, Evans K, Milks R, et al: The mechanics of polymethylmethacrylate augmentation. Clin Orthop Relat Res 2006;443:124-130.

DISCUSSION: The arrow is pointing to the posterior columns of the spinal cord that transmit position sense, vibratory sense, and proprioception. There are no motor tracts in the posterior columns. REFERENCES: Bohlman H, Ducker T, Levine A: Spine trauma in adults, in Herkowitz HH (ed): The Spine, ed 4. Philadelphia, PA, WB Saunders, 1992, p 911. Northrup B: Evaluation and early treatment of acute injuries to the spine and spinal cord, in Clark CR (ed): The Cervical Spine, ed 3. Philadelphia, PA, Lippincott Raven, 1998, p 545.

DISCUSSION: The smallest pedicle isthmic width is at L1, whereas T12 has the largest pedicle width in the upper lumbar and lower thoracic spine. Although smaller in diameter than T12, both T10 and T11 have larger pedicle widths than L1. REFERENCE: Ofiram E, Polly DW, Gilbert TJ Jr, et al: Is it safe to place pedicle screws in the lower thoracic spine than in the upper lumbar spine? Spine 2007;32:49-54.

DISCUSSION: In a review of 13,000 spinal procedures, nine patients were treated with heparin following development of pulmonary emboli. Of these patients, six had serious complications ranging from wound drainage to paralysis. Heparin therapy instituted within 10 days of the surgical procedure resulted in a 100% complication rate. Vena cava filter placement has a complication rate of 0.12% to 10.1%. Removable filters are currently in clinical trials. REFERENCES: Cain JE Jr, Major MR, Lauerman WC, et al: The morbidity of heparin therapy after development of pulmonary embolus in patients undergoing thoracolumbar or lumbar spinal fusion. Spine 1995;20:1600-1603. Roberts AC: Venous imaging and inferior vena cava filters. Curr Opin Radiol 1992;4:88-96. Becker DM, Philbrick JT, Selby JB: Inferior vena cava filters. Arch Intern Med 1992;152:1985-1994.

DISCUSSION: Although relatively common in people of Asian origin, OPLL has been reported in other races as well. The radiographic appearance can be variable as there are different types described, but some of the discerning characteristics are seen in these images. On the sagittal view, the bone posterior to the vertebral body extends along the entire length of C2 and C3. This is characteristic of OPLL, whereas cervical spondylosis and DISH more commonly are not confluent. Ankylosing spondylitis more commonly extends significantly into the spinal canal, and neurofibromatosis generally does not cause any bony growth. The axial view shows a large, oval bony projection into the spinal canal, a typical finding of OPLL. REFERENCES: McAfee PC, Regan JJ, Bohlman HH: Cervical cord compression from ossification of the posterior longitudinal ligament in non-orientals. J Bone Joint Surg Br 1987;69:569-575. Kricun R, Kricun ME: MRI and CT of the Spine. New York, NY, Raven Press, 1994, pp 126-130.

DISCUSSION: In osteopenic individuals, even those with excellent obtained or maintained balance, long instrumented fusions to the sacrum impart a high degree of strain, and the sacrum may fail in a transverse fracture or fracture-dislocation pattern. The risk of proximal functional kyphosis is unrelated to distal fixation as are coronal plane correction and rod contouring. Pubic ramus fractures have been shown to be associated with both fixation to the sacrum alone as well as to the ilium. REFERENCE: Hu SS, Berven SH, Bradford DS: Adult spinal deformity, in Frymoyer JW, Wiesel SW (eds): The Adult and Pediatric Spine, ed 3. Philadelphia, PA, Lippincott Williams and Wilkins, 2004, pp 465-477.

The patient has symptoms and signs of cervical radiculopathy despite a long course of nonsurgical management. Therefore, surgical decompression is indicated and is best performed through an anterior cervical diskectomy and arthrodesis. Single level anterior cervical diskectomy and arthrodesis have been shown to produce significant improvements in arm pain and neurologic function. Anterior cervical foraminotomy, while reported, has insufficient data to support its use and it places the vertebral artery at significant risk. Posterior cervical foraminotomy is contraindicated given the ventral spinal cord compression; foraminotomy places the patient at risk for spinal cord injury. The patient has one-level cervical disease, therefore a corpectomy is unnecessary. Posterior laminoplasty is used to treat myelopathy, not radiculopathy.

Incomplete cord syndromes have variable neurologic findings with partial loss of sensory and/or motor function below the level of injury. Central cord syndrome is characterized by greater motor weakness in the upper extremities than in the lower extremities. The pattern of motor weakness shows greater distal involvement in the affected extremity than proximal muscle weakness. This patient's presentation of hyperextension injury with upper extremity weakness is classic for central cord syndrome.

The patient’s neurologic examination is consistent with a C7 radiculopathy on the right side. In a patient with this symptom complex in the absence of trauma, a cervical disk herniation is the most common etiology for a C7 radiculopathy. There are eight cervical nerve roots and the C7 nerve exits at the C6-7 disk space and is most frequently impinged by a disk herniation at this level.

The patient has a congenitally small spinal canal with secondary multilevel degenerative changes causing stenosis and cord compression across multiple segments, including directly posterior to the vertebral bodies. Because the patient’s cervical lordosis is preserved, a posterior procedure such as laminoplasty or laminectomy would allow the cord to fall away from the anterior pathology and afford decompression.

The patient has a hyperostotic condition of the cervical spine, most likely ankylosing spondylitis. Because of a rigid and osteoporotic spine, relatively minor falls can result in unstable spinal injuries with significant instability and a high risk for neurologic sequelae. The patient has an unstable injury at C6 with an incomplete spinal cord injury, necessitating urgent decompression and stabilization. Studies have shown that, in patients with ankylosing spondylitis, stand-alone anterior stabilization results in a high failure rate. Halo-thoracic vests carry a high risk of septic and pulmonary issues, especially in the elderly. Uninstrumented fusion will provide insufficient stability in such patients.(SBQ13PE.22) A 11-year-old male is referred for evaluation of scoliosis by his primary care physician. He has a normal birth and development history and denies any neurologic deficits or pain. On physical examination, he is neurologically intact with normal reflexes and tone. A PA radiograph is shown in Figure A. What is the next best step?Review TopicCustom orthosis prescription to initiate bracingPhysical therapy referral and observationBending and lumbar oblique radiographsTotal spine CTTotal spine MRIA left thoracic curve is an abnormal finding and warrants further work-up with a total axis MRI in order to rule out concomitant neurologic abnormalities such as a spinal cord cyst and/or syrinx.In adolescent idiopathic scoliosis (AIS), the most commonly occurring curve is a right thoracic curve. Left thoracic curves are not as common, and warrants total axis MRI in order to rule out concomitant central axis abnormalities. This is imperative not only during initial work-up, but most importantly for operative planning.Spiegel et al. performed a a retrospective radiographic review on 41 patients with scoliosis associated with a Chiari I malformation and/or syringomyelia. Approximately 50% of patients had an "atypical" pattern (left thoracic, double thoracic, triple, long right thoracic). The authors recommend that MRI should be considered in these patients.Gillingham et al. provides a thorough review of early onset scoliosis and notes the relatively high incidence of concurrent central axis abnormalities, even in patients with normal neurologic exams. Rates have been reported upwards of 21.7%, with malformations including Chiari Type 1, dural ectasias, syrinx, and spinal cord cysts.Figure A exhibits a left thoracic curve. Further imaging in this patient revealed a syrinx which required decompression.Incorrect answers:thoraciccurve.

The clinical presentation is consistent with a minimally displaced fracture that extends through all three columns on the spine in a patient with ankylosing spondylitis. The most appropriate treatment is posterior spinal instrumentation and fusion.In patients with ankylosing spondylitis (AS), the rigid spine creates a long lever arm that makes even minimally displaced fractures potentially unstable. Thus, despite being minimally displaced in a neurologically intact patient, most fractures in AS warrant a posterior instrumentation and fusion, typically of three levels above and three levels below the fracture.Caron et al. present a retrospective review of patients with ankylosed spines (due to AS or DISH) and characterize their fractures and outcomes of treatment. Cervical fractures were most common (55%) and rates of occurrence decreased as they progressed down the spine, with lumbar fractures seen only 8% of the time. They found the most common successful surgical intervention was multilevel posterior instrumentation and fusion (with decompression when necessary for neurologic compromise).Wang et al. reviewed 12 cases of patients with AS who presented with traumatic spinal injuries. They reviewed clinical histories and available imaging. They found that MRI was the most sensitive test for identifying occult fractures of the spine, and recommend using MRI to rule out occult fractures as well as better characterize fractures seen on radiographs or CT imaging for patients with AS.Werner et al. present a review of spinal fractures in patients with AS. They note that non-operative treatment of these fractures is reserved only for patients who have an unacceptably high risk of undergoing surgery. For three column thoracolumbar fractures they recommend surgical stabilization with a long posterior construct.Figure A is a sagittal CT image of the lumbar spine with marginal syndesmophytes consistent with AS. The white arrow highlights a minimally displaced fracture that extends through all three columns on the spine. Illustration A are radiographs comparing DISH (on the left) with non-marginal syndesmophytes, and AS (on the right) with marginal syndesmophytes.Incorrect Answers:

Pediatric bony Chance fractures occur following severe flexion injuries as seen after motor vehicle accidents with lap belt restraints. In the absence of associated injuries, these fractures are best treated with immobilization.

Most thoracic disk herniations occur in the lower (caudal) third of the thoracic spine. This predilection may be related to the unique anatomic and biomechanical environment of that region. The 11th and 12th ribs do not join the rib cage anteriorly and do not form a true articulation with the transverse processes posteriorly. Furthermore, flexion and torsional forces tend to concentrate between T10 and L1.

Lumbar central stenosis is defined by an AP canal diameter of less than 10 mm or a cross-sectional area of less than 100 mm2 as measured on CT.

DISCUSSION: Laminoplasty or any posterior decompressive procedure is contraindicated in patients with cervical spondylotic myelopathy and cervical kyphosis. The residual kyphotic posture of the cervical spine results in persistent spinal cord compression. The other choices are not contraindications for laminoplasty. Concomitant cervical radiculopathy can be addressed at the time of laminoplasty with a keyhole foraminotomy.