6. Spine MCQs

Adult idiopathic scoliosis and adult "de-novo" scoliosis can present with a number of symptoms that relate to associated degenerative findings such as stenosis or spondylolisthesis. In the absence of these associated conditions, increased levels of pain in patients with scoliosis has been found to most closely correlate with sagittal imbalance. Thoracolumbar and lumbar curves and thoracolumbar kyphosis have both been found to closely correlate with increased symptoms and lower health-related quality of life (HRQL) outcome scores. Thoracic scoliosis, thoracic hypokyphosis, lumbar hyperlordosis, and lumbar disk degeneration have not been found to correlate with increased symptoms.

DISCUSSION: Facet subluxation reduction may be performed in awake patients. Posterior spinal laminectomy and fusion can result in worsening neurologic status and is not recommended in this setting. Generally, corpectomy in the setting of facet subluxation is not recommended because it does not facilitate reduction or fully alleviate spinal cord compression. High-dose steroid use is not supported by current literature. RECOMMENDED READINGS: Fehlings MG, Perrin RG. The timing of surgical intervention in the treatment of spinal cord injury: a systematic review of recent clinical evidence. Spine (Phila Pa 1976). 2006 May 15;31(11 Suppl):S28-35; discussion S36. Lee AS, MacLean JC, Newton DA. Rapid traction for reduction of cervical spine dislocations. J Bone Joint Surg Br. 1994 May;76(3):352-6.

Cauda equina syndrome is a medical emergency that must be quickly diagnosed and treated to avoid long-term complications. Cauda equina syndrome typically presents with low back pain, unilateral or bilateral sciatica, saddle sensory disturbances, bladder and bowel dysfunction, and variable lower extremity motor and sensory loss. Although a number of pathologies can cause cauda equine syndrome, disk herniation is the most common cause of acute onset cauda equina syndrome. Cauda equina syndrome should be evaluated on an emergent basis and admission for work-up is appropriate. Emergent MRI to evaluate the level of spinal compression and acute decompression surgery is the most appropriate treatment in this situation. Nonsurgical management consisting of medications, bed rest, and a home exercise program are not appropriate. Whereas radiographs could be useful in a patient with traumatic onset of symptoms, MRI is the best study for evaluation of the spinal canal. Office follow-up and outpatient diagnositc testing are also inappropriate in this scenario.

The most appropriate management is discontinuation of the spinal instrumentation procedure, including releasing any distractive forces. Given the ongoing changes, proceeding with the procedure and/or resetting the baseline amplitudes is inadvisable. If the SSEPS amplitudes fail to return in a timely fashion, it is strongly recommended to consider a wake-up test. The purpose of intraoperative neuromonitoring is to provide a real-time assessment of the functional integrity of the central and peripheral nervous systems during surgery to prevent iatrogenic injury. Sustained decreased SSEP amplitudes of greater than 50% and transcranial electric Motor-Evoked Potentials (tceMEP) amplitudes of greater than 75% are indicative of a possible significant intraoperative neurologic complication. Although intraoperative corticosteroids might be helpful, especially in the event of a continued SSEP change, the most important next step would be to release the distractive forces and reevaluate the patient's neurologic status.

The patient is having gait problems suspicious for spinal cord compression. MRI of the thoracic and cervical spine should be performed to evaluate for spinal cord compression. Reports of leg weakness in the absence of discrete motor weakness on manual testing, and the appearance of an unsteady wide-based gait are more consistent with myelopathy as a cause of the gait difficulty rather than lumbar stenosis. Although the MRI scan of the lumbar spine shows multilevel spinal stenosis that is mild to moderate, it does not clearly explain the patient's signs and symptoms. Electromyography and nerve conduction velocity studies of the lower extremities are unlikely to add significantly to the diagnosis. Epidural steroid injections are not indicated. Lumbar decompression is unlikely to help the patient because the source of the patient's problem does not originate in the lumbar spine. MRI of the brain could be considered as a secondary imaging study if the cervical and thoracic MRI scans fail to identify an obvious cause for gait instability.(SBQ12SP.92) A 36-year-old man presents to the emergency department after being involved in a motor vehicle collision. He is complaining of back pain and imaging shows the findings in Figure A. On neurological examination, he does not have any deficits. MRI shows approximately 25% canal encroachment and no evidence of injury to the posterior ligamentous complex. Which of the following is the most appropriate course in management?ReviewTopicStrict bedrest for six weeks then progressive weightbearingAmbulation as tolerated with or without a TLSOSurgical decompression and anterior stabilizationSurgical decompression and posterior stabilizationSurgical decompression and combined anterior/posterior stabilizationThe patient has a L1 burst fracture with minimal retropulsion of bony fragments in the spinal canal. In the absence of neurological deficits and injury to the PLC, the mostappropriate treatment is ambulation as tolerated with or without a thoracolumbrosacral orthosis (TLSO).Thoracolumbar burst fractures are typically caused by an axial load with flexion and commonly found in this location due to increased motion at these segments. With an intact posterior ligamentous complex (PLC) and no neural compromise, TLSO is the mainstay of treatment. If there is evidence of neurological deficit and/or PLC injury, decompression and fusion are indicated. The degree of acceptable kyphosis is controversial. The choice of anterior versus posterior approach is based on ease of decompression.Vaccaro et al. introduced a new classification system for thoracolumbar injuries, TLICS, based on morphological appearance, integrity of the posterior ligamentous complex, and neurological status. They advocate use of the system for nonoperative versus operative decision making and communication between surgeons.Bailey et al. completed a randomized, nonblinded controlled trial to determine the efficacy of bracing for AO type A0-A3 thoracolumbar burst fractures. Both groups were encouraged to ambulate as tolerated and the no brace group had bending restrictions for 8 weeks. They found no difference in the Roland Morris Disability Questionnaire (RMDQ) score at 3 months after injury.Figure A is sagittal CT scan of the lumbar spine showing a burst fracture of L1 with minimal retropulsion. Illustration A is the TLICS classification with score of 4 being the branch point for nonoperative versus operative management.Incorrect Answers:

DISCUSSION: Although all of the factors listed contribute to the pullout strength of transpedicular screw fixation, low bone density generally is felt to be the most influential. REFERENCES: Wittenberg RH, Shea M, Swartz DE, Lee KS, White AA III, Hayes WC: Importance of bone mineral density in instrumented spine fusions. Spine 1991;16:647-652. Zindrick MR, Wiltse LL, Widell EH, et al: A biomechanical study of intrapeduncular screw fixation in the lumbosacral spine. Clin Orthop 1986;203:99-112.

DISCUSSION: The exact anatomic event responsible for vocal cord paralysis associated with anterior cervical surgery remains a question. Apfelbaum and associates, in an excellent review of 900 anterior cervical surgeries, identified 30 patients with vocal cord paralysis, 3 of which were permanent. They showed that retractors placed under the longus coli for anterior cervical exposures can compress the laryngeal-tracheal branches within the larynx against the tented endotracheal tube rather than the recurrent laryngeal nerve, which is extrinsic to the larynx. By releasing the endotracheal cuff and allowing the tube to recenter itself after placement of the retractors, they were able to decrease vocal cord injury from 6.4% to 1.7%. Jewett and associates suggested that a left-sided approach may result in a lower incidence of injury. Endotracheal intubation is the second most common cause of vocal cord injury, with an incidence of approximately 2%. REFERENCES: Apfelbaum RI, Kriskovich MD, Haller JR: On the incidence, cause, and prevention of recurrent laryngeal nerve paralysis during anterior cervical spine surgery. Spine 2000;25:2906-2912. Jewett BA, Menico GA, Spengler DM, Coleman SC, Netterville JL: Vocal Cord Paralysis Following Anterior Cervical Spine Surgery. Paper presented at the annual meeting of the Cervical Spine Research Society, December 2000, Charleston SC, Paper #7.

Discussion: Clearance of the cervical spine can be difficult in the obtunded or unresponsive patient. Various trauma series have been reported to detect up to 95% of cervical fractures but only when ideal imaging views have been obtained, which is not often possible in the unresponsive or uncooperative patient. Passively performed cervical flexion-extension under live fluoroscopy has been suggested but is not without inherent risk in the potentially unstable cervical spine. CT of the cervical spine has gained acceptance for the evaluation of these patients given the excellent evaluation of the osseous anatomy and for the common availability in most emergency departments. Sanchez and associates, using a protocol to evaluate for cervical spine injuries after blunt trauma, were able to detect 99% of cervical fractures with 100% specificity.

Discussion: Asymptomatic spondylolysis in a child or adolescent should be observed for the possible development of spondylolisthesis, but no other active intervention is needed. The initial treatment of choice for symptomatic spondylolysis includes rest and activity modifications, nonsteroidal anti-inflammatory drugs, physical therapy, bracing, and casting. Immobilization with a TLSO or pantaloon spica cast may permit healing of an acute pars fracture. Rarely, surgical treatment may be necessary. Surgical options include posterolateral L5-S1 fusion or direct repair of the pars defect.

Discussion: Based on the radiographic findings of marked disruption of the posterior ligamentous complex with a relatively small anterior bony fracture, the patient has a classic Chance-type ligamentous flexion-distraction injury. The pathology is mostly in soft tissues with limited healing potential. The treatment of choice is posterior reconstruction of the tension band with a short segment fusion with instrumentation. Casting or bracing may result in a painful kyphosis with ligamentous insufficiency. The anterior bony column is mostly intact, so anterior reconstruction is not necessary.

DISCUSSION: The presence of any curve greater than 20 degrees in a nonambulatory patient with Duchenne muscular dystrophy is an indication for posterior fusion with instrumentation. Because of progressive cardiomyopathy and pulmonary deficiency, waiting until the curve is larger can increase the risk of pulmonary or cardiac complications during or following surgery. There is some disagreement as to whether all such fusions must extend to the pelvis. Bracing or other nonsurgical management is ineffective and is not indicated in this situation.

DISCUSSION: All of the factors listed contribute to some extent to the pull-out strength of lumbar pedicle screws, but bone mineral density correlates most precisely.

The patient has a grade 4 spondylolisthesis. Optimal surgical management is posterior spinal fusion from L4 to the sacrum. The use of instrumentation is controversial. Vertebrectomy is typically reserved for spondylo-optosis (grade 5) cases. Spinal fusion from L5 to S1 usually is not successful for a slip that is greater than 50%. Isolated anterior spinal fusion has not been successful, and direct repair of the pars defect is only useful for spondylolysis without spondylolisthesis.

DISCUSSION: With the notable exception of fusion for degenerative spondylolisthesis and scoliosis, there is a paucity of evidence on the indications for spinal fusion in patients undergoing laminectomy for spinal stenosis. However, it is generally recommended that if the spine is destabilized (for example by removal of one complete facet joint or by an iatrogenic pars fracture), spinal fusion should be considered. Although fusion can be considered for a very long laminectomy, a two-level laminectomy does not represent, by itself, a clear indication for the addition of a spinal fusion. The repair of a dural tear and the use of nicotine by the patient play no role in the determination of whether or not to add fusion to a laminectomy procedure. REFERENCES: Spivak JM, Connolly PJ (eds): Orthopaedic Knowledge Update: Spine 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2006, pp 299-409. Fischgrund JS, Mackay M, Herkowitz HN, et al: 1997 Volvo Award winner in clinical studies. Degenerative lumbar spondylolisthesis with spinal stenosis: A prospective, randomized study comparing decompressive laminectomy and arthrodesis with and without spinal instrumentation. Spine 1997;22:2807-2812.

DISCUSSION: Circumferential fusion is the preferred choice for patients undergoing revision surgery following failed posterolateral fusions for isthmic spondylolisthesis as well as for those patients having primary surgery for high-grade isthmic spondylolisthesis.

The strongest variable for predicting subsequent low back pain is current or prior low back pain, defined at time loss for back pain during the previous 6 months or at the time of initial examination; relative risk 60%. Smoking was associated with a 40% increased risk of reporting back pain.

A bone scan with SPECT is very sensitive and specific for spondylolysis not seen on initial radiographs. MRI can sometimes visualize spondylolysis, but it is not as sensitive nor as specific as a bone scan with SPECT. Flexion and extension viewshave no role in the evaluation of the patient who presents with classic spondylolysis-type symptoms. The most sensitive physical examination finding is pain with back extension. Oblique radiographs can be obtained, but they are not as sensitive or specific as a bone scan with SPECT. The patient does not have any signs of a disk problem; therefore, an evaluation of the disk is not helpful.(SBQ13PE.79) A 17-year-old male American football lineman presents with low back pain of insidious onset that is somewhat worse with activity. He has no neurologic complaints, night pain or fevers. His symptoms have been present for a few years but this is the first time he has sought medical attention. What physical examination finding is most likely to be found in this clinical scenario?ReviewTopicPopliteal angle of 5 degreesHeel cord tightnessIncreased femoral anteversionPain with lumbar extension in single leg stanceNumbness of the skin of the anterolateral calf and dorsum of the footThe patient demographics and clinical presentation are consistent with lumbar spondylolysis. Pain with lumbar extension is the most common physical exam finding.Office assessment of the patient with spondylolysis should note pertinent negatives that would signify other causes of back pain. The history is most commonly negative for neurologic symptoms such as weakness or numbness, although patients will occasionally have radicular pain. On exam, patients may have localized spasm or tenderness, step off (if there is spondylolisthesis), hamstring tightness. The most common finding is pain with lumbar extension.McCleary et al. review the diagnosis and treatment of spondylolysis in athletes. They identify three types of patients with spondylolysis: (1) female dancer or gymnast who is hyperlordotic, with increased motion and flexibility, (2) male weightlifter or football player undergoing a growth spurt, with decreased motion and flexiblity, especially of the spinal erectors, and (3) a novice athlete undergoing vigorous preparation for a new sport, with poor core strength and flexibility.Incorrect

DISCUSSION: When attempting a revision anterior cervical approach from the side opposite the original approach, it is important to evaluate the function of the vocal cords. If this evaluation reveals dysfunction of the vocal cord on the side of the original approach, then an approach on the contralateral side should not be attempted. Injury to the stellate ganglion, which causes a Horner’s syndrome, should not preclude an approach on the contralateral side. While the side of the symptomatology can influence the surgeon’s choice as to the side of an anterior approach, it does not preclude a certain approach. When approaching the lower cervical spine from the right side, the recurrent laryngeal nerve can cross the surgical field and should be preserved. Excessive intraoperative pressure on the esophagus can increase the incidence of dysphagia, but its incidence is no different with either approach. REFERENCES: Spivak JM, Connolly PJ (eds): Orthopaedic Knowledge Update: Spine 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2006, pp 387-394. Edwards CC II, Riew KD, Anderson PA, et al: Cervical myelopathy: Current diagnostic and treatment strategies. Spine J 2003;3:68-81.

DISCUSSION: According to the classification of Levine and Edwards, a type I Hangman’s fracture is minimally displaced without angulation and represents a stable injury. Good clinical success has been achieved with nonsurgical management consisting of use of a rigid collar until the patient reports pain relief, followed by quick mobilization. REFERENCE: Levine AM, Edwards CC: The management of traumatic spondylolisthesis of the axis. J Bone Joint Surg Am 1985;67:217-226.

The patient has spinal shock. Steroid administration and MRI are appropriate therapeutic and diagnostic procedures. Myelography with CT is of little value unless there is an unusual skeletal variant. Spinal cord-evoked potentials have no value. The best method to determine the patient’s neurologic recovery is repeated physical examinations over the first 48 to 72 hours.