Spine Flashcards
A 40-year-old man who was a restrained driver in a rollover motor vehicle collision is seen in the emergency department. He is strapped to a long board and immobilized in a collar with tape. He is awake and alert, not intoxicated, has no neck pain or neurological deficit, and no distracting injury. Class I medical evidence supports which of the following types of imaging to clear his cervical spine?
A. Three-view spine series with visualization of C7-T1
B. Clinical exam alone
C. Three-view spine series with visualization of C7-T1, plus oblique films D. MRI scan of cervical spine
E. CT scan of cervical spine
Clinical exam alone
Patients who are awake, alert, not intoxicated, neurologically intact, and without distracting injuries may be cleared with clinical exam alone. Radiographic evaluation is not required to clear the cervical spine.
During surgery of the ventral spine via a lateral extracavitary approach, unilateral division of one or more lower intercostal nerves is most likely to result in which of the following adverse sequelae?
A. Unilateral lower extremity weakness
B. Spinal cord infarction
C. Numbness in the distribution of the sectioned roots
D. Hemi-elevation of the diaphragm
E. Neurogenic bowel & bladder dysfunction
Numbness in the distribution of the sectioned roots
Sectioning of thoracic nerve roots will generally not cause significant morbidity, with exception of the T1 nerves (hand intrinsic weakness). That being said, sectioning of lower thoracic nerve roots can result in an abdominal pseudohernia, although not exceptionally common. If a thoracic nerve root is planned to be sacrificed during surgery, it should be sectioned proximal to the DRG to prevent a chronic pain syndrome. The most common complaint patients endorse after thoracic root sacrifice is numbness in the distribution of the affected nerve(s).
When the thoracolumbar approach is used, which of the following rib spaces is normally used to access a T12 vertebral body burst fracture?
A. T11
B. T12
C. T8
D. T10
E. T9
T10
The left sided thoracolumbar junction approach, also called thoracophrenico lumbotomy, is only necessary in extensive thoracolumbar junction trauma. It might be replaced by left sided thoracotomy or the lumbotomy, depending on fracture location. The incision is centered over the fractured vertebra. The length of the incision depends on many factors including number, location and classification of fractures, obesity of the patient, previous thoracic operations, etc.
It is necessary to confirm the correct level of the approach with fluoroscopy. In general, the incision is made over a rib. The rib is selected based on radiographic evaluation of the fracture and is usually the rib attached to the vertebra two levels above the fractured vertebra.
After a type II odontoid fracture, the integrity of which of the following ligaments/membranes most strongly influences treatment options?
A. transverse
B. apical
C. alar
D. interspinous
E. anterior longitudinal
transverse
Rupture of the transverse ligament (the most biomechanically important portion of the cruciate ligament) allows translation of C1 on C2, evidenced by an increase in the atlantodental interval (ADI). Incompetence of this ligament is a contraindication to odontoid screw fixation and is associated with delayed instability. Incompetence may be diagnosed based on either increase in the ADI (greater than 3 mm in adults, 5 mm in children < 15 years old, and 7 mm in Down’s syndrome considered abnormal) or magnetic resonance imaging findings. The other ligaments (alar, apical, interspinous and anterior longitudinal) are important in determining the degree of stability, need for bracing or internal fixation, prognosis for healing and other factors, but individually are less determinative of the specific operative approach, in particular the need for C1-2 bony fusion.
A 56-year-old woman is evaluated because of a four-month history of progressive, asymmetric muscular weakness and atrophy that are more prominent in the upper extremities. She also describes symptoms suggestive of fasciculations in the forearms and hands. Examination shows atrophy of the hand intrinsic muscles and moderate hyperreflexia in the upper and lower extremities. An MR image of the cervical spine is shown. Which of the following is the most appropriate next step in management?
A. Dual-energy x-ray absorptiometry
B. Electromyography (EMG)
C. Flexion-extension x-rays
D. Computed tomography (CT) of the cervical spine
E. Somatosensory evoked potentials
Electromyography (EMG)
In this case, the patient has both upper and lower motor neuron signs on physical exam, which is concerning for amyotrophic lateral sclerosis (ALS). While MRI of the cervical spine is a good initial test as a myeloradiculopathy with both central and foraminal stenosis can mimic ALS, in this case the MRI does not demonstrate any significant stenosis so ALS would be strongly suspected. EMG (along with neurology evaluation) is the best initial test, with evidence of lower motor neuron loss, evidence of reinnervation, and fibrillation and sharp waves or fasciculation potentials confirming
the diagnosis. This is based on the Revised El Escorial Criteria or the Awaji-Shima Consensus Recommendations.
A 62-year-old man with a fixed sagittal plane deformity has chronic low back pain and 11 degrees of lumbar lordosis, with autofusion from L1-L5. Long cassette plain x-ray films show that 35 degrees of correction will be needed to optimize sagittal vertical axis and pelvic tilt. Which of the following single-level lumbar procedures is most likely to provide adequate correction?
A. Smith-Peterson osteotomy
B. Vertebral column resection
C. Ponte osteotomy
D. Transforaminal lumbar interbody fusion
E. Pedicle subtraction osteotomy
Pedicle subtraction osteotomy
This patient has a severe sagittal plane deformity, with a 37-degree PI-LL mismatch. Although his SVA is quite low, he has substantial straightening of his thoracic kyphosis to compensate, along with retroversion of the pelvis. Given the autofusion across the L1-5 segments, it will be challenging to obtain a satisfactory correction without a 3-column osteotomy. In this case, a pedicle subtraction osteotomy should be considered to get a 30-degree correction. Transforaminal interbody fusion and posterior column osteotomies can provide around 5-10 degrees of correction (or greater with anterior longitudinal ligament release), but would not provide adequate correction with the fused segments. Vertebral column resection is another 3-column osteotomy that can provide substantial focal lordosis and coronal plane correction, but it is typically used in the thoracic spine.
A 32-year-old woman is evaluated because of the sudden painless loss of vision in the right eye. An MR image of the brain shows an edematous nonenhancing right optic nerve, and a T2- weighted MR image of the spine shows a region of high-signal intensity traversing several segments within the center of the spinal cord. Which of the following additional findings is most likely to be present on laboratory evaluation of this patient?
A. Myelin oligodendrocyte glycoprotein antibodies
B. Myelin Basic Protein
C. Anti-aquaporin-4 antibody
D. high IgG index
E. Oligoclonal banding
Anti-aquaporin-4 antibody
This should first be identified as Neuromyelitis optica. NMO-IgG is a disease-specific autoantibody found in both serum and CSF for neuromyelitis optica (NMO) and its target antigen is aquaporin-4 (AQP4) water channel. The sensitivity of anti-AQP4 antibody assay for NMO is 91% and the specificity is 100%. Myelin basic protein is commonly found in both NMO and MS but does not differentiate between the two as well as AQP4. Oligoclonal banding and high IgG index is found in both, but actually more often in MS. Myelin oligodendrocyte glycoprotein antibodies is found equally in both.
A far lateral herniated disc at L4-5 is most likely to cause which of the following signs or symptoms?
A. Weakness in knee extension
B. Sensory loss on the lateral calf
C. Weakness in plantar flexion of the foot
D. Weakness in knee flexion
E. Sensory loss of the posterior calf
Weakness in knee extension
A far lateral disc herniation at L4-5 will affect the L4 nerve root. The L4 nerve root controls knee extension. Sensory loss on the lateral calf and weakness in knee flexion represent L5 compression and weakness in plantar flexion of the foot and sensory loss of the posterior calf reflect compression on the S1 nerve root.
Which of the following statements about the use of bone graft extenders, recombinant human bone morphogenetic protein (rhBMP), and substitutes in spinal fusions is supported by Level I evidence?
A. The use of rhBMP-2 as a graft option has been associated with a unique constellation of complications that the surgeon should be aware of when considering the use of this graft extender/substitute.
B. The utilization of rh-BMP-2 can be used as a substitute for autologous iliac crest bone with threaded interbody cages for single-level ALIF procedures.
C. The use of demineralized bond matrix (DBM) should be used as a bone graft extender for 1- and 2-level instrumented posterolateral fusions.
D. The use of rhBMP-2 as a graft extender with either autologous iliac crest bone or local bone is an option in patients undergoing either instrumented or non-instrumented posterolateral fusions.
E. The use of rhBMP-7 when combined with local autograft as an alternative to autologous iliac crest bone/local autograft is an option for single-level instrumented fusions based on equivalent clinical and radiographic outcomes.
The utilization of rh-BMP-2 can be used as a substitute for autologous iliac crest bone with threaded interbody cages for single-level ALIF procedures.
Statement “The utilization of rh-BMP-2 can be used as a substitute for autologous iliac crest bone with threaded interbody cages for single-level ALIF procedures” was supported by Level I evidence, but due to several limitations, it has been re-evaluated and downgraded to Level II evidence; however, this is the best answer choice. Statement “The use of demineralized bond matrix (DBM) should be used as a bone graft extender for 1- and 2-level instrumented posterolateral fusions” has Level III and V evidence. Statement “The use of rhBMP-2 as a graft option has been associated with a unique constellation of complications that the surgeon should be aware of when considering the use of this graft extender/substitute” has Level IV and V
evidence. Statement “The use of rhBMP-7 when combined with local autograft as an alternative to autologous iliac crest bone/local autograft is an option for single-level instrumented fusions based on equivalent clinical and radiographic outcomes” has strictly Level II evidence. Statement “The use of rhBMP-2 as a graft extender with either autologous iliac crest bone or local bone is an option in patients undergoing either instrumented or non-instrumented posterolateral fusions” has Level III and V evidence.
Which of the following congenital abnormalities develops in the lower cervical or upper thoracic region, is of endodermal origin, and is often associated with vertebral anomalies?
A. Spina Bifida
B. Hemivertebrae
C. Neuroenteric Cyst
D. Arachnoid Cyst
E. Epidermoid Cyst
Neuroenteric Cyst
Neuroenteric cysts are extremely rare endodermally derived lesions of the central nervous system and are found in the lower cervical and upper thoracic region of the spine. They are ventrally located. Hemivertebrae and spina bifida are commonly associated with neuroenteric cysts.
Arachnoid cyst and epidermoid cysts are not lesions of endodermal origin.
A 75-year-old woman with severe back pain has no abnormalities on neurological examination. X-ray films are shown. She was diagnosed with scoliosis during her adolescence, and was treated with a Harrington rod construct. Which of the following radiographic parameters is most closely correlated with increased pain and functional disability?
A. Sacral slope > 30 degrees
B. Sagittal vertical axis >9.5cm
C. Thoracolumbar scoliosis > 30 degrees
D. Pelvic incidence-lumbar lordosis mismatch > 10 degrees
E. Pelvic tilt > 10 degrees
Sagittal vertical axis >9.5cm
This patient has a prior Harrington rod construct, but has developed a severe sagittal plane deformity, and is compensating with retroversion of the pelvis and bending her knees. She has a sagittal vertical axis of 18 cm, which classifies as a severe sagittal plane deformity. Based on the Schwab-SRS spinal deformity parameters, the greatest predictors of disability are PI-LL mismatch >20 degrees, SVA>9.5 cm, and pelvic tilt > 30 degrees.
The approach to the anterior cervical spine can be performed from the right or left side. Risk of damage to which of the following structures is higher with a left-sided approach than with a right- sided approach?
A. Recurrent laryngeal nerve
B. Thoracic duct
C. External jugular vein
D. Facial vein
E. Superior laryngeal nerve
Thoracic duct
The thoracic duct is the only structure that is more at risk on a left-sided approach. Though rare, when operating on lower levels the surgeon should be mindful of this structure. Injury to the thoracic duct can lead to a chyle leak. Veins have no anatomic predisposition, though they can be large and require cauterization, clipping, or tying off. The thoracic duct risk aside, the most discussed structure at risk during this approach is the recurrent laryngeal nerve (RLN), but the course of the recurrent laryngeal nerve on the LEFT side is more predictable and has more “slack” than the right side. Thus, the RLN is more at risk on the right side, and less at risk on the left side. That said, the RLN can still be damaged during a left-sided approach and the surgeon should always be mindful of staying away from the tracheoesophageal groove.
A patient with a spinal cord injury undergoes physical examination, which shows the presence of voluntary but nonfunctional strength in the lower extremities (more than half of the muscles have less than antigravity strength). Sensation to pain, temperature, and proprioception are markedly diminished distal to the injury. The patient’s American Spinal Injury Association (ASIA) impairment scale grade is which of the following?
A. E
B. D
C. B
D. C
E. A
C
The ASIA grading system was developed to standardize the reporting of spinal cord injuries. It is a modification of the Frankel scale. Grades range from A to E. Grade A lesions are characterized by no motor or sensory function detected below the level of the lesion, including the sacral segments. Grade B is characterized by no motor function detected below the level of the lesion and some preserved sensory function below the level of the lesion. Grade C patients characteristically have some voluntary motor function preserved below the level of the lesion, but this function is too weak to serve any useful purpose (defined as more than half of key muscles having a strength grade of 3 or less). Sensation may or may not be preserved. Grade D patients have functionally useful voluntary motor function below the level of the injury, while grade E patients have normal strength and sensation, although abnormal reflexes may persist. Based upon the above grading scheme, this patient’s injury would be categorized as grade C.
A 24-year-old woman is evaluated for right arm and leg weakness and left abducens nerve palsy immediately after being involved in a motor vehicle collision. X-ray film of the lateral cervical spine shows pre-vertebral soft tissue swelling of the upper cervical spine and a basion-dental interval of 16 mm. CT scan of the head shows no intracranial hemorrhage. Which of the following is the most appropriate management of this patient?
A. Immobilization in a hard collar
B. Traction followed by immobilization in a halo
C. In situ arthrodesis and immobilization in a 4-poster brace
D. Internal fixation and arthrodesis
E. Immobilization in a halo
Internal fixation and arthrodesis
The most appropriate treatment option is internal fixation and arthrodesis. Traumatic atlanto-
occipital dislocation frequently results in death at the time of injury. Surviving patients may present with a normal neurological exam, but often present with hemiparesis or quadraparesis. Cranial nerve palsies may be seen. This injury is extremely unstable and patients frequently deteriorate without timely occipitocervical instrumentation. Traynelis has classified these injuries as Type I (anterior), Type II (longitudinal), Type III (posterior), and other types (lateral, rotational, or multidirectional). The BAI-BDI (basion-axial-interval-basion-dental-interval) of Harris is an accepted method of diagnosing atlanto-occipital dislocation on a lateral cervical x-ray. The basion-axial- interval is the distance from the basion to a line drawn along the posterior wall of the C2 vertebral body. A distance of more than +12 mm indicates a Type I injury while a distance of -4 mm or more indicates a Type III injury. A basion-dental interval greater than 12 mm is also abnormal and is consistent with a Type II atlanto-occipital dislocation. An additional finding on imaging studies is upper cervical prevertebral soft tissue swelling. Because of the degree of dislocation and instability associated with this injury, in-situ fusion without reduction and compression or in-situ bracing (including halo) are poor management options. The use of traction in these highly unstable injuries is generally contraindicated and can be devastating.
The 71-year-old man whose CT scan is shown has an L5-S1 spondylolisthesis of which of the following Meyerding grades?
A. Grade 5
B. Grade 1
C. Grade 2
D. Grade 4
E. Grade 3
Grade 2
The Meyerding classification is determined by measuring the degree of anterolisthesis or retrolisthesis using standing, lateral x-rays of the lumbar spine. The degree of slip is divided into five grades: 0% to 25% is Grade I, 25% to 50% is Grade II, 50% to 75% is Grade III, 75% to 100% is Grade IV, and greater than 100% is Grade V. The image shows Grade II.
A 24-year-old man presents with progressive quadriparesis within three hours of sustaining a gunshot wound to the lower neck. CT scan of the cervical spine shows an epidural hematoma from C6 through T1. Which of the following is the most appropriate next step in management?
A. Initiation of high-dose methylprednisolone for a full 48 hours
B. Emergent surgical decompression
C. MRI of the C-spine to better evaluate for cervical disk hernation
D. ICU management with fluid boluses and pressors to increase mean arterial pressure
E. Repeat CT in 4 hours to evaluate if the epidural hematoma is expanding
Emergent surgical decompression
The most appropriate next step in management is surgical decompression and evacuation of the epidural hematoma. Surgical decompression is indicated for progressive neurologic deficits associated with compressive intra-canal hemorrhage, bullet or bone fragments. In these situations, the surgeon is led to conclude that neural damage is actively advancing secondary to spinal cord compression, and an immediate operation is indicated. Further diagnostic imaging (MRI C-spine) and delayed decompression in the setting of rapidly progressive neurologic deficit and an epidural hematoma is not appropriate. In certain instances when an individual has a fixed neurologic deficit and bullet removal is indicated, waiting 72 hours after initial injury may be warranted to minimize complications particularly in patients that are unstable from hemodynamic or cardiopulmonary standpoints. With regards to conus or cauda equina level injuries, Cybulski et al. (1989) found equivalent rates of neurologic recovery in patients undergoing decompressive laminectomy within 72 hours (47.5% improved) versus those operated more than 72 hours after injury (48.1% improved). Administering steroids in the setting of traumatic spinal cord injury remains controversial, but is not recommended by the AANS/CNS Disorders of Spine and Peripheral Nerve Joint Section Cervical Spinal Cord Injury 2013 Guidelines. Heary et al. (1997) demonstrated that administration of either methylprednisolone or dexamethasone regimens did not significantly improve neurologic recovery of patients with either complete or incomplete injuries due to gunshot wounds compared with those receiving no steroids. Observation in an intensive care unit with fluid boluses and pressors to increase mean arterial pressure or waiting for serial imaging to determine if the epidural hematoma is expanding is not appropriate in a patient with a progressive, incomplete spinal cord injury.
A 53-year-old woman is evaluated because of low back pain and inability to stand up straight since she underwent an L3-S1 instrumented fusion for degenerative spine disease one year ago. On physical examination, the patient stands with a flexed kyphotic posture. Motor and sensory examinations show no abnormalities. Scoliosis x-rays show a lumbar lordosis from L1-S1 that measures 30 degrees while the pelvic incidence is 44 degrees. Which of the following tests must be performed to determine if spine surgery is required?
A. Lumbar flexion-extension x-rays
B. CT of the lumbar spine
C. MRI of the lumbar spine
D. Standing scoliosis x-rays
E. DEXA
Standing scoliosis x-rays
Standing scoliosis x-rays are the most important diagnostic test to assess the presence of both global and regional spinal deformities. In this case the patient has PI-LL mismatch of 14 degrees, based on assessment from L1-S1. However, based on the physical exam there is clearly a kyphosis above the L3-S1 construct, which may be due to proximal junctional kyphosis or a pre- existing deformity across the thoracolumbar junction. Therefore a 14 degrees mismatch, which classifies as a moderate deformity, may be much more clinically significant if there is also pronounced kyphosis across the thoracolumbar junction, as T10-L2 typically has minimal lordosis or kyphosis. Additionally, it is critically important to assess for hip flexion contractures on physical exam, as even a perfectly balanced spine can result in a forward leaning posture if the patient cannot fully extend the hips, and either extensive physical therapy or evaluation for potential hip arthroplasty is then required. While the other diagnostic tests may be useful adjuncts, the standing scoliosis x-rays are the most important assessment.
A 57-year-old man undergoes a C5 corpectomy for severe cervical myelopathy. A fibular structural bone graft is cut, sized, and placed, and the adjacent vertebral bodies are plated to create axial loading on the graft. By placing the graft under loading forces, remodeling and strengthening are facilitated during healing. This is a conceptual application of which of the following principles?
A. Wolff’s law
B. Osteointegration
C. Osteoinduction
D. Davis’ law
E. Osteogenesis
Wolff’s law
Wolff’s Law is the correct answer. By Wolff’s Law, bone formation is stimulated by mechanical loading, but if the loading is excessive, high strains or unwanted motion can lead to fibrous tissue formation. Davis’ law is the soft tissue equivalent. Osteoinduction is the process by which osteogenesis is induced. Osseointegration is the stable anchorage of an implant achieved by direct bone-to-implant contact. Osteogenesis occurs when vital osteoblasts originating from the bone graft material contribute to new bone growth along with bone growth generated via the other two mechanisms. While all of these are occurring during a corpectomy, Wolff’s law is the specific concept being asked for.
A 19-year-old man has fatigue, headaches, long tract signs, a Chiari I malformation, and a cervical syrinx extending to T1. Proper treatment includes which of the following?
A. Ventriculoperitoneal shunt
B. Occiput to C2 fusion
C. Transnasal endoscopic odontoidectomy
D. Syringosubarachnoid shunt
E. Suboccipital craniectomy with laminectomy of C1 arch with or without duroplasty
Suboccipital craniectomy with laminectomy of C1 arch with or without duroplasty
Suboccipital craniectomy with laminectomy of the C1 arch is known as a Chiari decompression. Expansile duroplasty is commonly performed in the presence of a syrinx and there have been retrospective studies supporting expansile duroplasty in patients with syrinx in terms of clinical outcomes. However, complications rates of associated with expansile duroplasty are increased compared to extradural decompression only. Whether or not to perform an expansile duroplasty remains a source of controversy. Current evidence has not been able to control for inherent selection bias and there are several randomized controlled trials underway to answer this question. The other choices in this question stem are not first line options in the treatment of a type 1 Chiari malformation.
During posterior cervical foraminotomy at C5-6 for chronic degenerative foraminal stenosis, removal of which of the following bony structures will most directly result in nerve root decompression? In other words, what is the bony element that is directly compressing the nerve root dorsally?
A. C6 lamina
B. C5 superior articular process
C. C6 superior articular process
D. C5 inferior articular process
E. C6 inferior articular process
C6 superior articular process
A 65-year-old woman presents six months after a motor vehicle collision because of severe disabling neck pain. Cervical CT scans show a non-united type II odontoid fracture. Which of the following is the most appropriate management?
A. Occiput to C2 fusion
B. Halo immobilization
C. Anterior odontoid screw fixation
D. Posterior C1-C2 arthrodesis
E. Hard cervical collar
Posterior C1-C2 arthrodesis
Posterior C1-C2 fixation/arthrodesis immobilizes the entire C1-C2 complex, and is the treatment of choice in this condition. Generally, a fracture older than 3 months is considered a chronic fracture. Acute type II odontoid fractures do not respond well to external orthrosis (hard collar or halo), and healing rates are even poorer for chronic fractures. Published clinical series have reported 50% healing rates for anterior odontoid screw fixation in chronic fractures. Low healing rates are generally ascribed to pannus formation at the fracture site. Occiput to C2 fusion would significantly decrease cervical range of motion and should be reserved as a second-line surgical option.
A 58-year-old woman undergoes an L4 laminectomy with an L4-5 interbody fusion and instrumentation. The operation is prolonged by blood loss, and postoperatively she wakes up with weakness in knee extension and foot dorsiflexion. She also has numbness over the anterior thigh and medial lower leg. Which of the following nerves was most likely injured during the procedure?
A. Femoral nerve
B. L5 nerve
C. L4 nerve
D. Lateral femoral cutaneous nerve
E. Common peroneal nerve
L4 nerve
Given the location of surgery and distribution of exam findings, L4 is the most likely injured nerve during this procedure. The exiting nerve root is at risk during cage placement. The L4 nerve contributes to both knee extension and foot dorsiflexion, and provides sensation to a part of the anterior thigh and medial lower leg. A femoral nerve injury would be more commonly associated with a lateral interbody fusion at L4/5, not a posterior interbody fusion. Femoral nerve injuries would not cause a foot drop. Transient lateral femoral cutaneous nerve palsies (meralgia paresthetica) are not uncommon after prolonged prone positioning. This type of pressure palsy usually self-resolves within a few days. Although L5 contributes to foot dorsiflexion, it does not innervate knee extensors muscles. The common peroneal nerve is anatomically remote from the site of surgery, although intra-operative pressure palsies have been reported from improper positioning.
A 46-year-old woman with Meyerding Grade 3 L5-S1 isthmic spondylolisthesis undergoes an L5- S1 transforaminal lumbar interbody fusion. Immediately following the use of instrumentation to achieve a complete reduction, there is strong spontaneous EMG activity arising bilaterally from the L5 nerve roots. Which of the following is the most appropriate course of action?
A. Final tighten the screws in the reduced position, as the EMG is likely a transient phenomenon
B. Release the reduction, and inspect the L5 nerve roots for active compression
C. Final tighten the screws in the reduced position, and perform a wake-up test to ensure the patient has not developed a foot drop
D. Final tighten the screws in the reduced position, and perform a 3D reconstructed intra- operative scan to ensure there is no foraminal compression
E. Final tighten the screws in the reduced position, and perform nerve stimulation of the L5 roots to ensure they are working
Release the reduction, and inspect the L5 nerve roots for active compression
Although complete reduction of a spondylolisthesis is radiographically gratifying, it may come at a price to the exiting nerve roots. Reduction maneuvers allow the exiting roots to assume a new position within the neural foramen. It is important to ensure that the neural foramen of the exiting roots are clear prior to reduction. This can be done indirectly, by placing an interbody cage and increasing the height of the foramen, or via a direct foraminal decompression. If EMG activity is noted during the reduction maneuver, the first step of the surgeon should be to release the reduction, and inspect the L5 nerve roots prior to performing another reduction maneuver, or final tightening the screws in their current position. It is also important to ensure the L5 screws are appropriately positioned, and have not been placed through the inferior margin of the pedicle.
A 46-year-old woman is evaluated because of a grade I, L5-S1 spondylolisthesis. She has severe back pain at the lumbosacral junction, L5 root weakness, and bilateral sciatica. She has focal kyphosis at L5-S1 and lumbar lordosis/pelvic incidence (LL/PI) mismatch of 17 degrees. Which of the following is the most reliable surgical technique at L5-S1 to create lordosis and improve spinal alignment?
A. Anterior lumbar interbody fusion
B. Lateral interbody fusion
C. Transforaminal interbody fusion
D. Posterior lumbar interbody fusion
E. Posterolateral fusion
Anterior lumbar interbody fusion
Anterior lumbar interbody fusion provides the best route for providing focal lordosis at L5-S1, along with providing the greatest surface area for the cage or graft to minimize subsidence. At the upper lumbar levels, a lateral approach for interbody fusion with anterior longitudinal ligament release can also provide substantial focal lordosis, but this technique cannot be used at L5-S1 due to the location of the iliac crest.
Which of the following best describes pelvic tilt?
A. A position-dependent parameter that tests the angle between the angle of the S1 endplate and the horizontal line
B. A fixed parameter that tests the angle between the angle of the S1 endplate and the horizontal line
C. A position-dependent parameter defined by the angle between a line from the midpoint of the S1 endplate to the center of the bifemoral heads and the vertical axis
D. A fixed parameter defined by the angle between a line from the midpoint of the S1 endplate to the center of the bifemoral heads and the vertical axis
E. A fixed position that determines how much lumbar lordosis a person should have
A position-dependent parameter defined by the angle between a line from the midpoint of the S1 endplate to the center of the bifemoral heads and the vertical axis
Pelvic tilt is a compensatory measure that allows patients to maintain a horizontal gaze. An approximate cut-off often used as a sign that they are “compensating” for not enough lumbar lordosis compared to their pelvic incidence is approximately 20°. Answers A and B describe measuring sacral slope but note that sacral slope is a position-dependent parameter. A key equation to memorize for every neurosurgeon, not just spine surgeons, is that pelvic tilt + sacral slope = pelvic incidence. The higher the pelvic tilt, the more the patient is compensating, and the more likely a patient is to have pain from their lower back and leg muscles working excessively to maintain normal posture.
Which of the following is the most common spinal disorder in patients with Down Syndrome?
A. Rotary subluxation of the atlantoaxial joint
B. Tethered cord syndrome
C. Basilar invagination
D. Atlantoaxial instability
E. Klippel Feil Syndrome
Atlantoaxial instability
The most common spinal disorder in patients with Down Syndrome is atlantoaxial instability. Atlantoaxial instability affects up to 20% of patients with Down Syndrome. Klippel Feil is associated with Sprengel’s deformity and congenital scoliosis. The other choices can occur in patients with Down syndrome, but they are not as common as atlantoaxial instability.
A 45-year-old man is seen in the post-anesthesia care unit after undergoing an anterior cervical discectomy and fusion with plating at C6-7. Physical examination shows constricted pupil and ptosis. Which of the following is the most likely explanation of this patient’s condition?
A. Stage 2 of anesthesia awakening
B. Potential brain hemorrhage
C. Damage to the spinal cord
D. Damage to the C7 nerve root
E. Damage to the sympathetic plexus
Damage to the sympathetic plexus
The patient has a Horner’s syndrome from damage to the sympathetic plexus. A Horner’s syndrome consists of the following triad: miosis (constricted pupil), partial ptosis, and loss of hemifacial sweating (anhidrosis). The sympathetic chain rests >6mm lateral on the longus colli and is at risk of damage during the initial dissection or during retractor placement during an anterior cervical approach. When the longus colli muscles are elevate, excessive monopolar cautery or cutting into the muscle can damage the sympathetic plexus on top of the longus colli muscle. Moreover, if the retractors do not sit UNDER the longus, and they instead slip ventrally and sit on TOP of the longus colli muscles, the retractors themselves can damage the sympathetic plexus (especially if retractors are extended for many hours or there is downward pressure on the retractors). If this occurs, the patient can wake up with a Horner’s syndrome. Most get better with time, but some do not.
The sagittal vertical axis is the horizontal distance measured from a C7 vertical plumb line and which other structure?
A. Center of the Femoral Head
B. Posterior Superior Corner of S1
C. Midpoint of the L5 vertebral body
D. Midpoint of Upper Sacral endplate
E. Sacral promontory
Posterior Superior Corner of S1
Achieving appropriate sagittal balance has been recognized as fundamental for successful adult deformity correction. Historically, an ideal sagittal vertical axis (SVA) has been defined as SVA < 5 cm. More recently, studies from the International Spine Study Group have established that target spinopelvic parameters should consider patient characteristics. As such, age matched SVA should be considered in the preoperative planning phase. The SVA is measured as the distance from the plumb line from the center of the C7 to the posterior edge of the upper sacral endplate surface. The sacral promontory and midpoint of the L5 vertebral body are not used typically for sacropelvic parameter measurements. The midpoint to the center of the bifemoral heads is utilized for pelvic tilt and pelvic incidence.
A standing lateral radiograph of a 63-year-old man with low back pain and inability to stand fully upright is shown. Which of the following permanent anatomic pelvic parameters should be considered when determining the necessary amount of lumbar lordosis correction needed to obtain ideal sagittal balance?
A. Pelvic increment
B. Pelvic tilt
C. Sacral slope
D. Pelvic incidence
E. Pelvic morphology
Pelvic incidence
Pelvic incidence (PI) is a fixed morphological parameter that shows the relationship between the spinal column and the pelvis. The PI determines the amount of lumbar lordosis needed to maintain an upright and mechanically appropriate posture. The PI is equal to the pelvic tilt + the sacral slope (PI=PT+SS). The amount of lumbar lordosis should be within approximately 10° of the pelvic incidence. In 99.9% of cases, the PI is a “fixed parameter” that does not change. The PI can change in unique circumstances, such as puberty, sacral fracture, or some types of deformity correction. Some surgeons believe that a strong cantilever technique with or without S2-alar-iliac screws can change the PI. But again, for the purpose of this question and most scenarios, the PI is a fixed parameter.
Which of the following spinopelvic parameters remains constant before and after spinal deformity surgery?
A. Pelvic tilt
B. Pelvic Incidence
C. Sacral Incidence
D. Sacral slope
E. Lumbar Lordosis
Pelvic Incidence
The correct answer is pelvic incidence. Pelvic tilt is the parameter that allows the most compensation for a lack of spinal balance. It is a position-dependent parameter defined as the angle created by a line running from the sacral endplate midpoint to the center of the bifemoral heads and the vertical axis. Sacral Incidence is not a defined sacropelvic parameter. Sacral slope is the angle between the horizontal and the sacral plate. Lumbar lordosis is either increased or decreased in surgery often based on PI-LL mismatch.
A 60-year-old woman with a history of prior L4-S1 fusion and osteoporosis undergoes instrumented fusion from T10 to the sacrum for treatment of a sagittal plane deformity. She initially does well, but 6 weeks postoperatively she reports that she has pain at the top of her construct and is not able to stand as straight as she did immediately after surgery, and an x-ray is obtained. Which of the following is the most likely diagnosis?
A. Non-union
B. Hip flexion contracture
C. Proximal junctional kyphosis
D. Cervical deformity
E. Rod fracture
Proximal junctional kyphosis
This patient was initially well balanced, but now has significant proximal junctional kyphosis (and likely junctional failure), resulting in a new SVA of 12cm. Some newer data indicates that there is a greater risk of junctional kyphosis with poor bone quality at the upper instrumented vertebrae, so there should be consideration for anabolic therapy for bone density prior to a deformity correction operation in a patient with osteoporosis. Additionally, in this case the patient was already fused from L4 to S1 so pelvic supplemental fixation was not used, but it should be considered for long segment constructs when there is not fusion across the lumbosacral junction.
Thoracic pedicle morphology studies consistently show that the narrowest pedicle is most likely to be found at which of the following locations?
A. T10
B. T1
C. T12
D. T2
E. T6
T6
From T4-6 pedicles become increasingly smaller. Transpedicular screw placement may not be safe and screw placement may require an “in – out – in” technique. For the most part, thoracic pedicles both rostral and caudal to T4-6 increase in diameter. T1 and T2 pedicles are large compared to those in the middle of thoracic spine. These two pedicles typically will readily accommodate a pedicle screw approximately 5.0 mm in diameter. T10 and T12 are also relatively large compared to the middle of the thoracic spine. Often, these pedicles can accommodate pedicle screws approximately 6.0 mm in diameter.
Which of the following structures is indicated by the arrow at C2 in the image shown?
A. C2 Facet
B. Pars Interarticularis
C. C2 Transverse Process
D. C2 mamillary body
E. C2 lamina
Pars Interarticularis
The c2 pars interarticularis is the anatomical location for the hangman fracture. The pars is located in between facet joints and therefore C2 facet is not the correct answer. The transverse process extends lateral to the pars.
