2014 Spine

Question 1

1: During a retroperitoneal approach to the L4-5 disk, what structure must be ligated to safely mobilize the common iliac vessels toward the midline laterally and gain exposure?

1. Obturator vein
2. Iliolumbar vein
3. External iliac vein
4. Middle sacral artery
5. Hypogastric artery

Answer 1

PREFERRED RESPONSE: 2

DISCUSSION: To mobilize the common iliac vessels across the midline, the iliolumbar vein must be ligated. It has a short trunk and can be torn if mobilization is attempted without ligation. It is the only branch off the common iliac vessels (there are no arterial branches) prior to the terminal branches, and the internal (hypogastric) and external iliac vessels. The middle sacral vessels run distally from the axilla of the bifurcation and are a factor when accessing the L5-S1 disk.

Question 2

2: The injection shown in Figures 1A and 1B would most benefit a patient who reports which of the following symptoms?

Figure 1

1. Dorsal foot pain extending into the great toe
2. Foot pain extending along the lateral border of the foot
3. Pain extending into the foot in a stocking distribution
4. Anterior thigh and shin pain ending at the ankle
5. Lateral foot paresthesias

Answer 2

PREFERRED RESPONSE: 1

DISCUSSION: The images demonstrate an L5 selective root block as it exits the L5-S1 foramen. This root block best helps relieve pain or paresthesias in the L5 distribution, which is the dorsal first web space and the great toe. The lateral foot is an S1 distribution and would need to be blocked through the posterior first sacral foramen. The anterior shin and thigh represent the L4 root, which exits a level above this at the L4-5 foramen. A stocking distribution is nonanatomic and not indicative of a specific root.

Question 3

3: If a surgeon inadvertently burrs through the midlateral wall of C5 during a anterior corpectomy, what structure is at greatest risk for injury?

1. C5 root
2. C6 root
3. Internal carotid artery
4. Vertebral artery
5. Vagus nerve

Answer 3

PREFERRED RESPONSE: 4

DISCUSSION: The vertebral artery is contained within the vertebral foramen and thus tethered alongside the vertebral body, making it vulnerable to injury if a drill penetrates the lateral wall. The C5 root passes over the C5 pedicle and is not in the vicinity. The C6 root passes under the C5 pedicle but is posterior to the vertebral artery and is only vulnerable at the very posterior-inferior corner. The carotid artery and the vagus nerve are both within the carotid sheath and well anterior.

Question 4

4: What structure is located at the tip of the arrow in Figure 2?

Figure 2

1. Left L3 nerve root
2. Right L3 nerve root
3. Right L4 segmental artery
4. Right L4 nerve root
5. Left lateral disk herniation

Answer 4

PREFERRED RESPONSE: 2

DISCUSSION: The structure shown is the exiting nerve root at the L3-4 disk, which is the right L3 root.

Question 5

5: What structure is most at risk for injury from a retractor against the tracheoesophageal junction during an anterior approach to the cervical spine?

1. Esophagus
2. Trachea
3. Superior laryngeal nerve
4. Recurrent laryngeal nerve
5. Sympathetic chain

Answer 5

PREFERRED RESPONSE: 4

DISCUSSION: Although any of these structures can be injured by pressure from the medial blade of a self-retaining retractor, the recurrent laryngeal nerve runs cephalad in the interval between the esophagus and trachea and is vulnerable to pressure if caught between the retractor and an inflated endotracheal tube balloon.

Question 6

6: A patient with a left-sided C6-7 herniated nucleous pulposus would likely have which of the following constellation of findings?

1. Pain into the thumb, triceps weakness, and loss of triceps reflex
2. Middle finger numbness, wrist extensor weakness, and diminished brachioradialis reflex
3. Thumb numbness, wrist extensor weakness, and diminished brachioradialis reflex
4. Middle finger numbness, triceps weakness, and loss of biceps reflex
5. Middle finger numbness, triceps weakness, and loss of triceps reflex

Answer 6

PREFERRED RESPONSE: 5

DISCUSSION: A C6-7 herniation affects the C7 root. The C7 root has the middle finger as its predominant sensory distribution. Its motor function is the triceps, wrist extension, and finger metacarpophalangeal extension. The reflex is the triceps.

Question 7

7: Figures 3A and 3B show the sagittal T2- and T1-weighted MRI scans of a 25-year-old patient who is an intravenous drug abuser and who has low back pain that is increasing in intensity. Laboratory studies show a white blood cell count of 10,000/mm3 and an erythrocyte sedimentation rate of 80 mm/hour. Blood culture is negative. Initial management consist of

Figure 3

1. CT-guided closed biopsy.
2. open surgical biopsy.
3. antibiotic coverage for Staphylococcus aureus.
4. broad-spectrum antibiotic coverage.
5. a follow-up MRI scan in 8 weeks.

Answer 7

PREFERRED RESPONSE: 1

DISCUSSION: The MRI scans show vertebral diskitis/osteomyelitis. The treatment of spinal infection in adults should be organism specific; therefore, initial management should consist of CT-guided closed biopsy prior to administration of antibiotic coverage. An open biopsy is indicated for a failed closed biopsy or failure of nonsurgical management. Although Staphylococcus aureus is the most common bacteria, a history of intravenous drug abuse raises suspicion for other organisms, including Pseudomonas.

Question 8

8: A 27-year-old man sustained a gunshot wound to the lumbar spine and undergoes an exploratory laparotomy. An injury to the cecum is identified and treated. Management should now include

1. no antibiotics.
2. oral broad-spectrum antibiotics for 7 days.
3. intravenous broad-spectrum antibiotics for 48 hours.
4. intravenous broad-spectrum antibiotics for 7 days.
5. intravenous antibiotics specific for Staphylococcus for 7 days.

Answer 8

PREFERRED RESPONSE: 4

DISCUSSION: Gunshot wounds to the spine present relatively little risk of infection in most cases. When there has been an injury to the colon, the risk of infection can be minimized with a 7-day course of broad-spectrum antibiotics. Fragment removal is not indicated.

Question 9

9: A Trendelenburg gait is most likely to be seen in association with

1. a central disk herniation at L3-L4.
2. an ipsilateral paracentral disk herniation at L3-L4.
3. an ipsilateral paracentral disk herniation at L4-L5.
4. an ipsilateral paracentral disk herniation at L5-S1.
5. an ipsilateral far lateral disk herniation at L4-L5.

Answer 9

PREFERRED RESPONSE: 3

DISCUSSION: A Trendelenburg gait results from weakness of the gluteus medius, which is innervated by the L5 nerve root. A paracentral disk herniation at L4-L5 most commonly results in an L5 radiculopathy and thus weakness of the gluteus medius. A paracentral herniation at L5-S1 most commonly affects the S1 nerve root. A paracentral herniation at L3-L4, a central herniation at L3-L4, and a far lateral herniation at L4-L5 all affect the L4 root.

Question 10

10: Figure 4 shows the radiograph of a 64-year-old man who has neck pain and weakness of the upper and lower extremities following a motor vehicle accident. Examination reveals 3/5 quadriceps muscle strength and 4/5 hip flexors strength but no ankle dorsiflexion or plantar flexion. He has 1/5 intrinsic muscle strength and 3/5 finger flexors strength. He is awake, alert, and cooperative. Management should consist of

Figure 4

1. halo vest immobilization.
2. MRI.
3. Gardner-Wells tongs and closed reduction.
4. posterior open reduction and fusion.
5. observation until the patient’s general medical status improves, followed by closed reduction via Gardner-Wells tongs.

Answer 10

PREFERRED RESPONSE: 3

DISCUSSION: In patients with facet dislocations and an incomplete neurologic deficit, early decompression of the canal via reduction of the dislocation generally is considered safe if the patient is alert and can cooperate. However, patients who cannot cooperate with serial neurologic examinations during the reduction are at risk for increased deficit secondary to herniated nucleus pulposus, and MRI should be performed prior to either closed or open reduction.

Question 11

11: In a retroperitoneal approach to the lumbar spine, what structure runs along the medial aspect of the psoas and along the lateral border of the spine?

1. Ilioinguinal nerve
2. Genitofemoral nerve
3. Sympathetic trunk
4. Ureter
5. Aorta

Answer 11

PREFERRED RESPONSE: 3

DISCUSSION: The sympathetic trunk runs longitudinally along the medial border of the psoas. The ilioinguinal nerve emerges along the upper lateral border of the psoas and travels to the quadratus lumborium, and the genitofemoral nerve lies more laterally on the psoas. The ureter is adherent to the posterior peritoneum and falls away from the psoas and the spine in the dissection, as does the aorta.

Question 12

12: Flexion-distraction injuries of the thoracolumbar spine are most frequently associated with injury to what organ system?

1. Neurologic
2. Pulmonary
3. Gastrointestinal
4. Vascular
5. Lymphatic

Answer 12

PREFERRED RESPONSE: 3

DISCUSSION: In patients with flexion-distraction injuries of the thoracolumbar spine, 50% have associated, potentially life-threatening, visceral injuries that occasionally are diagnosed hours or even days after admission. Based on these findings, consultation with a general surgeon is recommended. Blunt and penetrating injuries to the cardiopulmonary system or aorta sometimes can be seen with this type of injury, but they are no more common than with other types of thoracolumbar fractures because of the relatively mild bony injury anteriorly. Neurologic trauma with this type of fracture is also somewhat rare.

Question 13

13: What is the most common adverse postoperative complication of laminaplasty for multilevel cervical spondylotic myelopathy?

1. Loss of cervical range of motion
2. Inadvertent closure of the laminaplasty postoperatively
3. Progressive cervical kyphosis
4. C5 nerve root palsy
5. Inadequate decompression of the spinal cord

Answer 13

PREFERRED RESPONSE: 1

DISCUSSION: A 30% to 50% loss of cervical range of motion is reported postoperatively in most patients following cervical laminaplasty. Inadvertent closure of the laminaplasty does occur but is rare. Laminaplasty is advocated in lieu of laminectomy to prevent progressive kyphosis and can effectively decompress the spinal cord. C5 nerve root palsies are a poorly understood but rare complication of surgical decompression for cervical spondylotic myelopathy.

Question 14

14: A patient who underwent an L5-S1 diskectomy 18 months ago has persistent pain in the left leg. Figures 5A and 5B show postoperative axial T1-weighted MRI scans at the L5-S1 level without and with gadolinium. What is the most likely diagnosis?

Figure 5

1. Epidural abscess
2. Neurilemmoma of the left S1 root
3. L5-S1 diskitis
4. Recurrent left L5-S1 disk herniation
5. Left S1 perineural fibrosis

Answer 14

PREFERRED RESPONSE: 5

DISCUSSION: Persistent or recurrent symptoms after lumbar diskectomy are troublesome and can be difficult to assess. Gadolinium-enhanced MRI scans may be helpful. The images show enhancement about the left S1 root, a finding that is most consistent with perineural (epidural) fibrosis. The root itself does not enhance. Root enhancement has been associated with compressive radicular symptoms. A disk herniation does not enhance with gadolinium. A neurilemmoma enhances with gadolinium, but the involved root would be enlarged. There is no evidence of a fluid collection, which would be consistent with an epidural abscess.

Question 15

15: If a laminectomy for spinal stenosis is performed, which of the following is an indication for concomitant arthrodesis at that level?

1. Prior laminectomy at an adjacent level
2. Ten degrees of degenerative scoliosis
3. Removal of 25% of each facet joint at surgery
4. Degenerative spondylolisthesis at the level of the laminectomy
5. Foraminal stenosis at the level of the laminectomy

Answer 15

PREFERRED RESPONSE: 4

DISCUSSION: A prospective randomized study of patients with degenerative spondylolisthesis and spinal stenosis by Herkowitz and Kurz showed significantly improved clinical outcomes in patients who also received a lumbar arthrodesis. Patients with a laminectomy at an adjacent level do not have improved outcomes with an arthrodesis. Minimal lumbar scoliosis does not require arthrodesis. Arthrodesis is indicated in cases where there is removal of more than 50% of the facets bilaterally but not with an associated foraminal stenosis.

Question 16

16: A previously healthy 30-year-old woman has neck pain and bilateral hand and lower extremity tingling with weakness after falling down stairs. She is alert and oriented. Examination reveals incomplete quadriplegia at the C6 level that remains unchanged throughout her evaluation and initial treatment. Radiographs show a bilateral facet dislocation of C6 on C7 without fracture. Attempts at reduction with halo cervical traction up to her body weight are unsuccessful. What is the most appropriate next step?

1. Posterior open reduction and fusion with fixation
2. Anterior open reduction and fusion with fixation
3. Technetium Tc-99m bone scan
4. Closed manipulation
5. MRI

Answer 16

PREFERRED RESPONSE: 5

DISCUSSION: A facet dislocation that cannot be reduced in an alert, awake patient with some preservation of cord function requires MRI to evaluate the disk prior to a reduction under anesthesia. The presence or absence of a disk herniation must be assessed, as this factor may influence the method of reduction.

Question 17

17: In a patient who has undergone fusion with instrumentation from T4 to the sacrum for adult scoliosis, at which site is a pseudarthrosis most likely to be discovered?

1. T4-T5
2. T7-T8
3. L2-L3
4. L4-L5
5. L5-S1

Answer 17

PREFERRED RESPONSE: 5

DISCUSSION: Although pseudarthrosis can be found anywhere within the spine that has been fused using long multisegmental fixation to the sacrum, it most commonly occurs at the lumbosacral junction. The thoracolumbar junction is another common site of potential pseudarthrosis. In this location, the anatomy changes from lumbar transverse processes to thoracic through the transition zone, and overlying instrumentation often makes it difficult to obtain enough sound bone on decorticated bone to achieve a successful fusion.

Question 18

18: When posterior fusion with instrumentation to the sacrum is used to treat adult scoliosis, what instrumentation technique best increases the chance of a successful lumbosacral fusion?

1. Addition of sublaminar wires to the midlumbar spine
2. Cross-linking of the longitudinal rods
3. Use of multiple claw-hook fixation in the upper thoracic spine
4. Use of large-diameter rods and pedicle screws
5. Fixation into both the ilium and the sacrum

Answer 18

PREFERRED RESPONSE: 5

DISCUSSION: As the chance of success of lumbosacral fusion increases with the stiffness and rigidity of the construct, fixation and stiffness improve with fixation into both the upper sacrum and the ilium. In a review of individuals treated with long constructs to the pelvis for adult scoliosis, Islam and associates reported that the rate of pseudarthrosis was significantly lower with sacral and iliac fixation compared with sacral fixation alone or iliac fixation alone. Iliac screws provide significant fixation anterior to the instantaneous axis of rotation for flexion and extension, as well as provides resistance to lateral bending and rotational forces. Numerous biomechanical studies support the concept of increasing biomechanical stabilization with increased fixation from the sacrum to the ilium.

Question 19

19: Which of the following complications is uniquely associated with an anterior approach to the lumbosacral junction?

1. Nerve root injury
2. Erectile dysfunction
3. Dural tear
4. Pulmonary embolism
5. Retrograde ejaculation

Answer 19

PREFERRED RESPONSE: 5

DISCUSSION: Retrograde ejaculation is a sequela of injury to the superior hypogastric plexus. The structure needs protection, especially during anterior exposure of the lumbosacral junction. The use of monopolar electrocautery should be avoided in this region. The ideal exposure starts with blunt dissection just to the medial aspect of the left common iliac vein, sweeping the prevertebral tissues toward the patient’s right side. Although erectile dysfunction can be seen after spinal surgery, it is not typically related to the surgical exposure because erectile function is regulated by parasympathetic fibers derived from the second, third, and fourth sacral segments that are deep in the pelvis and are not at risk with the anterior approach. The other choices are complications of spinal surgery but are not uniquely associated with an anterior L5-S1 exposure.

Question 20

20: An 18-year-old man sustained a knife injury to his midback, with the entry wound 2 cm to the left of the midline. Hemicord transection has been diagnosed. Neurologic examination will most likely reveal left-sided loss of

1. vibratory and light touch sensation and motor function, and right-sided loss of pain and temperature sensation.
2. pain and temperature sensation and motor function, and right-sided loss of vibratory and light touch sensation.
3. pain, temperature, vibratory, and light touch sensation and motor function.
4. motor function, and right-sided loss of pain, temperature, vibratory, and light touch sensation.
5. light touch and pain sensation and motor function, and right-sided loss of vibratory and temperature sensation.

Answer 20

PREFERRED RESPONSE: 1

DISCUSSION: Brown-Séquard syndrome results from an injury to one half of the spinal cord and is characteristically seen in penetrating injuries. The spinothalamic fibers cross the midline below the level of the lesion, resulting in contralateral loss of pain and temperature sensation. The posterior columns and corticospinal tracts carry vibratory, position, and light touch sensation, as well as motor function from the ipsilateral side of the body. This results in the characteristic neurologic findings seen with Brown-Séquard syndrome.

Question 21

21: A 40-year-old woman has had sciatic pain on the left side for the past 8 weeks. She reports that the pain radiates to her posterior thigh, lateral calf, and into the dorsum of her left foot. Neurologic examination shows weakness of the left extensor hallucis longus. Axial T2-weighted MRI scans through L4-L5 are shown in Figure 6. Management should consist of

Figure 6

1. CT-guided needle biopsy at L4-L5.
2. a bone survey.
3. anterior interbody fusion.
4. left L4-L5 microdiskectomy.
5. left L4-L5 hemilaminectomy and partial facetectomy.

Answer 21

PREFERRED RESPONSE: 5

DISCUSSION: The MRI scans show hypertrophy of the left L4-L5 facet joint and ligamentum flavum, with a synovial cyst. Appropriate surgical management consists of a hemilaminectomy and direct decompression of the neural elements. Fusion, in addition to the decompression, may be considered, particularly in patients with an associated spondylolisthesis.

Question 22

22: A collegiate football player who sustained an injury to his neck has significant neck pain and weakness in his extremities. Following immobilization, which of the following steps should be taken prior to transport?

1. His helmet should be removed.
2. His helmet and shoulder pads should be removed.
3. His face mask should be removed.
4. All equipment should be removed.
5. No equipment should be removed.

Answer 22

PREFERRED RESPONSE: 3

DISCUSSION: Prior to transport, the face mask should be removed so that the airway can be easily accessible. If serious injury is suspected, the helmet and shoulder pads should be left in place until the patient is assessed at the hospital and radiographs are obtained. Leaving the helmet and shoulder pads in place helps to keep the spine in the most neutral alignment. Removal of the helmet will result in extension of the neck, whereas removal of the shoulder pads will most likely result in flexion of the neck.

Question 23

23: Figure 7 shows the radiograph of a 56-year-old man who has neck pain after a rollover accident on his lawnmower. The injury appears to be isolated, and he is neurologically intact. Management of the fracture should consist of

Figure 7

1. posterior C1-2 fusion.
2. anterior C2-3 fusion.
3. Gardner-Wells traction for 6 weeks, followed by 6 weeks of halo vest immobilization.
4. halo vest immobilization.
5. a hard collar.

Answer 23

PREFERRED RESPONSE: 4

DISCUSSION: The radiograph shows a type IIa hangman’s fracture, and the classic treatment is halo vest immobilization. Traction should be avoided in type IIa injuries because of the risk of overdistraction. A lesser form of immobilization such as a hard collar or a Minerva jacket can be used for nondisplaced (type I) fractures. Surgery generally is reserved for type III fractures (includes C2-3 facet dislocation), or extenuating circumstances such as multiple trauma or other fractures of the cervical spine that require surgical stabilization.

Question 24

24: Degenerative spondylolisthesis of the cervical spine is most commonly seen at which of the following levels?

1. C1-2
2. C3-4
3. C5-6
4. C6-7
5. C7-T1

Answer 24

PREFERRED RESPONSE: 2

DISCUSSION: Degenerative spondylolisthesis of the cervical spine is seen almost exclusively at C3-4 and C4-5; this is in contrast to degenerative changes, which are most commonly seen at C5-6 and C6-7.

Question 25

25: When treating thoracic disk herniations, which of the following surgical approaches has the highest reported rate of neurologic complications?

1. Video-assisted thoracoscopic approach (VATS)
2. Posterior
3. Posterior-lateral
4. Transthoracic
5. Transpedicular

Answer 25

PREFERRED RESPONSE: 2

DISCUSSION: Numerous surgical approaches have been used for thoracic diskectomy, including the most recent VATS. One of the first approaches described, posterior laminectomy, involves manipulation of the spinal cord, which the other approaches avoid. The posterior approach had dismal results, including further neurologic deterioration and even paralysis.

Question 26

26: When harvesting iliac crest bone graft during a posterior spinal decompression and fusion, injury to what structure can result in painful neuromas or numbness over the skin of the buttocks?

1. Ilioinguinal nerve
2. Superior gluteal nerve
3. Superior cluneal nerves
4. Iliohypogastric nerves
5. Lateral femoral cutaneous nerve

Answer 26

PREFERRED RESPONSE: 3

DISCUSSION: The superior cluneal nerves (L1, L2, and L3) are most at risk when harvesting iliac crest bone graft during a posterior decompression and fusion. These nerves pierce the lumbodorsal fascia and cross the posterior iliac crest, beginning 8 cm lateral to the posterior superior iliac spine. The ilioinguinal nerve is more at risk during exposure of the anterior ilium during retraction of the iliacus and abdominal wall muscles. Iliohypogastric nerve injury may arise in a manner similar to that of ilioinguinal neuralgia. The lateral femoral cutaneous nerve lies in close proximity to the anterior superior iliac spine and is also at risk with anterior iliac crest bone graft harvesting. The superior gluteal nerve courses through the sciatic notch and supplies motor branches to the gluteus medius, minimus, and tensor fascia lata muscles. Injury results in hip abduction weakness.

Question 27

27: A 42-year-old man sustained a burst fracture at L2 in a motor vehicle accident. Examination reveals that he is neurologically intact. Figure 8 shows a cross-sectional CT scan through the fracture. If the fracture is managed nonsurgically for the next 2 years, the retained fragments can be expected to

Figure 8

1. remain essentially unchanged in size.
2. result in neurologic deterioration.
3. gradually resorb and widen the spinal canal.
4. potentially migrate within the spinal canal.
5. increase the risk of further injury to the adjacent dural sac.

Answer 27

PREFERRED RESPONSE: 3

DISCUSSION: Numerous articles have reported that both surgical and nonsurgical management of burst fractures are associated with resolution of impingement at long-term follow-up. If the patient is neurologically intact and appropriately treated at the time of injury, neurologic deterioration is not expected nor is there a risk of injury to the dural sac. The retained fragments can be expected to gradually resorb and widen the spinal canal.

Question 28

28: A 50-year-old man reports the onset of back pain and incapacitating pain radiating down his left leg posterolaterally and into the first dorsal web space of his foot 1 day after doing some yard work. He denies any history of trauma. Examination reveals ipsilateral extensor hallucis longus weakness. MRI scans are shown in Figures 9A through 9C. What nerve root is affected?

Figure 9

1. Left L4
2. Right L4
3. Left L5
4. Right L5
5. Left S1

Answer 28

PREFERRED RESPONSE: 3

DISCUSSION: The MRI scans clearly show an extruded L4-5 disk that is affecting the L5 root on the left side. In addition, the L5 root has a cutaneous distribution in the first dorsal web space. S1 affects the lateral foot, and L4 affects the medial calf.

Question 29

29: What region of the spine is most susceptible to changes in the vascular supply to the spinal cord during an anterior approach?

1. C7-T1
2. T1-T3
3. T4-T7
4. T8-T12
5. L1-L3

Answer 29

PREFERRED RESPONSE: 4

DISCUSSION: The thoracic spinal cord is characterized by a variable and, at times, complicated blood supply. The artery of Adamkiewicz, also known as the great anterior medullary artery, most typically arises off the left side of the aorta between T8 and T12. It represents the sole medullary blood supply to the thoracic spine. When this artery is divided or injured, the blood supply to the thoracic cord may be interrupted. It is important to avoid electocautery of blood vessels within or near the thoracic foramen because this is a site of important, albeit limited, collateral circulation.

Question 30

30: What is the most common presenting sign or symptom in an adult with lumbar pyogenic infection?

1. Fever
2. Night sweats
3. Unexplained weight loss
4. Foot drop
5. Back pain

Answer 30

PREFERRED RESPONSE: 5

DISCUSSION: Pain is very common but is often nonspecific; therefore, the diagnosis of spinal infection is often delayed. Fever and sepsis can occur but are not common. Neurologic manifestations also can occur but are absent in most patients. In findings reported by Carragee, the urinary tract is a common source for hematogenous spinal infection, but the source was found in only 27% of 111 patients. Direct inoculation during spinal surgery is uncommon.

Question 31

31: The natural history of cervical spondylotic myelopathy is best described as

1. slow, steady deterioration.
2. rapid deterioration.
3. stable over time.
4. stable for long periods with stepwise deterioration.
5. substantial improvement after an initial episode of severe symptoms.

Answer 31

PREFERRED RESPONSE: 4

DISCUSSION: The natural history of cervical myelopathy has been described by Lees and Turner as exacerbations of symptoms followed by often long periods of static or deteriorating function (or very rarely improvement). This stepwise pattern of decreasing function has been corroborated by Clarke and Robinson. These authors described long periods of stable neurologic function, sometimes lasting for years, in about 75% of their patients. In the majority of the patients, however, the condition deteriorated between quiescent streaks. About 20% of their patients showed a slow, steady progression of symptoms and signs without a stable period, and 5% had rapid deterioration of neurologic function.

Question 32

32: A 35-year-old woman undergoes an L4-5 anterior fusion via a left retroperitoneal approach. Postoperative examination reveals that her right foot is cool and pale. Her neurologic examination is normal, and her pedal pulses are asymmetric. What is the most likely reason for the right foot finding?

1. Injury to the lumbar sympathetic chain
2. Injury to the parasympathetic nerve
3. Immune response to the allograft bone
4. Occlusion of the left iliac vein
5. Prolonged retraction of the left iliac artery

Answer 32

PREFERRED RESPONSE: 1

DISCUSSION: The lower extremity symptoms are consistent with a sympathectomy that is the result of an injury to the sympathetic chain, ipsilateral to the approach along the anterior border of the lumbar spine. This results in a warm, red foot, which creates the appearance that the normal cooler foot may have compromised circulation. The latter generally attracts greater attention because of the risks associated with limb ischemia. The condition usually is self-limited and does not require any specific treatment.

Question 33

33: A 30-year-old man has had a 3-day history of severe, incapacitating low back pain without radiation. He reports improvement with rest. He denies any history of trauma, has no constitutional symptoms, and his neurologic examination is normal. What is the best course of action?

1. Facet injections
2. Epidural steroid injection
3. MRI of the lumbar spine
4. Bed rest for 2 weeks with continued restrictions
5. Early return to activities as his symptoms allow

Answer 33

PREFERRED RESPONSE: 5

DISCUSSION: There are no red flags in the history or examination to warrant MRI. Limited bed rest (less than 3 days) has been shown to be more beneficial to early recovery compared with prolonged bed rest (more than 7 days). No data support the use of epidural or facet steroid injections for acute low back pain.

Question 34

34: Which of the following patient factors is associated with recurrent radicular pain following lumbar diskectomy for sciatica?
1. Initial symptoms of more than 3 months’ duration
2. Large annular defects seen intraoperatively
3. Large sequestered disk herniations
4. Initial treatment with lumbar epidural steroid injections prior to diskectomy
5. Preoperative reproduction of sciatica with straight leg raising (SLR)

Answer 34

PREFERRED RESPONSE: 2

DISCUSSION: A large annular defect at the site of a lumbar disk herniation is associated with persistent radicular pain postoperatively. Large sequestered herniations and a positive SLR preoperatively correlate with good outcomes after diskectomy. Neither symptoms of more than 3 months’ duration nor preoperative epidural steroid injections correlate with postoperative results after diskectomy.

Question 35

35: A 65-year-old woman has substantial neck pain after falling and striking her head. A radiograph and sagittal CT scan are shown in Figures 10A and 10B. What is the most likely diagnosis?

Figure 10

1. Degenerative spondylolisthesis
2. Superior facet fracture
3. Inferior facet fracture
4. Perched unilateral facet dislocation
5. Bilateral facet dislocation

Answer 35

PREFERRED RESPONSE: 4

DISCUSSION: The radiograph shows a displacement of C5 on C6 of approximately 25%. The CT scan shows a perched facet at C5-6. There is no evidence of a facet fracture. A bilateral facet dislocation would show a displacement of more than 50%.

Question 36

36: Immediately after undergoing lumbar instrumentation, a patient reports severe right leg pain and has 4+/5 weakness. Figure 11 shows an axial CT scan of L5. Exploratory surgery will most likely reveal

Figure 11

1. transection of the L5 root.
2. displacement of the L5 root.
3. partial laceration of the L5 root.
4. segmental artery injury.
5. spinal fluid leakage.

Answer 36

PREFERRED RESPONSE: 2

DISCUSSION: The most common finding at exploration of an inappropriately placed pedicle screw is displacement of the nerve. Pedicle breach is common, ranging from 2% to 20%, but most are asymptomatic. All of the choices are possible, but in a large series conducted by Lonstein and associates, the authors reported that displacement of the root, most often medial, was the most common finding. Laceration, contusion, or transfixion usually was not seen. Spinal fluid leakage occurs less frequently and is not expected in the minimal breach illustrated.

Question 37

Return to question
37: A 17-year-old boy who plays high school football is seen for follow-up after sustaining an injury 3 days ago. He reports that he tackled a player, felt numbness throughout his body, and could not move for approximately 15 seconds. A spinal cord injury protocol was initiated on the field. Evaluation in the emergency department revealed a normal neurologic examination and full painless neck motion. He states that he has no history of a similar injury. An MRI scan of the cervical spine is normal. During counseling, the patient and his family should be informed that he has sustained

1. a spinal cord injury and he cannot participate in contact sports.
2. no obvious injury and can return to all sports without risk of recurrence.
3. no obvious injury, but he is at a high risk for breaking his neck in athletic competition.
4. transient quadriplegia only, but this places him at greater risk for future spinal cord injury and he should refrain from all contact sports.
5. transient quadriplegia and that there is no evidence of increased risk of permanent spinal cord injury should he return to contact sports.

Answer 37

PREFERRED RESPONSE: 5

DISCUSSION: The long-term effect of transient quadriplegia is unknown. Based on a history of one brief episode of transient quadriplegia and normal examination and MRI findings, the risk of permanent spinal cord injury with a return to play is low. There is a risk of recurrent episodes of transient quadriplegia after the initial episode.

Question 38

38: Figures 12A through 12C show the MRI scans of a 30-year-old woman who weighs 290 lb and has low back and left leg pain. She also reports frequent urinary dribbling, which her gynecologist has advised her may be related to obesity. Examination will most likely reveal

Figure 12

1. ipsilateral weakness of the tibialis anterior.
2. ipsilateral weakness of the peroneus longus and brevis.
3. ipsilateral weakness of the extensor hallucis longus.
4. a positive Beevor sign.
5. a positive ipsilateral Gaenslen sign.

Answer 38

PREFERRED RESPONSE: 1

DISCUSSION: The patient will most likely exhibit ipsilateral weakness of the tibialis anterior. Gaenslen sign is designed to detect sacroiliac inflammation as a source of low back pain. Beevor sign tests the innervation of the rectus abdominus and paraspinal musculature (L1 innervation). The extensor hallucis longus is predominantly innervated by L5. The peroneals are predominantly innervated by S1.

Question 39

39: Which of the following statements regarding conus medullaris syndrome is most accurate?

1. Conus medullaris syndrome most commonly accompanies injuries at the T12-L2 region.
2. Conus medullaris injury is a lower motor neuron injury, resulting in an excellent prognosis for recovery of bowel and bladder dysfunction.
3. The conus medullaris houses the motor cell bodies for the lumbar roots.
4. Lower extremity weakness is a common sign of conus medullaris syndrome.
5. Autonomic dysreflexia is common.

Answer 39

PREFERRED RESPONSE: 1

DISCUSSION: Conus medullaris syndrome most frequently occurs as a result of trauma or with a disk herniation at L1, resulting in a lower motor neuron syndrome but with a poor prognosis for recovery of bowel and bladder dysfunction. The conus region, as the termination of the spinal cord, contains the motor cell bodies of the sacral roots. The syndrome is usually a sacral level neural injury; therefore, lower extremity weakness is uncommon.

Question 40

40: Which of the following factors has the greatest effect on the pull-out strength of a lumbar pedicle screw?

1. Depth of vertebral body penetration
2. Percentage of pedicle filled by the screw
3. Bone mineral density
4. Tapping of the pedicle
5. Screw diameter

Answer 40

PREFERRED RESPONSE: 3

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.

Question 41

41: An inverted radial reflex is associated with

1. spinal cord compression with myelopathy.
2. acute cervical radiculopathy.
3. chronic cervical radiculopathy.
4. Parsonage-Turner syndrome.
5. peripheral neuropathy.

Answer 41

PREFERRED RESPONSE: 1

DISCUSSION: An inverted radial reflex is a hypoactive brachioradialis reflex in combination with involuntary finger flexion. It is a spinal cord “release” sign and is associated with upper motor neuron pathology as seen in cervical stenosis with myelopathy. Radiculopathy is characterized by a diminished reflex but no finger flexion. Peripheral neuropathy is not associated with any reflex change. Parsonage-Turner syndrome is an idiopathic brachial neuritis.

Question 42

42: Figures 13A and 13B show the radiograph and CT scan of a 48-year-old man who has diffuse spinal pain. What is the most likely diagnosis?

Figure 13

1. Rheumatoid arthritis
2. Diffuse idiopathic skeletal hyperostosis (DISH)
3. Normal findings
4. Ankylosing spondylitis
5. Osteopetrosis

Answer 42

PREFERRED RESPONSE: 4

DISCUSSION: The studies show marginal syndesmophyte formation characteristic of ankylosing spondylitis. These patients typically have diffuse ossification of the disk space without large osteophyte formation. DISH typically presents with large osteophytes, referred to as nonmarginal syndesmophytes. In this patient, the zygoapophyseal joints are fused rather than degenerative as would be seen in rheumatoid arthritis, and the costovertebral joints are also fused. Osteopetrosis does not normally ankylose the disk space.

Question 43

43: The cervical disk herniation shown in the MRI scans in Figures 14A and 14B will most likely create which of the following constellations of symptoms?

Figure 14

1. Right thumb and index finger numbness and triceps weakness
2. Right thumb and index finger numbness and wrist extensor weakness
3. Right wrist extensor weakness and diminished triceps reflex
4. Right middle finger numbness and diminished brachioradialis reflex
5. Right little and ring finger numbness and diminished brachioradialis reflex

Answer 43

PREFERRED RESPONSE: 2

DISCUSSION: The MRI scans reveal a right-sided C5-6 herniated nucleus pulposus. A disk herniation in this region encroaches on the C6 root and is accompanied by a sensory change along the thumb and index finger, alterations in the brachioradialis reflex, and possible wrist extension weakness. Although the nerve root associated with the vertebral body passes above the pedicles such that the C6 root passes above the C6 pedicle, it is still the C6 root that is encroached on because the herniation affects the exiting root rather than the traversing root as seen in the lumbar spine.

Question 44

44: A 21-year-old man has had posterior neck discomfort for the past 6 months. A whole-body bone scan and a cervical single-photon emission CT reveal increased activity at the C7 spinous process. MRI reveals multifocal involvement of the spinous process lamina and facet of C7. A CT-directed needle biopsy reveals osteoblastoma. What is the best course of action?

1. Observation
2. Radiation therapy
3. Curettage
4. En bloc excision with stabilization
5. En bloc excision followed by radiation therapy

Answer 44

PREFERRED RESPONSE: 4

DISCUSSION: En bloc excision is the recommended treatment of osteoblastoma. Treatment should consist of en bloc removal of the lamina, facet, and spinous process. Facet removal would necessitate fusion. Radiation therapy is not recommended. Intralesional curettage has a high rate of recurrence.

Question 45

45: What is the most likely consequence of a vertebral compression fracture associated with osteoporosis?

1. The fractured vertebral body gradually becomes more stiff than before the fracture.
2. Scoliosis develops.
3. There is an increased risk of more vertebral fractures.
4. Overall sagittal alignment remains stable because the adjacent segments of the spine are able to compensate.
5. The extensor musculature will often hypertrophy in an attempt to stabilize the painful fracture.

Answer 45

PREFERRED RESPONSE: 3

DISCUSSION: After an osteoporotic vertebral compression fracture, the risk of subsequent fractures at adjacent levels increases. This is thought to be the result of a shifting of the sagittal alignment more anteriorly, putting more stress on the osteopenic vertebral bodies and their anterior cortices. Pain generally resolves with rest, but this may take weeks or months. It has been demonstrated experimentally that osteoporotic vertebral bodies are actually less stiff and weaker after a compression fracture; therefore, deformity predisposes to further deformity. The extensor musculature often fatigues over time and usually does not hypertrophy. Frontal plane deformity is a rare development.

Question 46

46: What is the most appropriate treatment for a chordoma involving the sacrum?

1. Chemotherapy
2. External beam radiation therapy
3. En bloc surgical resection with negative margins
4. Intralesional resection followed by radiation therapy
5. Intralesional resection followed by chemotherapy

Answer 46

PREFERRED RESPONSE: 3

DISCUSSION: Chordomas are very resistant to radiotherapy and chemotherapy; therefore, en bloc resection with a negative margin is the preferred treatment. Lesions at or below S3 can be resected without compromising pelvis stability, and continence usually is maintained. The mean survival rate for patients with sacral chordomas is approximately 7 years. Patients with chordoma of the mobile (cervical, thoracic, or lumbar) spine have a mean survival rate of approximately 5 years. This difference is most likely the result of an earlier diagnosis.

Question 47

47: Which of the following is NOT considered a risk factor for nonunion of a type II odontoid fracture?

1. More than 6 mm of initial displacement
2. Patient age older than 60 years
3. Smoking
4. Inability to achieve reduction
5. Obesity

Answer 47

PREFERRED RESPONSE: 5

DISCUSSION: Although obesity can make brace or halo wear difficult, it has not been associated with an increased risk for nonunion.

Question 48

48: A 27-year-old woman has a bilateral C5-C6 facet dislocation and quadriparesis after being involved in a motor vehicle accident. Initial management consisted of reduction with traction, but she remains a Frankel A quadriplegic. To facilitate rehabilitation, surgical stabilization and fusion is planned. From a biomechanical point of view, which of the following techniques is the LEAST stable method of fixation?
1. Anterior cervical plating with interbody bone graft
2. Posterior cervical plating with lateral mass screw fixation
3. Posterior sublaminar wiring
4. Simple posterior interspinous wiring
5. Bohlman interspinous wiring

Answer 48

PREFERRED RESPONSE: 1

DISCUSSION: In two different biomechanical studies performed in both bovine and human cadaver spines, all posterior techniques of stabilization were found to be superior to anterior plating in flexion-distraction injuries of the cervical spine. These injuries usually have an intact anterior longitudinal ligament that allows posterior fixation to function as a tension band. Anterior plating with grafting destroys this last remaining stabilizing structure and does not allow for a tension band effect because all of the posterior stabilizing structures have been destroyed with the injury. In clinical practice, however, anterior plating can be effective in the treatment of this injury with appropriate postoperative orthotic management.