Case of the Month, November 2018

Submitted by  Joseph Kallini, MD and Thomas Learch, MD

39-year-old man with complete loss of lower extremity motor function and sensation after falling from a height.

History of Present Illness 

A 39-year-old man presents to the Emergency Department with complete loss of motor function and sensation of his lower extremities after falling 15 feet. The patient and his friend were sitting on a glass skylight on a rooftop. The rooftop shattered, and both individuals fell through it. The patient landed rear-end-first onto a staircase. Immediately afterwards, he was unable to feel or move his lower extremities.

Allergies and Relevant Past Medical and Surgical Histories
  • No known drug allergies
  • Ulcerative colitis, status post total colectomy with J-pouch formation
Initial Physical Exam
  • BP: 119/63
  • RR: 16
  • SpO2: 100% on room air
  • Constitutional: Lethargic.
  • Musculoskeletal: Focal tenderness to palpation of the mid lower back.
  • Neurological: Complete loss of sensation to pain and deep touch from the lower abdomen to both lower extremities. 0/5 strength in both lower extremities. Absent anal reflex.
Relevant Laboratory Analysis
  • White blood cell count: 11,320 /UL
  • Creatinine: 1.6 mg/dL
Imaging

CT thoracolumbar spine

Sagittal CT of the thoracolumbar spine (Figure 1a) shows complete disruption of the anterior and posterior columns with at least grade 2 anterior translation of T11 over T12. There is an anterior superior endplate compression fracture of the T11 vertebral body. Axial CT through the level of T11-T12 (Figure 1b) shows complete obliteration of the spinal canal at this level.

Figure 1a (below). Sagittal CT of the thoracolumbar spine (1a) shows complete disruption of the anterior and posterior columns with at least grade 2 anterior translation of T11 over T12. There is an anterior superior endplate compression fracture of the T11 vertebral body. Axial CT through the level of T11-T12 (1b) shows complete obliteration of the spinal canal at this level.

Figure 1b (below). Sagittal CT of the thoracolumbar spine (1a) shows complete disruption of the anterior and posterior columns with at least grade 2 anterior translation of T11 over T12. There is an anterior superior endplate compression fracture of the T11 vertebral body. Axial CT through the level of T11-T12 (1b) shows complete obliteration of the spinal canal at this level. 

MR thoracolumbar spine

Sagittal short tau inversion recovery (STIR) imaging of the thoracolumbar spine (Figure 2a) shows similar anterior translation of T11 over T12, disruption and edematous signal along the anterior longitudinal ligament, and disrupted posterior longitudinal ligament, all of which confirm anterior and posterior column compromise. The spinal canal is completely transected. Axial T2 section through the level of T11-T12 (Figure 2b) shows complete discontinuity of the spinal cord. 

Figure 2a (below). Sagittal short tau inversion recovery (STIR) imaging of the thoracolumbar spine (2a) shows similar anterior translation of T11 over T12, disruption and edematous signal along the anterior longitudinal ligament, and disrupted posterior longitudinal ligament, all of which confirm anterior and posterior column compromise. The spinal canal is completely transected. Axial T2 section through the level of T11-T12 (2b) shows complete discontinuity of the spinal cord.

Figure 2b (below). Sagittal short tau inversion recovery (STIR) imaging of the thoracolumbar spine (2a) shows similar anterior translation of T11 over T12, disruption and edematous signal along the anterior longitudinal ligament, and disrupted posterior longitudinal ligament, all of which confirm anterior and posterior column compromise. The spinal canal is completely transected. Axial T2 section through the level of T11-T12 (2b) shows complete discontinuity of the spinal cord.

Diagnosis

AOSpine Type C Injury: Complete displacement of the spinal column at the T11-T12 level with spinal cord transection.

Discussion

Numerous systems have been proposed to classify thoracolumbar injuries in order to provide spine surgeons from different institutions with consistency in diagnosis and management.(1) The AOSpine Thoracolumbar Spine Injury Classification system classifies spine injury into three main groups: type A—compression (subgroups A0 to A4); type B—tension band injury (subgroups B1 to B3); and Type-C—translation injuries (Figure 3). This system also includes the patient's neurologic status (N0 to N4 and Nx, unknown).(2)

Figure 3 (below). The AOSpine Thoracolumbar Classification System categorizes thoracolumbar spine injuries as Types A, B, and C.(3)

The AOSpine system recommends a three-step algorithm when evaluating thoracolumbar spine fractures.(3) The first step is to assess if there is spinal column displacement; these fall under Type C injuries. Type C injuries are segmental injuries with interruption of both the anterior and posterior spinal columns. The disruption of the anterior vertebral segment may be through the intervertebral disk or vertebral body. The disruption of the posterior elements may be through the spinous process, lamina, pars interarticularis, or posterior ligamentous complex (Figure 4).(2) The end result is translation of the spinal column, sometimes severe enough to result in cord transection.

Figure 4 (below). AOSpine Type C injury. Note the anterior translation of the involved vertebral bodies and disruption of both the anterior column (via the intervertebral disk) and posterior elements.(3)

If a translational injury is not identified, the next step is to determine if there is injury just of the posterior constraining elements – a Type B injury. In the case of the thoracolumbar spine, these are the facet joints and posterior ligamentous structures, which resist kyphotic forces. These structures compose the ‘tension band’ or the posterior ligamentous complex (PLC). Tension band injuries fall into the distraction category. Of note, the classic Chance Fracture – a horizontal fracture through the pedicles – is a Type B injury (namely B1).

If there is neither dislocation nor tension band injury, the third step is to determine if the vertebral body has been fractured, which is classified under Type A. Type A injuries are due to failure of the anterior elements under axial compression. These can be seen with both types B and C. Of note, a fracture of the posterior vertebral body wall, Type-A4, is a Burst Fracture.(2)

The last step is to determine the degree of neurological involvement. This is based on clinical exam and ranges from N0 to N4. N0 indicates neurological intactness. N4 indicates complete spinal cord injury.

In this case, there is at least a grade 2 anterior translation of T11 over T12 consistent with a Type C pattern. Associated vertebral body fractures should be coded separately (under the type-A classifications). The anterior T11 vertebral body was fractured, which is categorized as A1. The patient had complete spinal cord transection consistent with N4. The injury is thus classified as Type C, T11/T12 (T11: A1) N4.

Each thoracolumbar injury is amenable to different types of treatment. Type C injuries are highly unstable lesions because of the total ligamentous complex disruption. Surgical treatment with posterior long segment fusion is always indicated.(2) The patient in the described case underwent posterior spinous fusion of T9 to L2 (Figure 5). He did not recover sensory or motor function.

Figure 5 (below). Lateral radiograph of the thoracolumbar spine shows interval posterior fusion of T9 through L2 with realignment of the spinal columns at the T11-T12 level.

References

1)   Kepler CK, Vaccaro AR, Schroeder GD, Koerner JD, Vialle LR, Aarabi B, et al. The Thoracolumbar AOSpine Injury Score. Global spine journal. 2016;6(4):329-34.

2)   Reinhold M, Audigé L, Schnake KJ, Bellabarba C, Dai LY, Oner FC. AO spine injury classification system: a revision proposal for the thoracic and lumbar spine. European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society. 2013;22(10):2184-201.

3)   Vaccaro AR KF, Fehlings M, Shanmughanathan R. AOSurgical Reference 2014 [cited 2018 12/14/2018]. Available from: https://www2.aofoundation.org/.

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