Article Figures & Data
Figures
- Fig 1.
Illustration of the safe triangle for needle placement during the subpedicular TFESI approach. The safe triangle sides are defined in the anteroposterior projection as the inferior edge of the corresponding pedicle, the superior edge of the nerve, and the lateral margin of the neural foramen. Copyright 2016 Lydia Gregg.
- Fig 2.
Depiction of the arterial anatomy of the NF showing the measurements used in this study. A, Illustration of ISA anatomy including the principal supply to the thoracolumbar spinal cord from an anterior oblique view. The ISA originates from the aorta and divides into medial, dorsal, and lateral branches. A complete spinal branch is shown entering the NF at the left L1 vertebral level and providing a retrocorporeal artery, a prelaminar artery, and a radicular artery; the latter crosses the dura to continue as an ARMA and anastomoses with the anterior spinal artery. The shaded regions and quadrant grids depicted at the L1 NF clarify the working projection and measurement definitions depicted in B and C. B, FPCA, left L1 ISA injection, sagittal reconstruction (thickness = 0.2 mm) demonstrates the working projection used to take measurements. The image documents the location of an ARMA within the NF (red arrow) in a 59-year-old women investigated for acute onset paraplegia. Spinal angiography and FPCA revealed severe stenosis of the left proximal L1 ISA, resulting in an episode of spinal cord ischemia. Measurements were performed with the anterior surface to the left side. C, Measurements included the NF height (B to B′), which was defined as the long axis from the posterior edge of the vertebral pedicle to the superior edge of the pedicle below. The NF was divided into quadrants by measuring the width (C to C′) at the midpoint of the height. The ARMA location was evaluated by measuring the distance from the center of the artery to the superior (D) and anterior (E) walls of the NF and the vertical (F) and horizontal (G) distances to the quadrant divisions. ASQ indicates anterosuperior quadrant; PSQ, posterosuperior quadrant; PIQ, posteroinferior quadrant; AIQ, anteroinferior quadrant. Copyright 2016 Lydia Gregg.
- Fig 3.
Scatterplots visualizing the location within the NF of arteries that provide a thoracolumbar ARMA. A, Raw measurements in millimeters. Zero values for the x- and y-axes represent the approximate center of the neural foramina in 78 patients. B, Normalized measurements, shown as a percentage of the height of the NF (NF height = 100%) to compare the relative location of the artery within the foramina of different sizes (Measurements / NF Height × 100 = Percentage NF Height) in 78 patients.
- Fig 4.
FPCA, left L2 ISA injection. This case illustrates the intraforaminal course of an ARMA in a 42-year-old woman investigated for progressive myelopathy. Spinal angiography and FPCA findings were unremarkable. A, Sagittal MIP reconstruction (thickness = 0.2 mm) documents the location of an ARMA (white arrow) within the NF. The retrocorporeal artery (gray arrow), L2 (white asterisk) and L3 pedicles (black asterisk), and portions of the internal vertebral venous plexus (black arrowheads) are also visible. B, The same sagittal MIP reconstruction with graphics indicates recorded measurements, including the NF height (B to B′), NF width (C to C′), distance of the ARMA to the inferior border of the L2 pedicle (D), the posterior wall of the L2 vertebral body (E), and the vertical (F) and horizontal (G) distances to the quadrant divisions. C, Coronal-oblique MIP reconstruction (thickness = 1.7 mm) documents the same ARMA (white arrows) within the NF and its anastomosis with the anterior spinal artery (black arrows). The L2 (white asterisk) and L3 pedicles (black asterisk) and a portion of the internal vertebral venous plexus (black arrowhead) are also visible. D, Axial MIP reconstruction (thickness = 9.3 mm) documents the same L2 ARMA (white arrows), the anterior spinal artery (black arrow), portions of the internal vertebral venous plexus (black arrowheads), and the dorsal branch of the L2 ISA (white arrowheads).
- Fig 5.
FPCA, left L1 ISA injection, in a 77-year-old man with severe spinal canal stenosis investigated for myelopathy. Spinal angiography and FPCA findings were normal. This case illustrates how NF width estimates were derived from abnormal foramina. A, Sagittal MIP reconstruction (thickness = 0.2 mm) documents the location of a branch providing an ARMA (white arrow) within the NF. An osteophyte (gray asterisk) on the L1 vertebral body distorts the width of the NF between the L1 (white asterisk) and L2 pedicles (black asterisk), while the NF height appears unaffected. B, The same sagittal MIP reconstruction with graphics indicating recorded measurements includes the following: the NF height (B to B′), estimated NF width (C to C′), distance of the artery to the inferior border of the L1 pedicle (D), the estimated posterior wall of the L1 vertebral body (E), and the vertical (F) and horizontal (G) distances to the quadrant divisions. C, Coronal-oblique MIP reconstruction (thickness = 1.8 mm) documents the same branch providing an ARMA (white arrows) within the NF and its anastomoses with the anterior spinal artery (black arrow). The L1 (white asterisk) pedicle and a dilated anterior median spinal vein (black arrowheads) are also visible. D, Axial MIP reconstruction (thickness = 9.0 mm) documents the same branch providing an ARMA (white arrows) and dorsal branches of the L1 ISA (white arrowheads).
Tables
- Table 1:
Vertebral level and side of included FPCA acquisitions documenting a radicular branch and the ARMA course within the NF
Vertebral Level L Side (No.) L Side R Side (No.) R Side L and R Sides, Total (No.) L and R Sides, Total T2 1 1.3% – – 1 1.3% T3 – – – – – – T4 – – 1 1.3% 1 1.3% T5 1 1.3% 1 1.3% 2 2.6% T6 – – – – – – T7 4 5.1% – – 4 5.1% T8 5 6.4% 3 3.8% 8 10.3% T9 10 12.8% 5 6.4% 15 19.2% T10 2 2.6% 5 6.4% 7 9.0% T11 6 7.7% 1 1.3% 7 9.0% T12 7 9.0% 3 3.8% 10 12.8% L1 14 17.9% 5 6.4% 19 24.4% L2 2 2.6% 1 1.3% 3 3.8% L3 1 1.3% – – 1 1.3% Total 53 67.9% 25 32.1% 78 100.0% Note:— L indicates left; R, right.
Vertebral Level No. Measurement Mean Range SD Thoracic ARMAs 55 NF height 16.2 9.7–21.2 2.4 NF width 8.0 5.4–12.7 1.8 ARMA diameter 1.0 0.6–1.4 0.2 Lumbar ARMAs 23 NF height 20.6 14.8–25 2.3 NF width 10.3 8.1–13.6 1.4 ARMA diameter 1.1 0.7–1.7 0.3 All ARMAs 78 NF height 17.5 9.7–25 3.1 NF width 8.7 5.4–13.6 2.0 ARMA diameter 1.0 0.6–1.7 0.2 ↵a Data are in millimeters.
