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AP of Spine

- See:
      - Pillar View

- Discussion:
    - this view demonstrates C3 thru C7 vertebral bodies, spinous processes and lateral masses;

- Evaluates:
    - lateral mass fractures
    - sagittal plane frxs (also called vertical compression frx) may be visualized on the anteroposterior view;
    - this view may show altered separation between spinous process tips caused by flexion-induced injuries;
    - signs of direct injury:
         - malalignment of the spinous processes on the anterior view;
         - lateral tilting of the vertebral body on the anterior view;
         - because dislocation/sublux may be subtle on plain series any rotation of spinous processes on AP view should alert M.D. to exam oblique views where fascet relationships are best seen;
    - saggital plane frx is verticle compression frx, but more specifically it is sagittally and not coronally oriented;
         - this frx often occurs in combo with other fractures in the same or adjacent vertebrae, for example, laminar fracture, facet
              dislocation, or teardrop fracture dislocation, extensive ligamentous damage, and paralysis;
         - key feature is a midsagittal fracture plane extending from one vertebral end plate to other, which is best seen on AP view;
         - lateral radiograph may show no abnormality at all;

- Radiographic Anatomy:
    - 1st & 2nd vertebrae are obscurred in this projection by mandible and basiocciput, whereas lower cervical vertebrae & cervico-throracic 
           junction are well seen;
    - lateral masses appear as bilateral smooth undualing margins, & spinous processes are in the midline;
    - interspinous distances should be symmetric throughout;
         - interspinous distance 1.5 times distance above or below level may indicate a dislocation or subluxation;
         - unilateral facet dislocation may result in lateral rotation of one spinous process with respect to the others;

- Radiographic Technique:
    - patient is erect or supine
    - central beam is directed toward the C4 vertebra (at the point of Adam's apple) w/ 15-20 deg cephalic tilt;
    - mandible is held open (open mouth anteroposterior) to see C-1 & C-2;
    - in comatose pt, place gauze roll between teeth;
         - shooting one view w/ beam slightly angulated cephalad and another w/ it slightly caudad increased likelihood of visualizing C-1
              & C-2 well, especially in pt w/ limited mandibular excursion

Comparison of computerized tomography parameters of the cervical spine in normal control subjects and spinal cord-injured patients.