1. Interactive Case Tutorial

2.  Review the history and signalment for the client  Evaluate the radiographs provided  Explore the interactive images and compare the answers given with your own interpretations. When you’ve clicked on the image, click the same spot again to make the label disappear.  Answer the questions regarding a diagnosis and recommendations  Review the radiologist’s findings

3.  Signalment: 2 year old, MI, Pekingese  History: Obtained from a puppy mill 3 weeks ago; has been ataxic and falling over since acquired; seems to be stronger  Neurologic exam: normal mentation and cranial nerves; ambulatory tetraparetic; decreased conscious proprioception in the thoracic limbs and normal in pelvic limbs; intact spinal reflexes  Study: lateral and VD views of cervical spine  Technique note: views were obtained without sedation

4. Wedging is positional artifact Dens is absent C2 is dorsally displaced relative to C1

5.  Provide a diagnosis based on your findings. Submit Atlantoaxial subluxation secondary to aplasia of the dens of C2 Feedback Continue

6.  Provide your recommendation for this client. Submit Surgical fusion/stabilization of the atlantoaxial subluxation to minimize the risk of future paralysis. This involves placing pins or screws to hold the vertebrae in appropriate alignment while it fuses together Feedback Continue

7.  The dens of C2 is not present  C2 is displaced dorsally relative to C1

8.  Patient returned for surgical stabilization of the atlantoaxial subluxation  Articular surfaces of C1 and C2 were scarified using a curette. Two screws and two pins were placed through the ventral aspect of C2 into C1. Bone allograft was packed between the C1-C2 joint space. Methyl-methacrylate was applied to the ventral aspect of the pins and screws.  Patient must have activity restricted for 4-8 weeks after which slow introduction of regular exercise regimen can occur