case_images: PMC5443404_01
case_images: Stress radiography of the cervical region with ventral flexion. The space between
  the dorsal lamina of the C1 and the dorsal spinous process of the C2 was 3.7mm
  (arrow). Ventral subluxation of C2 (arrowhead).
case_images: OpenVetJ-7-65-g001.jpg
case_images: PMC5443404_01_OpenVetJ-7-65-g001.jpg
case_images: F1
case_images: Stress radiography of the cervical region with ventral flexion revealed that the distance between the caudal margin of dorsal arch of C1 and the cranial margin of spinal process of C2 was 3.7 mm (Fig. 1) (normal range <4 mm).
case_images: Sagittal MRI image (T2-weighted) of the cranial cervical spine. Severe compression
  of spinal cord at C1 to C2 level (arrow) and indentation of caudal cerebellum
  (arrowhead).
case_images: OpenVetJ-7-65-g002.jpg
case_images: PMC5443404_01_OpenVetJ-7-65-g002.jpg
case_images: F2
case_images: Sagittal MRI of the cranial cervical spine revealed severe compression of the spinal cord at C1 to C2 level and indentation of the caudal cerebellum (Fig. 2).
case_images: Sagittal CT image of the cervical region. Occipital bony defect (arrow).
  Cranial-most aspect of dorsal arch of the C1 was inserted to intracranial region
  from foramen magnum (arrowhead).
case_images: OpenVetJ-7-65-g003.jpg
case_images: PMC5443404_01_OpenVetJ-7-65-g003.jpg
case_images: F3
case_images: Sagittal computed tomography (CT) revealed an occipital bony defect, and the cranial-most aspect of the dorsal arch of C1 was inserted into the intracranial region from the foramen magnum (Fig. 3).
case_images: The dorsal atlanto-occipital membrane were incised and expansile duroplasty by
  using artificial dura mater.
case_images: OpenVetJ-7-65-g004.jpg
case_images: PMC5443404_01_OpenVetJ-7-65-g004.jpg
case_images: F4
case_images: The dorsal atlanto-occipital membrane was incised and expansile duroplasty was performed by using artificial dura mater (Gore-Tex; Japan Gore, Tokyo, Japan) (Fig. 4).
case_images: Two threaded-pins are placed across each of the ventral articular facets between
  the axis and atlas (arrows). Implanted pins are fixed by using bone cement
  (arrowhead).
case_images: OpenVetJ-7-65-g005.jpg
case_images: PMC5443404_01_OpenVetJ-7-65-g005.jpg
case_images: F5
case_images: Finally, implanted pins were fixed by using bone cement (Osteobond; Zimmer, Tokyo, Japan) (Fig. 5).
case_images: 134 days after the first consultation, ventro-dorsal radiograph of the cervical
  region revealed no loosening of thread pins and bone cement (arrow).
case_images: OpenVetJ-7-65-g006.jpg
case_images: PMC5443404_01_OpenVetJ-7-65-g006.jpg
case_images: F6
case_images: Ventro-dorsal radiograph of the cervical region in 134 days after the first consultation revealed no loosening of thread pins and bone cement (Fig. 6).