History: 12 month history of progressive hind limb ataxia.
Imaging Studies: 3 lateral views and 3 VD views of a thoracolumbar myelogram were provided to the candidate.
Lateral views: Attenuation of both contrast columns over vertebral body T12. Bulbous widening of dorsal contrast column dorsal to caudal T12 – T13 vertebral bodies. (Mild dorsal deviation of ventral contrast column over several intervertebral disc spaces).
Ventrodorsal views: Bulbous widening (“teardrop shape”) of left contrast column over caudal half of T12 vertebra; attenuation of contrast columns cranially. Spinal cord compressed and displaced to the right.
Subarachnoid cyst/diverticulum at T12 (left-sided and dorsal) resulting in spinal cord compression; (incidental multifocal disc bulges).
Surgery to decompress spinal cord (Candidates did not lose points if additional imaging such as CT was recommended prior to surgery, but ultimate recommendation should have been surgery).
Inability to determine location of lesion (intramedullary vs. intradural-extramedullary vs. extradural).
Inability to recognize that lesion represents dilation of subarachnoid space rather than an intradural-extramedullary mass.
Failure to recommend surgical decompression due to compressive nature of the lesion.