2009 Radiology Exam - CT/MRI Case 1

Signalment: 5 year old male neutered Greyhound

History:

• extremely depressed, blind, pyrexic (39.6C)
• no pupillary light response bilaterally, no menace response bilaterally, no gag reflex, atrophy affecting masticatory muscles

See images below. Click to enlarge.

Observations:

• study comprises transverse T1-weighted images pre- and post-gadolinium, T2-weighted images and FLAIR images, and sagittal T2-weighted image
• diffuse thickening of the pachymeninges over the entire cerebrum, most marked on the left
• lesion is hyperintense in T2-weighted images; marked enhancement after gadolinium administration
• herniation of the cerebellum
• signal intensity of muscles appears normal despite history of atrophy

Synthesis:

• diffuse meningeal lesion suggests meningitis as the principal differential diagnosis; diffuse meningeal neoplasia is less likely
• cerebellar herniation is evidence of increased intracranial pressure
• MR lesions are compatible with signs

Management: CSF analysis is indicated as a means of confirming diagnosis; however, increased intracranial pressure is a contraindication to puncture of cerebellomedullary cistern; a lumbar puncture should be considered instead