2010 Radiology Exam - CT/MRI Case 1

Signalment: 5-year female Springer spaniel

History:

Tetraparesis progressing to recumbency over 2 days
dog was stuporous with vertical nystagmus, absent gag reflex and drooling
no voluntary movement seen in the thoracic limbs; reduced voluntary movement in the pelvic limbs
reduced spinal reflexes in thoracic limbs

See images below. Click to enlarge.

Observations:

Generalised slight dilatation of the ventricular system
marked dilatation of the fourth ventricle impinging on cerebellum and brain stem
swelling and diffuse, poorly marginated T2 hyperintensity affecting the cervical spinal cord
no enhancement after gadolinium
flow artifact in the mesencephalic aqueduct (hyperintense in T1- and hypointense in T2-weighted images)

Synthesis:

• Symmetrical dilatation of the ventricular system suggests obstructive hydrocephalus
• morphology of cord lesion suggests diffuse oedema
• evidence of increased intracranial pressure
• MR lesions are compatible with the clinical signs
• principal differential diagnosis is myelitis

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.

Examples of errors by candidates:

• failure to recognise that the combination of ventricular dilatation and diffuse spinal cord oedema was compatible with an inflammatory condition
• assumption that fourth ventricular dilation represented an arachnoid or epidermoid cyst
• diagnosis of Chiari-like malformation despite incorrect breed, severity of clinical signs, and lack of cerebellar herniation or lesions to suggest syringomyelia.