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9 year FS DSH Subacute, progressive paraparesis and significant spinal pain. Indoor/outdoor cat. Hx tail injury x 1-2mo ago. Neuro exam localizes to both T3-L3 and L4-S1 myelopathy.

Sagittal STIR images, thoracolumbar spine

Sagittal T2-weighted images, TL spine

sagittal T2-weighted images, lumbar spine

Sagittal/transverse T2-weighted images of the TL spine

Sagittal/transverse T1-weighted images, post-contrast

What's your diagnosis? Answers posted after the Imaging Interpretation Session

  • A focus of left lateral extradural abnormal tissue compresses spinal cord in the mid caudal thoracic spine (mid caudal aspect of T8 to the T 11-12 intervertebral disc), but most compressed at T9-10 and T10-11
  • Possible intradural-extramedullary abnormal tissue, in addition to the extradural and paravertebral abnormal tissue with similar signal intensity
  • Abnormal centrally located intramedullary hyperintensity in the spinal cord
  • Moderate abnormal enhancement of the abnormal tissue described
  • Possible abnormal tissue in the epidural space surrounding the terminal portion of the thecal sac at L6 and L7, based on the heterogeneity seen in this area with areas of more normal-appearing intermixed fat
  • Increased conspicuity or mild enlargement of the spinal nerves at L6 and L7 with possible bilateral L6 nerve enhancement
  • Non-neurologic abnormalities include: ~Numerous hyperintense hepatic nodules in T2 & STIR images; not distinguished in the post-contrast but there is more motion. ~ Enlarged sternal lymph node is seen in the limited examination of the thoracic cavity, measuring 0.9 cm in diameter and is mildly rounded

1) Left-sided mid caudal thoracic compressive myelopathy associated with suspected infiltrative extradural and paraspinal (possibly intradural-extramedullary enhancing tissue.

2) Possible similar epidural infiltrative tissue at L6 and L7.

3) Diffuse nodular hepatopathy with high signal in T2 & STIR images.

4) Sternal lymphadenopathy.

Neoplasia was considered primarily based on the MRI findings of multifocal abnormalities involving the spine, liver and sternal lymph node. Consideration of the patient’s age contributed to this consideration. No pyrexia was reported with the spinal pain, which made infectious/inflammatory processes less likely. However, the pain and the regional paraspinal changes can be seen with spinal empyemas. This meant this could not be ruled out but was considered unlikely with the liver and node lesions.

This study was submitted by the neurologist for interpretation after surgery and at the request of the owner. The radiologist and neurologist reached the same conclusion, except the additional hepatic nodules and sternal node was not detected prior to surgery. Surgery was performed to decompress the spinal cord and obtain a biopsy for definitive diagnosis. A 2.5 inch long blade of grass awn was identified within the compressive extradural in the caudal thoracic epidural space and was surrounded fibrous tissue.

Biopsy results confirmed just inflammation and fibrosis.

References

Spodnick et al. (1999) Spinal lymphoma in cats: 21 cases (1976-1989). J Am Vet Med Assoc. 1992 Feb 1;200(3):373-6.

Whitty et al. (2013) Use of magnetic resonance imaging in the diagnosis of spinal empyema caused by a migrating grass awn in a dog. N Z Vet J. 2013 Mar;61(2):115-8. doi: 10.1080/00480169.2012.731717. Epub 2012 Nov 8.

Granger at al. (2007) Successful treatment of cervical spinal epidural empyema secondary to grass awn migration in a cat. J Feline Med Surg. 2007 Aug;9(4):340-5. Epub 2007 Apr 20.