HISTORY / CLINICAL SIGNS: According to the owner, the patient had been acting normally, running around on the ownerโs large property until he suddenly went down and could no longer walk. The patient was brought into a local veterinary clinic immediately once the owner discovered him down outside.
PAST HISTORY: Previous left cranial cruciate ligament tear. Otherwise, no previous major medical issues.
CURRENT MEDICATIONS: None. Receives monthly heartworm, flea, and tick preventives.
PHYSICAL / NEUROLOGICAL EXAM FINDINGS:
- Acute onset lameness.
- Non-ambulatory tetraparesis.
- Non-painful, no hyperpathia noted.
- Mentation: BAR.
- Head posture: upright/normal.
- Cranial nerve exam: within normal limits.
- Thoracic limbs:
- conscious proprioceptive (CP) deficits (worse on the right front limb),
- depressed spinal reflexes (worse on the right front limb),
- weak withdrawal (worse on the right front limb),
- sometimes looks like extensor rigidity but can bend.
- Pelvic limbs:
- conscious proprioceptive (CP) deficits (worse on the right rear limb, but neither pelvic limb as severe as in the thoracic limbs),
- normal to increased spinal reflexes,
- brisk/strong withdrawal,
- strong muscle tone,
- positive crossed extensor.
- Superficial and deep pain present.
- Anal tone present.
- Bladder control present.
- Otherwise, physical exam is unremarkable.
Where is the neurolocalization of this lesion?
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LESION LOCALIZATION: C6-T2 myelopathy (right >>left)
What is on your differential diagnosis list? What diagnostic tests would you order? Any other questions?
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INITIAL DIFFERENTIALS:
- Fibrocartilagenous embolism (FCE)
- Non-compressive intervertebral disc disease (IVDD)
- Spinal cord tumor (that may not be visible on spinal radiographs)
- Myelitis (inflammatory vs. infectious)
DIAGNOSTIC TESTS & RESULTS:
- Bloodwork: mild stress leukogram; otherwise, unremarkable
- IDEXX 4Dx SNAPยฎ Test: negative
- Spinal radiographs: no obvious lesions
- Advanced imaging declined by owner
Based on this patientโs signalment, clinical signs, physical exam findings, and test results, what is your diagnosis, recommended treatment, and prognostic outlook?
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DIAGNOSIS: Fibrocartilagenous Embolism (FCE)
This patient has a presumptive fibrocartilagenous embolism. An FCE occurs when a piece of nucleus pulposus from a spinal disc dislodges and forms an embolism (blood vessel blockage) in the spinal cord, blocking off oxygen and nutrient supply from that segment of spinal cord, resulting in myelopathy (or spinal cord dysfunction). Though overall uncommon, FCE is most likely to occur in active young adult dogs (primarily large breed dogs and miniature Schnauzers) following activity, such as jumping or running around. (This patient is a very active dog, enjoying running after wildlife on his ownerโs property of several acres.)
FCE causes asymmetric neurological deficits, affecting only one side of the body. (This patient appears to be more affected on the right side, indicating the FCE has lodged in the right side of the spinal cord between segment C6-T2.) The gray matter of the spinal cord is more severely affected by FCE because disc material enters the spinal cord terminal vessels upon kinetic injury and causes ischemic damage. Relative to white matter, gray matter tends to be more affected by ischemia because it has a higher metabolic demand (for glucose, oxygen, etc.). FCE tends to be painful at initial occurrence (the animal may cry out) but then is usually non-painful thereafter. (This would explain why this patient is currently non-painful.) The mid-caudal cervical spine is most commonly affected by FCE. FCE should be differentiated from traumatic intervertebral disc disease (or IVDD). IVDD tends to be much more painful than FCE but can otherwise be a look-alike of FCE based on clinical signs. Ideally, an MRI would have been performed as this is the only concrete means of differentiating FCE from traumatic IVDD; on MRI, the spinal disc appears normal if FCE. However, owners declined a neurology consultation with advanced imaging and further diagnostics.
TREATMENT:
Following his neurological evaluation, this patient was kept in-hospital for several days for monitoring and physical therapy exercises. He was given buprenorphine initially (later discontinued as it became evident that the patient was non-painful) as well as carprofen. Treating a fibrocartilaginous embolism involves physical therapy and cage rest to prevent further injuries. Surgery to remove the lodged fibrocartilagenous disc material is not necessary as new blood vessels will form to re-supply the starved spinal cord segment of vital oxygen and nutrients, allowing it a chance to heal.
PROGNOSIS:
If the FCE results in an upper motor neuron (UMN) lesion, the prognosis is good so long as the lesion is less than 2 vertebrae long and involves less than 67% intramedullary. For a lower motor neuron (LMN) lesion, the prognosis is fair. If loss of nociception occurs (which is uncommon for an FCE), the prognosis is poor.
Fortunately for this patient, he developed enough strength and control to rise to a standing position on his own within 2 days of the initial injury, also attempting to take a couple of steps before falling. This early-stage walking appears to be โdouble-engineโ gait. With continued supportive care and at-home physical therapy exercises performed by his educated owners, he continued to make great progress and returned to full mobility within several months.
Any other questions, comments, or suggestions?
Unless otherwise stated, these clinical cases are real-life cases that I have managed as a veterinarian in general small animal veterinary practice or else assisted with as a student in vet school. These cases are a great real-world learning tool for vet students and other veterinary professionals. They shall be used for learning purposes and collaboration of knowledge only. These cases are not intended to diagnose or treat any disease by pet owners. – Maranda Elswick, DVM
