Clinical Reasoning in Veterinary Neurology


A very interesting article was published in 2024 that just made it across my “desk”. It’s titled “Outcome of the Use of Clinical Reasoning Alone in Dogs with Acute Thoracolumbar Myelopathy and/or Pain” by Drs. Bruno Scalia and Paul Freeman. (Animals, 2024) This is not a journal I typically peruse so I don’t know it’s reputation but the article was interesting, nonetheless.

Here is the premise: in veterinary medicine we often base a diagnosis on a collection of patient information and known details about specific diseases. Specifically, signalment, history, and clinical exam (that includes the neurology exam) help narrow the list of diseases.  In the absence of cross-sectional imaging (MRI or CT scan), we make a “best guess”, or top differential diagnosis, and proceed with treatment based on that “best guess”. This is clinical reasoning. Hopefully we also communicate the broader differential diagnoses (top 3 possible causes, for exam) to a client.
This study aimed to answer 3 questions:

  1. For dogs presenting with acute T3-L3 myelopathy treated conservatively for presumed intervertebral disc extrusion (IVDE), ischemic myelopathy (ex: FCE), or acute noncompressive nucleus pulposus extrusion (ANNPE), what proportion does not improve satisfactorily and subsequently requires imaging?

  2. For how many of these is the final diagnosis different from the initially suspected diagnosis?

  3. What is the outcome for all these patients?

 
Results
One hundred thirty-nine dogs were included. Dogs were placed in 1 of 3 groups as follows:

  • Group 1: successful outcome, no imaging needed. Medical management only.

  • Group 2: initially unsuccessful medical management therefore imaging was performed. The initial presumptive diagnosis matched the imaging diagnosis. Dog eventually improved.

  • Group 3: unsuccessful outcome with medical management, leading to imaging. Initial diagnosis did NOT match the imaging diagnosis. Dogs that did not receive any imaging were also included here.

 
Intervertebral disc extrusion
There were 123 dogs that were initially treated for presumptive IVDE. Of these, 100/123 (81%) were in group 1, 19/123 (16%) in group 2 and 4 /123 (4%) were in group 3. If clinical signs worsened, and imaging was obtained, the initial diagnosis was correct in 90% of cases.

Presumptive ischemic myelopathy or ANNPE
This group included 16 dogs. There were 15/16 (94%) in group 1; and 1 case in group 3. No dog met the group 2 criteria.

How did they do it?
Dogs with IVDE were reported to be painful more often than dogs with ischemic myelopathy or ANNPE. Moreover, an incident just before or at the time of the onset of the myelopathy was reported in almost 70% of dogs with ischemic myelopathy or ANNPE. Compared to about 9% of owners of dogs with a final diagnosis of IVDE, dogs with ischemic myelopathy or ANNPE more often reported activity-induced signs in their pets. Most of the dogs in this study were ambulatory, paraparetics. Furthermore, dogs that were non-ambulatory were all hospitalized for 24 hours for observation. This is critical because dogs at home may not have been as closely monitored for progression. Dogs in Group 2 underwent imaging about  6 days after the initial evaluation. Dogs that are non-ambulatory may be better suited to surgery; therefore hospitalization and close monitoring is preferred. Overall only 3% of dogs had a different diagnosis than the initial one. 
 
Key points
If a patient presents with difficulty walking, do a neurologic examination. If they localize a T3-L3 myelopathy, ask the following questions:

  1. Do they have spinal pain? If yes, IVDE is more likely. (But tumor, discospondylitis, or meningitis are still possible)

  2. Did this happen acutely, during an activity (like running or playing)? If yes, this is more likely ischemic myelopathy or ANNPE. (But IVDE cannot be fully excluded.)

  3. According to this study, if you localize correctly, use the above two questions to help guide a diagnosis, and monitor closely for progression, 81% of dogs with IVDE and 94% of dogs with ischemic myelopathy/ANNPE will improve with medical management. These numbers are risky because all dogs, with any level of severity of clinical signs, were lumped into one diagnosis group. We suspect dogs with loss of deep pain secondary to IVDE will do poorly compared to dogs that are ambulatory and diagnosed with IVDE, for example. 

  4. Progressive worsening = get them referred for a confirmed diagnosis and possible surgery.

Thanks for reading! I hope you enjoyed this TidBit and look forward to working with you soon!