IVDH Consensus Statement – Medical Management Data

In July 2022, the ACVIM Consensus Statement on the diagnosis and management of acute canine thoracolumbar intervertebral (IVD) disc extrusion was published. This is the first of two installments about this consensus statement as a TidBit Tuesday. For this one, we will discuss the expected outcomes from medical vs. surgical management and what entails medical management. Enjoy!

The recommendations by the committee were graded as being supported by high, medium and low levels of evidence. Recommendations with high level of confidence include multiple randomized controlled trials with concordant findings. The evidence strongly supports the conclusions. Medium level of confidence includes retrospective studies with concordant findings, or small placebo-controlled trials. The evidence suggest that the findings are likely to be real. Lastly, low levels of confidence include isolated or small retrospective studies or single non-controlled trials. The evidence suggests that the findings might be real.

Medical vs. Surgical IVD extrusion management

A very helpful table was presented to help guide appropriate treatment for dogs presenting with signs consistent with TL IVD extrusion. The “%” represent the % of dogs that respond favorably to medical (M) or surgical (S) treatment.

·         Pain only: M 80%, S 98.5% à lateral extrusion may lead to reduced response to medical management.

·         Non-ambulatory paraparesis: M 81%, S 93% à level of recovery was less with medical management.

·         Paraplegia with deep pain: M 60%, S 93% à medical recovery is prolonged and less complete.

·         Paraplegia loss of deep pain: M 21%, S 61%

This is based on moderate level of evidence.  The statement here is “In paraplegic deep pain negative dogs, success with medical management is largely poor with an increased frequency of progressive myelomalacia. Surgical management is recommended.” – moderate to high level evidence.

What is medical management?

“At least 4 weeks of restricted activity is recommended, putatively to promote the healing of the annulus fibrosus. This period should include confinement to a restricted area 9crate, ideally, or small room without furniture) except when performing rehabilitation exercises or outdoor toileting. There should be no off-leash walking, no jumping on or off furniture and no access to stairs during this time”. This statement was supported by low level evidence. Corticosteroids are NOT recommended (moderate level evidence). Dogs with NSAIDs had a higher quality of life score than those on corticosteroids but NO STUDIES specifically address the use (or no use) of NSAIDS. Pain management is discussed, but no recommendations were made because of the lack of studies evaluating different medication protocols. Acupuncture was noted to be good adjunctive treatment for medical management but is not a recommended substitution for surgical management. What are my typical recommendations? For an uncomplicated T3-L3 myelopathy without MRI, with a strong suspicion of IVDH, I recommend NSAIDs, muscle relaxants and most importantly, cage rest for at least 3 weeks.

I hope this was enlightening. Please reach out with questions and stay tuned for the next update on the consensus statement. I hope you have a wonderful week. I am enjoying our tiptoe into fall and hope you are too!

Consensus Statement for Intervertebral Disc Herniation in Dogs, 2022

October, 2022... We have long known that intervertebral disc herniation type I (IVDH) affects chondrodystrophic dogs, at a young age, disproportionately compared to non-chondrodystrophic dogs. We also know that many dogs benefit from surgical and medical intervention. We also know that the neurologic examination is a major predictive factor on recovery (medical and surgical intervention). What we don't know, is how to put what we know into a digestible nugget for clients to hear and understand when in our exam rooms with a dog with suspected IVDH.

First things first... We diagnose IVDH with MRI, CT, CT-myelogram or just myelogram. We don't diagnose IVDH on plain radiographs, or on neurologic exam. (Sorry, soapbox here.) When I say a dog "with IVDH" I mean that they have undergone some sort of diagnostic imaging (MRI, CT, CT-myelography or myelogram) and have been found to have compression to the spinal cord from suspected or confirmed herniated disc material. Presumably, of type I nature for this TidBit. If we don't have diagnostic imaging, but have a chondrodystrophic dog (beagles are included in this group) with appropriate neurologic signs we can call it "presumptive or suspect IVDH". We should, honestly, discuss other differential diagnoses with clients to ensure they understand that there are other possible causes so their decisions are informed. Common diseases that can mimic IVDH could include (but are not limited to) meningomyelitis, neoplasia, Syringohydromyelia, discospondylitis, and spinal trauma/fracture.

Medical intervention... The cornerstone of medical intervention is bedrest for 3+ weeks, anti-inflammatory (typically NSAIDS, but some neurologists prefer steroids), and muscle relaxants or pain management, if the pet is painful. See below for the consensus statement recommendations for medical intervention.

Surgical intervention.... I think this one is self explanatory (mostly). One small point I'll make is that fenestration is not always included when discussing surgical intervention. I consider fenestration an important part of surgical treatment but it does NOT decompress the spinal cord and is therefore excluded in lots of literature. Fenestration means to make a "window" in the affected disc UNDER the spinal canal and remove disc through a lateral or ventral incision (TL vs C-spine). This is also performed in adjacent discs in most cases.

July 2022...ACVIM consensus statement on diagnosis and management of acute canine thoracolumbar intervertebral disc exclusion (doi/epdf/10.1111/jvim.16480). A few key points are listed below and I will have more to share with you in future weeks.

Outcome of dogs managed medically or surgically, based on severity of presenting signs

• Pain only. 80% of dogs had positive outcomes with medical management. 98.5% of dogs had positive outcome with surgical management.

• Non-ambulatory paraparesis. 81% had positive outcomes with medical management however the level of recovery was less complete with medical management. 93% had positive outcomes with surgical management.

• Paraplegia, deep pain intact. 60% of dogs had positive outcomes with medical management however this was prolonged and less complete compared to surgical management. 93% of dogs had positive outcomes with surgical management.

• Paraplegia, deep pain absent. 21% of dogs had a positive outcome. 61% of dogs had a positive outcome.

• The loss of deep pain causes the biggest shift in predictive statistics for surgical intervention. If you have any question about checking deep pain, please ask!

Medical management key points

• Strict rest of 4 weeks is recommended based on low-level evidence to allow for healing of the annulus fibrosus. Strict rest is recommended by all, the 4 weeks part has low-level evidential support in the literature.

• Corticosteroids are NOT recommended in acute intervertebral disc herniation and their use did not demonstrate superior outcomes in many studies. The exception is management of chronic signs in which corticosteroid use may show some benefit. (Not addressed in this article.)

• NSAID use is recommended for at least 5-7 days, assuming no specific contraindication exists.

• There is low-level evidential support for acupuncture or rehabilitation for dogs.

Surgical management key points

• Much of the information provided is useful if you perform the surgery. If you do, please seek out the article as I won't be presenting those points here.

• The timing of surgical decompression is hotly contested amongst neurologists (and surgeons performing neurosurgery). Conventional wisdom suggests early decompression leads to better long-term outcomes, and faster. This has not been consistently shown in the literature therefore the consensus statement elected to skirt the issue and not provide a "optimal window of time" recommendation. My thoughts (I was not on the consensus team, please note) is that if your client is able to seek surgical management please do so as quickly as possible.

That's it for this week. This is supposed to be a "TidBit" so I don't want to overwhelm you and discourage you from reading. If you perform these surgeries, or refer frequently, please consider reading the consensus statement. If you have any questions about what I've covered so far, or IVDH in general, please reach out! I will cover more from this statement paper in future TidBit Tuesdays!

Have a great week, stay warm, and enjoy these glorious sunny days of fall!

Intervertebral Disc Herniation in Cats

Intervertebral disc herniation (IVDH) does occur in cats but is reported at a much lower prevalence than dogs. Is this because the disease is less prevalent or because owners are less likely to pursue advanced diagnostic imaging to obtain a diagnosis? I don't know the answer, however a recently published article reported on 35 cases of feline TL IVDH over 21 years. That sounds like a lot fewer cases than we see for dogs!

Clinical Presentation

Like dogs, the most common presenting complaint is difficulty walking and/or pain. In this study, They found 2 cats had grade I, 20 cats were grade II, 7 cats were grade III, 3 cats were grade IV and 3 cats were grade V on presentation. (Grading scale listed at the bottom). There was no significant difference between outcome at discharge or follow up and initial presenting grade. Does that mean that we shouldn't rush to get cat's seen, imaged, and cut? Probably not. Of the 3 grade V cats (the ones that we would consider a surgical emergency), one improved, one was static and the other was lost to follow-up. What was the timeline for surgery? Unknown. Dogs have a 50% chance of improvement if they are grade V and undergo surgery within 24 hours. This is debated amongst neurosurgeons but as a general rule I subscribe to the plan of cut ASAP whenever possible if deep pain is absent.

Location of the Offending Disc

In the referenced study, thoracolumbar disc herniation was most common at L6-7. This is slightly different from the previous reports in which L7-S1 was reported to be most common, but not far off. I think it is safe to say that cats are more likely to have low lumbar disc herniation than T11-L2 disc herniation, like dogs. Why? Cats are SO MUCH more flexible than most dogs (especially the chondrodystrophic type) that the vertebral dynamics are different as well. Previous reports suggest obesity is more common in cats with IVDH (and in my experience, too) but this cannot be the entire answer. It remains to be seen, why cats are more likely to have a low lumbar disc herniation than TL. When someone knows...I'll tell you!

Key Points:

• Intervertebral disc herniation does occur in cats

• The most common presenting sign is weakness or lumbar pain

• Surgery can be done and SHOULD be done (when appropriate for the patient)

If you have a cat patient with lumbar or lumbosacral pain, reach out. I'd love to see them! Schedule a consult using my online scheduler (for veterinary use only) and let's get your patients feeling better, soon!

Grading scale:
Grade I: normal gait with hyperpathia
Grade II: ambulatory paraparesis
Grade III: non-ambulatory paraparesis
Grade IV: paraplegia with intact nociception
Grade V: paraplegia with absent nociception

Reference: https://journals.sagepub.com/doi/pdf/10.1177/1098612X211028031