Age isn't a disease, right? No, it isn't but disease is associated with age. The older pet with seizures is more likely to have structural disease (i.e. neoplasia instead of idiopathic epilepsy), compared to the younger pet. That said, none of us want to diagnose a terminal disease in an older patient simply because the patient is older!
Can the Neurologic Examination Help Vets differentiate disease in Older Patients?
Let's look at the two most commonly performed parts of the neurologic examination and see how they related to disease. The menace response and paw replacement testing (previously called conscious proprioception) both assess the forebrain and are some of the most commonly performed parts of the neurologic examination. Here is what a recent group from Australia found in reference to finding evidence of forebrain disease on MRI:
Menace response
Sensitivity: 72%
Specificity: 47%
Odds ratio: 2.26
Proprioception
Sensitivity: 54%
Specificity: 72%
Odds ratio: 3.08
If age is then factored into the analysis, dogs greater than or equal to 6 years of age were more likely to have a forebrain disease detected by MRI if they had a menace or proprioceptive deficit.
As a "field" neurologist (without a pocket MRI...yet) this tells me that I should encourage diagnostic imaging in patients with menace deficits, and possibly for those with proprioceptive deficits depending on concurrent findings. The chances (or Odds) of a patient having underlying forebrain disease is higher if they have these deficits than if they don't. Seems intuitive, but proprioceptive testing isn't as sensitive as assessing the menace response.
What's the take-away message here? If you have an older pet with seizures, and the neurologic examination is NORMAL, you might miss underlying structural brain disease if you do an MRI but, then again, you might now. If you have an older pet with seizures and a menace or proprioceptive deficit is noted you'll LIKELY MISS a structural brain disease if you skip the MRI.
Although this TidBit is a repeat from 2020, I liked this study and thought it was worth repeating...again.
Chan MK, Jull P. Accuracy of selected neurological clinical tests in diagnosing MRI-detectable forebrain lesion in dogs [published online ahead of print, 2020 Jul 15]. Aust Vet J. 2020;10.
Thanks for reading! I look forward to working with you soon. Have a great week!