head tilt

How reliable is the neurologic exam for patients with vestibular disease?

We (neurologists) like to think that the neurologic examination is the ultimate-be-all-end-all tool. But in dark corners, we talk about how incredibly hard it can be to do on patients with vestibular disease. 
First, there are three parts that we need to consider for the lesion localization, correct? 
1) Brainstem
2) Cerebellum
3) Peripheral CN 8
My rule of thumb is this: If the pet has ipsilateral hemiparesis/monoparesis, ipsilateral paw replacement deficits or decreased mentation (obtunded, stupor, coma) it is a brainstem lesion. If the pet has hypermetria, or intention tremors along with the vestibular signs, it is cerebellar in origin. Finally, in absence of those findings the lesion is localized peripherally. 

An article out of Europe in 2019, dispelled our fears of the neurologic examination failing us and (thankfully) helped us sleep better at night when it was published that the neurologic examination correctly predicted if the vestibular signs were central (brainstem or cerebellum) or peripheral (cranial nerve 8) over 90% of the time. 


Interestingly, central disease was more common in this study and, it was localized correctly MORE often than peripheral disease was localized correctly. In other words, dogs with central disease were more likely to be localized on the exam as having central disease compared to dogs with peripheral disease which were occasionally incorrectly localized with central disease. 

A few more good reminders:

  • Nystagmus are not a localizing sign! (E.g. 8 dogs with peripheral and 5 dogs with central disease had horizontal nystagmus.) 

  • The onset of disease does not predict it's lesion localization. (E.g. Acute and chronic onset of signs were not statistically different between the central and the peripheral groups.)

  • They had a lot of French Bulldogs in the study! Huh..I'm not sure I've noticed an over representation of French Bulldogs in my clinical work. It's good to learn something new everyday. 

So, what does that mean for us?

It means if you do a thorough neurologic exam, you'll be correct about 90% of the time when you guide a client towards an MRI and spinal tap  (for central disease) or treat for idiopathic or otitis (for peripheral disease). If you're unsure, err on the side of it being a central lesion and recommend a full work up. (Or contact me for a consult!) Oh, and 68% of dogs diagnosed with peripheral vestibular were idiopathic! Idiopathic disease means we have a lot more to learn...so let's get back to it!

(Bongartz U, et al. Vestibular Disease in dogs: association between neurological examination, MRI lesion localization and outcome. JSAP 2019). 

Thanks for reading! This was an oldie, but a goodie and I hope you enjoyed revisiting it along with me. Please reach out if you have any questions. Have a great week

Heat Tilt, Turn or Neck Turn...so what?

Does a head tilt help with neurolocalization?
 

A recent study by Nagendran et al (The value of a head turn in neurolocalization, JVIM 2023) described 4 distinct areas of neuroanatomic lesion localization for head turn, head tilt and neck turn and looked at head and body position in each of these localizations. If you see a patient with their head deviated to one side yet parallel to the floor, that would be a head turn. If a patient has their head deviated to one side NOT parallel to the floor, we would consider this a head tilt. The head tilt can be anything from 1-90% from the x axis! If the neck is turned to one direction it would be called torticollis and may be (and often is) associated with either head tilt, head turn, or both. This recent article looked at these three signs, in reference to the neuroanatomic lesion localization, with the goal of trying to sort out the underlying neuropathology (totally cool but not "light reading" and therefore saved for another conversation).
Key Points:

  • Forebrain disease – The majority or patients had an ipsilateral head turn, with less than ½ of the dogs demonstrating ipsilateral body/neck turn.

  • Brainstem disease – All dogs had an ipsilateral head turn, and 5/9 had an ipsilateral head tilt, with a rare dog demonstrating a neck turn.

  • Cerebellar disease – All dogs had an ipsilateral head turn and the majority had a contralateral head tilt with a rare neck/body turn noted showing a contralateral neck/body turn.

  • Cervical spinal cord disease – all dogs had a contralateral head turn along with a majority (6/7) showing a ontralateral head tilt.

Summary:

  • Head turn ONLY – consider forebrain disease

  • Head turn with neck turn (ipsilateral) – consider forebrain disease, but the neck turn is an inconsistent finding in many dogs with foreain disease.

  • Head turn, neck turn AND head tilt – most likely cervical spinal cord disease but cannot rule out cerebellar disease.

  • Head tilt only – likely brainstem disease (or peripheral vestibular disease!)

Take Home Points:
A head tilt, head turn, or neck turn is a useful physical examination finding to point you at neurologic disease however they aren’t discretely localizing on their own. Using the information above, you may be able to support a localization noted in concurrence with your other neurologic findings.

Thanks for reading! I made the difficult decision to increase my consultation fees this year so if you didn’t get an announcement please reach out and I can send you the updated fee schedule. Lastly, it’s winter!! That means sometimes travel can be hazardous and cancelations can happen. I don’t charge if we cancel due to inclement weather and will do my best to work your patient into the schedule as quickly as possible afterwards. I appreciate your business very much and do my best to meet your expectations. Have a great week!