Peripheral or Central vestibular lesion?

Re: Peripheral or Central vestibular lesion?

Beats — Mon, 17 Feb 2014 17:53:06 GMT

Final update:

Owner had initially thought a bit of improvement on the prednisolone, so just kept to that so as not to get confused as appeared to have waxed and waned a bit before - sure enough deteriorated again after a few days.

On exam, could crush hard enough with forceps either side of upper lip to leave an imprint without the dog biting me or looking concerned - I took that as a probable indication of involvment of further nerves bilaterally and therefore either a polyneuropathy or central lesion (I thought the latter more likely). The temporal muscles appeared atophied which I might have put down to the steroids, but did wonder if they were a bit assymetrical also...

Either way, wasn't looking particularly promising for a recovery with a long course of antibiotics/steroids, so decided to euthanase... Main thing was I didn't want to miss otitis that might be resolvable and I think the progression of things probably was not typical of that.

Re: Peripheral or Central vestibular lesion?

Beats — Tue, 28 Jan 2014 19:05:11 GMT

OK, update today.

Examined dog conscious on his back and thought that there was perhaps vertical nystagmus in the left eye in certain positions? The right eye maintained rotatory nystagmus as the only type present again in certain positions.

I've videoed the possible vertical nystagmus on my phone and will try to upload to see if anyone is convinced by this or whether is just me imagining it.

www.vetsurgeon.org/.../2248.Video0002.avi

Took a look down both ears under GA and other than mild erythema and possibly mild stenosis in horizontal canals I didn't see anything in external ear canal; the tympanic membrane looked normal to my untrained eye for what I could see of it looking down a poorly focused cheap otoscope.

Fired off a single bulla xray just in case was something obvious on it, wasn't well positioned and is overlying the atlas I think, but nothing outrageously obvious showing up.

Based on the possible vertical nystagmus, I'm leaning towards a probably central lesion, but am very weary that this dog doesn't end up euthanased due to a lack of antibiotics for an undiagnosed otitis media/interna, so will probably try to convicne the owner to try 6 weeks of cephalexin @ 25mg/kg q12hrs, but this will be stretching the budget rather and I wouldn't want to convince him to try this unless there is a reasonable logic behind it.

Home on 0.5mg/kg pred q12hrs for a week and then phoning with update. I decided worth trying some preds given that expensive diagnostics won't be an option.

Toyed with the idea of throwing in some betahistine also, but don't know if there's much point to that really?

Video of nystagmus uploaded to "my files" as an .avi also in case doesn't work in this post. Can be accessed at http://www.vetsurgeon.org/members/Beats/files/default.aspx

Let me know if an alternative video file type is more suited to this site and I can convert and reupload.

Cheers!

Re: Peripheral or Central vestibular lesion?

Anthony Dennison — Mon, 27 Jan 2014 12:50:59 GMT

I have use cephalexin in the past, it's not quite as expensive as amoxyclav long term and I find it more effective.

Re: Peripheral or Central vestibular lesion?

Beats — Fri, 24 Jan 2014 19:27:34 GMT

Thanks Mark & Anthony!

I'll report back if get anywhere or it resolves etc.

Is coming in next week to get GA and ear examined (for all the good that is likely to do...)

[quote user="Anthony Dennison"]I was caught out recently when a dog I had put on TMPS developed acute hepatitis due to the meds [/quote]

I've never knowingly seen a dog develop acute hepatitis as a result of TMPS before, so thanks for the heads up. He did seem more depressed while on the drugs, but then his signs have been waxing and waning anyway for a few weeks so could be conincident. Still, makes me bit reluctant to give a 4-6 week empirical antibiotic course for bacterial otitis media/interna that might not exist... but then again would be a real shame if ended up being euthanased for lack of antibiotics with a condition that could have been resolved! Frustration

What antibiotic/dose would you choose if you were going for an empirical course without knowing whether there was actually any bacterial otitis media/interna? I went for TMPS so as not to blow the whole budget on an empirical treatment while still being pretty broad spectrum, but given that there's probably not much diagnostically that can be done with a high diagnostic yield within the owner's means, perhaps I can justify another more expensive drug OK. Shame can't use cheaper human tablets anymore

Re: Peripheral or Central vestibular lesion?

Anthony Dennison — Fri, 24 Jan 2014 17:45:43 GMT

It may be an idea to do bloods to check liver enzymes. I was caught out recently when a dog I had put on TMPS developed acute hepatitis due to the meds (though the owner had kept giving the tablets until the scheduled recheck, by which point the dog was bright yellow...)

Re: Peripheral or Central vestibular lesion?

Mark Lowrie — Fri, 24 Jan 2014 10:52:15 GMT

Given this history then I think otitis media/interna or potentially idiopathic VD would be most likely. However, although there are no specific signs of central vestibular disease it does not rule it out completely so a brain tumour or severe cerebrovascular event (that is slowly improving) remains possible. Given the signs have been going on a little over a month now further imaging would be indicated and as we are most interested in the caudal fossa, MRI would be best although CT will help to rule in/out ear disease.

Re: Peripheral or Central vestibular lesion?

Beats — Thu, 23 Jan 2014 14:23:14 GMT

Thanks Mark!

Really appreciate the insights!!

Case at hand is a 8.5 year old male neutered labrador.

Problem started at beginning of December and appears to have waxed and waned (i.e. it hasn't remained static the whole time), but i don't think there has been either an overall improvement or deterioration from then to now - any improvement that the owner has noted I think has been with the dog's ability to cope with the vestibular disease rather than anything else. There has always been at least a moderate head tilt at all times. On the most recent of the 2 occasions I have examined the patient, there was a severe head tilt - kind of like one of those bunnies I sometimes see that is falling over itself - more severe than I normally see in dogs.

I will try turning the dog on its back to see if vertical nystagmus can be induced; with the dog in ventral recumbency, then there was only the rotatory nystagmus with the head turned to the left, all other positions did not result in nystagmus.

I haven't identified any other cranial nerve deficits - I'd wondered whether the "positional ventral strabismus" of the right eye could have been an indicator of another CN involved, but I understand from what you're saying that this is simply consistent with the vestibular lesion already identified.

I couldn't demonstrate any clear-cut proprioceptive deficits to my non-expert eye. I could drag the right hind about 10-15cm laterally perhaps before the dog would lift it and replace it (this is more than I would typically expect, but I wasn't sure that this was demonstrating a proprioceptive deficit as such rather than again being consistent with the vestibular lesion that was present, i.e. the dog was happy to have its leg dragged in that direction as it already felt that it was falling over thyat way or something?). On knuckling of the right hind, it left a couple of central toes a little bent over on couple of the attempts, bvut again I wasn't hugely convinced that this was a clear-cut demonstration of a propriocetpive deficit rather than a consequence of me holding the dog up in an 'unnatural' position for it given the vestibular disease?

There had been NO clear mentation changes other than about a week and a half ago (about 5 days into a course of TMPS @ 30mg/kg q12hrs) when the dog became withdrawn and lethargic. This reolved either as a consequence of or coincident to the discontinuation of the TMPS. Over the last number of weeks, the dog has seen withdrawn on occasions, but the owner (I think correctly) has put this down to not wanting to get up and go for a walk because is simply falling over on those days (i.e. is withdrawn on days that balance is at worst and lies in bed mostly).

I have not noted any cerebellar signs, though may have missed these. The menace response is normal. The gait is much as one would expect for a moderately-to-severely affected viestibular lesion.

I'm pursuing a possible peripheral lesion by admitting for a general anaesthetic to perform otoscopy and perhaps bulla rads+ultrasound and piercing the ear drum with a sharpened plastic cannula to aspirate for culture, but on conscious exam there is no clear signs of otitis. Advanced video otoscopy or advanced imaging are out of this client's budget unfortunately.

Other than that I've suggested trying to see if there is a response to preds 1mg/kg q12hrs initially +/- betahistine (after ear exmained under GA), but with the caveat that the preds could screw with future diagnostic testing such as bloods, T4, CSF analysis etc (although it is unlikely that the owner can afford a full investigation and I didn't think there was a high chance that any of these things would be massively helpful presently).

I thought if I could decide whether peripheral or central, then that would make any other suggestions as logical as possible, but I was finding it hard to decide on that first question!

Re: Peripheral or Central vestibular lesion?

Mark Lowrie — Thu, 23 Jan 2014 09:19:00 GMT

Not sure I can say too much without more details (e.g. age, breed, when the problem started and whether it has progressed, improved or remained static). However, the majority of the signs you mention (including the strabismus) simply suggest vestibular disease is present and don’t help distinguish whether the problem is central or peripheral. If you have any of the following signs then central disease is far more likely:

· Vertical nystagmus – may be worth turning dog on its back to see if this can be induced

· Multiple cranial nerve signs

· Proprioceptive deficits

· Mentation changes

· Cerebellar signs

If this is peripheral then idiopathic or ear disease are most likely but history is helpful to determine which is more likely.

If the problem is central then history will again help determine the most likely cause but neoplasia and cerebrovascular accidents are generally most common.

If you post more details I may be able tor refine what I have said above.