Yikes! Another week has gone by and we have completed our Neurology rotation… (no more neurology until we face our final year exams – not sure how I feel about that) This week felt slightly more manageable than Medicine week, maybe it is because we have familiarized ourselves with the routine of reading up history -> consults -> clinical/neuro exam -> discuss with clinician -> write notes/letters. It was pretty busy nevertheless, with our days starting at 8am and ending between 5-7pm depending on our cases. Sometimes you get emergency cases and that can be quite unpredictable as well! In addition, we also worked an evening shift each (at least 1) during the week which lasted until 9pm. So here is the rough structure of my blog post:
- Overall feelings and thoughts
- Useful things I have learnt/ picked up during the week
- A basic neurology consult & exam (notes for reference)
1. Overall feelings and thoughts – Before this rotation, I was worried because neurology seemed like a scary and unknown subject to me, having seen only 1 or 2 neuro cases in my past EMS placements. But actually, it wasn’t that bad. By the end of the week, I guess I was convinced by the clinicians that it is not as complicated as one might think! I came to enjoy neuro because of how systematic it was, where you go through the 6 components of a neurology exam (explained later in this post) and assess for any deficits and abnormalities to get to your neurological localisation. Once you have your localisation, you combine your clinical findings and signalment and can usually narrow it down to a handful of differentials (using VITAMIN D). In that sense, it feels more simple than Medicine where it could be any of the organ systems involved if you’re given vague signs like lethargy and inappetence. However, I did find that with Neurology it can be a lot harder if you have a case presenting with mild non-specific deficits. It involves a lot more case discussion and is not as clear cut as Medicine when it comes to the diagnosis (well, before conducting the advance imaging, MRI tests etc). For example, if you have a Medicine case with increased liver parameters in the blood work up, there is most likely a liver pathology involved. But if you have an animal presenting with spinal pain and increased inflammatory markers in the blood work up, it could be degenerative disc disease, infectious, inflammation or even a foreign body.. so you would have to do imaging and further tests to help your diagnosis.
One of the things I didn’t enjoy about neuro week was the number of breed-related cases you tended to see. It is unfortunate, but French bulldogs and Dachshunds tend to have a high risk of breed-related spinal diseases. It is not only unfair for the animal, but also a cause of emotional and financial distress for the owner. While waiting for better breeding laws to catch up in the UK, we can only hope that prospective pet owners think responsibly and read up on the genetic welfare problems of pets before choosing a specific breed.
2. Useful notes (compiled throughout the week)
- Differentiating central vs peripheral vestibular lesions
- proprioceptive deficits – seen in central vestibular lesion
- mentation deficits – central (however, difficult to assess, as peripheral vestibular can cause animal to be nauseous and present ‘depressed’ without actual mentation deficits)
- cranial nerve involvement other than CN 7, 8, sympathetic trunk – central
- vertical nystagmus – more likely central
- direction of nystagmus changes when direction of head position changes – central
- When presenting on rounds or carrying out a neuro exam, it is useful to drill yourself to get used to this format:
- mentation + behaviour – adequate?
- gait (ataxic/ paraparetic and ambulatory/non-ambulatory *important*) + posture (head tilt etc)
- proprioception/ postural reaction – deficits?
- spinal reflexes – deficits?
- cranial nerves
- Differentiating central and peripheral blindness
- lack of PLR response -> peripheral blindness
- as PLR pathway is subcortical and does NOT involve forebrain
- lack of menace response -> central blindness
- involves forebrain as it is a conscious response, so lack of it indicates a forebrain lesion as you lack the perception of a menace event!
- more info
- nb: menace response usually develops in animal 3 month old and above in dogs (or 5-6 weeks depending on breed and species)
- lack of PLR response -> peripheral blindness
- Acute phase proteins APP: albumin is a -ve APP while CRP is a +ve APP
- so low albumin (alb) indicate inflammation, high CRP indicate inflammation; hence can be useful to assess if both correlate when looking at biochemistry test and suspicious of an inflammatory process going on)
- low alb in inflammation occurs as increase leaky endothelial cells causes alb to leak into extravascular space, increased degradation, cytokine act on hepatocytes to downregulate ALB production and upreg SAA production, more info
- Treatment for degenerative disc disease is SUPPORTIVE, pain relief and CAGE REST – possibly NSAIDs or steroids to reduce inflammation around disc and TIME for the annulus fibrosis or nucleus pulposus to heal
- When getting a thorough history from client
- Get comfortable asking owner weird questions – does dog eat horse poo (as could indicate ivermectin toxicity, toxoplasma or neospora infection through poo consumption)
- Clarify the time of onset of the neuro abnormality (seizure, off its back legs etc) AND TIME of progression, when exactly did it get worse?
- For spinal pain patients, ask: are they still climbing up and down stairs; showing any urinary/ faecal incontinence
- Nb: a normal gait in client’s perspective is not necessarily normal, so it is important to gauge (according to the owner’s perspective) if it has changed or not (to ensure you are detecting the actual abnormality and not the inherent breed related problem)
3. A Basic Neurology consult and exam
Key questions for a neurology consult
- Onset – peracute/ acute/ chronic (peracute: hours to a day (eg. dog was fine in the morning, when you popped to the shops and got back, found dog has hind limb paralysis), acute: roughly 1-3 days, chronic: roughly weeks to months)
- Progression – did it get worse or did it improve?
- Symmetry – owner notice any symmetry in signs, ie. is one side worse than the other
- (Signalment- breed may not necessarily be important but parameters like age are more important, eg. SRMA usually in dog < 3 years old so if you have a 6yo dog with neck pain it is less likely to be SRMA)
Neurology exam is a systematic exam, with 6 main components
- Mentation and behaviour – observe patient when client bring it in, while chatting to the owners you can observe a lot from patient (depressed, BAR..)
- Gait analysis (3 different types of ataxia- vestibular, cerebellar, proprioceptive ataxia) & posture (head tilt, kyphosis, more info in this VIN article
- Cranial nerves – you can observe quite a lot even before touching the animal
- CN II – vision (owner report if animal is stumbling into objects, see if animal can follow object movement when walking into consult room)
- CN III – pupil size (constricted if normal, dilated if have lesion. Parasympathetic NS involved in constricting pupils, sympathetic NS involved in dilating pupils)
- CN III, IV, VI – eye movement (so if animal able to move eyes around)
- CN V – chewing and face sensation (notice any temporal m. atrophy)
- CN VII – facial expression (notice any droopy eyelid, lips)
- CN VIII – vestibular (head tilt, pathological nystagmus – flicking of eyes L to R or vice versa when head is stationary, a vet once told me an easy way to remember the lesion site is to see where the eye is running AWAY from (like running away from something bad), so if eye position moves L to R, it is running away from the L, therefore lesion site is on the L side)
- then you carry out the cranial n. exam checking for all the cranial n. (using your forceps for facial sensation, corneal reflex.. etc)
- side note: 2 CN tests that also check for forebrain/ conscious response are the menace response and the nasal sensation response (place forceps into nasal planum and trigger response)
- tip on doing menace response: to ensure you get the attention of your dog, could do palpebral test first, then as you have their focus you carry out the menace response!
- Proprioception/ postural reactions (knuckling, placing test..etc)
- with the knuckling test, it is not a weight bearing test so ensure you support the weight of animal when carrying out this test
- Spinal reflex
- Besides the muscle stretch reflexes (extensor carpi radialis, patellar reflex..), perineal reflex and cutaneous trunci reflex (start CAUDALLY and move cranially), the main one to consider is the pedal withdrawal reflex!
- The pedal withdrawal reflex involves pinching the webbing between digits to elicit a withdrawal response. Observe the strength and completeness of the response and not the speed. Ideally you want all 3 joints to flex completely and to look for subtle differences between thoracic & pelvic limbs or R and L limbs. Ideally do it while animal is in lateral recumbency but if animal is too stress you could do it while animal is standing. (but bear in mind there is the added difficulty of working against gravity to flex those joints.)
- Palpate pain
Differentials – use VITAMIN D! nb: below is not a complete list but just the main ones we discussed in the morning introduction session*
- V: vascular, for example FCE is peracute onset and improves quickly without pain usually (or pain subsides in 24 hours)
- I: inflammation or infectious, common ones being MUO, toxoplasma, neospora
- T: trauma
- A: anomaly, structural abnormalities like chiari malformation
- M: metabolic would see more symmetrical and generalised signs
- I: idiopathic, usually epilepsy
- N: neoplasia
- D: degenerative, commonly disc diseases
Thank you for making it all the way to the end of this post, hope you are all safe and well, take care and see you in 2 weeks! In the meantime, I am attempting to finish a few vet school videos for the Youtube world. 😊