Neurology Flashcards
list spinal reflexes used in horses NE
- thoracolaryneal adductor response
- spinal segmental: cervicofacial, panniculus
- tail/anal
gait factors assessed
- proprioceptive deficits
- ataxia
- paresis
- dysmetria
brain regions
- forebrain
- brainstem/CNs
- cerebellum
spinal cord regions
- C1-C6
- C6-T2
- T3-L3
- L3-S5
peripheral neuro regions
- brachial plexus (FLS)
- HLs
- NMJs
- (primary muscle issue)
RAS is active in what brain regions
- brainstem
- cerebrum
hypermetria, intention tremors, strength –> region?
cerebellar disease
seizures, blindness, dementia, mild ataxia/weakness –> region?
cerebral disease/forebrain
gait deficits, altered consciousness –> region?
brainstem
tail/bladder paralysis, perineal hypalgesia –> region?
sacral
front limb ataxia worse than hind –> region?
C6-T2
what spinal segment lesions may result in horner’s?
C1 - C5
C6-T2
3 types of ataxia
- proprioceptive (spinal)
- vestibular
- cerebellar
2 types of paresis
LMN vs UMN
tests of proprioception
- Posture
- Truncal sway
- Circling: circumduction, interference, pivoting
tail pull at rest tests
extensor strength - LMNs
tail pull while walking tests
extension and flexion
UMNs and LMNs
muscle fasciculations are assoc. w/
LMN weakness
Grade 1 ataxia
mild/inconsistent ataxia at walk, worse when manipulated
Grade 2 ataxia
obvious ataxia at walk, worse when manipulated
Grade 3 ataxia
prominent ataxia, fall over if manipulated
Grade 4 ataxia
severe + might fall
Grade 5 ataxia
recumbent + can’t get up
px hendra
euthanasia
Hendra incubation and shedding
shed 2 days before CS
5-16 days incubation
Dx Hendra
- rectal, nasal, oral swabs –> EDTA blood
- -> ELISA, virus isolation PCR
medications assoc. w/ seizures if intracarotid
- xylazine, flunixin
- bute
- procaine pen (IV at all)
dx of bacterial meningitis and px
CSF tap –> poor px
fungal cause of meningitis in WA
cryptococcus
ddx for neurogenic blindness
- forebrain dz
- PPID (optic chiasm compression from macroadenoma formation)
- trauma
- neonatal encephalopathy
- toxins
- intra-carotid injections
ddx. diffuse/multifocal disease
- arboviral encephalomyelitides
name 2 alphaviruses assoc. w/ encephalomeningitis
- ross river virus
- eastern/western/venezuelan equine encephalitides
names 2 flaviruses assoc. w/ encephalomeningitis
- west nile virus/kunjin variant
- murray valley encephalitis/japanese encephalitis
cs of ross river virus
- polyarthralgia + effusions
- distal limb oedema
- systemic illness
- not usu ataxia
cs of west nile fever/kunjin virus
- muscle tremors (esp. muzzle)
- variable fevers
- variable RAS signs - obtundation/hyper-altert
- ataxia/weakness
- recumbency
px west nile
50% have residual signs
mortality ~ 30%
recovery in 3-4wks
rank the encephalitides viruses in order of highest to lowest mortality
- EEE
- VEE
- WEE
- WNV (Kunjin)
- JE
CSF tap findings of viral encephalitides
neutrophilic –> lymphocytic
tx of viral encephalitides
- anti-inflam: flunixin, dex
- anti-ox
- cooling
- IVFT/lytes/glucose
- anti-oedema tx
incubation/pathophys of ABLV
- long, variable incubation period (2wks->6months) –> delayed progression/viral replication in muscle cells at wound
- ascends via peripheral or cranial nerves to brain
- reduced production of normal functional proteins –> fatal in 3-10days
ABLV CS
- cerebral signs: mania/aggression, seizures, obtundation
- RAS: altered consciousness
- CN: dysphagia
- Spinal: ataxia, weakness, paralysis, cauda equina
dx of ABLV
PM test –> euthanase
- refrigerated brain –> direct FA test, negri bodies in purkinje cells
management of ALBV
- vaccination in endemic areas
- human vax
- euthanasia of suspect
pathogen of EPM
Sarcocystis neurona
CS of EPM
- often vague/subtle multifocal disease
- asymm. ataxia/atrophy
dx of EPM
CSF/serology antibodies
Tx of EPM (and px)
Ponazuril/Diclazuril - at least 28days
- 60% horses response to tx +/- relapses
pathogens of verminous myeloencephalitis
usu aberrant migration of;
- halicephalobus
- strongylus
- parelaphostronglylus
cerebellar dx in arabian foals ddx
cerebellar abiotrophy
cs of shivers
- cerebellar disease
- hindlimb elevation: diff. trimming hind feet, backing, turning
- high fat, low sugar diet? +/- PSSM
- draught horses
annual and perennial ryegrass toxicity cs
- vestibulocerebellar signs w/ diffuse spinal or peripheral nerve involvement
- severely affected horses may stumble or fall –> tetanic muscle spasms
- signs often improve w/ recumbency
- excitement or blind-folding exacerbates the signs
- removal from affect fx (recovery 1-3wks)
px of annual vs. perennial ryegrass toxs
annual –> suddenly dies - may never fully recover
perennial –> usu good recovery
toxin in annual ryegrass tox
tunicaminyluracil ABs
toxin in perennial ryegrass tox
lolitrem B
ddx. trigeminal neuropathy
guttural pouch disease, ear mites, other hyoid disorders, EPM
trigeminal neuropathy presentation and cs
- 8-10yrs, Geldings > mares
- flicking/tossing nose, rubbing nose, snorting
- often mistaken ‘bee-sting’
medical management of trigeminal neuropathy
- cyproheptadine - serotonin antagonist/antihistamine
- carbamazepine - anti-convulsant
- nose-nets
cs of vestibular syndrome
- head tilt (poll towards lesion)
- nystagmus
- ataxia with strength (if peripheral)
- lean/circle towards lesions, truncal sway
- other signs if central - weakness, somnolence, CNs
ddx peripheral vestibular syndrome
- temporal osteopathy
- trauma - fx of stylohyoid
- middle/inner ear disease
- idiopathic
ddx central vestibular syndrome
- trauma
- EPM
- abscess/neoplasia/mass
- migrating parasites
- tremorgenic toxins
- diffuse encephalitis
signs inc or decrease w/ peripheral vestibular syndrome when blindfolded?
worse!! thus signs increase
ddx facial nerve paralysis
- trauma, GA (headcollar)
- multifocal
- GP disease (Strangles!)
Cervical vertebral stenotic myelopathy causes
cord compression - stenosis of vertebral canal –> Wobblers
typical presentation for Wobblers
TBs + WBs
Males > Females * large rapid growth
4 months - 4yrs (and older)
2 major CVSM subtypes
- Dynamic: young horse, C3-5, stenosis is dependent on position
- Static: older horse, C6-7, stenosis not position dependent
typical CS of type 1 CVSM
- weanling to ~24months
- symmetric
- pelvic limbs > thoracic limbs
- neck pain is rare
- C3-5
typical CS/presentation of type 2 CVSM
- older horses 18mo to 4yrs
- occ. asymmetry
- pelvic limbs > thoracic limbs
- neck pain more likely - OA of facet joints
- C5-T1
list 4 subjective rad measurements when assessing for CVSM
- alignment
- vertebrae shape and size
- intervertebral foramen
- facet joints
list 2 objective rad measurements when assessing for CVSM
- intervertebral sagittal ratios: abnormal <0.485
- intravertebral sagittal ratios: abnormal if vertebral canal is less than half the size of the vertebral body
limitations of myelography to diagnose CVSM
- requires GA in an ataxic horse
- no as sensitive/specific as first thought
treatment of CVSM in foals
- restrict calories
tx of cervical facet disease (OA)
- pain w/out neuro signs –> usu older horses
- tx w/ corticosteroids
why might a horse present with spinal neuro signs days after a known trauma?
they can actually ‘splint’ a fracture w/ their own muscle strength but after a few days they fatigue and fx may displace and cause neuro signs
ddx urinary incontinence
- EHV
- trauma eg. foaling
- multifocal/systemic neuro
- chronic sudan grass tox
- urogenital causes
pathophysiology of EHV-1
vasculitis (capiliary endothelia) –> thrombosis –> ischaemia –> myeloencephalitis
+/- resp/repro disease
cs of EHV-1
- initial biphasic fever: URT infection –> viraemia
- rapid progression (peaks at 24-48hrs) then plateuaus
- spinal cord signs usu. ascending - symmetric paresis and ataxia *HLs, bladder atony (overdistension)
+/- CN/brainstem signs
*usu larger horses, >5yo
dx of EHV-1
- nasal swab and whole blood (buffy coat) –> PCR and virus isolation
- serology (paired titres)
- CSF: xanthochromia, increased protein, normal cell count (albuminocytologic dissociation)
management of EHV-1
- Notifiable disease
- NSAIDs
- Antivirals: valcyclovir
- Anti-coags: heparin
- Supportive: limb support, bladder catheter
MOA of tetanus
blocks GABA release - an inhibitory neurotransmitter –> tetany
pathophys of clostridium tetani
<1-3wks incubation period
- peripheral/cranial neuropathy: somatic and autonomic nerves affected, symmetrical
- hyperaesthesia and hypertonicitiy: spastic paralysis
CS of tetanus
- head then limbs
- muscle rigidity ‘saw-horse’ stance
- muscle spasms: nictitans prolapse (extraoc. muscles), trismus, dysphagia
- sympathetic overdrive
- recumbency
- resp. failure and death
tetanus management
- reduce stim: dark, quiet, ear plugs
- Sedation: ACP, phenobarbital
- Muscle relaxation: Methocarbamol, Diazepam, Midazolam CRI, Dantrolene, MgSO4
- Source control: Debride and flush wound, metronidazole > Pen.G, antitoxin
indicators of good px w/ tetanus
- response to ACP
- stabilises w/in 48hs
- able to eat and stand unassisted
- –> recovery 6-8wks
tetanus vax protocol
2 primary vaccines 4-6wks apart –> boosters thereafter
MOA of botulism
prevents ACh release from NMJ –> flaccid paralysis
tx for botulism
- resp support
- nutritional support
- ABs for secondaries
damage to the suprascap nerve causes
sweeney
stringhalt is caused by what plant?
Hypochaeris radicata (yellow daisy one)
cs of stringhalt + recovery
- laryngeal hemiplegia
- recumbency
- bilateral or polyneuropathy
