Vestibular and cerebellar disease Flashcards
Classic signs - ataxia
- overstep
- cross over legs
2 types of ataxia with alcohol
- APPENDICULAR: jerky, uncoordinated limbs mvt, as though each mm were working independently from others
- TRUNCAL: postural instability, gait instability - disorderly wide-based gait with inconsistent foot positioning
Define ataxia
neurological sign consisting of gross incoordination of muscle movements. It is an aspecific clinical manifestation
What to look at when observing ataxia. How to differentiate from MSK problems
- limbs, head and how trunk moves during locomotion
- becomes better coordinated when running (MSK problems get worse with running
3 types of ataxia
sensory, vestibular and cerebellar
Define hypometria
shorter protraction phase of gait
Define hypermetria
longer protraction phase of gait
Define dysmetria - 3
ability to control teh distance, power and speed of an action in impaired. combination of hypo- and hypermetria
Neurolocalisation - sensory ataxia
General proprioceptive pathways:
- peripheral nn
- dorsal root
- SC
- brainstem
- forebrain
CS - sensory ataxia
- abnormal postural reactions
- limb paresis
Neurolocalisation - vestibular ataxia
Vestibular apparatus:
- vestibular nuclei (central)
- vestibular portion of CN 8
- vestibular receptors (peripheral_
T/F vestibular system is a unilateral system
True - the RHS controls the RHS and vice versa
CS - sciatica
arched back as this provides greatest pressure relief on nn root.
How does the vestibular system affect the extensors?
Causes excitation/ tone to extensors –> head tilt and limp limbs if not working properly
CS - vestibular ataxia
- head tilt
- leaning, falling or rolling to one side
- abnormal nystagmus (slow side always to side with lesion)
- positional strabismus
- normal (peripheral) or abnormal (central) postural reactions
Is prognosis of a vestibular problem affected by localisation (i.e. central/ peripheral)?
No
T/F: nervous system copes better with acute than chronic changes
False - oppositve
Why might you get reduced ear movement with vestibular disease?
lesion may spread and affect facial nerve –> paresis/ paralysis due to close proximity
CS - Cerebellar ataxia
- wide based stance
- intention tremors of head
- loss of balance and truncal sway
- delayed onset and dysmetric hopping
- ipsilateral menace deficits with normal vision
- no limb paresis OR conscious proprioception deficits
- pendular nystagmus
How do forebrain and cerebellum interact?
Forebrain - initiates movement
Cerebellum - coordinates movement
How are the 3 types of ataxia differentiated (sensory, vestibular, cerebellar)?
CS
Outline the neuro exam in terms of observation and hands-on examination parts
OBSERVATION: mental status and behaviour posture gait identification of abnormal voluntary movements HANDS-ON EXAMINATION postural reaction testing cranial nerves assessment spinal reflexes, mm tone and size sensory evaluation
2 components of inner ear
semicircular canals and cochlea (hearing)
What part of the vestibular system detects head motion and angular acceleration?
semicircular canals
What part of the vestibular system detects head position and gravity?
saccule and utricle
Which nn does bulla disease affect?
facial and vestibulocochlear nn and SNS trunk (–> Horner’s)
Where do vestibular nuclei receive input from? 3
- semicircular canals
- saccule and utricle
- visual/ proprioceptive and tactile inputs
- cerebellum: primarily inhibitory
- spinal cord
- potine reticular formation
- contra-lateral vestibular nuclei
With the occulovestibular reflex, turning the head causes what?
Increased firing on the side where the head is turning to and decreased firing on the side the head is turning away from.
Where do vestibular nuclei communicate with?
- forebrain, perceived orientation
- SC and cerebellum
- oculomotor system, eye movements
Outline head tilting
- rotation of median plane of head
- one ear lower than other
- often indicates a vestibular disorder (i.e. a disorder of the balancing system)
Outline head turning
- where the median plane of the head remains perpendicular to the ground, i.e. nose turned to one side
- may indicate a forebrain disorder
Describe pendular nystagmus
- siamese, birman, himalayan (melanin disorder and more fibres cross over)
- congenital abnormality (larger # fibres cross chiasma)
- cerebellar disorders and visual deficits
- jerk nystagmus: horizontal, vertical and rotary
Name different types of nystagmus
- physiological
- pendular
- searching
- jerk (horizontal, vertical, rotary)
Name the 5 features of Horner’s syndrome (SA)
= loss of sympathetic innervation to eye:
- enopthalmos
- TE protrusion
- ptosis
- miosis
- (congested BVs)
Features of Horner’s syndrome in horses
- ptosis - examine eyelashes closely
- miosis
- enophthalmus
- prominent TE
- conjunctival and nasal hyperaemia
- sweating
Name 4 important CS to determine whether a vestibular lesion is central or peripheral
- conscious proprioceptive deficit
- consciousness
- cranial nerve deficits
- vertical nystagmus (will often improve with time)
Outline difference in CS between central and peripheral nystagmus
CENTRAL: possible conscious proprioceptive deficit, consciousness (normal, obtunded, stupor, coma), cranial nerves (5-8 may be affected), vertical nystagmus (yes)
PERIPHERAL: no conscious proprioceptive deficit, consciousness (alert, disorientation possible), cranial nerve deficits (8 only), no vertical nystagmus
What is the first Q that should be asked when examining a pupil for a peripheral vestibular proble?
Ototoxic drugs
What is a myringotomy?
sx procedure, penetration of TM, remove fluid from middle ear, relatively safe, very diagnostically helpful
CS - bilateral vestibular problem
- no nystagmus
- no occulovestibular response
- head swaying from left to right
3 parts - cerebellum
- vestibulo-cerebellum (central)
- spino-cerebellum (central)
- cerebro-cerebellum (peripheral)
3 functions - cerebellum
- maintain equilibrium
- regulate mm tone (–> preserves mm position at rest and mvt)
- coordinate mvt
If the head tilt is away from the sign of the proprioceptive deficit, what should you consider?
paradoxical vestibular problem (head tilt usually towards lesion but may be away from it and thus also away from the proprioceptive deficit)
Name different regions of the cerebellum 5
- rostral lobe
- caudal lobe
- flocculonodular lobe
- caudal cerebellar peduncle
- cerebella nuclei fragment
CS - cerebellar syndrome
- spastic, dys- or hyper-metric ataxia (goose-stepping)
- intention tremor
- ipsilateral menace deficit + normal vision
- broad-based stance
- postural reactions delayed with exaggerated responses
- menace deficit (ipsilateral) with normal vision
+/- anisocoria (pupil dilate contralateral to side of lesion)
+/- opisthotonus (rare)
+/- vestibular signs
Define opisthotonus
tetanic spasm in which the body is bent back and stiffened, head will be in an extended position
