Principles of brainstem disease Flashcards
Which cranial nerves have parasympathetic function?
3, 7, 9, 10
What are the parts of the brainstem?
midbrain
pons
medulla oblongata
each include cranial nerve nuclei of CN 3-12
What are the brainstem functions?
highway for all ascending and descending info
maintains consciousness (ARAS)
gait generation
CN 3-12
cardiorespiratory function
vomiting reflex
coordination and balance
What are clinical signs of brainstem disease?
reduced mentation: obtunded, stuporous, comatose
head tilt, decerebrate rigidity
paresis and general proprioceptive ataxia, +/- vestibular ataxia
reduced/absent postural reactions in all limbs or ipsilateral to lesion
deficits in function of CN 3-12
cervical hyperaesthesia and increased muscle tone possible
cardioresp abnormalities possible
What are the signs of decerebrate rigidity?
LMN limbs/trunk/neck released from UMN inhibition
opisthotonos extensor tone ++ in thoracic/pelvic limbs
unconscious: stupor/coma
midbrain lesion
What are the signs that ataxia is general proprioceptive?
brainstem/spinal cord affected
delayed protraction, lengthened stride, abduction/adduction of limbs, scuffing, dragging, knuckling
What are the signs that ataxia is vestibular?
central (brainstem)/ peripheral (vestib. organ or CN 8)
falling, leaning, circling, other signs of vestibular disease
What are the signs that ataxia is cerebellar?
hypermetria, wide based stance, titubation and other signs of cerebellar disease
What are the most common inflammatory brainstem diseases?
Meningoencephalitis of unknown aetiology (MUA)
What are the most common infectious brainstem diseases?
feline infectious peritonitis FIP
What is the most common vascular brainstem disease?
cerebrovascular infarct
What is the motor function of CN 3 oculomotor?
extraocular muscles: movement of globe
levator palpebrae superioris: elevation of dorsal eyelid
What are the clinical signs of motor dysfunction of CN3 oculomotor?
lateral strabismus
ptosis
What is the parasympathetic function of CN 3 oculomotor?
iris sphincter muscle: pupil constriction/miosis
ciliary muscle
What are the clinical signs of parasymapthetic dysfunction of CN3 oculomotr?
mydriasis +/- aniscoria
interal ophthalmoplegia/paresis
What is the motor function of CN 4 trochlear?
extraocular muscle: movement of globe
What are the clinical signs of motor dysfunction of CN 4 trochlear?
lateral extortion of ipsilateral pupil if affecting trochlear nerve
lateral extortion of contralateral pupil if affecting trochlear nucleus
What is the motor function of CN6 abducens?
extraocular muscles: movement and retraction of globe
What are the clinical signs of motor dysfunction in CN6 abducens?
medial strabismus
failure to retract the eye
What signs tell us the strabismus is caused by a problem with CN 8?
only apparent with changes in head/neck position aka positional
ventrolateral direction
additional signs of vestibular dysfunction
What signs tell us that the strabismus is caused by a problem with CN 3, 4 or 6?
apparent regardless of head position aka fixed
lateral
lateral extortion (dorsal pole of globe rotates laterally)
medial
additional signs of CN 3, 4, 6 dysfunction