Principles of Brainstem Diseases Flashcards
What clinical signs does forebrain syndrome include?
Altered mentation
Pacing/head pressing/pleurothotomus
Contralateral blindness and decreased/absent menace response with normal PLR
Deficits in contralateral limbs
Muscle tone can be increased
Hypoalgesia with decreased facial sensation, hyperalgesia syndrome and high cervical or skull pain
What are the three areas of the forebrain? What are each of the three areas associated with?
Neocortex = association areas in the cerebral cortex Archicotex = emotional areas in the limbic system Paleocortex = olfactory areas in the olfactory bulb
What are the functions of the brainstem?
Mentation
Autonomic control of respiratory patterns and cardiovascular systems
Multiple cranial nerve nuclei situated there
Vestibular system
UMN pathways causing paresis to plegia if damaged
What clinical signs does brainstem syndrome include?
Altered mentation
Paresis of all four limbs, opisthotomus, deretrate rigidity
CNs III-XII can be affected
Postural reaction deficits in all four limbs or ipsilateral to lesion
Spinal reflexes normal to increased in all four limbs or ipsilaterally
Muscle tone normal to increased
Decreased facial sensation, pain on cervial/skull palpation
What is the visual pathway of the optic nerve?
Optic nerve -> optic chiasm -> optic tract -> lateral geniculate nucleus -> optic radiations -> occipital cortex
What is the pathway of the menace response?
Optic nerve -> optic chiasm -> optic tract -> lateral geniculate nucleus -> optic radiations -> occipital cortex -> primary motor cortex -> pontine nucleus -> ipsilateral cerebellar cortex -> facial nucleus -> muscles blink
What is the pathway of the PLR?
Optic nerve -> optic chiasm -> pretectal nucleus -> parasympathetic nucleus of CN II -> ciliary ganglion -> post-ganglionic parasympathetic supply to the iris
What methods are there for testing the optic nerve?
Vision (maze/obstacle course)
Menace response
PLR
Dazzle reflex
What tests the oculomotor, trochlear and abducens nerve?
Oculovestiblar reflex and PLR
What muscles does the oculomotor nerve innervate? What happens to eye position if innervation is lost?
Dorsal, ventral and medial rectus, ventral oblique and levator palpebrae superioris
Ventro-lateral pupil position
Which eye muscle does the trochlear nerve innervate? What happens to eye position if innervation is lost?
Dorsal oblique
Can only see in cats and the pupil tilts so that it runs from dorsolateral to ventromedial
What eye muscles does the abducens nerve innervate? What happens if innervation to the muscles is lost?
Lateral rectus and retractor bulbi
Pupil moves medially
What does the trigeminal nerve innervate?
Sensory to the face and motor to masticatory muscles
How do you test the function of the trigeminal nerve?
Palpebral reflex tests the ophthalmic and maxillary sensory branches
Lower jaw sensation test the mandibular sensory branch
Tone/atrophy of masticatory muscles tests motor branch
What is the function of the facial nerve?
Responsible for facial expression, taste, rostral 2/3 tongue and lacrimation/sensation
