Neuro 3 Flashcards
Which CNs are sensory only?
1,2,8
**therefore no LMN signs
Where do CNs originate from?
From cerebrum or brainstem
-ipsilateral signs (no crossing over)
Which CN is the only one that does not go through the thalamus?
CN I
CN II
Optic nerve
-issues if Blind, loss of menace or loss of PLR
-often circle towards side of lesion?
CN III
Occulomotor nerve
-deficits= dilated pupil, loss of PLR
CN V
Trigeminal Nerve
-deficits= decreased jaw tone, atrophy of mastication muscles, loss of facial sensation
CN VII
Facial nerve
Deficits:
-drooped face
-loss of blink
-loss of lip twitch, ear twitch
-decreased tear production
CN VIII
Vestibulocochlear nerve
deficits:
-loss of balance
-head tilt
-loss of hearing
CN IX and CN X
9= glossopharyngeal
10=vagus
deficits:
-dysphagia
-loss of gag reflex
-laryngeal paralysis
CN XII
Hypoglossal nerve
deficits:
-loss of tongue strength
-tongue atrophy
-tongue deviation to strong non lesion side (contralateral)
Horners syndrome
-loss of Sympathetic NS input to eye
- +/- miotic pupil
- +/- 3rd eyelid prolapse
-ptosis (small palpebral fissue)
-enophthalmous (sunken eye)
-peripheral vasodilation on side of the lesion (ear, nose, neck) = increased sweat
*in horses, lack on innervation= reduced sweating
3 parts that are affected in horners syndrome
- First order
-rare. intracranial or cervical cord lesions - Second order (preganglionic)
-T1-T3, brachial plexus, nerve roots T1-T3, cranial mediastinal mass, cervical soft tissue trauma, neoplasia - Third order (postganglionic)
-otitis media/interna, neoplasia middle ear, retrobulbar injury or neoplasia
Whats the forebrain?
cerebral cortex and diencephalon (thalamus/hypothalamus)
Signs of a cerebral cortex/forebrain lesion
-seizures **almost always
-altered behaviour/mentation
-cortical blindness (opposite)
-diminished facial sensation (opposite)
-may circle/pace towards lesion
-inconsistent/mild loss of proprioception on side opposite of lesion
-gait may be normal
-hemi-neglect (hypoalgesia/blindness)
Signs of a brainstem lesion
-altered mental state (depression, stupor, coma)
-ipsilateral proprioceptive ataxia and UMN hemiparesis
-multiple cranial nerve deficits
-+/- vestibular signs
Lesions of vestibular system
-head tilt
-balance problems
-vestibular ataxia
-nystagmus
-proprioceptive ataxia if brainstem disease
Vestibular disease
-central and peripheral
-head tilt towards lesion
-spontaneous nystagmus at rest (fast phase away from side of lesion) = horizontal or rotary
-nystagmus may get worse or only be apparent with changes in body position (positional nystagmus)
-vomiting
-motion sickness
Peripheral vestibular disease signs
-nystagmus always horizontal or rotary and does not change direction with changed head position
-posture and proprioception is normal
-other CNs are not affected. EXCEPT can see concurrent horner’s and/or CN7 paralysis if middle/inner ear disease
Central vestibular disease
-vertical nystagmus; changes direction as change in head position
-abnormal postural reactions/proprioception on same side as lesion
-other cranial nerves (except 7) affected
Signs of cerebellar disease
-mentally normal
-strong, hypermetric
-exaggerated limb responses; goose stepping
-loss of fine tuning or motor control
-may see head tremor or intention tremor
Paradoxical vestibular disease
Head tilt towards the normal side (opposite of the lesion)
-occurs because cerebellar vestibular nuclei should inhibit brainstem vestibular nuclei and if a cerebellar lesion is present then inhibition so normal side has less activity than abnormal side
Paradoxical vestibular disease signs
-head tilt to one side
-postural reaction deficits and other CN deficits on opposite side (due to brainstem lesion)
-lesion on the side with postural reaction deficits and CN deficits (side opposite head tilt)
