11 – Neuro III Flashcards
What are the sensory only CNs?
- CN 1, 2, 8
- *NO LMN SIGNS
What is the only CN that’s pathway does NOT go through the thalamus?
- CN 1
What CNs does the menace response test?
- Sensory: CN II
- Motor: CN VII
What CNs does the palpebral/corneal response test?
- Sensory: CN V
- Motor: CN VII
What CNs does the pupillary light reflex (PLR) (direct/consensual) test?
- Sensory: CN II
- Motor: CN III
What CNs are involved in facial sensation?
- CN V
- CN VII
What CNs are involved with strabismus (extra-ocular muscles)?
- CN III
- CN IV
- CN VI
What CNs are involved in the gag reflex?
- CN IX
- CN X
- CN XII
CN II (optic): deficit
- *can the animal see?
o If unilateral damage in right cerebral cortex=lateral of R, medial of L=circling towards lesion cause can’t see - Blind
- Loss of menace
- Loss of PLR (CN III is not getting any info to respond)
CN III (oculomotor): deficit
- Dilated pupil
- Loss of PLR (CN II giving sensory input, put not able to do the motor end)
CN V (trigeminal): deficit
- Decreased jaw tone (dropped jaw)
- Atrophy muscles of mastication
- Loss of facial sensation
- *mixed nerve
CN VII (facial): deficit
- Drooped face (can be difficult when bilateral)
- Loss of blink (motor)=no palpebral!
- Loss of lip twitch and ear twitch
- Decreased tear production
- *muscles of facial expression
CN VIII (vestibulocochlear): deficit
- Loss of balance
- Head tilt
- Loss of hearing
CN IX (glossopharyngeal) and X (vagus): deficit
- Dysphagia
- Loss of gag reflex
- Laryngeal paralysis
CN XII (hypoglossal): deficit
- Loss of tongue strength
- Tongue atrophy
- Tongue deviation: opposite side of lesion
Horner’s syndrome: clinical signs
- Miosis (small pupils)
- Prolapsed 3rd eyelid
- Ptosis (smaller palpebral fissure)
- Enophthalmos: sunken eye
- **DUE TO DECREASED INPUT OF THE SNS INPUT TO THE EYE
- In large animals: might see peripheral vasodilation=sweating on side of lesion OR opposite can happen as well
Horner’s’: first order (central)
- Rare
- Intracranial lesion
- Cervical cord lesion
Horner’s: secondary (preganglionic)
- SC T1-T3
- Brachial plexus
- Nerve roots T1-T3
- Cranial mediastinal mass
- Cervical soft tissue trauma
- Neoplasia
Horner’s: third order (postganglionic)
- Otitis media/interna
- Neoplasia middle ear
- Retrobulbar injury or neoplasia
Forebrain
- Cerebral cortex
- Diencephalon
Cerebral cortex/forebrain lesions:
- Altered behaviour/mentation
- Cortical blindness (opposite)
- Diminished facial sensation (opposite)
- May circle/pace TOWARDS lesion (‘wide’)
- Inconsistent/mil loss of conscious proprioception on side opposite lesion
- Gait may be normal
- Hemi-neglect (hypoalgesia/blindness)
Brainstem lesions
- Altered mental state: depress, stupor, coma
- IPSILATERAL proprioceptive ataxia
o UMN hemiparesis - Multiple CN deficits
- +/- vestibular signs
Vestibular system lesions
- Head tilt
- Balance problems (‘tight circles)
- Vestibular ataxia
- Nystagmus
- Proprioceptive ataxia if brainstem (central) disease
Vestibular disease: central AND peripheral signs
- Head tilt towards lesion (tilt to least active side)
- Spontaneous nystagmus at rest (fast phase away from side of lesion): horizontal, rotary, vertical
- 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
o Does NOT change direction as change head position - Postural reactions and proprioception are ALWAYS normal
- Other CN NOT affected
o Except may see concurrent Horner’s syndrome and/or CN7 paralysis if middle/inner ear disease
Central vestibular disease signs
- VERTICAL nystagmus (or horizontal or rotary)
o Changes DIRECTION as change head position - Abnormal postural reactions/proprioception on SAME SIDE of lesion
- Other CN nerves (besides CN VII) affected
Cerebellar disease: signs
- Mentally normal
- Strong, hypermetric
- Exaggerated limb responses: goose stepping
- *loss of fine tuning of motor control
- May see head tremor or intention tremor
Paradoxical vestibular disease
- Normally cerebellar nuclei inhibit brainstem vestibular nuclei
- If cerebellar lesion=decrease normal inhibition of adjacent brainstem
vestibular - Normal brainstem side will have LESS activity than other side
- *head tilt towards normal side (opposite to side of lesion)
- Ex. if lesion on right side of cerebellum=more active side=head tilt to least active side
When do you recognize paradoxical vestibular disease?
- Head tilt to one side
- Postural reaction deficits and other CN deficits on OPPOSITE side (due to brainstem lesion)
- *lesion is on side with postural reaction deficits and CNS=side opposite the head tile
