Principles of brainstem disease Flashcards
What are the 3 different areas of the Brain?
Forebrain, Cerebellum, Brainstem
What is the reticular formation and what is its function?
Diffuse network of nerves in the brain
- All info goes through the RF before forebrain
- Main influence of mentation
What are the different levels of mentation?
level of consciousness
- Alert
- Obtunded
- Stuporous
- Coma
What are the 3 parts of the forebrain?
- Association areas - Cerebral Cortex (Neocortex)
- Emotional areas - Limbic system (Archicortex)
- Olfactory areas - Olfactory bulb (Paleocortex)
What does pleurothotonus mean?
Body curved laterally - head turn
What does forebrain syndrome include?
- Mentation
- Posture/Gait
- Cranial nerves
- Altered mentation
- pacing, head pressing, pleurothotonus
- Contralateral blindness + decreased menace response with normal PLR
What does forebrain syndrome include?
- Postural reactions
- Spinal reflexes
- Palpation
- Pain - sensation/perception
- Deficits on contralateral limbs in positioning
- Normal to increased on contralateral limbs
- Muscle tone can be increased
- Hyperalgesia syndrome
(thalamus); Pain on cervical spine, skull
Hypoalgesia; decreased facial sensation
What are the factors used to analyse quality of mentation?
- Altered awareness
- Altered mood
- Altered personality
- Altered sleep/wake state
What does altered quality of mentation indicate?
Forebrain lesion
What does altered level of mentation indicate?
Brainstem lesion
Define Obtunded:
Animal is lethargic and less responsive to its environment but still has the capability to respond in a normal manner.
Define Stuporous:
Animal appears asleep when undisturbed but can be aroused by painful stimulus
Define Comatose:
Unconscious, does not respond to painful stimulus, reflex activity can be present
What is the function of the forebrain?
Control of autonomic and endocrine function (appetite, thirst, temperature, electrolyte and water balance), sleep, consciousness, or better wakefulness.
Involves olfactory function, vision, and emotional behavioural patterns
What clinical signs can be present if there is a brainstem lesion? (Think function)
- Altered mentation - level = O/S/C
- Cranial nerves deficit - III - XII
- Proprioceptive deficits
- Central vestibular syndrome
- Abnormalities in respiratory and cardiovascular function
- Hemi/tetraparesis (all limbs) (UMN)
(Hemi-paresis towards the side of the lesion)
Describe brainstem syndrome
- Mentation
- Posture/Gait
- Cranial nerves
- Altered mentation level
- Paresis -all 4 limbs ipsilateral, opisthotonus, decerebrate rigidity
- III-XII
What does brainstem syndrome include?
- Postural reactions
- Spinal reflexes
- Palpation
- Pain - sensation/perception
- Deficits all four limbs or ipsilateral
- Normal to increased in all or ipsilateral limbs
- Muscle tone normal or increased
- Decreased facial sensation
Pain on palpation high cervical, skull
others: cardio and resp abnormalities
What are the Cranial nerves?
I Olfactory VII Facial II Optic VIII Vestibulocochlear III Oculomotor IX Glossopharyngeal IV Trochlear X Vagus V Trigeminal XI Accessory VI Abducens XII Hypoglossal
What does it do and how to test?
CN I: Olfactory
Smell; deficit would be Anosmia (loss of sense of smell). Very hard to assess
What does it do and how to test?
CN II: Optic
Vision
Assess with menace, pupillary light reflex, and dazzle reflex
Pretectal nuclei - PLR
Cross over of optic nerves at the optic chiasm - around 75% to the other side
What does it do and how to test?
CN III: Occulomotor
Innervates muscles of the eye:
Dorsal/ventral/medial rectus m
Ventral oblique m
Levator palpebrae superioris m
Deficits cause ventrolateral strabismus and parasympathetic dysfunction
What does it do and how to test?
CN IV: Trochlear
Rotates the eye; in a dog,
deficit will not be noticeable (since they have round pupils);
Cat, will notice rotation of the pupil (since NOT round pupils)
What does it do and how to test?
CN V Trigeminal
Facial sensation and motor to masticatory muscles
Deficits
- loss of facial sensation
- atrophy in the masticatory muscles, loss of jaw tone
What does it do and how to test?
CN VI: Abducens
Innervates medial muscle of the eye; deficit will cause medial strabismus
