Coma scores, ICP, deteriorating mental status Flashcards
Five patient evaluation parameters that aid in lesion localization and prognosis for recovery include:
(1) level of consciousness
(2) motor activity
(3) respiratory patterns
(4) pupil size and reactivity
(5) oculocephalic reflex.
Stupor or Semicoma:
Coma:
are segmental spinal reflexes are present?
patient responds only to vigorous or painful stimuli
not respond consciously to any stimuli
yes
cranial nerve reflexes may be present, depending on the location of the lesion causing the coma
Importance of RAS:
anesthetized cats, transection of the brainstem at the level of the pons and midbrain =
transection medulla and cervical spinal cord =
coma
no coma
mentation abnormalities result from structural or metabolic disease affecting:
cerebrum or reticular activating system (brainstem)
lesion rostral to brainstem rarely have gait abnormalities aside from:
contralateral proprioceptive reactions
describe lesion location and difference between decerebrate and decerebellate:
rostral pons and midbrain
- opisthotonus with extensor rigidity of all four limbs
- mentation is stuporous to comatose
acute cerebellar lesions
- opisthotonus with extensor rigidity of the thoracic limbs and either extension or flexion of the pelvic limbs
- patient should be responsive and have voluntary movement
Cheyne-Stokes breathing:
location:
- periods of hyperpnea alternating with
- periods of apnea
diffuse cerebral
thalamic disease
metabolic encephalopathies
Central neurogenic hyperventilation:
location:
Apneusis:
location:
Irregular or “ataxic” breathing:
location:
persistent hyperventilation - respiratory alkalosis midbrain lesions
pauses for a period at full inspiration
pontine lesions
irregular frequency and depth typically precedes
lower pons and medulla
pupil size
_____ innervation is particularly important when evaluating for neurologic deterioration because:
parasympathetic
- mediated through the midbrain & CNIII
- loss of parasympathetic innervation results in mydriasis
Lesion Localization
Unilateral mydriatic, unresponsive pupil:
Bilateral miosis:
Bilateral, mydriatic, unresponsive pupils:
- loss of parasympathetic innervation
- destruction/compression of ipsilateral midbrain or CN III
- often associated w >ICP & unilateral cerebral herniation
- RO unilateral topical ophthalmic atropine or tropicamide
- metabolic encephalopathies
- or diffuse midbrain compression w >ICP
- may precede mydriatic, unresponsive pupils
- severe, bilateral compression midbrain or CNIII
- bilateral cerebral herniation; grave prognosis
Loss of the oculocephalic reflex occurs with lesions of the __________
which coordinates functions of cranial nerves ____
medial longitudinal fasciculus
III, IV, and VI
indicates a poor prognosis
neurologic evaluation should be repeated at least every ____ in patients with severe head injuries to assess for deterioration and/or to monitor tx
30 to 60 minutes
An almost linear correlation between this scoring system and the:
Platt SR. Px MGCS in head trauma in dogs
J Vet Intern Med, 15 (2001)
immediate or short-term survival of dogs w TBI
not long term (also exclude animals with concurrent inj.)
MGCS <8 = < ___% survival
50%
Motor Activity (6-1)
Brainstem Reflexes (6-1)
Level of Consciousness (6-1)
Motor Activity
Normal gait, normal spinal reflexes 6
Hemiparesis, tetraparesis, or decerebrate activity 5
Recumbent, intermittent extensor rigidity 4
Recumbent, constant extensor rigidity 3
Recumbent, constant ext. rigidity w opisthotonus 2
Recumbent, hypotonia of m, depr./absent spinal reflexes
Brainstem Reflexes
Normal PLR and oculocephalic reflexes 6
Slow PLR & normal to reduced oculocephalic reflexes
Bilateral, unresponsive miosis w normal/reduced oculoc
Pinpoint pupils w reduced/absent oculocephalic reflexes
Unilateral, unresponsive mydriasis w reduced/absent oc.
Bilateral, unresponsive mydriasis with reduced to absent oculocephalic reflexes 1
Level of Consciousness
Occasional periods of alertness/respon to environ 6
Depression or delirium, capable of responding but response may be inappropriate 5
Semicomatose, responsive to visual stimuli 4
Semicomatose, responsive to auditory stimuli 3
Semicomatose, responsive only noxious stimuli 2
Comatose, unresponsive to noxious stimuli 1
Mild size discrepancy between the two pupils (<3 mm) in humans and outcome:
not been assoc. significantly w patient outcome in humans
hippus
In humans, bilateral optic nerve injury may result in bilaterally fixed or sluggish pupils, sometimes with autonomic balance fluctuations causing spontaneous fluctuations in diameter
Pupils that respond appropriately to light, even if miotic, indicate adequate function of:
In the absence of concurrent ocular trauma, miosis may indicate a _____ lesion, particularly in the ____ because this area represents the origin of the SNS pathway
rostral brainstem, optic chiasm, optic nerves, and retinas
diencephalic lesion
hypothalamus
unilateral mydriasis and loss of direct light reflex in one eye commonly implies a cranial nerve III paralysis and commonly is accompanied by ptosis and ventrolateral strabismus - in humans, this can be a sign associated with:
extradural bleeding and warrants immediate advanced imaging
Oculocephalic reflexes may be impaired in animals with brainstem lesions as a result of either involvement of cranial nerve nuclei that innervate the extraocular muscles or the interconnecting ascending:
medial longitudinal fasciculus w.in the pons & midbrain
Absence of eye movements upon irrigation of the external auditory canal with ice-cold water (oculovestibular reflex) is indicative of profound brainstem failure and is an accepted …
criterion of brain death in humans
However, such a test should not be performed if there is any suspicion of a cranioaural fistula or a skull base fracture
Four categories of survival are recognized and are listed as
good recovery
moderate disability (independent but disabled)
severe disability (conscious but dependent)
vegetative state
Full Outline of UnResponsiveness (FOUR) score
-also includes important information not assessed by the human GCS, including:
The FOUR score has four components:
/cat maximal value of 4
not translated easily into a veterinary scoring system
simpler, more accurate, and more consistently used in human medicine
most likely a similar improved scoring system will be available in veterinary medicine in the near future.
determination of eye opening, blinking, and tracking; presence of abnormal breath rhythms & resp drive
eye responses
motor responses
brainstem reflexes
respiratory pattern
