COMA Flashcards
Definition of consciousness
a state of full awareness of self and the
relationship to the environment
For there to be a state of consciousness what must be intact?
Arousal (aka alertness or awareness) and content must be intact
What is arousal?
global state of responsiveness
What is awareness?
brain’s ability to perceive specific environmental stimuli in different domains including visual, auditory, interceptive and somatosensory.
What is the definition of a coma?
A state of unrousable unresposiveness.
Can also be defined as a state of reduction
in the level of consciousness to a point where the patient/subject can not make meaningful responses to environmental stimuli.
What parts of the brain control consciousness?
Cerebral hemispheres (cortex provides the content of consciousness)
Ascending R.A.S (brainstem).
-arouses & maintains alertness
-spans dorsal upper pons, mesencephalon, thalamus
What is the neurophysiology of a coma?
What must happen for a coma to occur?
Failure of the arousal system resulting from injury to the brainstem
Extensive (usually bilateral) injury to
the cortex resulting in failure of the cortex to respond to the stimulus of the ARAS
What are the coma mimics?
These are disorders that can easily be mistaken for coma but do not involve interruption of the ARAS-thalamocortical pathway.
- Locked-in syndrome
- Neuromuscular paralysis
- Akinetic mutism
- Psychogenic unresponsiveness
What do you do to exclude psychogenic unresponsiveness?
diagnosis of exclusion: hand-drop
test nose hair tickle test
All sensory information passes through the thalamus except?
Olfactory information
Which part of the brain is affected in locked in syndrome?
Ventral pons
What movements is the patient limited to in locked in syndrome?
Vertical eye movements
What is the Pathophysiology of a coma?
Coma will result if there is severe disruption of anatomic or physiologic functioning of these critical structures by structural, chemical or infectious etiologies.
Coma requires dysfunction of either the:
* Brainstem reticular activating system, or
* Bi-hemispheric cerebral dysfunction
What are the types of cerebral herniation?
Which 2 are the worst type?
- Uncal (very bad): involves the midbrain
- Central
- Transfalcial
- Foraminal (worse): the patient has coned, the brainstem organs have herniated into the foramen magnum
Do Unilateral insults to the cerebral hemisphere result in unconsciousness?
Unilateral insults to the cerebral hemisphere will not result in unconsciousness
unless there is secondary brain stem compression, caused by transtentorial
herniation, compromising the ARAS.
Therefore it is very rare
What part of the brain is affected in akinetic mutism?
Angular gyrus (brodmann area 39), causing them to be akinetic (lacking the ability to move or showing a lack of movement)
It is a neurological condition characterized by a lack of voluntary movement (akinesia) and speech (mutism), despite preserved consciousness
The approach to diagnosis of the comatose patient consists of 2 vital steps which are?
- Resuscitate & stabilize the patient and treat presumptively all life threatening disorders.
- Establish an etiologic diagnosis from general and neurologic examination
which will guide further investigations and treatment - Assessment and intervention needs to be done simultaneously
i.e. IV access, RBG, a high flow oxygen supply, cardiac and O2 saturation monitoring as soon as feasible, with a 12-lead ECG and pulse oximetry, inserting a NGT to prevent aspiration pneumonitis and urinary
catheterization to monitor urine output.
Cerebral lesions of the left will affect which side of the body and why?
Cerebellar lesions of the left will affect which side of the body and why?
- On the opposite side (right) due to decussation
- On the same side (left) due to double decussation
Causes of a coma
V - vascular eg. Stroke, arterovenous malformation, PRES
I - Infections eg. Meningitis, cerebral abscess, empyema, encephalitis
T - Toxins (and trauma) eg. Lead poisoning, arsenic poisoning, CO poisoning
A - Anoxic injury eg. In fetuses during Prolonged labour - Alcohol intoxication and withdrawal
M - Metabolic eg. Hypoglycemia, hyperglycemia, hyponatremia, hypernatremia,
I - Inflammatory eg. SLE
N - Neoplasms: primary or secondary, primary: neoplasm of paired organs eg. Lungs, kidneys, breast adrenal gland etc.
D - Demyelinating eg. MS, - Development, - Degenerative
Discuss the A-B-C-D2-E approach of management for coma: Airway
- Airway (ensure patency-clear any airway obstruction e.g. dentures, secretions etc ±
intubation, if spine instability is suspected tracheostomy should be performed)
Discuss the A-B-C-D2-E approach of management for coma: Breathing
- Breathing (Adequacy of ventilation can be established by the absence of cyanosis, RR > 8/min and the presence of symmetric breath sounds on auscultation)
Discuss the A-B-C-D2-E approach of management for coma: Circulation
- Circulation (Pulse and BP measurement rapidly assesses the circulatory status and any embarrassment should be treated with IVFs, pressor agents and antiarrhythmic drugs as indicated)
Establishing IV access and withdraw blood for:
Estimation of glucose
Other biochemical parameters (CHEM 7, LFTs, FBC, Clottology)
Drug screening
Institute treatment for seizures if present.
Discuss the A-B-C-D2-E approach of management for coma: Drugs
Drugs used in the resuscitation phase of coma management called
“coma cocktail,” remembered by the mnemonic “DON’T Flush”
D-dextrose (IV 50 mL of 50% Dextrose Water in double dilution should be
given bolus)
O-oxygen (high flow-SpO2<92%)
N-naloxone (opioid antagonist)
T-thiamine/Bcomplex (100 mg IV-alcoholics and severe malnutrition)
F- Flumazenil (BZD (benzodiazepine eg. diazepam, lorazepam) antagonist)
Discuss the A-B-C-D2-E approach of management for coma: Disability
Disability Neurologic
Glasgow coma scale
Provides easily reproducible and somewhat predictive basic neurologic exam
Allows rapid assessment and record of baseline neurologic status
Allows tracking neurologic changes over time even with multiple examiners
How do we assess coma according to GCS
Individual elements as well as the sum of the score are important.
Hence, the score is expressed in the form “GCS 8 = E2 V3 M3 at 07:35”
Generally, comas are classified as:
Severe AMS or Coma, with GCS ≤ 8
Moderate AMS, GCS 9 - 12
Minor AMS, GCS 13-14
NB: GCS<4 may be termed vegetative state
Discuss the A-B-C-D2-E approach of management for coma: Exposure
Exposure means conducting a thorough examination of the patient from
head to toes while avoiding hypothermia.
Palpate the entire surface of the body to detect any clues that may
explain the condition or may become life threatening, as well as those that
may be left untreated
Each system and every orifice should be systematically examined.
A log roll to examine the back must be performed.
