Coma

1
Coma

• A state of unarousable psychologic
  unresponsive-ness in which the subjects lies with
  eyes closed
• Coma vs. Consciousness
• Consciousness wakefulness and responsiveness
• The severity of coma is measured by comparing the
  intensity of an external stimulus and the
  complexity and purposefulness of the response

2

• Hypersomnia
• excessive drowsiness and excessive sleep
• narcolepsy, hypothalamic disorders, drugs
• Akinetic mutism
• silent, alert, and awake appearance
• regular sleep-wake cycles
• no evidence of response to the environment,
  mental activities, or spontaneous movements

3

• Locked-in syndrome
• total paralysis of all somatic musculature
• preserved consciousness and most sensory
  modalities
• preserved vertical eye movements
• ventral pontine infarct
• Persistent vegetative state
• preserved brainstem function, including breathing
• spontaneous eye opening and regular sleep-wake
  cycles
• no recognizable cognitive function

4
Three categories of Coma

• Diffuse brain dysfunction
• matabolic encephalopathy
• drug intoxication
• Primary brain stem disorders
• brainstem stroke
• brainstem neoplasm, absecess
• Supratentorial mass lesions
• causing secondary brain stem compression

5
Systemic evaluation of Coma

• Is there systemic illness causing brain failure?
• Is there evidence of diffuse or focal brain
  injury?
• Is the patient improving or deteriorating?

6
Neurological examination in Coma

• Response to external stimulation
• Motor response
• Size and reactivity of pupils
• Eye movements and ocular reflexes
• Pattern of breathing

7
Response to external stimulation

• In order of verbal command, shouting, shaking,
  and noxious stimulation
• Localizing pain
• preserved brain stem function and intact
  connections to the appropriate cerebral
  hemisphere
• Eye opening
• preserved function of RAS

8
Motor responses

• Absence of any motor response
• severe brain stem damage
• severe sedative drug ingestion
• Decorticate, flexor posturing of the arms
• bilateral cerebral hemisphere damage
• toxic/metabolic encephalopathy
• Decerebrate, extensor posturing of the arms
• destructive lesions of the midbrain and upper
  pons
• hepatic and anoxic-ischemic encephalopathy

9
Pupillary responses

• Small, reactive pupils
• metabolic
• IICP with hypothalamic dysfunction
• Very small pupils (pinpoint)
• pontine lesion
• narcotic (opioids) overdose
• Bilateral dilated fixed pupils
• seizure, anoxic encephalopathy
• exogenous catecholamimes

10
Pupillary responses

• Midposition and fixed pupils
• midbrain dysfunction
• brain death
• Unilateral dilated pupil
• damage to IIIrd nerve from trnastentorial
  herniation

11
Eye movements

• Spontaneous roving, horizontal and conjugate eye
  movements
• intact brain stem
• diffuse or metabolic cortical dysfunction
• Conjugate lateral deviation
• massive hemispheric lesion (eyes toward lesion)
• pontine lesion (eyes away from lesion)

12
Eye movements

• Dolls eyes reflex
• intact brainstem function with depressed cortical
  influences
• normal sleep, coma, persistent vegetative state
• Ice water caloric test
• eyes toward the side of cold water
• absence in brainstem lesion, inner ear disease,
  deep drug coma, and anticonvulsants overdose

13
Pattern of breathing

• Cheyne-Stokes respiration
• Central neurogenic hyperventilation
• Apneustic breathing
• Irregular periodic breathing
• Ataxic breathing
• Yawning

14
Cheyne-Stokes respiration

• Periodic breathing, crescendo-decrescendo
• The result of the loss of frontal lobe controls
• Blood PCO2 drives brain stem respiratory center
• Posthyperventilation apnea
• Causes
• Frontal lobe damage, unilateral or bilateral
• Secondary to cardiac or respiratory failure

15
Central neurogenic hyperventilation

• Sustained, rapid, deep hyperpnea
• Not secondary to hypoxemia and acidemia
• Causes
• Upper brain stem lesion
• Metabolic disorders, especially the early stages
  of hepatic coma

16
Apneustic breathing

• Prolonged inspiratory gasp
• Discrete lesions of the mid-to-lower pons
• Need early intubation and ventilation
• Causes
• pontine infarct
• hypoglycemia, anoxia, or severe meningitis

17
Ataxic and irregular periodic breathing

• Completely irregular pattern
• Slow and progressed to apnea
• Respiratory center - dorsomedial medulla
• Terminal states
• Causes
• posterior fossa lesions
• medullary damage
• overdoses of opiate and sedatives

18
Differential diagnosis of Coma

• Metabolic and toxic causes
• presence of pupillary light reflex
• confusion and stupor precedes
• symmetric motor signs
• asterixis, myoclonus, tremor, seizures
  (generalized)
• central hyperventilation

19
Differential diagnosis of Coma

• Supratentorial mass lesions
• focal neurologic sings
• progresses in a rostral-caudal fasion
• Subtentorial masses or destructive lesions
• sudden onset of coma
• history of brain stem dysfunction (the 6 Ds)
• abnormal eye movements
• cranial palsies
• irregular respiration

20
Diagnostic procedures

• Metabolic or toxic causes
• blood, urine, gastric aspirates testing
• EEG
• Intracranial mass lesions, head injury
• CT
• Acute subarachnoid or intracerebral hemorrhage
• CT
• lumbar punctures
• Meningitis or encephalitis
• lumbar punctures

21
Treatment of Coma

• Immediate treatment, even when the diagnosis is
  uncertain, to prevent further brain damage
• Oxygenation and airway protection
• ET tube
• ventilation
• Blood pressures maintain
• volume replacement with isotonic solutions
• hemodynamic monitoring
• inotropic and vasopressor drugs

22
Treatment of Coma

• Glucose (50 mL of 50 glucose)
• Thiame (100 mg, with the glucose)
• Seizures stop
• Intracranial hypertension lower
• Systemic infections control
• Acid-base and electrolytes imbalances correct
• Hyperthermia treat

23
Prognosis Hypoxic-ischemic encephalopathy

• 1st day absence of pupillary responses predicts
  poor outcome
• 2nd day no patients lack corneal reflex regained
  consciousness
• After 3rd day lack or purposeful motor responses
  predict poor outcome

24
Persistent Vegetative State (PVS)

• A form of eyes-open permanent unconsciousness.
• Periods of wakefulness and physiologic sleep/wake
  cycles.
• Unaware of self or environment.

25
Persistent Vegetative State (PVS)

• No voluntary action or behavior. Only primitive
  reflexes and vegetative functions.
• Careful and extended clinical observation,
  supported by laboratory studies.
• In cases of hypoxic-ischemic encephalopathy,
  observation period of one to three months.
• Prolonged survival.
• No pain or suffering.

26
Neurological criteria for Death

• The Uniform Determination of Death Acts
• irreversible cessation of circulatory and
  respiratory functions, or
• irreversible cessation of all functions of the
  entire brain, including the brain stem
• The determination of death must be made in
  accordance with accepted medical standards

27
Diagnosis of Death by neurologic criteria

• A clinical diagnosis, with preconditions and
  confirmatory tests
• The core of the clinical diagnosis is to
  establish unresponsiveness and brain stem
  areflexia
• The preconditions
• the cause of coma be known
• the cause be adequate to explain the coma

28
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