DISORDER OF CONSCIOUSNESS

DR. SREEMAYEE KUNDUMD Paediatrics

• Consciousness is the state of awareness of self and environment.

• Dimensions: a) Wakefulnessb) Awareness• Clouding of consciousness: Minimal

reduction of wakefulness or awareness-main difficulty attention.

• Confusion: State of impaired ability to think and reason clearly at a developmentally and intellectually appropriate level.

• Sleep: Biologically active state with identifiable behavioral and EEG stages, with appropriate stimulus intensity and duration sleeping person can be aroused to a normal state of consciousness.

• Coma and other states of consciousness warrant medical emergency.

Pathophysiology

Pathophysiology

Integral Consciousness requires an intact - 1) Ascending reticular activating system,2) Cerebral cortex, 3) Healthy projections between the two

systems.

Reticular Formation

Pathophysiology: afferent and efferent connections of reticular formation

Pathophysiology: ARAS

Pathophysiology: ARAS

• Begins in the lower brainstem and extends upward through pons, midbrain, thalamus

• Finally project throughout cerebral cortex- into two pathways

a) through subthalamus b) through thalamus

Pathophysiology

• The state of wakefulness is mediated by neurons of the ascending reticular activating system(ARAS).

• Neural pathways from these locations project throughout the cortex , which is responsible for awareness.

Loss of consciousness will result if

• The function of ARAS neurons compromised or

• Both cerebral hemisphere are sufficiently affected by disease.

Proper function of ARAS and both cerebral hemisphere depends on:

• Presence of substrate for energy production• Adequate blood flow• Absence of abnormal metabolic wastes or

toxins• Normal body temperature• Absence of abnormal neuronal excitation or

irritation from seizure activity• Absence of CNS infections• Normal intracranial pressure

Etiology of impaired consciousness and coma

• Infectious or inflammatory• Structural• Metabolic, Nutritional, Toxic

Etiologies of Impaired Consciousness and Coma

1.Infectious or InflammatoryA. Infectious

• Bacterial meningitis• Viral encephalitis• Rickettsial infection• Protozoan infection• Helminth infestation

B. Inflammatory• Sepsis-associated encephalopathy• Vasculitis, collagen vascular disorders• Demyelination• Acute disseminated encephalomyelitis• Multiple sclerosis

Etiology –cont.2. StructuralA. Traumatic

Concussion Cerebral contusion Epidural hematoma or

effusion Intracerebral hematoma Diffuse axonal injury Abusive head trauma

B. NeoplasmsC. Focal Infection

• Abscess• Cerebritis

D. Hydrocephalus

E.Vascular Disease• Cerebral infarction

Thrombosis Embolism Venous sinus thrombosis

• Cerebral hemorrhage Subarachnoid hemorrhage Arteriovenous malformation Aneurysm

• Congenital abnormality or dysplasia of vascular supply

• Trauma to carotid or vertebral arteries in the neck

Etiology –cont.3.Metabolic, Nutritional, or

ToxicA. Hypoxic-Ischemic

Encephalopathy Shock Cardiac or pulmonary failure Near-drowning Carbon monoxide poisoning Cyanide poisoning Strangulation

B. Metabolic Disorders Sarcoidosis Hypoglycemia Fluid and electrolyte

imbalance Endocrine disorders

With acidosis Diabetic ketoacidosis Aminoacidemias Organic acidemias

With hyperammonemia Hepatic encephalopathy Urea cycle disorders Disorders of fatty acid metabolism Reye’s syndrome Valproic acid encephalopathy

Uremia Porphyria Mitochondrial disorders Leigh’s syndrome

Etiology -contC. Nutritional

Thiamine deficiency Niacin or nicotinic acid

deficiency Pyridoxine dependency Folate and B12 deficiency

D. Exogenous Toxins and Poisons Alcohol intoxication Over-the-counter

medications Prescription medications (oral

and ophthalmic)

Herbal treatments Heavy-metal poisoning Mushroom and plant

intoxication Illegal drugs Industrial agents

E. Hypertensive Encephalopathy

F. Burn Encephalopathy

Impairment of consciousnessstates

• Impairment of consciousness with activated mental state

• Impairment of consciousness with reduced mental state

• Impairment of consciousness along the continuum of coma–vegetative state–minimally conscious state and related conditions.

1) Impairment of consciousness with activated mental state

• Hallucination : Perception of sensory input that are not present.

• Illusion : Misinterpretation of actual sensory stimuli.

• Delusion : Incorrect thoughts or beliefs that do not change when challenged by contradictory evidence or logical reason.

• Delirium : Activated mental state that may include disorientation, irritability, fearful-responses, and sensory misperception.

2) Impairment of consciousness with reduced mental state

• Drowsiness• Obtundation arousal is present to stimuli• Stupor

State Stimulus needed for arousalDrowsiness Verbal and light touchObtundation Deep touchStupor Vigorous, painful, or noxious

stimulation

3) Impairment of consciousness along the continuum of coma–vegetative state–minimally conscious state and related conditions.

Coma

• State of deep, unarousable, sustained pathologic unconsciousness with the eyes closed that results from dysfunction of the ascending reticular-activating system in the brainstem or in both cerebral hemispheres.

• Patients in coma lack both wakefulness and awareness.

Vegetative state

• Complete unawareness of self & environment accompanied by sleep-wake cycles with complete/partial preservation of hypothalamic and brainstem autonomic function.

• Demonstrate : variety of sounds, emotional expressions, body movements, smile/shed tears.

• Lack of sustained visual fixation or tracking.

Clinical course of evolution to vegetative state- • Acute injury Coma several days-week

appearance of sleep-wake cycle.• Decorticate & decerebrate posturing, roving

eye movements, eye blinking appeared earlier.• Diagnosis – Clinically mainly.

Minimally conscious state

• Severely alterered consciousness, demonstrates minimal evidence of self / environmental awareness.

• Neurologic recovery-better.• Life expectancy- longer than vegetative state.

Locked-In Syndrome

• Retain consciousness & cognition but unable to move or communicate because of paralysis.

• Involvement – Descending corticospinal & corticobulbar pathways at or below Pons/ Peripheral nervous system.

• Rare in children.• Communication – using eye movements.

Akinetic Mutism• Rare condition.• Pathologically slowed or nearly absent bodily

movement accompanied by loss of speech.• Wakefulness and Self awareness - Preserved.• Mental function- Reduced.• Area Involved – damage to paramedian

mesencephalon,basal diencephalon,inferior frontal lobes.

Brain Death• Irreversible cessation of all functions of entire

brain,including brainstem.• Determination of death using neurologic

criteria.• Legally accepted in US as equivalent of death.• Universally not accepted.• Clinical diagnosis- 3 key components-

Irreversible coma with a known cause, Absence of brainstem reflexes and Apnea

Apnea• Absence of respiratory effort in response to

an adequate stimulus.• Apnea Clinically confirmed by apnea test.• Test is performed if first two criteria of brain

death are met.

• Absence of respiratory effort with pCO2 > 60

mm Hg and > 20 mm Hg above baseline then,

Apnea has been demonstrated, supporting the

diagnosis of brain death criteria.

Ancillary neurodiagnostic studies• Electroencephalography- Absence cerebral

activity over 30 min recording.• Radionuclide imaging – Absence of radionuclide

detection in brain parenchyma and large vessels.• Cerebral angiography – Absence of intracranial

filling of large cerebral arteries & branches.• Transcranial Doppler ultrasound- loss of

diastolic flow, systolic flow,flow reversal.

Observation periodAge 7 days to 2 months Two examinations 48 hours apart and one EEG Age 2 months-1 year Two examinations 24 hours apart and one EEG

or perfusion scanAge >1 year Two examinations 12 to 24 hours apart.EEG and

isotope angiography optional

Severe Disorders of ConsciousnessCondition Self-

AwarenessPain andSuffering

Sleep–WakeCycles

Motor Function RespiratoryFunction

Coma Absent No Absent No purposeful movement

Variablydepressed

VegetativeState

Absent No Intact No purposeful movement

Normal

MinimallyconsciousState

Very limited

Yes Intact Severe limitation of movement

Variablydepressed

Locked-in-syndrome

Present Yes Intact Quadriplegia,Eye movements +

Normal to variably depressed.

Brain Death

Absent No Absent None Absent

Approach to a child with coma

• Incidence of non-traumatic coma is 30/100,000 children per yr & traumatic brain injury is 670/100,000

• It is clinically useful to categorize the causes of coma into:

1) Coma with focal signs 2) Coma without focal signs and with

meningeal irritation 3) Coma without focal signs and without

meningeal irritation

Etiology of coma• Coma with focal signs

Intracranial hemorrhage Stroke: Arterial ischemic or sinovenous thrombosis Tumors Focal infections: Brain abscess Post seizure state: Todd’s paralysis Acute disseminated encephalomylelitis

Etiology: cont.• Coma without focal signs and with meningeal

irritation: Meningitis Encephalitis Subarachnoid hemorrhage

• Coma without focal signs and without meningial irritation:

• Hypoxic-ischemia: cardiac or pulmonary failure,cardiac arrest, shock, near drowning

Etiology: cont.• Metabolic disorders:

Hypoglycemia Acidosis: DKA, organic acidemias Hyperammonemia: hepatic encephalopathy, urea

cycle disorders, valproic acid encephlopathy, Reye syndrome.

Uremia Fluid and electrolyte disturbance (dehydration,

hyponatremia, hypernatremia)• Systemic infections :

Gram negative sepsis, TSS, meningitis shigella/enteric encephlopathy

Etiology: cont.• Post infectious disorders:

Acute Disseminated Encephalomyelitis Acute necrotising encephalopathy Hemorrhagic shock and encephalopathy syndrome

• Post immunisation encephalopathy Whole cell pertusis vaccine

• Drugs and toxins • Cerebral malaria• Rickettsial : lyme disease, rocky mountain spotted fever• Hypertensive encephalopathy• Post seizure states• Non-convulsive status epilepticus

Rapid assessment and stabilization

Rapid assessment and stabilization• Establish and maintain airway: Intubate if

GCS<= 8 ,impaired airway reflexes, abnormal breathing pattern, signs of raised ICT, oxygen saturation<92% despite high flow oxygen, fluid refractory shock

• Ventilation, Oxygenation • Circulation: Establish IV access, take samples.• Fluid bolus: In circulatory failure (20ml/kg NS),

inotropes if required • Blood glucose : Strip testing , if <50mg/dl give

10% D , 2ml/kg.

• Identify signs of cerebral herniation or raised ICP: ( if GCS<8,abnormal pupil size and reaction, absent dolls eye movements, abnormal tone or posturing, hypertension with bradycardia, abnormal respiratory pattern)

Act immediately – Fluid restriction, Elevate the Head end of bed at 30 degree, Intubate & short term Hyperventilation,20% Mannitol (0.5-1g/kg)/ Furosemide /3% NS(if in shock), Sedation, Barbiturate therapy, reduce fever, high dose of corticosteroids, Decompressive craniectomy.

• Temperature : Treat fever and Hypothermia• Acid-base and electrolyte imbalance: to be

corrected.• Specific Antidotes: Naloxone - opiate

overdose, Flumazenil – benzodiazepine overdose.

• Stop seizures: Specific treatment for status epilecticus & other seizure emergencies. Give IV lorazepam 0.1-0.2mg/kg , then phenytoin 20mg/kg loading.

• Treat infection: Appropriate antibiotic/antiviral therapy to be started

• Manage agitation : May increase ICP, difficult to control respiration under MV – Sedate.

History: AgeInfant Child Adolescent

CNS infection (meningitis,encephalitis)

Ingestion Drug/Alcohol overdose

Systemic infection with shock CNS infection Intentional poisoning

Metabolic disorders Seizure Trauma, seizures

Abuse / Trauma, Abuse / Trauma CNS infection,

Inborn errors of metabolism,seizures

DKA, Reye syndrome

DKA, , Reye syndrome

Post immunisation encephalopathy, hemorrhagic shock and encephalopathy syndrome

History: Onset, episode • Sudden onset: Intracranial haemorrage or a

convulsion• Acute onset in normal child: Ingestion of drug,

toxin, poison.• Gradual onset : Infectious process, metabolic

derangement.• Intermittent episode : Ingestion, Drug overdose,

IEM.• Recurrent episode : use of ophthalmic drops

Brimonidine-can cause coma in 1month child,epilepsy,IEM.

History: Associated symptoms• Fever – Infections• Headache, Vomiting, Diplopia – Increased

ICP• Neck stiffness – Meningitis, SAH• Rash - Meningococcemia• H/o excess cry, irritability, enlarging head in

infants – Meningitis, Hydrocephalus• Retinal hemorarhage,metaphyseal #, rib #,

subdural hge, Bleeding from ear/nose – Traumatic brain injury• Seizures – ICH, ICSOL, Epilepsy, Post-ictal

History• H/o of infectious disease – Mumps (Parotid

swelling), measles (rash), TB, Malaria, Dengue.• Failure to thrive, vomiting, peculiar skin & urine

odour – Metabolic cause• Jaundice, abdominal distension, hematemesis,

melena, bleeding - Hepatic encephalopathy• ↓ Urine output, swelling, periorbital puffiness,

Nausea, vomiting, loss of appetite – Uremic encephalopathy

• H/o use of stove/ heater – CO poisoning.

History• H/o loose stools- HUS, Hypovolemia,

Ingestion of toxins/poisons, medications• H/o Diabetes – hypoglycemia / ketoacidosis• H/o Congenital heart disease – brain

Abcess/ infarction• H/o Immunocompromised state, malignancy• Family h/o TB, migraine, epilepsy• Birth H/o: Birth asphyxia• H/o envenomation

Clues to etiology of coma in general examinationLook for if present ,think ofPallor Cerebral malaria, intracranial bleed, hemolytic uremic

syndrome

Icterus Hepatic encephalopathy, leptospirosis, complicated malaria

Rashes Meningococcemia, dengue , measles, rickettsial diseases, arboviral diseases

Petechiae Dengue, meningococcemia , hemorrhagic fevers

Head and scalp hematomas

Traumatic/ non accidental injury

Dysmorphism,neurocutaneusmarkers

Possibility of seizures

Abnormal odour DKA, hepatic coma

Cyanosis Cyanotic congenital heart disease, Hypoxia

Oedema CHF, Renal failure

Dehydration Hypovolemic shock, HUS

Vital Signs• Temp: Fever – Sepsis, pneumonia, meningitis, encephalitis,

intracranial abscess,empyema.Hypothermia - Sepsis, shock, alcohol, barbiturate

poisoning, hypoglycemia.Very high fever and dry skin – Heat stroke.• HR: Bradycardia - ↑ ICT, myocardial injury due to

hypoxia, sepsisTachycardia - Shock, Infections, Fever, Heart failure Irregular - Arrhythmia.

Vital Signs• RR: Bradypnea/ Apnea - Drug intoxication, septicemia Tachypnea - Metabolic Acidosis, Pneumonia, Asthma,

Pulmonary embolism, Brainstem lesion. Cheyne-Stoke breathing - B/L cortical damage with intact

brainstem Irregular - medulla involved Slow periodic – raised ICP• BP: HTN - ↑ICP or stroke, HTN encephalopathy Hypotension - Shock, sepsis, myocardial injury / failure,

drug ingestion , adrenal insufficiency.• SPO2 monitoring:

Respiratory pattern

• Patient breathing pattern is also helpful in localising area of CNS dysfunction. They are :

Cheyne-Stokes respirationBiot’s breathing / Cluster breathing Kussmaul’s breathingApneustic breathingAtaxic breathingCentral neurogenic hyperventilation

Neurogical Assesment

Level of consciousness Pupillary responsesBrainstem function Motor response Other neurological findingsHerniation syndrome

A. Level of conciousness

• The level of conciousness must be recorded in the form of an objective scale.

• The Glasgow coma scale is a useful tool for the grading of the degree of altered consciousness and the severity of CNS insult.

• Glasgow coma scale is used for adults and older children and its modification is used in infants and young children.

Glasgow coma scaleACTIVITY

BEST RESPONSE

Adults/Older Children Infants ( modified GCS ) Score

Eye Opening( E )

1. Spontaneous2. To speech3. To pain4. None

1. Spontaneous2. To speech3. To pain4. None

4321

Verbal( V )

1. Appropriate speech2. Confused speech3. Inappropriate words4. Incomprehensible or

none specific sounds5. None

1. Coos, babbles2. Irritable, cries but

consolable3. Cries, inconsolable4. Moans to pain

5. None

54

32

1

Motor( M )

1.Obeys commands

2.Localizes pain3.Withdraws to pain4.Decorticate to pain5.Decerebrate to pain6.None

1. Spontaneous movement

2. Withdraws to touch3. Withdraws to pain4. Decorticate to pain5. Decerebrate to pain6. None

6

54321

B. Size and reactivity of pupilsPupils Lesion/Dysfunction

Pinpoint Pons, opiates, cholinergic intoxication

Mid position –fixed or irregular

Midbrain lesion

Unilateral , dilated and fixed

Uncal herniation

Bilateral , dilated and fixed

Diffuse damage, central herniation, global hypoxia ischemia, barbiturates, atropine

C. Brainstem function

1)Pupillary light reflex

2)Oculocephalic reflex (doll’s eye reflex)

3)Corneal reflex

4)Oculovestibular reflex (caloric reflex)

5)Gag and Cough reflex

Pupillary light reflex

• Area tested – CN II ,III, midbrain.

• Midposition (4-6mm) or fully dilated pupils,not reactive to light – consistent with brain death.

Oculocephalic reflex

• Area tested – CN III, VI and VIII, midbrain , pons.

• Should not be performed patient with cervical injury.

• Intact patient – eyes remain fixed on a distant spot as if maintaining eye contact.

• Brain death- eyes move with patient head movement.

Corneal reflex

• Area tested – CN III,V and VII, pons.

• Intact patient – touch result in eyelid closure and eye may rotate upward.

• Brain death– no response.

Oculovestibular reflex

• Area tested – CN III, IV, VI and VIII, pons, midbrain.

• Brain death – Absent of eye movement.

Gag and Cough reflex

• Area tested – CN IX and X , medulla.

• Brain death – absence of both cough and gag reflex.

D. Motor response

• Single best indicator of the depth and severity of coma

1. Spontaneous movements.2. Tone and reflexes3. Induced movements.

• Decorticate posturing with flexion of the upper extremities and extension of the lower extremities suggests involvement of the cerebral cortex and preservation of brainstem function.

• Decerebrate posturing with rigid extension of the arms and legs is indicative of cortical and brainstem damage.

• The flaccid patient with no response to painful stimuli has the gravest prognosis with injury sustained to deep brainstem lesions.

E. Other neurological findings

• Fundus examination : Papilloedema Retinal hemorrhages• Signs of meningeal irritation• Cranial nerve Examination

E. Herniation syndromes• Brain tissue deforms intracranially and moves from higher

to low pressure when there is asymmetric, unilateral or generalised increase in intracranial pressure.

• Signs of cerebral herniation1. Glasgow coma score <82. Abnormal pupil size and reaction (unilateral or bilateral)3. Absent doll’s eye movements4. Abnormal tone (decerebrate/decorticate posturing, flaccidity)5. Hypertension with bradycardia6. Respiratory abnormalities (hyperventilation, Cheyne- Stokes breathing, apnea, respiratory arrest)7. Papilledema

Clinical features of herniation syndrome

Types Clinical manifestation

Central herniation Impaired consciousness, abnormal respiration, small reactive / midposition fixed pupil decorticatea evolving to decerebrate posture

Uncal Herniation Impaired consciousness, abnormal respirations,unilateral dilated pupil, ptosis, unilateral hemiparesis

Foramen magnum or Tonsillar herniation

Impaired consciousness, neck rigidity, opisthotonus, decerebrate rigidity,vomiting, irregular respirations, apnea, bradycardia

Other Systemic Examination

• CVS : Arrhythmias, Murmurs (Congenital heart disease, Infective endocarditis)

• RS : Signs of lung disease• P/A : Tender hepatomegaly (Hepatitis, Sepsis),

Hepatosplenomegaly (malaria), palpable abdominal mass (intussuception encephalopathy)

Investigations

Neuroimaging:• CT scan: Any comatose child or infant in whom

the neurological findings suggest a structural lesion or in whom the clinical diagnosis is evasive, done after stabilistion of a patient.

• Magnetic Resonance Imaging (MRI) of brain is valuable in identifying evidence of herpes simplex encephalitis or an acute demyelinating process, such as acute disseminated encephalomyelitis.

Biochemical investigations

Other Investigations

Electroencephalography

EEG findings Interpretation

•High voltage slow waves

•Slowing of background activity•Triphasic waves•PLEDS Periodic Lateralised Epileptiform Discharges

•Underlying supratentorial lesion•Metabolic coma

•Hepatic coma

•Herpes encephalitis

EEG findings in coma

Rapid assessment and stabilization

Evaluate: Establish & maintain airway Ventilation, Oxygenation Circulation Fluid bolus Blood glucose Identify cerebral herniation/^ICP Temperature

History Examination Neurological assessment

Investigate: CT CSF (suspected meningitis/ encephalitis) Investigation as presentation

Manage: Shock Sepsis Hypoglycemia Seizures Raised ICP Treat dyselectrolytemia Treat Acid-base imbalance

Specific management: Acute febrile encephalopathy (antibiotic,steroids) Antimalarials DKA Hypertensive encephalopathy Toxidrome Envenomation

Second line investigation: MRI EEG Drug levels Metabolic work-up Urine toxicology screen ESR and autoimmune screen Thyroid profile

Prognosis• The prognosis for recovery from coma depends primarily

on the cause, rather than on the depth of coma.• Coma from drug intoxication and metabolic causes carry

the best prognosis.• Prolonged coma after a global hypoxic ischemic insult

carries a poor prognosis.• Infectious encephalopathies have a good outcome with

mild or moderate difficulties only.• Children who survive traumatic injury have a better

prognosis than children who suffer a global hypoxic-ischemic injury

List of references

• Pediatric Neurology , fourth edition; Swaiman,• Nelson Textbook of Pediatrics 20th Edition,• Indian Journal of Pediatrics,• Human Physiology C.C.Chatterjee,• Ganong’s Review Of Medical Physiology

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