Decreased Conscious Level in a Child

Context

Children presenting to an emergency department (ED) with decreased consciousness pose many diagnostic and management challenges. There is evidence that in cases of non-traumatic coma with Glasgow Coma Score (GCS) <12 for >6 hours, patients have a high morbidity and mortality.

The differential diagnosis is wide and this session provides an overview of the main causes.

Decreased consciousness is a non-specific sign with a wide differential diagnosis. Causes may include (but are not limited to):

• Shock: hypovolaemic, distributive and cardiogenic
• Sepsis
• Trauma
• Intracranial infection
• Epilepsy
• Poisoning
• Raised intracranial pressure
• Metabolic disease
• Hypertension

Delays by the emergency physician to identify these causes, select appropriate investigations and initiate treatment can have devastating consequences for the child.

Simultaneous resuscitation, diagnosis and treatment should be initiated within the first hour after presentation. [1]

The goals are to stabilise, establish the cause of decreased consciousness and prevent deterioration. [2]

Definition

The child with a decreased consciousness level is defined as a Glasgow coma score of 14 or a V,P or U on the AVPU score [1].

The AVPU system relates to A = Alert; V = Responding to voice; P = Responding to pain; U = Unconscious.

Fig 1: The reticular system

Consciousness is a continuous physiological variable [1], dependent on the reticular activating system (RAS) and cerebral cortex (Fig 1).

The RAS lies within the brainstem and midbrain and controls respiration and cardiovascular functions and via the thalamic nuclei causes activation of the cerebral cortex [3]. The cerebral cortex is necessary for conscious awareness and where actions are conceived and initiated [4].

A decreased consciousness is caused by depression of both cerebral cortices or localised abnormalities of the ascending reticular activating system.

Failure of both cerebral cortices results from:

• Inadequate blood supply
• Inadequate substrate: oxygen or glucose, required for normal metabolism
• Trauma
• Toxins: infection, metabolites, poisons

The assessment and management of Airway, Breathing, Circulation and Disability is as per the advanced paediatric life support (APLS) guidelines [5]. The history taken may need to be brief in the first instance whilst ABCs are assessed.

Early recognition of a decreased consciousness is essential and several conscious level scoring systems have been described [5].

AVPU

A   Alert
V   Responsive to verbal stimuli
P    Responsive to painful stimuli
U   Unresponsive

Glasgow Coma Score (GCS)

The modified Glasgow coma score (GCS) is recommended for recognition and for assessing changes in conscious level in a child (Table 1) [1,6].  Changes in conscious level should be observed by recording the modified GCS every 15 minutes if GCS is less than or equal to 12, or every hour if greater than 12 [1].  Performing an accurate GCS recording is easier said than done, particularly in the preverbal child.

Table 1 Child’s Glasgow Coma Scale [5]

	Score	>5 years of age	<5 years of age
Eye opening	4	Spontaneous	Spontaneous
	3	To voice	To voice
	2	To pain	To pain
	1	None	None
Verbal	5	Orientated	Alert, babbles, coos, words or sentences normal for age
	4	Confused	Less than usual ability, irritable cry
	3	Inappropriate words	Cries to pain
	2	Incomprehensive sounds	Moans to pain
	1	No response to pain	No response to pain
Motor	6	Obeys commands	Normal spontaneous movements
	5	Localises to supraorbital pain	Withdraws to touch
	4	Withdraws from nailbed pain	Withdraws from nailbed pain
	3	Flexion to supraorbital pain	Flexion to supraorbital pain
	2	Extension to supraorbital pain	Extension to supraorbital pain
	1	No response to supraorbital pain	No response to supraorbital pain

The nationally-developed evidence-based guideline outlines the management of children and young people with a decreased conscious level. [1]

The key questions on presentation should explore prodromal events leading to decreased consciousness with reference to the wide differential diagnosis: any recent illness and length of symptoms [1,2]:

Category	Symptoms
Shock	Abdominal pain, excessive diarrhoea and vomiting may suggest fluid loss or surgical cause. [6]
Sepsis	Vomiting, headache, fever, rash and infectious exposure may suggest infection. However recent antibiotic use may mask classical presentations of meningitis in the early phase. A detailed history is recommended.
Trauma	Trauma may or may not be evident particularly in the case of a shaken baby. [7] Inappropriate responses or inconsistencies and delays in seeking help arouse suspicion of non-accidental injury.
Intracranial	History of ear pain is suggestive of otitis media; ask about frontal headaches, facial pains and purulent nasal discharge which are suggestive of sinusitis. Intracranial extension can occur.
Epilepsy	There may be a family history or prior seizures or a history of neuro developmental delay
Poisoning	No history may be given. Examination may give clues to potential source. [8-10]
Raised intracranial pressure	If there is a past history of neurosurgery or neuro-developmental problems, check whether a shunt has been inserted or if there is a history of hydrocephalus. Make enquiries regarding recent head injuries.
Metabolic	Recent weight loss, polydipsia or polyuria may suggest a metabolic cause. A family history should be sought including if any consanguinity which may suggest inborn errors of metabolism.
Hypertension	A review of medication history may give a clue to the cause.

General Questions

Exploring developmental milestones, past medical, travel, immunisation and family history including infant deaths further guides management.

Learning Bite

Non-accidental injury may be behind the cause of reduced consciousness, consider child protection issues. [1,7]

Monitoring

The following should be monitored:

• Cardiac monitoring
• Blood pressure (usually falls late)
• Respiratory rate
• Oxygen saturations
• Temperature

In addition, a 12-lead ECG should be taken if tachyarrthymia suspected.

Core Blood and Urine Tests

Children with a reduced conscious level should have a capillary glucose tested within 15 minutes of presentation. [1]

In all cases, Blood gas: pH, pCO2, bicarbonate and lactate may provide useful information in cases of shock, sepsis, trauma, respiratory distress, or suspected acid-base imbalance.

Sepsis-specific cases: Urinalysis, full blood count: haemoglobin, white cell count and differential, and platelet count; blood culture (meningococcal pcr depending on clinical presentation), CRP.

Metabolic-specific cases:

• Venous/arterial blood gas
• Glucose: rapid capillary estimation should be confirmed with laboratory analysis of a venous sample [11]
• Urine ketones – obtained on a urine dipstick
• Liver function tests: aspartate/alanine transaminase, alkaline phosphatase, albumin or protein
• Serum ammonia (telephone laboratory and send within 30 minutes for analysis)
• Urea and electrolytes: sodium, potassium and creatinine give information regarding hydration, suspected metabolic and endocrine derangements, and kidney function
• See further investigations for hypoglycaemia)

Overdose cases: Plasma, serum and urine to be saved for later analysis of specific agents e.g. opiates, tricyclics.

Lumbar puncture

Perform a lumber puncture (LP) if there are no contraindications and the investigation does not delay critical treatment such as antibiotic therapy.

Indications: sepsis/bacterial meningitis; herpes simplex encephalitis, tuberculous meningitis and cause unknown. [1]

Analyse the CSF for:

• Microscopy
• Gram staining
• Culture and sensitivity
• Glucose, protein and PCR for herpes simplex and other viruses [1]

Contraindications are:

• GCS 8 or less or deteriorating
• Focal neurological signs or abnormal posture
• Prolonged seizure lasting 10 minutes or more and a GCS of 12 or less
• Shock
• Systemic meningococcal disease
• Signs of raised intracranial pressure: unilateral or bilateral dilated pupils or sluggish pupillary reaction
• Bradycardia or hypertension
• Abnormal breathing pattern

Cerebral Imaging

A CT scan is indicated if there is raised intracranial pressure, intracranial abscess or the cause of a decreased consciousness is unknown.

Learning Bite

The CT scan may be normal, yet there may be raised intracranial pressure. Clinical correlation is needed. [1]

General Management

General management is as per APLS guidelines. [5]

Airway and breathing

Hypoxia alone may be responsible for reduced consciousness level. Oxygen should be administered. The seriously unwell infant may present with intermittent apnoeic spells associated with bradycardias and may look relatively ‘well’ in between.

Practically, GCS scoring can be difficult in the neonate/young child and repeated assessment is needed.

Consider intubation in a child with a GCS of 8 or less [1] or they have either of the following points [1]:

• their GCS is deteriorating;
• >40 mls/kg fluid resuscitation is needed;
• status epilepticus;
• signs of raised ICP.

Circulation

Circulatory shock is suspected with a delayed central capillary refill time, tachycardia, tachypnoea, mottled cool extremities and poor peripheral pulses, which are often hard to feel in an infant.

Important: Treat shock with a fluid bolus of 10ml/kg of crystalloid or colloid, and assess for response. Repeat up to 40ml/kg but seek expert help before you approach this point.

Blood pressure: A blood pressure can be attempted but values vary for age. You need to use the correct sized cuffs and the procedure may distress the child. The BP should be reviewed against normal values for age.

Urine output: Ask the parents when the last wet nappy occurred. You would expect at least 3-4 wet nappies per day. Nappies can feel dry even if they have 40mls of urine due to high absorbency materials used in the nappy. If there is any doubt, weigh the nappy and compare to a dry one.

Disability

In addition to GCS and pupillary examination, [5], the fontanelle, tone and posture should be assessed. Blood glucose is also needed.

 

Specific Management: Shock

Sepsis, trauma, anaphylaxis, hypovolaemia and heart failure may present with shock and reduced level of consciousness.

The first four diagnoses—sepsis, trauma, anaphylaxis and hypovolaemia—can be made relatively easily with careful clinical examination and history taking.

New-onset heart failure can be missed in the ED. It is worth spending time listening properly to the heart sounds as a gallop rhythm can be heard even at relatively fast heart rates.

For shock, fluid boluses are guided by clinical response, up to 60 ml/kg may be required.  If more than 40 ml/kg is given, inotropic or vasopressor treatments should be considered, the child should be monitored on a critical care unit and intubation and ventilation considered.

The appropriate specialists should be involved.

 

Specific Management: Sepsis

Assessment of the child with a feverish illness should include a documentation of the presence/absence of markers that signify a risk of serious illness (NICE guideline provides information). [13]

The child should have a risk assessment i.e. red, amber, green and a paediatric early warning score based on the vital signs recorded in the ED notes.

Consider sepsis as a cause if:

• Reduced consciousness
• Abnormal vital signs, and
• A temperature of greater than 38oC if age is <3 months
• A temperature of less than 35.5oC

Investigation of the febrile child without a source for infection is required for children who score amber or red as per the NICE traffic light system for serious illness and for all children under 3 months of age.

 

Specific Management: Trauma

The child with a decreased consciousness and evidence of trauma should be managed as per APLS [5] /ATLS [7] and the NICE head injury guidelines. [14]

In the infant, trauma may not be immediately obvious, for example in the cases of non-accidental injury (NAI), where the history may not correlate. Children may be treated for other causes of reduced consciousness, e.g. sepsis, before the diagnosis is discovered. [7, 15]

 

Specific Management: Metabolic Illness

Children may present in a variety of ways, including reduced level of consciousness. Four main metabolic causes are briefly described here.

Hyperglycaemia

Diabetic ketoacidosis is diagnosed if capillary glucose is >11, pH<7.3 and ketones in the urine. This should be managed as per the NICE guidelines. [16]

Hypoglycaemia

A metabolic cause should be considered if blood glucose less than 2.6 mmol/l.

Past medical history of consanguinous relationship should be sought. The child should be examined to look for physical clues which may suggest an underlying metabolic problem, such as dysmorphism, hypotonia, failure to thrive and enlarged liver.

The causes of hypoglycaemia in children include severe sepsis, exogenous or endogenous insulin excess, disorders of hormone production: Addison’s disease, growth hormone deficiency or congenital adrenal hyperplasia, disorders of fatty acid oxidation e.g. medium chain acyl CoA dehydrogenase deficiency (MCAD), organic acidurias/acidaemias and glycogen storage disorders. [1]

Treatment of hypoglycaemia

As per APLS [5] guidelines, the treatment is with 2 ml/kg of 10% dextrose bolus. An infusion of 10% dextrose solution should be given to maintain normal blood glucose: between 4-7 mmol/l.

Hyperammonaemia

High ammonia levels are neurotoxic. A plasma ammonia level of 200 micromol/l is significantly raised and needs actively treating.   The higher the peak or the longer the level remains high the worse the prognosis.  A level of 200 micromol/l can be reduced with a sodium benzoate infusion.  If the levels remain high or are greater than 500 micromol/l, emergency haemodialysis is required. [5]

Non-hyperglycaemic ketoacidosis

Inherited conditions: organic acidopathies, amino acidopathies, fatty acid oxidative defects, mitochondrial electron transport chain defects and urea cycle enzyme defects can present as acute encephalopathy with a pH <7.3 and ketones in the urine.

Further investigations include plasma lactate, plasma and urinary amino acids and urinary organic acids.  Advice should be sought from a metabolic medicine unit and careful monitoring of fluid balance to avoid raised intracranial pressure is required.

 

Specific Management: Intracranial Infection

Seven causes are outlined briefly here.

Bacterial meningitis

Diagnosing meningitis may be difficult particularly in children <2 years. Classical symptoms such as decreased consciousness, neck pain/stiffness, vomiting and rash may be seen in the older child. Children, especially those <12 months old, may present as a fit with a fever. Clinical post-fit recovery may be delayed arousing suspicion of a non-benign cause.

Treatment with broad spectrum antibiotics is needed until a definitive diagnosis can be made.

Treating with steroids (dexamethasone 0.15 mg/kg prior to first dose of antibiotics) reduces profound hearing loss if the causative agent is Haemophilus influenza type B (HIB) and less so in cases of meningococcal or streptococcal infection. [17]

Herpes simplex encephalitis

Herpes simplex encephalitis should be suspected in a child with a decreased consciousness and focal neurological signs, fluctuating consciousness, contact with herpetic lesions or no obvious alternative cause. [18]

The diagnosis of herpes simplex encephalitis can be made with positive cerebrospinal fluid (CSF) for herpes simplex virus DNA in PCR of CSF. A positive PCR of CSF is highly sensitive and specific.

A magnetic resonance image scan and an abnormal EEG can strengthen the diagnosis. Nevertheless, waiting to perform a lumbar puncture should not delay treatment with intravenous acyclovir (see the British National Formulary (BNF) for body surface area dose calculation).

Intracranial abscess

A history of recent antibiotic use, neurosurgery or cyanotic congenital heart disease is relevant. [19]

Clinical signs may include a reduced consciousness, focal neurological signs, signs of sepsis and raised intracranial pressure.  Diagnosis is with a CT scan of the head. [19]

Treatment is with broad spectrum antibiotics and neurosurgical referral.

Tuberculous meningitis

Tuberculous meningitis should be suspected if the child has had contact with pulmonary tuberculosis.

Diagnosis is with a positive CSF PCR for TB DNA.

Further management should be guided by microbiology.

Raised intracranial pressure

A child with decreased consciousness and raised intracranial pressure may have complaints of a headache, display altered behaviour and vomiting. Signs include unilateral or bilateral dilated pupils or unreactive pupils, abnormal posture, papilloedema, a relative bradycardia for age and hypertension.

Manage the patient with the head in the midline, raised 20 degrees and aim to maintain normal physiology, which may require intubation and ventilation.  Consider mannitol or hypertonic saline.

Hypertensive encephalopathy

Headache, nausea, vomiting, visual disturbances and focal neurological deficits and seizures may occur.

Hypertension is defined as the systolic blood pressure >95th centile for age.

Further management should be guided by a paediatric nephrologist or intensivist.

Prolonged convulsion/post convulsive state

Convulsions lasting more than 10 minutes need treating as per the APLS guidelines. [5] In infants, in addition to the core investigations calcium and magnesium should be requested at presentation.

Post-convulsive state should last for less than one hour; if this is prolonged and the blood glucose is normal, the core investigations should be performed.

Review all the possible causes of reduced conscious level concurrently rather than sequentially.  No individual cause is more important than another and several may coexist in the same child. If you encounter problems in making the diagnosis, it is worth starting from the beginning with the history and performing a full physical examination rather than relying on information passed on by another clinician.

No clinical clues to the cause

If there are no obvious clinical signs broad spectrum antibiotics and acyclovir should be started and supportive treatment implemented.  Further investigations include a CT, lumbar puncture, urine toxicology screen, urine organic and amino acids and plasma lactate.  If the cause remains unknown an EEG to exclude non-convulsive status epilepticus; ESR and autoimmune screen to exclude cerebral vasculitis; thyroid function test and antibodies to exclude Hashimoto’s encephalitis should be performed. [20] Further management should involve a paediatric neurologist.

Non-accidental injury (NAI)

Non-accidental injury or other child protection issues may be behind the cause of reduced consciousness in children. NAI has the highest prevalence in infants. [15]

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