Paediatric raised intracranial pressure

Introduction

• Normal ICP 6-18cmH20
• Higher in the morning when supine and asleep
• Symptoms therefore worse in morning
• 20mL/hr of CSF normally
• Total volume 50mL in infant and 150mL in adult
• Produced by choroid plexus in lateral third and fourth ventricles
• Flows through foramen of Montro into third ventricle, then down aqueduct of Sylvius to 4^th ventricle, then via foramina of Luschka and Magendie to basal cisterns
• Reabsorbed by arachnoid villi in superior sagittal sinus

Causes

• Increased CSF (hydrocephalus)
  • Decreased absorption – Obstructive vs.
    communicating
  • Increased production (Rare)
• Swollen contents
  • Meningitis
  • Encephalitis
  • Cerebral oedema
    • Hypo/hypernatraemia
    • Post-ischaeic
    • Post-traumatic/DAI

Infants

• Need high index of suspicion for diagnosis
• Cranial sutures fuse throughout childhood so ICP can cause diastasis up to 7yo (rarely older)
• Measurement of head circumference is crucial
• Palpation of anterior fontanelle up to 9-18mo

Clinical presentation

• Gradual onset e.g. tumor
  • Progressive drowsiness/lethargy/morning irritability and vomiting
  • Expanding head circumference
  • Progressive early morning headaches in older children
  • Focal neurological signs may arise
  • Head tilt due to unilateral 4^th nerve palsy with vertical strabismus (posterior fossa tumors typically)
  • Paralysis of upward gaze (sunset eyes) if 3^rd nerve palsy from obstructive hydrocephalus
  • Regression in milestones
  • Personality changes

• Raised ICP itself may cause symptoms
  • Impingement on cranial nerve
  • Impingement on blood vessel
  • Stretching of corticospinal tract around dilated ventricles causing upper motor signs in legs
  • Focal seizures and Todd’s paresis
• Rapid onset conditions e.g. haemorrhage
  • Rapid onset drowsiness, vomiting, focal neurology
  • Herniation syndromes (see next)

Central herniation syndrome

• Midbrain herniates through tentorium cerebri
• Dysfunction of midbrain
• Drowsiness
• Small reactive pupils then mid-range fixed
• Decorticate posturing then decerebrate
• Bilateral 6^th CN palsies
• Cushing’s triad (hypertension, bradycardia, abnormal respiration)

Lateral mass herniation syndrome (uncal)

• Contralateral hemiplegia
• Drowsiness
• Ipsilateral pupillary dilatation (partial 3^rd nerve palsy)
• Complete 3^rd nerve palsy (can be bilateral)
• Ipsilateral hemiplegia (midbrain pushed against tentorium)
• Cushing’s triad

Cerebellar tonsillar herniation syndrome

• Stiff neck
• Drowsiness
• Nystagmoid eye movements
• Apnoea

Peripheral neurological signs

• Handedness under 1yo is often muscular or neurological issue
• Hydrocephalus may produce lower limb signs with gait disturbance
• Scissoring of lower limbs due to spasm of adductors

Investigations

• CT/MRI depending on acuity
  • Can be falsely reassuring in meningitis and pseudotumor cerebri
• LP contraindicated in suspected raised ICP

Management of raised ICP

• Acute severe raised ICP
  • Resuscitation, maintaining oxygenation and perfusion of brain
  • RSI +- measures to prevent spike in ICP (not routine)
  • Mannitol 1g/kg IV (contraindicated if in shock)
  • Head up
  • Inline stabilisation
  • No neck compression
  • pCO2 35-40mmHg unless herniation progressing despite above, in which case can drop to 25 for brief period while further measures are undertaken
  • Neurosurgical involvement ASAP
  • Consider treatment of seizures, reducing metabolic demand with thiopentone coma
  • Treat underlying cause e.g. Sodium, vasogenic oedema, seizure, haemorrhage

Idiopathic intracranial hypertension (IIH)

• Usually due to reduced CSF absorption
• Most common in young obese females
• Presents with headaches and morning vomiting
• Transient visual obscuration sometimes
• Unilateral or bilateral 6^th nerve palsies causing diplopia on lateral gaze
• Papilloedema often the only physical finding
  • Can lead to loss of vision with ultimate loss of peripheral visual fields
• Ix
  • CT or MRI then LP
  • Therapeutic CSF taps should reduce ICP by 50% under the guidance of neurology
  • In most cases, this has to be repeated +- acetazolamide

• Causes
  • Idiopathic
  • Venous obstruction
  • Metabolic – Hypervitaminosis A, hypoparathyroidism, Addison’s, Obesity, pregnancy, galactosaemia
  • Drugs – OCP, glucocorticoids, tetracyclines, isotretinoin, nitrofurantoin
  • Haematological – Anaemia, polycythaemia
  • Infections– Roseola infantum, chronic complicated otitis media
  • GBS

Last Updated on November 10, 2021 by Andrew Crofton