Raised intracranial pressure, HIE and cerebrovascular injury

Definition / Overview

Intracranial haemorrhage (ICH) and cerebrovascular injury in children encompass a spectrum of conditions that are pathophysiologically and aetiologically distinct from adult presentations. The major syndromes relevant to the PICU are:

• Subarachnoid haemorrhage (SAH): bleeding into the cerebrospinal fluid-filled subarachnoid space, most commonly from aneurysm rupture or arteriovenous malformation (AVM)
• Subdural haematoma (SDH): blood accumulating between the dural border cell layer and the arachnoid, typically from bridging vein disruption
• Intraparenchymal / intracerebral haemorrhage (IPH): haemorrhage within brain substance, from vascular malformation, coagulopathy, hypertension, or tumour
• Intraventricular haemorrhage (IVH): bleeding into the ventricular system, often secondary to adjacent parenchymal or choroid plexus haemorrhage
• Cerebral venous sinus thrombosis (CVST): occlusion of dural venous sinuses or cortical veins causing venous infarction, haemorrhage, or both

Children are not small adults: the aetiological spectrum, physiological response, and management priorities differ substantially across the neonate-to-adolescent range.

Pathophysiology

Subarachnoid Haemorrhage

In children, SAH most commonly arises from rupture of an intracranial aneurysm or AVM, though the proportion attributable to AVM is higher than in adults. Traumatic SAH also occurs. Blood in the subarachnoid space causes direct meningeal irritation, obstructive hydrocephalus (via arachnoid granulation blockade), and secondary cerebral arterial vasospasm, particularly 3-14 days post-ictus. Vasospasm causes delayed cerebral ischaemia, a major contributor to morbidity.

Subdural Haematoma

The absence of a true subdural space means SDH represents a dissection through the innermost dural cell layer. In infants, the bridging veins traversing a relatively larger subarachnoid space are under greater tension; minor rotational forces can cause tearing. Acute SDH causes mass effect and raised intracranial pressure (ICP). Chronic SDH is isodense to hypodense on CT as haemoglobin degrades. In children, SDH without adequate explanation raises the possibility of non-accidental injury (NAI).

Intraparenchymal Haemorrhage

Primary causes in children include AVMs (risk approximately 2-4% per year per lesion), cavernous malformations, coagulopathies (including haemophilia and anticoagulant therapy), hypertensive crises, and rarely amyloid angiopathy. Haematoma expansion causes direct tissue destruction, perilesional oedema, mass effect, and transtentorial herniation.

Cerebral Venous Sinus Thrombosis

CVST occurs when thrombosis of dural sinuses (most commonly the superior sagittal sinus or transverse sinus) raises venous backpressure, reducing cerebral perfusion pressure, causing cytotoxic and vasogenic oedema, haemorrhagic venous infarction, and seizures. In neonates, CVST is often associated with dehydration, sepsis, or prothrombotic disorders. In older children, prothrombotic states (inherited or acquired), meningitis, mastoiditis (septic lateral sinus thrombosis), and systemic inflammatory disease are common precipitants.

Aetiology by Age Group

Clinical Features and Diagnosis

Subarachnoid Haemorrhage

• Classic presentation: sudden severe headache ("thunderclap"), vomiting, meningismus, photophobia, altered consciousness
• In younger children and infants: irritability, bulging fontanelle, seizures, apnoea
• Focal neurological deficits suggest parenchymal extension or vasospasm
• Grading: Hunt and Hess / World Federation of Neurosurgical Societies (WFNS) scales apply in older children; correlate with prognosis and guide intervention timing

Subdural Haematoma

• Acute SDH: rapid deterioration, contralateral hemiplegia, ipsilateral pupil dilatation (herniation), seizures
• Chronic SDH: insidious course; lethargy, vomiting, macrocephaly (infants), personality change
• Bilateral SDH in an infant without adequate mechanism demands NAI assessment
• Retinal haemorrhages, metaphyseal fractures, and bruising at different stages heighten NAI concern

Intraparenchymal Haemorrhage

• Sudden onset focal deficit, seizures, declining consciousness
• Cerebellar haemorrhage: ataxia, nystagmus, vomiting, rapid deterioration from fourth-ventricle obstruction

Cerebral Venous Sinus Thrombosis

• Seizures (focal or generalised) are the most common presenting feature in neonates and infants
• Older children: headache, papilloedema, focal deficits, encephalopathy
• Associated findings may include thalamic haemorrhage, IVH, cortical haemorrhagic infarction
• History of recent ear infection or mastoiditis points to septic lateral sinus thrombosis
• Hypernatraemia, dehydration, or known prothrombotic disorder increases pre-test probability

Investigation

Neuroimaging

• Non-contrast CT head: first-line; immediately available, detects acute blood (hyperdense), mass effect, hydrocephalus, midline shift, herniation
  • Sensitivity for SAH approaches 95% within 24 hours; falls rapidly thereafter
  • CT is superior for acute cortical bone and fracture detail; less sensitive for posterior fossa, small SDH, and diffuse axonal injury
• CT angiography (CTA): essential when vascular malformation or aneurysm is suspected; near-equivalent sensitivity to conventional angiography for aneurysms $\geq 3\,\text{mm}$
• MRI with MR venography (MRV): investigation of choice for CVST; also superior for diffuse axonal injury, subacute SDH, posterior fossa lesions, and parenchymal extent of injury
  • MR with susceptibility-weighted imaging (SWI) detects microhaemorrhage and cavernomas not visible on CT
• Conventional catheter angiography: gold standard for aneurysm characterisation and endovascular treatment planning; may be required when non-invasive imaging is inconclusive
• Lumbar puncture: if SAH strongly suspected and CT is negative, LP demonstrating xanthochromia (spectrophotometry) or persistently blood-stained CSF supports the diagnosis; defer if raised ICP is suspected until imaging confirms safety

Laboratory Investigations

• Full blood count, coagulation screen (PT, APTT, fibrinogen), blood film
• Group and screen; massive transfusion protocol activation if coagulopathic bleeding
• Metabolic panel, calcium, glucose, renal and hepatic function
• Thrombophilia screen (protein C, S, antithrombin III, factor V Leiden, prothrombin gene mutation, antiphospholipid antibodies): ideally prior to anticoagulation, though should not delay treatment
• Blood culture if septic CVST is suspected
• Haemoglobin electrophoresis if sickle cell disease is a possibility

Monitoring in the PICU

• Continuous EEG monitoring: high rate of non-convulsive seizures (NCS) and non-convulsive status epilepticus (NCSE) in all ICH subtypes; mandatory in comatose patients
• ICP monitoring: indicated when GCS $\leq 8$, clinical concern for raised ICP, or when ongoing neurological assessment is unreliable (sedation, paralysis)
  • Target cerebral perfusion pressure (CPP): $\geq 40\,\text{mmHg}$ in infants; $\geq 50\,\text{mmHg}$ in children; $\geq 60\,\text{mmHg}$ in adolescents
• Near-infrared spectroscopy (NIRS) for non-invasive cerebral oximetry where ICP monitoring not in situ
• Transcranial Doppler (TCD): vasospasm surveillance in SAH

Management

General PICU Principles (All ICH Subtypes)

1. Airway and breathing: intubate for GCS $\leq 8$, airway compromise, or refractory seizures; use rapid sequence induction with agents minimising ICP surge (thiopentone $4\text{-}7\,\text{mg/kg}$ IV or propofol in older children; fentanyl $1\text{-}2\,\text{mcg/kg}$ IV prior to laryngoscopy; suxamethonium $2\,\text{mg/kg}$ IV $< 10\,\text{kg}$, $1.5\,\text{mg/kg}$ in larger children)
2. Ventilation targets: normocapnia ($\text{PaCO}_2\,35\text{-}40\,\text{mmHg}$); avoid hypoxia ($\text{SpO}_2 \geq 95\%$); hyperventilation only as a temporising bridge to definitive ICP therapy
3. Circulation: maintain euvolaemia; target age-appropriate MAP to maintain CPP; avoid hypotension
4. Glucose: target normoglycaemia ($4\text{-}10\,\text{mmol/L}$); both hypoglycaemia and sustained hyperglycaemia worsen outcomes
5. Temperature: treat fever aggressively; hyperthermia worsens secondary injury; active cooling to normothermia is standard
6. Sodium: maintain serum sodium $\geq 140\,\text{mmol/L}$ (mild hypernatraemia tolerated to reduce cerebral oedema); avoid hypotonic fluids; treat hyponatraemia cautiously
7. Seizure management: benzodiazepines first-line (midazolam $0.1\,\text{mg/kg}$ IV or intranasal); escalate per local status epilepticus protocol; consider prophylactic levetiracetam or phenytoin in high-risk ICH with cortical involvement

ICP Management Ladder

1. Head of bed 30 degrees, midline positioning
2. Adequate sedation and analgesia (minimise noxious stimuli); morphine $0.05\text{-}0.1\,\text{mg/kg}$ IV PRN or infusion; midazolam infusion
3. Hyperosmolar therapy: 3% saline $2\text{-}5\,\text{mL/kg}$ IV bolus (preferred in children; maintains intravascular volume); mannitol $0.25\text{-}0.5\,\text{g/kg}$ IV (use with caution if hypovolaemic)
4. Short-term controlled hyperventilation to $\text{PaCO}_2\,30\text{-}35\,\text{mmHg}$ as temporising measure
5. Neurosurgical consultation for refractory ICP: CSF drainage, haematoma evacuation, decompressive craniectomy

Subarachnoid Haemorrhage-Specific Management

• Aneurysm: early neurosurgical or endovascular intervention (coiling preferred where feasible; clipping for certain morphologies); timing guided by grade and institutional expertise
• AVM: multidisciplinary decision (microsurgery, stereotactic radiosurgery, embolisation, or combined); acute management focuses on haematoma and ICP
• Vasospasm prevention: nimodipine $0.5\text{-}1\,\text{mg/kg/day}$ IV or enteral in older children (limited paediatric data; extrapolated from adult evidence); maintain euvolaemia; avoid hypovolaemia
• Hydrocephalus: external ventricular drain (EVD) for acute obstructive hydrocephalus; shunt if chronic
• Re-bleed prevention: strict blood pressure control; avoid large swings in MAP

Subdural Haematoma-Specific Management

• Acute SDH with mass effect or herniation: emergency craniotomy or burrhole drainage; do not delay for anticoagulation reversal if immediately life-threatening
• Acute coagulopathy reversal: fresh frozen plasma $10\text{-}15\,\text{mL/kg}$ IV, tranexamic acid $15\,\text{mg/kg}$ IV (max 1 g), cryoprecipitate $5\,\text{mL/kg}$ for low fibrinogen; vitamin K $0.3\,\text{mg/kg}$ IV if vitamin K antagonist-related
• Chronic SDH: often managed conservatively; burrholes if symptomatic
• NAI: safeguarding referral mandatory; involve child protection team, social work, ophthalmology (retinal haemorrhage assessment); full skeletal survey; document meticulously

Intraparenchymal Haemorrhage-Specific Management

• Surgical evacuation for cerebellar haematoma $> 3\,\text{cm}$, brainstem compression, or obstructive hydrocephalus
• AVM-related IPH: stabilise first; definitive AVM treatment after the acute period
• Haemophilia-related: immediate factor replacement (factor VIII or IX to 100% activity) in coordination with haematology; avoid lumbar puncture until corrected

Cerebral Venous Sinus Thrombosis-Specific Management

• Anticoagulation: low-molecular-weight heparin (enoxaparin $1\,\text{mg/kg}$ 12-hourly SC; neonatal dosing $1.5\,\text{mg/kg}$ 12-hourly) is the cornerstone of treatment, even in the presence of haemorrhagic infarction (strong evidence that benefit outweighs risk); unfractionated heparin preferred where rapid reversal may be needed
• Duration: typically 3-6 months anticoagulation; lifelong if underlying prothrombotic disorder; guided by haematology
• Septic CVST (e.g. lateral sinus thrombosis from mastoiditis): broad-spectrum antibiotics (ceftriaxone $50\,\text{mg/kg}$ IV 12-hourly + metronidazole $7.5\,\text{mg/kg}$ IV 8-hourly); surgical source control (mastoidectomy) in consultation with ENT
• Seizure management: treat promptly; consider maintenance anticonvulsant for 3-6 months given high recurrence risk
• Raised ICP / pseudotumour: acetazolamide $5\text{-}10\,\text{mg/kg/day}$ in divided doses; serial LP if safe; EVD for acute hydrocephalus
• Repeat MRV at 3-6 months to assess recanalisation

Complications and Special Considerations

Non-Accidental Injury

• Any infant with subdural haemorrhage, particularly bilateral, multi-layered, or at different stages, requires systematic NAI evaluation before an accidental or medical aetiology is assumed
• Ophthalmology review for retinal haemorrhages (extensive bilateral retinal haemorrhages are highly specific for abusive head trauma)
• Involve the child protection team early; contemporaneous documentation is essential

Hydrocephalus

• Acute obstructive hydrocephalus can develop rapidly; EVD provides simultaneous ICP monitoring and CSF drainage
• Chronic communicating hydrocephalus occurs weeks to months post-SAH or post-IVH; watch for progressive macrocephaly, developmental regression, or worsening headache

Vasospasm Post-SAH

• Monitor with TCD for mean flow velocities; symptomatic vasospasm treated with induced hypertension and hypervolaemia where tolerated; endovascular options in refractory cases

Neurodevelopmental Outcomes

• ICH in children carries significant risk of motor deficits, epilepsy, cognitive impairment, and behavioural difficulties
• Early rehabilitation, neurodevelopmental surveillance, and school liaison are components of post-PICU planning
• CVST outcome is variable; approximately 80% of neonates with CVST survive, but neurological sequelae are common

Thrombophilia Screening

• Do not delay anticoagulation in CVST pending thrombophilia results; draw bloods before commencing anticoagulation where feasible
• Inherited thrombophilias (protein C/S deficiency, factor V Leiden, prothrombin gene mutation) have implications for duration of anticoagulation and family screening

Viva and Hot Case Framing

Key SPPE viva hooks:

• Distinguishing arterial ischaemic stroke, CVST, and ICH on clinical grounds before imaging is available
• Justifying anticoagulation in CVST with haemorrhagic infarction: the mechanism is venous obstruction; anticoagulation treats the underlying thrombosis and reduces propagation, outweighing haemorrhage expansion risk in most cases
• Managing the infant with acute SDH: parallel workup for NAI while providing active neurocritical care; these are not mutually exclusive
• ICP target thresholds are age-adjusted: an adolescent CPP target of $\geq 60\,\text{mmHg}$ is inappropriate in a 6-month-old
• Recognising the signs of impending transtentorial herniation (Cushing's triad: hypertension, bradycardia, irregular respirations; unilateral pupil dilatation) as an emergency requiring immediate osmotherapy and neurosurgical escalation
• The role of continuous EEG: clinical seizures are frequently absent in the setting of electrographic status; NCS/NCSE significantly worsens neurological outcome and must be excluded in any obtunded child with ICH