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Head CT: Cerebral Malaria

Cerebral malaria is a life-threatening manifestation of Plasmodium falciparum infection defined clinically by coma (Blantyre Coma Score <=2 or GCS <11) in the presence of asexual parasitaemia after exclusion of other encephalopathies. Head CT is used chiefly to exclude alternative or coexisting surgical and infective causes of altered consciousness and to detect diffuse cerebral oedema, which carries prognostic weight. Imaging is frequently normal early in the disease, and a normal scan does not exclude the diagnosis, which remains clinical and parasitological.

Indications

Severe P. falciparum malaria with impaired consciousness, coma or persistent obtundation
New-onset or repetitive seizures, status epilepticus in an endemic setting
Focal neurological deficit raising concern for stroke, abscess or mass lesion
Failure to regain consciousness after correction of hypoglycaemia and control of seizures
Clinical deterioration or signs of raised intracranial pressure before lumbar puncture
Exclusion of alternative causes of coma (meningitis, encephalitis, intracranial haemorrhage) in a febrile comatose patient

Contraindications & Cautions

No absolute contraindication for non-contrast CT in an obtunded emergency patient; benefit outweighs radiation risk
Pregnancy (common in endemic regions): shield the gravid abdomen; head CT fetal dose is negligible but justify the study
Iodinated contrast: caution with acute kidney injury from severe malaria (blackwater fever, ATN) and dehydration; hydrate and check renal function where feasible
Prior severe contrast reaction warrants premedication or avoidance of contrast
Apply ALARA and paediatric dose-reduction protocols, as many patients are children

Patient Preparation

Stabilise airway, breathing and circulation; treat hypoglycaemia and seizures before transfer
Correct hypoglycaemia (common and treatable mimic of coma) and check point-of-care glucose
Secure intravenous access and continue antimalarial therapy (IV artesunate) without delay for imaging
Supine positioning with head immobilised; sedation or intubation may be required for the agitated or fitting child
Obtain consent from accompanying guardian where possible; proceed under emergency provision if not
Remove metallic hair ornaments and monitor oxygen saturation throughout

Technique & Parameters

Non-contrast helical head CT from foramen magnum to vertex, gantry angled to the orbitomeatal line
Typical adult parameters 120 kVp, 250-350 mAs with automatic exposure control; reduce mAs and kVp for children
Reconstruct 4-5 mm axial slices for brain and thin 0.6-1 mm for bone; add coronal and sagittal reformats
Review on brain (W80/L40), subdural (W150-200/L50-80) and bone windows
Add iodinated contrast (approximately 1-2 mL/kg) only if abscess, empyema, tumour or venous thrombosis is suspected
CT venography if cerebral venous sinus thrombosis is considered in the differential

Systematic Review

Assess grey-white matter differentiation and sulcal/cisternal effacement as markers of diffuse oedema
Evaluate ventricular size and configuration for compression or hydrocephalus
Search for parenchymal, subarachnoid or intraventricular haemorrhage on soft-tissue windows
Inspect for focal hypodensity indicating infarction (arterial territory or watershed)
Check basal cisterns and brainstem for effacement suggesting transtentorial herniation
Look for ring-enhancing lesions or extra-axial collections if contrast given
Review bone windows and scalp for trauma as an alternative cause of coma

Key Findings & Significance

Diffuse cerebral oedema: sulcal effacement, small ventricles, loss of grey-white differentiation - associated with poorer outcome
Often normal parenchyma early despite deep coma
Petechial or larger haemorrhages reflecting microvascular sequestration and endothelial injury
Territorial or watershed infarction from microvascular obstruction
Brainstem compression or effacement of basal cisterns indicating impending herniation
Absence of a mass lesion or meningeal enhancement helps exclude surgical and alternative infective causes

Differential Considerations

Diffuse oedema with coma: cerebral malaria versus hypoglycaemic or hypoxic-ischaemic encephalopathy
Ring-enhancing lesion: pyogenic abscess, tuberculoma, toxoplasmosis, neurocysticercosis
Meningeal enhancement and hydrocephalus: bacterial or tuberculous meningitis
Lobar or deep haemorrhage: hypertensive bleed, venous infarction, coagulopathy
Focal infarct: embolic stroke, vasculitis, sickle cell vasculopathy in coexisting haemoglobinopathy
Dense venous sinus (cord/dense triangle sign): cerebral venous sinus thrombosis

Pearls & Pitfalls

A normal CT never excludes cerebral malaria; the diagnosis is clinical and parasitological
Malarial retinopathy on funduscopy is more specific than imaging and supports the diagnosis
Always exclude and treat hypoglycaemia before attributing coma to malaria
Diffuse oedema and small ventricles can be subtle - compare with age-expected sulcal pattern in children
Beware coexisting pathology: bacterial meningitis and malaria can occur together
Motion and beam-hardening in the posterior fossa can mimic or obscure brainstem changes

Structured Report

State scan type, coverage and whether contrast was administered
Comment on presence and severity of cerebral oedema (grey-white differentiation, sulcal/cisternal effacement)
Describe any haemorrhage, infarction, mass lesion or extra-axial collection
Assess for mass effect, midline shift and signs of herniation with measurements
Explicitly address alternative causes of coma (abscess, meningitis, haemorrhage, thrombosis)
Impression: correlate with parasitaemia, glucose and retinopathy; advise MRI if diagnostic uncertainty and clinical stability permit

References

WHO Guidelines for the Treatment of Malaria (severe malaria management)
ACR Appropriateness Criteria: Altered Mental Status, Coma, Delirium and Psychosis
Mohanty S et al., Brain swelling and mannitol in cerebral malaria (RadioGraphics/clinical neuroradiology literature)
Osborn's Brain: Imaging, Pathology, and Anatomy (infection chapter)

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.

Head CT: Cerebral Malaria

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References