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Cortical Laminar Necrosis

Summary

  • Cortical laminar necrosis (CLN) is a pattern of cerebral cortical injury characterised by selective necrosis of specific cortical layers
  • Typically occurs due to severe hypoxia or ischaemia, often in the context of global hypoperfusion
  • Imaging findings evolve over time, with characteristic gyriform T1 hyperintensity on MRI in subacute to chronic stages1

Mechanism

  • Results from energy failure and subsequent neuronal death in metabolically active cortical layers
  • Most commonly affects layers 3 and 5, which have high metabolic demands
  • Proposed mechanisms:
    • Excitotoxicity from glutamate release
    • Free radical formation
    • Apoptosis
  • Common causes:
    • Hypoxic-ischaemic encephalopathy
    • Status epilepticus
    • Hypoglycaemia
    • Carbon monoxide poisoning

Imaging Appearance

  • CT:
    • Acute: Normal or subtle cortical hypodensity
    • Subacute to chronic: Gyriform hyperdensity of affected cortex
  • MRI:
    • Acute (< 24 hours): Cortical diffusion restriction
    • Subacute (> 2 weeks): Gyriform T1 hyperintensity
    • T2/FLAIR: Variable signal, often hyperintense
    • Contrast enhancement may occur
    • Chronic: Cortical atrophy and gliosis
  • Evolution of imaging findings:
    1. Diffusion restriction (acute)
    2. T1 hyperintensity (subacute to chronic)
    3. Atrophy and gliosis (chronic)

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  • A 50-year-old patient presented with right sided weakness.
  • CT showed progressive hypoattenuation in the left MCA and ACA territory up to day 4.
  • At day 10 post-admission, cortical hyperdensity (obscuring the ACA infarct) was consistent with cortical laminar necrosis.

Clinical Relevance

  • A marker of prior cortical injury rather than a disease in its own right; there is no specific treatment
  • Key pitfall: the gyriform T1 hyperintensity is laminar necrosis, not haemorrhage or calcification
  • Most commonly reported in neonates with hypoxic-ischaemic encephalopathy, and in adults following cardiac arrest or severe hypotension
  • Clinical presentation reflects the underlying cause and extent of injury, and may include altered mental status, focal neurological deficits and seizures

Differential diagnosis

Differential Diagnosis Differentiating Feature
Cerebral infarction Follows vascular territory; CLN respects cortical layers
Encephalitis Diffuse involvement; CLN is more localised to cortex
Hypoxic-ischaemic injury More diffuse white matter involvement; CLN primarily affects cortex
Posterior reversible encephalopathy syndrome (PRES) Predominantly affects posterior regions; CLN can occur anywhere
Status epilepticus May show diffusion restriction; CLN shows T1 hyperintensity
Creutzfeldt-Jakob disease Diffusion restriction in cortex and basal ganglia; CLN spares basal ganglia
Metastases Nodular enhancement; CLN shows gyriform enhancement
Moyamoya disease Involves deep white matter and basal ganglia; CLN is cortical
Cerebral venous thrombosis Involves both gray and white matter; CLN is cortical
Mitochondrial encephalopathy Involves basal ganglia; CLN spares deep gray matter

  1. Cernigliaro et al. Pediatric Migraine Aura Status and Cortical Laminar Necrosis: A Clinical Case and a Narrative Review. 2026. Revista de neurologia - Open in new tab. ↩