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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 stages

Pathophysiology

  • 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

Demographics

  • Can occur at any age
  • More commonly reported in:
    • Neonates with hypoxic-ischaemic encephalopathy
    • Adults with cardiac arrest or severe hypotension
  • No clear gender predilection

Diagnosis

  • Clinical presentation varies based on underlying cause and extent of injury
  • Common symptoms:
    • Altered mental status
    • Focal neurological deficits
    • Seizures
  • Diagnosis often made on imaging, supported by clinical history

Imaging

  • 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 (obsuring the ACA infarct) was consistent with cortical laminar necrosis.

Treatment

  • No specific treatment for CLN itself
  • Management focuses on:
    1. Treating underlying cause
    2. Supportive care and prevention of secondary injury
    3. Rehabilitation for neurological deficits
  • Potential interventions:
    • Neuroprotective strategies in acute phase (e.g., therapeutic hypothermia in neonatal hypoxic-ischaemic encephalopathy)
    • Anticonvulsants for seizure control
    • Physical, occupational, and speech therapy for functional recovery

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