Teaching points
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Causes of GRD include, but are not limited to, vascular occlusion.
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Non-stroke GRD in adults may be due to haemodynamic, metabolic, infectious and rarely genetic causes.
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These conditions pose a diagnostic challenge and vary in treatment and outcomes.
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Identifying patterns of GRD and additional involvement of other anatomic structures often helps to diagnose the aetiology.
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GRD related to some aetiologies is reversible.
Introduction
Haemodynamic alterations: hypoxic-ischaemic encephalopathy
Haemodynamic alterations: post-ictal changes
Metabolic causes: hypoglycaemia
Metabolic causes: hyperammonaemia
Infections: Cerebritis
Infections: herpes encephalitis
Infections: Creutzfeldt-Jakob disease
Genetic: MELAS
Aetiology | Pattern | Cortical predilection | T2 signal | GRE susceptibility | PGE | Other involvement |
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HIE | B/L, symmetric | Perirolandic, occipital cortex | + | +/− | − | Basal ganglia, thalami, cerebellum |
Post-ictal | U/L or B/L, diffused or localised | Any lobe, +/− hippocampus | ++ | − | +/− | +/− Splenium |
Hypoglycaemia | B/L, symmetric > asymmetric or U/L | Parieto-occipital, +/- hippocampus | ++ | − | +/− | +/− basal ganglia, splenium |
Hyperammonaemia | B/L, symmetric | Insula, cingulate gyrus | ++ | − | − | − |
Cerebritis | U/L, localised | Temporal, frontal | ++ | +/− | + | Sinusitis/mastoiditis |
Herpes | Initially U/L, progresses to asymmetric B/L | Orbitofrontal, mesiotemporal, insula | ++ | + | ++ | Leptomeningeal enhancement |
CJD | Diffuse, symmetric/asymmetric | Insula, cingulate gyrus, superior frontal gyrus | + | − | − | Pulvinar |
MELAS | U/L, migratory, waxing-waning | Parietal, temporal, occipital | ++ | +/− | +/− | − |